( from evbatt.txt )

 ```  -------------------------------------------------------------  {Last Update 11/14/2001: added Zinc battery detail} [Permission to reprint David Coale's work in Bruce Parmenter's EV    Battery report info package, given to  BruceDP(at)yahoo.com]   ...  Item Subject: Trojan Report (EAA SF,CA,USA Chapter)  Date:    Wed, 29 Mar 1995 11:25:34 PST  From:    David Coale  David@evcl.com  Subject: Batteries and Range  A consolidation of notes from the presentation at the SF Peninsula   Chapter of the Electric Auto Association.  What battery should I use in my EV?  This is the age old question; what battery should I put in my EV?  There is no standard answer to this, it depends on what you want  out of your EV.  The old rule of "thumb" if you will, is the more  lead the greater the range and the poorer the performance due to  the increase in weight.  It is also true that the higher the voltage  the better the performance (acceleration and top end speed).  This is  of course also dependent on the type of driving and on the controller.  Since these are fixed for any given EV, these generalizations are not  too far off.  Two designs illustrate this:  Long range: 96 to 120 volt system using 6 volt deep cycle batteries.  This will give you lots of amp hours and weigh 976 to 1420 bls.  This type of battery pack should last two to three years depending  on the type of driving.  High performance: 96 to 144 and up using 12 volt batteries.  If you  use a starting battery your car will be light (400 to 700 bls.) and quick  and your batteries will last about 3 to 6 months or less.  If you use  deep cycle batteries (12V) your batteries can last as long as one and  a half to two years but the car may be heavier depending on the battery.  So what is the range in each case?  Isn't that what we want to know;  how far will my EV go?  Answering this will help you decide what  battery you will use.  To find out how far a particular battery pack will take us, we need  to know how much energy is in the pack and how much energy the EV  uses per mile.  Range = Energy in pack/(energy used per mile)  The energy in the battery pack (wired in series) is the amp hour rating  times the pack voltage.  The amp hour rating is how may amps a battery  can supply over a given time.  Most batteries are measured over a 20  hour period.  This is a standard that is used to compare batteries with,  and can be found in the specs. on most batteries.  The 20 amp hour rating  has to be adjusted for EV use.  The faster one draws current from a battery  the less capacity there will be.  This is due to the chemistry of the  battery and the internal resistance.  Therefore the capacity of a battery  at the 20 hour rate is more then the capacity at the 1 hour (EV) rate.  The  following is a table from Trojan Battery Company showing the conversion  factor for finding the X hour rate given the 20 hour rate:  Conversion of 20 hour rate to X hr rate.     X hr  Conversion     rate  factor       1   .57       2   .67       3   .74       4   .77       5   .82       6   .84       7   .86       8   .87       9   .89      10   .91      20   1.0  Note: these values will be a little different for each battery.  One can see from the table above that as you drive faster the range will  decrease due to reduced available capacity.  This does not take into account  wind resistance which also increases with speed.  Now we need to know the energy or watt hours per mile that your EV gets.  The table below lists some common EVs and their watt hours per mile rating.  Impact  = 130 W-hr/mi (AC drive very good aerodynamics)  Metro   = 160 W-hr/mi (PM drive good aerodynamics)  Metro   = 200 W-hr/mi (DC drive good aerodynamics)  Truck   = 350 W-hr/mi (DC drive poor aerodynamics)  This table was developed using several cars for each category traveling  at highway speeds (60 mph).  The numbers reflect the efficiency of the cars  listed.  With the following information the range equation for a smaller  type of EV on the freeway would be:             20 amp/hr rating X .57 X pack voltage  Range =    -------------------------------------                  200 watts hours per mile  >From this equation we can make a table using some commonly used batteries.     Bat.    20 AH   Wt. pack   pack  range  Cycle  miles  miles X cycles  type     rate  Lbs. volts   Wt.  miles  life   /Lbs.  /Lbs.  T-105    217   61     96   976   59.4   754   .06086   45.89 \                       120  1220   74.2                         |  T-125    235   66     96  1056   64.3   650   .06089   39.58  | 6 volt                       120  1320   80.4                         > Batteries  T-145    244   71     96  1136   66.8   625   .05880   36.75  |                       120  1420   83.4                        /  T-875    165   63     96   756   45.1   540   .05965   32.21   8 volt                       120   945   56.4                          Batteries  27TM     105   52     96   416   28.7   210   .06906   14.50 \  27TMH    117   60     96   480   32.0   358   .06669   23.88  |                       120   600   40 0                         |                       144   720   48.0                         |  30XHS    130   66     96   528   35.6   325   .06742   21.91  |                       120   660   44.5                         > 12 volt                       144   792   53.4                         | Batteries  5SHP     165   86     96   688   45.1   560   .06555   36.74  |                       120   860   56.4                         |                       144  1032   67.7                        /  As you can see there are no clear cut answers.  The miles per pound  are better with the 12 volt batteries but the cycle life is not as  good; and the converse is true.  The last column is an attempt to find  a single number to compare the batteries with.  This does not show price  however, and this will be a factor in any EV conversion.  The above table is for comparisons only and may not reflect your actual  range.  The information shown here is by way of Kitty Rodden of Trojan  Battery Company.  I do not have any affiliation with Trojan Battery Co.  This is just the information I have at hand.  David Coale  ----------------------------------------------------------------------  ....................................................................  Item Subject: EAA Peninsula Chapter, Report (Batteries)[~circa 3/95]   Kitty Rodden of Trojan Battery was the quest speaker at this meeting.       [Trojan Battery Company makes many types for batteries.] ...       Deep cycle batteries are used quite a bit in Electric buses for  mass transit as well as school buses, they are used in many types of  EVs that includes forklifts, Electric cars, and golf carts.       Marine batteries are true deep cycle and we are a large supplier  in the industrial market, forklifts and pallet jacks.   {slide placed on over head}       I get many phone call questions asking why is Trojan only making  lead-acid batteries? I won't go through many of these numbers, but  there is certainly alot of batteries out there. There seems to be a  battery break-through a week that comes up in the [news]paper and we  can talk about those batteries a little bit.       