Re: An Electric Autocross Car

["Scott Hull" <scott@m-cad.com>]

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