Re: An Electric Autocross Car

[Rich Rudman <rmanzan@tscnet.com>]

Scott Hull wrote:
> 
> Jerry Dycus wrote:
> 
> >...For cheaper racing batts regular
> starting batteries might be better to get higher amps
> and voltage at a lighter weight ...<
> 
> A better cheap alternative would be Costco Group 24 Deep Cycle Marine
> batteries. They will deliver 500 amps when kept above 80% SOC, weigh only 45
> lbs, and cost only $43. I use them in my Manx EV (shortened VW chassis, 1840
> lbs, 144 volts, 500 amps) and have thought that it would make a good
> autocross car. I've got over 3000 miles on them and they are still going
> strong. For high power use you have to keep them nearly full. As it drops
> below 80% SOC, the voltage will sag badly at high current. Below 50% SOC,
> you have to keep it at <100 amps. An Autocross is usually short, so you
> should be able to complete it while staying above 80% SOC. Here are some
> reading I took last year in the 80-90% SOC range (they do even better right
> off a full charge):
> 
> 100 amps = 135 volts = 13.5 KW
> 150 amps = 132 volts = 19.8 KW
> 200 amps = 128 volts = 25.6 KW
> 300 amps = 122 volts = 36.6 KW
> 400 amps = 115 volts = 46.0 KW
> 500 amps = 97 volts = 48.5 KW
> 
> They have about the same footprint as an Optima. So, if it works and you
> have the money, you can always upgrade later.
> 
> SAH

Are these the same batteries that I completely murdered in less than 150
cycles?? If so. they are NOT a good idea for ANY EV that 
sucks more than about 150 amps. Humm NOT for me. Been there done that. I
remeber the sinking feeling watching the cell seperators float to the
top of the acid. Felt floating in the H2SO4, not good. I had twin stacks
at 48 volts and a 2000 amp controller. Still not enough grunt for fun. I
can extract more power from 72 volts of Optimas that 144 volts of these
batteries. Come on show up to a Autocross. At the end of the day those
with Optimas, or hawkers, will have the smiles.

Madman
-- 
http://www.manzanitamicro.com