( 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 
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 
     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 
     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 
     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 
     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- 

{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 
     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 
  |                       | 
  `                       | 
  . \                     | 
  .  \                    | 
 -------- ---------2.38V--|-------------------------- 
  .   . `                 | 
  .   .    ` .            | 
  .   .        `  - . _   | 
  .   .                 \ | 
 ---------------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 
     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 

     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 
     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 
     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 

100%-     .  .   .                                              -100% 
    |   .   |          .     .      .       .     . 
80% - .     |                                           .       - 80% 
    |       |                                           | 
60% -       |                                           |   .   - 60% 
    |       |                                           |   | . 
    |       |                                           |   | 
    |       |                                           |   |    . 
    |       |                                           |   | 
    |       |                                           |   |      . 
  New      100    200    300    400    500     600     700     800 

 Cycle Life test - Sealed Marine battery 

100%-    .   .             -100% 
    |  . |      . 
80% -    |        .        - 80% 
    | .  |        |  . 
60% -.   |        |      . - 60% 
    |    |        |      | 
    |    |        |      |  . 
    |    |        |      | 
    |    |        |      | 
    |    |        |      |     . 
  New      100    200    300 


     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 
     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 
     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 
     After you have done all your quick little calculations, you can 
look at all the different batteries [specifications to use in your 
     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/ 
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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 

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 

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 

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 

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 

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 
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 

Sears---------------------Dates are stamped on the cover near one post. 
                                  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. 
                                  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" <ev@listproc.sjsu.edu>
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 

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 %