As you look at these [figures] they have both energy density,  which how much range can you go for the pounds of the batteries. But,  also is the power density [figures]. An Electric car require a  tremendous amount of power to get out the way of a big semi truck. So,  when you look at different batteries, you also have to look at if the  [battery's] power is enough.       One example is the zinc-air battery, and the Nickle-iron battery  [both] have very good energy density. But if we talk about energy  density in terms of Watt-Hours per Kilogram, Lead-Acid is about  35WH/Kg. Nickle-iron is about 50-60WH/Kg, which is about 50% better,  however Nickle-iron's power is not very good.       So, on some of these systems {on the slide} although the energy  would propel you, especially the Zinc-air, ... the zinc-air for  example could propel the Impact perhaps for 300 Miles, however it  can't get out of anything's way, so alot of the Zinc-air cars that  have been built have also had Ni-Cad batteries as an accelerator  battery, to be able to launch it onto the freeway.       So, when you start looking at [these batteries,] the cost starts  going up dramatically. This chart talks a little about the life cycles  [of the batteries, but] you also need to look at the cost of the  materials, which is in Dollar\$ per Kilo Watt Hour.       There are alot of good chemistries coming down the road, for  example Nickle-metal Hydride is great chemistry. It has 1.5 times more  energy than Lead-Acids. They are fantastic in cellular phones. I would  not hesitate to go out and spend \$80 for a Nickle-metal hydride  cellular phone battery for my cellular phone.       However, if you look at the amount of energy in that battery,  divided by the cost of that battery, you are talking, \$4000-\$5000 per  KWHr. Now, lets see, my EV needs about 20KWHr onboard, so you can do  the math to see that you are talking up to \$50K for that battery pack.  That does not make good economic sense. ... Lithium batteries are also,  up and coming.       When you go to seek out new batteries, you must ask yourself 5  questions:  What is the cost [of the batteries]?  What is the life [of the batteries]?  What is the energy [of the batteries]?  What is the power [of the batteries]?  What is the recyclablity [of the batteries]?       After answering those questions, you really can't know lead. Lead  is cheap, and that is why Trojan is staying with Lead. Lead is cheap at  about \$1/lb.  {From slide}  Battery type      Life    \$KwrHr  ==============-=========-=========  Pb 35-45KWHr   400-1000  \$100-\$150  NiCad          500-1000  \$400-\$800   ...       {Referring to the next slide} There is a whole family of Lead-  acid batteries. First there is the Automotive style Lead-acid  batteries. Their characteristics are that they have very thin plates,  very high power. All you need to start an engine is 800Amp for 10secs.  Then after the engine is started, the alternator recharges that  battery.       So, all it has done is discharge maybe 1% of it's total capacity.  They way the manufacturers do this, they use very thin plates, not  much [lead] paste to give high power, and sense it doesn't cycle much,  the life of the battery is not much of an issue.       Now, when you discharge that battery down to 50-80%, that battery  is not going to survive well. I have heard of people taking die-hard  batteries batteries from Sears, and trying to put them in EVs. They  will last only 1 to 2 months, because of this technology.       Also, there is the Deep-Cycle batteries. They are designed to be  discharged to 80%. They have thicker plates, and more dense paste,  that causes a little less power. You are not going to see the 800 cold  cranking amps [of an auto battery], more like 500amps. Deep cycle  batteries are typically a little higher energy density batteries [than  Auto batteries], and in a Deep-Cycle application, they have a long  life.       The last category is advanced Lead-acid. There are basically two  different ways of doing that. There is a quasi-bipolar technology, and  there is a bipolar technology. Normal Lead-acid, you have two plates, a  positive plate and a negative plate, with separators and electrolyte in  between.       The Lead-acid technology is capable of quite a bit higher energy  level than 35WH/Kg. There is all this lead in the battery that acts as  electrical conduit: top strapping, cases, separators. One of the ideas  is to remove some of the lead that is not involved with giving you  capacity. Removing that lead, reduces the weight of the battery.       One way, is in Quasi-bipolar technology, the positive plate and  negative plate, butted together to make their connections. The joined  plates are alternated, which removes the non-energy lead in the battery.       The bipolar technology, which puts a positive plate and a negative  plate together with a thin membrane between them. This allows ions to  pass between them but not electrons. This removes even more non-energy  lead.       Because of the plate design, both these batteries are capable of  both high energy and high power.  {from slide}  Auto/UPS             Deep Cycle        Advanced Lead Acid  ----------------------------------------------------------------------  Thin Plates          Thicker Plates    Thickest Plates  High Power           Lower power 500A  High Power  10Sec/800Amp         Higher energy     High Energy  Poor Life            Excellent life     Quasi Bi polar  Not dense paste      80% discharge     (45WHr/Kg) get rid of some lead  Not serviceable -                      Bi Polar  after 50% discharge                    (55WHr/Kg) ions not electrons   ...  {next slide}       Even in Lead-Acid, there are even more breakdowns [different  types]. There is a flooded Lead-Acid and a sealed Lead-acid. Sealed  doesn't mean completely sealed, really it is valve regulated. There  is a valve inside so that as gasses reach a certain pressure, the  valve will actually burp, so that it doesn't explode.       Under the flooded category, there are two different types,  maintenance-free, and the maintenance types. The maintenance free  batteries, will leak if tipped over. There is a lead-calcium in the  paste which reduces the water consumption on a charge. The battery  engineers, when making a 36 month battery, put in exactly how much  electrolyte you will need for 36 months of use. So, it is not  surprising to have that 36 month battery fail on the 37th month.       The lead-calcium in the paste makes the deep-cyclablity not as  robust. With the lead-calcium you can deep-cycle to about 50%, with  that you can get from 100 to 300 cycles.       Maintenance batteries are usually made of a Lead-antomonity.  Because of the Lead-antomonity, the battery is capable of going down  to 80%, in the depth of discharge, and you can get from 300 to 700  cycles, depending on the battery design.       