Hey,I am still trying to figure out components and my car is space challenged. It looks like a Hyper 9 motor will be the power, I have read that I may need up to 5 18650's. This is not even a weekend driver it is a race vehicle with a VW transaxle. I need as much torque and rpms as I can get for six (6) 90 second runs in an event and some slow driving to and from actual course. Car will be turned off for about 10 minutes between each run. Can I get by with 3 or 4 ? I could stack 5 if necessary.
I'll start out by saying I LOVE the Hyper 9, it's a great all around motor, and man does it sound awesome! But if this is a race car and you aren't backed by a fortune, then go DC. I recommend a Warp 9 and zilla z1k for starters, but I don't know your performance targets. The max "rated" voltage on a Warp 9 is 170V, so if you want max power for that motor, you need a pack with voltage probably around 200V. You want a strong pack that is pretty stiff so that under 1000A load, it hopefully will sit around 170V - that's the goal. That will give you 350 ft lbs of torque @ 1000A from 0 to about 2500 or so RPM. You will be making at least 175 HP or so as well with that. Duncan is right, build your car around the battery pack. If you want more power, go with a zilla z2k, but you'll need high performance lithium for that. I would recommend building a custom pack if you're building a race car. Then design the rest of your car around that. I would recommend Kokam 75ah HP (high power) cells. They're rated for 1200A for 10s. I've got an 80S custom pack of those built into 4 modules, with a z1k and warp 9. All in a bug and it kicks butt!
I would recommend elcon 6.6kW charger and elcon 1kW DC/DC converter though, really reliable and great bang for your buck. Let me know if you want some help with planning or sourcing parts, I can help get you the best prices (chargers, motors, controllers, fuses, anything).