# 6v vs 12v batteries



## ga2500ev (Apr 20, 2008)

Conventional wisdom is that the lead plates of the 6V batteries are thicker than the 12V batteries so they are considered to be sturdier and longer lasting than 12V batteries.

My current thought process though is observing that you can get started with half the batteries at 12V, do all of your shakeout testing at full voltage, then add a second string to extend range.

So I'm actually thinking about the Sams group 29 deep cycle marine batteries. I think they are $6 more. And of course the $9 core charge.

Anyway back to your question. Each battery is about the same weight, size, and energy capacity with the 12V batteries holding a bit more energy than the 6V ones. The 12V are @ 125 Ah giving 1500 Wh of energy while the 6V are @ 225 Ah giving 1350 Ah of energy.

Note then that the 12 12V batteries will be about half the pack size of the 24 6V batteries, so expect half the range.

Hope this helps,

ga2500ev


----------



## TheSGC (Nov 15, 2007)

chamilun said:


> I was at Sams tonight, and saw the CG2 (GC2?) batteries for $66. they are golf cart batteries.
> 
> so cheap, and tempting. does anyone know a way to calculate the tradeoff between 24 6v batteries (amps vs weight) or 12 12v batteries?
> 
> thanks


The 6 volts will take you farther as they hold twice (if not more) than the 12 volt batteries. I think the tradeoff comes when you have passed the 144 volt line, like 156+ volts is when the 6 volts are too heavy to even consider in most cars.


----------



## chamilun (Jun 17, 2008)

interesting,
so the extra weight of the 6V string does not offset its effective increase in range/energy.

if weight and drag are what limits the effective range of an EV, Im surprised the extra weight of the 6V pack does not counteract the increase ah.

thanks guys


----------



## ww321q (Mar 28, 2008)

chamilun said:


> interesting,
> so the extra weight of the 6V string does not offset its effective increase in range/energy.
> 
> if weight and drag are what limits the effective range of an EV, Im surprised the extra weight of the 6V pack does not counteract the increase ah.
> ...



When comparing batteries you need to compare on equal ground . As a general rule 2 6v 60lb. ea. batteries in series will have slightly higher ah rating than 2 12v60lb. ea. batteries in parallel . 6 Volt batteries will last longer and give a little longer range but it seem that 12 volt batteries give better performance at a shorter life . Know what I mean Vern ?  J.W.


----------



## marthaspears (Jul 9, 2008)

better settle for 6 volt batteries than 12 volt batteries because of their reliability and performance.


----------



## CPLTECH (Sep 14, 2007)

marthaspears said:


> better to settle for 6 volt batteries than 12 volt batteries because of their reliability and performance.


As the owner of 20-6V batteries (1400#), I wish to second that emotion.


----------



## chamilun (Jun 17, 2008)

if i go with the t-105s, I may do 12 t-105s and 12 GC2s. that way, i could potentially save a few bills and determine how much better the Trojans may be.

however, I may just stick with the original plan of using t-145s, which increase my range quite a bit. range is what I am most concerned with. a 20mile EV seems like a waste. the original design had 12 12V Trojans


----------



## TheSGC (Nov 15, 2007)

chamilun said:


> if i go with the t-105s, I may do 12 t-105s and 12 GC2s. that way, i could potentially save a few bills and determine how much better the Trojans may be.
> 
> however, I may just stick with the original plan of using t-145s, which increase my range quite a bit. range is what I am most concerned with. a 20mile EV seems like a waste. the original design had 12 12V Trojans


What ever you choose for batteries, always keep all the batteries the same. Don't mix batteries with different brands, even if they have the same ratings because they probably have different performances and life spans.

As for a 20 mile EV, you can do that with six 12 volt batteries easily, so it should not be a problem. 144 volt system should easily be able to do 35 miles, if not more like 50-60 if you use T105s and probably up to 75 miles if you use t145s.


----------



## Qer (May 7, 2008)

Only prob is that 24 T-105 weights 672 kilo and 24 T-145 weights 792! It's tricky to find a donor that can handle those kinds of weights and still get them through the registration. At least in Sweden it is. A Chevrolet S-10 Blazer is only allowed a cargo weight of 330 kilo and even without engine and stuff I think it'll be hard to stuff all those batteries in and still have a few kilos left for a passenger. 

How do you solve the weight problem in the states? Is it possible to "upgrade" a car for more cargo or how do you manage to register a car totally loaded with lead?


----------



## chamilun (Jun 17, 2008)

SGC,
if i get 70mile range, Ill be dancing in the streets, or at least rolling down the street more often.

Qer,
my plan is to have three packs: one in front engine compartment, one in middle under rear seat, where the gas tank currently is, and one in the trunk, or the boot, as those Kiwis like to say.

I may upgrade the springs to handle the weight, but Im not certain yet. as far as 250 lbs difference, Im not certain how concerning that would be.

i am not concerned about exceeding the weight posted on the door, mostly because that will not be checked in this state. Id be more concerned about sway and poor handling. again, Im not certain yet how concerning this will be.

and yes, I just said 'concerned' 100 times


----------