In the Sealed batteries, there are two types. The absorbed glass  mat (AGM), they use the lead calcium, there is a glass mat in the  middle, there is just enough electrolyte to dampen the middle. THere  isn't an excess of electrolyte at all. AGM batteries can have high  power, but only a depth of discharge (DOD) of 50%, and the life cycles  are going to be from 100 to 300.       In gel technology there is a gelled material in the electrolyte  to immobilize the electrolyte. Because the electrolyte is immobilized,  there will be lower power. DOD will be 50%, and life cycles will be  from 100 to 300.  {from slide}                     Lead-acid Battery types               Flooded                   Sealed(valve regulated)  ================-=================-===============-===============  Maint Free       Maint             Absorbed Glass   Gelled  (Don't add-      Lead Antimony     Mat AGM          Lead Calcium   water)          Deep Cycle 80%    Lead Calcium     immobilized-  Lead calcium     300-700 cycles    High power        electrolyte  Deep Cycle 50%   Robust            Deep Cycle 50%   Deep Cycle 50%  100-300 cycles   good service-     100-300 cycles   100-300 cycles                   ablity            No extra-                                      electrolyte   ...  {next slide}       The voltage is the electromotive force or potential [of the  battery]. There is a difference between when we talk about open  circuit voltage and as well as voltage under load. But generically, a  Lead-acid battery is made up of 2 volt cells.       I have heard many time people say "Well 6V batteries are better  than 12V batteries. Well, I would state that the battery is made of 2V  cells. The battery manufacturer will design the plates differently, so  that one [battery] may have better life cycle than the other, based on  the plate design.       Whether we (the battery manufacturers) made 6V or 12V [batteries]  depends on what the application is, and what we expect you to pickup  (lift). If we are going to make a large battery, we will make it is a  6V battery, so you can lift 60 pounds. If we made [a large battery] in  a 12V, you would be looking at a 120 pound [12V] battery.       Here is a myth I would like to dispel. Sulfation seems to cause a  panic among battery users. 'Oh my [goodness], my battery Sulfated while  I was talking to you!'. Sulfation is normal chemical reaction that is  formed on the positive & negative plates during a battery's discharge.       When [the battery is] fully charged, the positive plates are going  to be Lead-Dioxide. Your negative plate is going to Lead. The  electrolyte is going to be sulfuric acid. When you discharge the  battery, Both plates are going to turn into Lead-Sulfate, and your  electrolyte is going to [change to] about water, [in the process] you  going to release some electrons to make the car go.       If we didn't have [both plates in a Lead-Sulfate state], we would  not give up electrons. This is not hazardous [to the battery] or  anything like that. The problem comes in, when you discharge your  battery down to about 80% DOD, and you let it sit in that state for an  extended period of time. That is when Lead-Sulfate crystals will grow.       At low [battery] energy states there are these small crystals of  Lead-Sulfate in a high energy state. High energy state likes to change  to low energy states. So, if you let the battery sit in this state the  small crystals will grow into large crystals.       When you finally do put a charge on your battery, it is difficult  to get these crystals to break down these large Lead-Sulfate crystals.  There are ways to get by that but, this is when Sulfation really happens.  {from slide}  Pb02+Pb+2H2SO4 --> 2PbSo4 + H2O+2E  +    -         <-- +        electrolyte                     -  Sulfate Crystals will grow if left in a discharged state.   ...   {next slide}       Stratification happens in all Lead-acid batteries. As you are  charging and discharging, remember your electrolyte is changing from  acid to water, from acid to water, ... . Well, sulfuric acid weighs  more than water, and go to the bottom of the battery, and the water is  going to go to the top.       Over time you will see a difference in specific gravity depending  on the height [of the electrolyte] of the battery. This specific  gravity gradient results from ineffective overcharging.       Where you would normally see, straight from the factory, 12.65  gravity, after a full charge, if you have not been adequately over  charging the battery, you may find as high as 1400 in the bottom of  the plate, and close to water at the top of the plate. The reason this  bad, is that close to pure water does not conduct electricity well.       The only conductivity is in the lower half of your plate. So, you  are only able to use half of your battery, or half of the capacity.  Also, the very high specific gravity content at the bottom will eat  the lead of the plates. This is very high acid, and will start  breaking down the active material. So, it is very important to equalize  the battery.       You may have heard of people trying to be clever and cut down on  the water consumption, so they change their charger back to avoid the  gassing state, don't do that. It is very important that you allow the  battery to gas, vigorously, the gassing actually stirs this  electrolyte. You will get long life and good capacity.  {from slide}  Stratification - Specific Gravity gradients  That may be from ineffective overcharging  1.080    - low acid             normal SpG = 1.265 Full Charge  1.400    - high acid   Allow gassing for 2 hours at 4 amps once every 10 days or every 10   cycles.  ...       Every EV has a mission. You want to give yourself enough range,  you want to give yourself enough voltage, to be able to do what you  want to do. There are differences even among Trojan batteries in our  life cycles. So, you need to figure out what your design criteria is,  how long you want the battery [array/pack] to live.       If for some reason there is not the right battery for the amp-  hour you need, but you like the life characteristics of a particular  one, you can do a series circuit, where you put batteries [together]  positive, negative, positive, negative ..., in which the voltage is  additive, but the amp-hour capacity stays the same. [Using T125  batteries in the string of batteries, the amp-hours for the array/  pack is 220AHr, but the voltage is now 6V times the number of  batteries in the array/pack].       In a parallel circuit, here is an opportunity to take two  smaller batteries that you like, parallel them, for twice the amp-  hour capacity. [The smaller batteries may fit in you car easier].  So, [in] a parallel circuit, when you [connect] positive to positive,  negative to negative, you will have the same voltage, but your current  [or amp-hour capacity] is additive. If you have two 220AHr and  [another] 220AHr in parallel, you now have a total off 440AHrs.  {from slide}  In a Series circuit Current is equal, Voltage is additive.  In a Parallel circuit Voltage is equal, Current is additive   ...  {next slide}       One of the main questions asked, is if you have a battery in your  car, how do you determine the state of charge? There are essentially  two ways to determine the State of Charge (SOC) of your battery:  1) Is to measure the specific gravity of each cell, or a couple of    pilot cells in the pack.  2) Or looking at the open circuit voltage. According to the battery    council International, the only valid measurement of open circuit   voltage is after the battery has rested for 24 Hours [with no   charge, recharge, or load of any kind on the battery].       With my experience, you can get away with [a measurement in] 3 or  4 hours. It is not as accurate as 24 Hours [but ok].       {pointing to slide} This is a brief description of how you can  determine SOC vs your gravity and open circuit. If anyone one wants  copies of this [slide], you can contact me at Trojan.       What this is trying to show you, is when you are under load, the  battery voltage does a number of things. When somebody calls me on the  phone and says they are discharging, on their 12V battery. I ask them  what their voltage is, and they tell me 13V, I know they are charging.       In this curve I am looking at a 2V cell. In a 2V cell at fully  charged in an open circuit, it is at 2.1V per cell. As you discharge  there is a co-de-fo-wae. It is an immediate drop of the voltage,  and then as you are discharging with a constant current through the  DOD, this voltage will slowing ramp off.       But you will notice this big knee at the end [of the slide]. At  about the 80% DOD you are running out of active material. You are  converting from Lead Di-oxide to Lead-sulfate, so potential drops of  very quickly.       Most EVs cruise at about 75Amps. When you are cruising at 75Amps  or less [at a constant current], one number to look for on your  volt meter, is when your voltage drops to about 1.5V per cell. That is  about when you want to stop. I recommend not going any further. {120V  pack has 60 cells, or 1.5V x 60. Need to stop when a 120V system  discharges to a voltage of 90V.}       If you discharge beyond that point, you can get battery reversals,  &/or battery gets very hot. As a battery reverses, you can have a SOC  of 1.75V then with in a few minutes, the voltage will go to 0V, then  will actually go negative to .5V . Meanwhile, the battery is getting  very hot, you may see steaming of the electrolyte. It causes permanent  damage to the plates.       Our batteries are pretty robust about this. We have had this  happen, but most batteries you don't even want to get close to letting  this happen.       Conversely, on the charge, if you discharge to 80% DOD, and you  stop your EV, naturally the voltage is going to come back up. It is  going to come back up to a little less than this 2.1V per cell. When  you put it on a charge, it is going to go up a little bit, and it is  going to stay at that voltage, pretty constant, and slowly ramp up [as  it charges].       At about 2.38V per cell, you have about 80% State of Charge.  Chemically, up until that 80% charge, just about all of the Amp-Hours  or energy to have been putting into the battery has been going fairly  efficiently into reconverting the active material.      At about 80% SOC, again you are running out of active material to  convert. The charge efficiencies starts going down, at this point most  chargers, voltage regulators start tapering the current. The voltage  starts rapidly rising. The battery will start to begin getting hotter  {as the battery is now more of a resistance}.      The importance of this graph is that at the 80% is about 2.38V per  cell. And Trojan recommends that you fully charge the cell, & that you  will see about 2.58V per cell.       Notice on this graph, if someone is trying to avoid water  consumption, and turns their charger down to avoid the 80% point, or  the gassing point, you can see they only put in 80% of the energy. So,  as they discharge, they are not going to be able to go as far as they  could. And over time there are other affects that happens. So, you  really need to [occasionally] fully charge [your pack].  {from slide}  OCV or VOC Voltage measurement made after 24Hrs of Battery rest with  no load  OCV vs State of Charge (SoC)   Voltage under         v/cell  Charge                               Discharge   ------------------2.58V--|--------------------------    |                       |    `                       |    . \                     |    .  \                    |   -------- ---------2.38V--|--------------------------    .   . `                 |    .   .    ` .            |    .   .        `  - . _   |    .   .                 \ |   ---------------2.10V--- `-. ------------------------    .   .                   | \ _    .   .                   |     ` -    .   .                   |          ` .    .   .                   |                .    .   .                   |                   .   ------------------1.75V----------------------- . ----    .   .                   |                     . \    .   .                   |                     .  '    .   .                   |                     .   '   ---------------------------------------------------|-    .   .                   .                     .   .  100% 80%                 0%                    80% 100%  Charge                                        Discharge  { graph Corrected by: David Coale }  On charge less than 2.1V/cell  2.58V 100% of charge  2.38V 80% of charge charger efficiency goes down  Recommend fully charge your pack.  [Perform an over charging maintenance cycle to your pack once every 10  days, or 10 cycles, at about 4 amps for about 2 hours. This will gas  enough to mix the electrolyte, and bring the pack to a full charge]   ...   BruceDP: IMHO (In My Humble Opinion):   This routine of a maintenance overcharge might be a good feature to  have on our EV chargers. My EV smart charger wish list/requirements are:  1) To have a dual 120V/208-220VAC input voltage capability (Level B)  2) Be able to handle higher charge currents of 30+ Amps.  3) Have dashboard preset selections that can be made, of charger    currents (5, 10, 15, 20, 25, 30+ amps). {No popped breakers}  4) Have charger circuitry be smart enough to charge at higher    currents (if desired) on the first part of the charge, rolling off    at the 80% point reducing the charge current flow.  5) A dashboard button I could set so that the charger, would do a    maintenance overcharge of low current (4Amps) for 2 hours to    equalize the pack.                                                  ]   ...  {New slide}       There definite trade offs in EVs, between range and performance.  [EV] Range is function of how many Kilo Watt Hours of energy/battery  storage you have on board, what is the vehicle weight, what are the  aerodynamic features of the vehicle (drag coefficient), system  efficiency, rolling resistance of the tires, brake drag, and  transmission drag.       So when I have a new customer that eagerly converted his Chevy  S-10 pickup truck and he calls me up as says, "Oh man I am really  disappointed. Your batteries aren't working, I only get 30 miles  range." I get out my calculator and do the calculations, and say,  "Yea, that is about right". Because of all this other things [have  to be factored in].       [EV] performance is a function of the not the batteries, but the  motor/controller power range. Everyone knows that if you have a 250HP  [ICE] engine, you are going to blow the socks of someone who has a  100HP engine. Well, the same thing is true with [EV] motors and  controllers. So, performance has been mainly, motor and  controller power limits. As opposed to battery's power limits.       Gear ratios are a function of what your performance is. [Even  with a] fabulous [controller] system, with the wrong gear ratio, the  performance [will be lacking].       Battery voltage is a key parameter with vehicle performance.  Power which is a [factor] of the performance, power is the voltage of  your system, time the current limit of your system, and that is terms  of Watts.       If you change Watts to Horse Power with a simple conversion  [equation]. 1 HP is 746 Watts. Anyone who has the Curtis 1221B  120V 400Amp controller [which is a] 48KW system, when you convert it,  it is 60HP. So, [you will] have the [HP] power of a VW Bug.  {from slide}  Range                            Performance  Batt storage                     Motor/Controller power limit  Vehicle weight                   Gear ratios  System efficiency                Battery voltage  Rolling resistance               Vehicle weight  Drag coefficient  Power energy  V x A=W  1HP=746W Voltswagon Bug 60HP   ...  Capacity:       Energy is the size of your fuel tank. This is the voltage of  your system, time the capacity of your batteries, rated in AmpHours.  When multiplied all together, you get WattHours.      The [normal rating] that all battery manufacturers list their  batteries is the 20Hr rate. That was established back when ICE were  started, and they had to keep the battery companies honest. So, they  decided, that Maine is the darkest place in the country, where it can  stay dark for 20 Hours. Hence, the 20 Hour rate.      Well, that is great, but has nothing to do with electric vehicles.  What the 20 Hr rate is [stating], is if you discharge the battery over  a 20 Hour period, you will get a 100% of your battery capacity.      If you discharge it faster than that, because it is a electro-  chemical device, it only can keep up with you as fast as it can. As an  example, if you discharge over a six hour schedule, you will get 80% of  the 20 Hour rate.      If you discharge over a three hour rate, you only get a 74% of the  20 Hour rate. And if you drive like myself, and you discharge at a one  hour rate, you will only get about 57% of the energy you have onboard.      Which means you are carrying around 1000 pounds of batteries, but  you are really only able to utilize 57% of of the capacity.      20Hr capacity vs Reserve capacity  % ---------------------------------  1.0 ------------------------_.=====                            ' |  .85 ---------------.  '     |                   . |        |                 .   |        |  .74 ---------.     |        |             . |     |        |  .57 -----.   |     |        |         . |   |     |        |  -----.-----------------------------           1   3     6        20 Discharge Hrs   ...   Temperatures:       If you are in the cold climates, keep in mind, [Lead-acid]  batteries are like people. They don't like hot or cold temperatures.  If you can keep them about 77 degrees, they will be happy.       Here is quick little equation so you can calculate the loss of  capacity of the battery as with the function of temperature. For every  15 degrees F. below 77 degrees F., you will have a 10% loss of  capacity.       If you are at 30 degree F., which is about freezing, you will  only have 65% usable capacity. That makes a dramatic difference in the  range of your vehicle in the cold.       One of the things people on the East coast are doing is trying to  insulate their batteries, so they don't get so cold so fast. Or trying  to keep [their EV] inside, and not on the driveway [outside].       The electrolyte freezing point: When the battery is fully charged,  the electrolyte has 1200 to 1265 specific gravity, which freezes at  about -10 degrees F., and that is not too much of a problem.       If for some reason your battery is not fully charged, and your  specific gravity is 1100, then it can freeze at +20 degrees F. This  freezes the cases, and the plastic gets brittle.       High temperatures causes a reduction in life because of the  increased corrosion of oxygen and lead. This is one thing that comes  up in golf courses in Phoenix.   ...       Typically when you we are asked what our capacity, and cycle  life [is of our batteries], we will quote a BCI (the Battery Council  International) standard tests. Which is typically you discharge the  battery down to the 80% level.       So we could take the T105 at 80% DOD, you get about 700 cycles.  If you discharge the 50% you can increase the cycle life by 50%. The  photo-voltaic industry definitely sees that.       In EVs with people trying to get the maximum range, you will see  these batteries {the T series wet types}, live about 3 to 4 years of  life, with normal watering maintenance.       In a photo voltaic applications, with only a 30% DOD, the life  cycles can last as long as 2000 cycles. So there is a non-linear  relationship. What that is saying is the less you stress the active  material, the longer the battery will survive. Some of the PV industry  sees a 8 to 10 years life.       One of the tests of our T105 battery with the BCI schedule: What  this [slide] is trying to show, is that when you have a brand new  battery, [as the slide shows] it is only [at] 80 to 90% capacity. So,  please understand, don't go out and do your range test the first  couple cycles, because the battery is not at the full capacity.       All the batteries vary, but they will reach their full capacity  after about 50 to 100 cycles. And then [for wet cell batteries] it  pretty well stays constant. Then once it passes 3/4 of it's life, it's  going to be on it's way down [with progressively less and less  capacity].       What you will notice at about the half way point of [the  battery's] life, the water consumption is going to up, dramatically.  This is not to say that "Gee, I had to add more water in this battery,  I'd better replace this battery." You have plenty of time, it is at  the half way point.       Chemically, what is happening [in the Lead antimony batteries],  some of the Antimony on the positive plates, starts plating on the  negative plate, which changes some of the charge characteristics, and  ends up using more water. So just expect this [at that point].       You can get 750 cycles [with a wet cell], as opposed to if we  take out the maintenance issue, we get less cycles. A sealed Lead  Calcium Marine battery manufacturer claiming 700 cycles, [really isn't  700 cycles in an EV application]. When a sealed battery [is new], it  starts out at 80% of capacity, it will quickly ramp up [in capacity]  to a 100% capacity in a few cycles, but almost as quickly start [ramp  down] in capacity, [after reaching that 100% capacity point], and will  be less and less [as the cycles increase].       