Battery Questions (and a few others :D)

Conversion Kits
1

Alright so i am in a state of despair trying to decide on what batteries to go with. Due to cost i am almost guaranteed to go with Lead-Acid, (i cannot really afford more than about a $4000 battery pack). But i have looked a number of different brands and types and am pretty unsure.

My planned conversion is a Mk3 VW golf coupe, with an initial curb weight of about 2500lbs. I am going to use a Netgain Warp 9 (or an 11" if the weight is looking high) and a 144v system (750amp WarpCore Controller).

My final contenders are looking like 18 of the Trojan T-890 rolling in at 31kg (70lbs) or 12 of the T-1275 at 37kg a piece (82 lbs). I picked trojans partially for their famed durability but primary because they were the only batteries that i could find with A/H ratings over 150. To sum up i basically have 3 questions,

-I am hoping for aprx a 50km+ range (31+ miles) how many amp hours should i allow for? The T 890s provide 190, and the T-1275 provide 150. Do i even need that many amp hours or should i be looking at something like the Optima Yellows tops in a 75 A/H configuration?

-With my total curb weight sitting between 3500 and 3800 lbs should i be looking at the Netgain 11 inch motor (or even a 13"?) instead of the 9? I don’t want to end up much below stock ICE acceleration. Will 11" motors drop my efficiency considerably?

-Am i at all in the right direction with my components considering the weight of my car and my hopeful range?

I would also like to mention i am not completely without an clue lol i just have not been able to get a really firm idea of what i need because my conversion is looking considerably heavier than most.

Thanks so much!
-Geoff

2

Amp hours mean nothing, it is watt-hours you need to work with.

In theory 18 T-890 wired in series will give you 27.3 Kwh of capacity, but that is not real or usable. For a FLA battery you will never want to discharge it more than 50% without a recharge, unless you want to replace them every year or two.

So at 50% you really only get 13.7 Kwh. But there is still another catch all battery manufactures play with their rating. The T-890 has a 190 AHJ rating at the 20 hour discharge rate. Your Ev will be discharging at a much higher discharge rate like 1 or 2 hour. When you apply the correction factor of .65 @ a two hour rate, thg eT890 now becomes a 125 AH battery. So now that 13.7 Kwh rating now gets dropped to 9 Kwh capacity.

So to get 31 miles means your vehicle will need an efficiency of 9000 wh / 31 miles = [B]290 wh / mile[/B]