These [sealed batteries] are tested as per the BCI tests which  says you can keep testing [and counting cycles] until you have reached  [a reduction to ] 60% of the capacity. So, [in this battery] 60% means  80 minutes, at 25amps. So, this battery for BCI failed at 325 cycles.  But you as an EV driver are going to think it failed [at much less  cycle count] because you are going to be coming home late for dinner.       So be wary of the sealed battery [numbers quoted, they will have  less power, and cycle life than a wet cell battery].   {from slide}   Cycle Life test - T105 Wet cell battery  Capacity  100%-     .  .   .                                              -100%      |   .   |          .     .      .       .     .  80% - .     |                                           .       - 80%      |       |                                           |  60% -       |                                           |   .   - 60%      |       |                                           |   | .      |       |                                           |   |      |       |                                           |   |    .      |       |                                           |   |      |       |                                           |   |      .  ----------------------------------------------------------------------    New      100    200    300    400    500     600     700     800  Cycles   Cycle Life test - Sealed Marine battery  Capacity  100%-    .   .             -100%      |  . |      .  80% -    |        .        - 80%      | .  |        |  .  60% -.   |        |      . - 60%      |    |        |      |      |    |        |      |  .      |    |        |      |      |    |        |      |      |    |        |      |     .  --------------------------------    New      100    200    300  Cycles   ...   Range:       Everyone knows that with an ICE range is a function of the MPG  times the number of gallons of fuel onboard is your range. We all under-  stand that a Geo Metro, because it is light weight and aerodynamic, gets  50MPG, a sedan vehicle typically gets 25MPG, and a truck because of it's  heavy weight, large tires, and lower drag coefficient, gets less than  15MPG.       The same [range ratios] holds true for EVs. In this case we talk  about our gas tank is the Watt Hours in the battery times the Watt  Hours/mile which is characteristic of both aerodynamics, and your  drive train, whether you have an AC system, an DC system, or regen.  braking, and that equals your range.       As an example the original Impact was designed with an AC system,  it weighed 2300Lbs, very aerodynamic, and used about 130 Watt Hours/  mile. [Solectria's] Geo metro uses DC Permanent Magnet motors, gets  about 160 WHr/Mi. There are Geo metro conversions using Adv DC [motors]  and the Curtis controllers, you are looking at about 200 WHr/Mi. And  DC series wound motor [conversions], you are looking at about 350 WHr/  Mi., sometimes higher depending on the vehicles.       So, how far can my EV go? What type of simple calculations do you  do before you select a battery [to use]. This is something I did on my  own Porche 914, when I got the job at Trojan battery. I knew my com-  mute was 25 Mi each way. I knew that for me to sell my ICE car and use  an EV as my only commuter, I would need about 80 Mi range to be able  to run around L.A.       So, I took the specifics of [what I would need]. I knew I was  going to run a 120V system, [with a converted weight of 3000Lbs], I  was going to use a DC drive train, and the Trojan T105 gives about  217 AHr at the 20 Hour rate.       So, how do we go through this. What we first do is calculate  what the total energy is from your battery pack. 120V times 217 AHrs  means that I have 26000 Watt Hours of energy onboard. That's total  energy. But, again I am a lead foot driver, so I am going to  discharge at a 1 Hour rate.   {To change the 20 AHr rate to a 1 Hour rate multiply the rate times   .57 (Kitty's number) to give a good estimate of a 1 Hour rate.}       Let calculate what my usable energy is. Which is really, 26000  Watt Hours times the .57, which was, remember was the 1 hour factor,  and that gives me 14800 Watt Hours onboard. And that is [a usable  number].       Now my range is the 14800 Whrs divided by my drive train MPG  or in this case is 200 Watt Hours / Mile. Which in this case gives  me 74 Miles [of range]. My spec is about 80 Miles, so that seems  about right.       And that is as big [a weight] I want to put in that vehicle  with out going over the [design weight capacity], collapsing the  suspension.       After you have done all your quick little calculations, you can  look at all the different batteries [specifications to use in your  conversion].   ...       I would like to point out in this slide, is you all have heard  of our 6V batteries, the T105, T125, and the T145. They are basically  the same dimensions, they are 6V batteries, their AHr capacities goes  up a little bit, their weights goes up a little bit, from 61 Lbs  all the way up to 71 Lbs.       But what I wanted to so you is the life cycles. These are the  thick plate, designed for the bulk current industry, designed to be  robust. So, on life cycles your are looking at anywhere from 754 to  625 cycles.      We have about 30 different 12V deep-cycle batteries. As we talked  about earlier, there are different design critrea's. We can make very  high cycling 12V batteries, but alot of our market has been in the  Marine application. So, there are several 12V batteries, that I have  [next slide], the about the only one I would recommend for EV  application is the 5SHP, which has about 560 cycles.      The 27TMH has about 300 cycles, this could be about a year or year  and a half of life [for the battery]. Again it depends on what your  mission is. If life is not an issue, you want a light weight battery  pack, and you only need to go 25 miles, [this would work].      [There are people who use this battery for EVs, and they love them.  Just take the cycle life] and the cost in consideration.  {from slide}  [How far will an EV go?  Porche 914, 25 miles each way  approx: 90 mi range  120V DC system, 3000 converted weight, Curtis controller]   Using T105's at 217 AHr at a 20AHr rating  Total energy is 120V x 217 AHr = 26040 WHr  Usable energy is: 120V x (217 AHr x .57 {1 Hr rate} ) = 14,843 WHr  Range is: (14843 WHr) / (200 WHr/Mi) = 74 Mi  Battery  -- AHr --       Cycle   Type    20Hr  2Hr   Lb  Life (BCI)  -----------------------------  T105     217   135   61  754    \  T125     235   154   66  650     - 6V  T145     244   184   71  625    /  -----------------------------  5SHP     165    92   86  560   \  EV8D     216   155  138  300    \  30XHS    130    80   66  325     - 12V  27TMH    117    76   60  315    /  -----------------------------   ...   [And that is the end of my presentation], Thank you very much.  [End of Report]   ---  *Disclaimer: Report taken from my notes and is not to be used   against Trojan Battery or Kitty. Feedback to me, is welcome.           ____          {Statements may not be my Employer's}        __/o|__\~        EVangel: messenger bringing good news  =)---'@ -----@'      'Electric cruis'n the Santa Clara Valley'  132V S-10 Blazer http://geocities.com/brucedp/  BruceDP (at) yahoo.com  Electric Vehicle List Editor      http://groups.yahoo.com/group/EVList/messages/  EAA San Jose EVents Officer       http://geocities.com/sjeaa/  Renewable Energy News Editor      EV & AE List sysop          % Use Renewable Energy to charge your EV %  .......................................................................  Item Subject: EVA: Battery Performance & Life Cycle Costs  [As Downloaded from the Internet EV List BB]  Date:    Wed, 3 Jan 1996 08:13:06 -0500  From:    Bob Batson   Subject: Battery Performance & Life Cycle Costs  Frequently, there is the question regarding charging after some  minimal miles (5-10 miles) vs charging after some greater distance  (30-60 miles). There are a number of considerations to optimize the  performance (range) of deep cycle batteries and to minimize the life  cycle costs.  Deep Cycle (Lead Acid) Batteries exhibit the following behavior:  1. They develop a memory! Their performance is a function of their     performance in the previous cycle. If they saw very little range or     no range in their previous cycle, this cycle will be affected.  If     they typically see only a shallow discharge, they will not provide     an extensive increase in range when required. Batteries must be     exercised just like an athlete in order to perform. If they are not     exercised, they will lose performance (range).  2. It takes 30-50 cycles to maximize range. If you are entering your     EV in a race, finish the EV early to get these cycles on the     battery. We recommend 10 miles on the first cycle, and then adding     5 miles (12V batteries) or 10 miles (6V batteries) each cycle until     you get near your design point. Range is a function of pounds of     lead - referred to as pounds of fuel. So a 1400 lb battery pack     gives more range than a 800 lb battery pack.  Acceleration is a     function of voltage and current limit.  3. Inactivity decreases performance. If the batteries sit for any     length of time, they lose capacity and must be broken in again.     EVs that sit idle over a weekend have less performance on Monday -     than they did on the previous Friday. If the EV sits idle for a     week, it may lose 25-50 percent of its range. Even if you do charge     it the night before.  The economics of battery life are based on:  1. The cost to charge (\$/mile). This is based on the kw-hrs per mile,     miles/ charge, and the cost per kw-hr for electricity.  Free     electricity from an employer or off-peak rates decrease this cost     substantially. However, frequent charging will decrease range and     increase battery life costs (\$/mile).  2. The life cycle cost of the battery. This is based on the cycle life     of the battery. Cycle life does not increase directly as the depth     of discharge decreases. For example, if you only discharge the     batteries 10 percent DOD, you do not get 8 times the cycle life of     discharging it 80 percent DOD. The cycle life only increases by a     factor of 4-5 in this case; therefore, the actual miles is about     30-40 percent less compared to 80 percent DOD.  Our conclusions from our own experience and our hundreds of EV  customers are:  1. Performance (range) requires exercise. The EVs that utilize the     capacity of the battery have better range. Typically, you buy a     battery for range, utilize its capacity.  2. Use of the battery to 50-80 percent DOD decreases life cycle costs.     If your EV has a range of 50 miles, this means you should charge     after 30-50miles in order to maximize battery life.  Our customers     have gotten 18,000 miles out of Trojan T-145 and 5SHP batteries.  3. Equalization to 2.55-2.58 volts/cell will increase performance and     life. If the batteries are constantly undercharged, their     performance and life will decrease. Equalization must be done once     every 5-10 cycles. If equalization is done every cycle, the cost     per charge increases.  4. Batteries are tough. If they have been under utilized, exercising     will bring them back. Most batteries are discarded before they     fail. Frequently batteries are replaced when their capacity is less     than 80 percent of their original capacity. However, these     batteries can be sold or given to someone else who requires less     range.  We have seen battery packs being used by one customers that are dated  1981! Yes, 1981! Another customer is using batteries from 1987.  Both  packs are Trojan T-105. So use your batteries and consider how their  life can be maximized - it will decrease your EV cost.  Bob Batson  (EVAmerica@aol.com)  Electric Vehicles of America, Inc. (EVA)  Tel# 508-897-9393, Fax# 508-897-6740  48 Acton Street, Maynard, MA 01754 USA  EVA - " Customer Service is No. 1! "  Authorized Distributor for Advanced DC Motors, Curtis Controllers,  Albright Contactors, and other EV component manufacturers. Free  catalog. Largest EV Component supplier in the East for electric cars,  trucks, motorcycles, boats, ski-dos, and more.  **********************************************************************   ---  Date:    Fri, 5 Jan 1996 07:17:20 -0500  From:    Bob Batson EVAmerica@AOL.COM  Subject: MORE ON BATTERIES  Our message on Battery Performance generated more questions.  According to "Battery Book One" by Curtis Instruments, the  manufacturer's battery capacity is given as 100 percent discharge;  however, the recommended usable capacity is 80 percent of the rated  capacity.  The amp hour rating of a battery is almost meaningless for a deep  cycle battery. This is typically given for a 20 hr rate. Think about  it. The rate might be 200 amp hrs. That translates into 20 hrs at 10  amps. Most EVs operate at 100-200 amps.  The meaningful number by the manufacturers is the number of minutes at  75 amps. A Trojan T-105 is good for 105 minutes (recently upgraded to  107). That translates into 131 amp hrs. Notice the significant  decrease in amp-hr capacity.  A rule of thumb that we developed is that if the amperage is doubled,  the number of minutes is cut in half minus 10 percent for losses. So  the T-105 using this rule of thumb at 150 amps is good for 47  minutes. It's actual rating is 44 minutes.  To determine the performance of an EV, you need to develop a number of  equations similar to those in Paul Shipps manuals or Bob Brant's book  "Build Your Own EV" and then combine those equations with Battery  Performance.  Or you can contact us. We have developed our own calculations over  the last 10 years. We provide free calculations modeling the EV and  the battery pack. The calculations identify range as a function of  speed and percent grade. In Florida (0 percent grade) you can get  almost twice the range as you can in New England. (2-5 percent grade).  Calculations are essential to know performance before you buy.  There is much interest in the new Trojan 8V battery. We evaluated its  use in our Bradley GTII comparing 16 T-145 (6V) batteries to 15 T-875  (8V). Our calculation predicted a decrease in performance even though  the voltage increased from 96V to 120V. We had to wonder about this  since the battery was built for one golf cart manufacturer to go from  36V to 48V without changing his design. The difference is that the 8V  was replacing a T-105 battery not a T-145 battery. A T-145 is good  for 145 minutes at 75 amps vs 105 minutes for the T-105. That's a 38  percent increase! That's why we recommend T-145 in our truck designs.  As another example, the EV8D (12V) battery is used in an imported EV.  It is a diesel truck starting battery not an EV battery. These had to  be replaced in one of the EVs after only three months. They were not  designed for the deep discharge.  Anyway ask questions. But ask EV Users not battery salesmen. Salesmen  know batteries, but they do not know EVs.  By the way, Curtis Battery Book One and Bob Brant's book "Build Your  Own EV" are available from us at Electric Vehicles of America.  Visa/Mastercard/Discover accepted for your convenience.  Bob Batson  (EVAmerica@aol.com)  Electric Vehicles of America, Inc. (EVA)  Tel# 508-897-9393, Fax# 508-897-6740  48 Acton Street, Maynard, MA 01754 USA  EVA - "Customer Service is No.1 !"  Authorized Distributor for Advanced DC Motors, Curtis Controllers,  Albright Contactors, and other major EV manufacturers. Free catalog  Largest EV component supplier in East EV Components for electric cars  (Escorts, VW, Saturn, etc), trucks (S10, Ranger, Ram 50), boats (14-40  ft), motorcycles, and much more  **********************************************************************   ---{End}  --  Open Circuit voltages (after resting several hours) [of 12V  lead-acid batteries (6v batteries /2)].  % charge        Flooded         Gel             AGM  100             12.60-12.70     12.85-12.95     12.8-12.9  75              12.40           12.65           12.60  50              12.20           12.35           12.30  25              12.00           12.00           12.00  0               11.80           11.80           11.80  These values are typical, but they'll vary somewhat according  to the design of each individual battery.   "David Roden (Akron, Ohio, USA)"  roden@ald.net   --  From: Daniel Ames  daniela@wenet.net   Date: Tue, 08 Feb 2000 18:40:29 -0800   reference to date coding. So one could tell when their batteries were made.  Like on US Battery  the battery  terminal will be stamped 2 digits for  the month followed with a single digit for the year i.e. 8 would be 1998  etc. 10 7 would be October 1997.     Here is more battery info. This will line up properly if using a fixed  pitch font.  Major Brand                             Sub Brand  ------------                  -----------  Delco                                   Dura, Power, Freedom, Voyager  Douglas                         Omni, Guardian  East Penn                               Deka, Hitech, Unitech, Inferno, Dominator  Exide                                   Universal Edge, Max, Muscle Man, Arctic Edge                                          Nautilus, Nautilus Gold, Commander's Edge                                          Anglers Edge, Mariner's Edge, Sure Start                                          Cutting Edge, Challenger, Power GLX, Titan                                          Mage Cell, Heat Guard, Mega Cycle  Firestone                               Extra Life, Supreme, Valulife  Goodyear                                Double Eagle  GNB                                     Action Pack, Champion, High Energy                                          Power Breed, Super Crank, Switch, Scorcher  NAPA                                    the Power, the Legend, Sure Start  Sears                                   Diehard, Heat Handler, Gold  Wal-Mart                                Omega, Energizer  Auto Zone                               Dura-Last  Motorcraft                              Tested Tough  -------------------------------------------------------------------------  To find the DATE of Birth for your battery....  Brand                                   Code  ----------------   Johnson-Controls  Interstate  Motorcraft  East Penn  GNB ----------------------Usually on a sticker or hot-stamped on the side  of                                      the case. A=January B=February the letter I is not                                     used and is skipped. The number next to the letter                                    is the year of SHIPMENT. Example  B0=Feb 2000  Delco  Sears---------------------Dates are stamped on the cover near one post.  The                                     first number is the year. The second character is                                     the month A-M skipping I. The last two are area codes.                                    Example 0BN3=2000 Feb.  Douglas-------------------Douglas used the letters of their name to indicate the                                    year of manufacture and the digits 1-12 for the month.                                    D=1994                                    O=1995                                    U=1996                                    G=1997                                    L=1998                                    A=1999                                    S=2000                                    Example S02=2000 Feb  Exide---------------------The fourth character is the month.   The ffth character is the year. A-M skipping I. Example RO8B0B=Feb. 2000  Trojan--------------------Stamp on post, 2 Months AFTER manufacture date.  Tony Ascrizzi  ElectricVehicleSystems.com  34 Paine St., Worcester, MA 01605  (508) 799-5650  --  - From: "Todd Hunter" Date: Tue Nov 13, 2001 9:01 pm Subject: Evercel Nickel-Zinc batteries Everthing is based on C1 discharge rate. The Evercell is an estimated price. BATTERY Unit price WATTS/LB WATTS/\$ USB 125 - \$74 13 12 US Battery model 125 PANASONIC EV - \$336 14.3 1.96 SAFT NICAD100 - \$347 21.4 1.73 3000 cycles EVERCELL Zinc ~ \$400 24.9 2.49 600 cylces SAFT NIMH - \$1900 30.4 .69 Watts/lb is the number of watts in a pound of the given battery and does not take into account voltage sag. The Higher number the better. Watts/\$ - how many watts a dollar will buy. The Higher number the better. - Compiled by: Bruce Parmenter  BruceDP(at)yahoo.com  All my work is free. If this package is reproduced, it must be intact.  *If want to give all the free work I do, consider being a member of the San Jose Chapter of the EAA.  http://geocities.com/sjeaa           ____          {Statements may not be my Employer's}        __/o|__\~        EVangel: messenger bringing good news  =)---'@ -----@'      'Electric cruis'n the Santa Clara Valley'  132V S-10 Blazer http://geocities.com/brucedp/  BruceDP (at) yahoo.com  Electric Vehicle List Editor      http://egroups.com/group/EVList/ EAA San Jose EVents Officer       http://geocities.com/sjeaa/          % Use Renewable Energy to charge your EV %```