Interesting challenge. I don't know much about hillclimbing events, but sounds to me as if it's the perfect event to show off the strengths of an EV.
That's exactly what I thought! Short bursts of power.
Not sure you even need to match the 150 kW of the petrol competition because of the torque advantage of electric motors, but assuming you do, you should only need that maximum power for short bursts, so your motor can be rated for a much lower power output, say 30-50 kW. With only a six-minute sprint, the motor shouldn't have time to overheat if you run it at much higher power outputs for short periods.
The sprints are usually around a minute, although you do have to compete a few times at an event.
Until recently most EV speed and acceleration records were set with Lead Acid batteries. Even they are going to need a basic monitoring and protection system. Both NiMh and Li chemistries will die an early and possibly spectacular death without protection. You can't just simply scale up model car/aircraft practice.
OK. Could you explain why, please? I realise that I took a rather simplistic look at this and my understanding is in its infancy.
Accelleration is about torque NOT power, only the speed you can accelerate to is determined by the power. You may well NEVER use the peak power available from your batteries and/or controller. This would be very true of somewhere like Prescott.
Acceleration is directly related to torque at the wheels (assuming perfect traction). Power and torque are related too, only power factors in the speed too. If I have a motor producing 50lb-ft of torque, there won't be 50lb-ft of torque at the wheels (unless there's a 1:1 gear ratio). If I have a motor producing 50bhp, there will be 50bhp at the wheels too (assuming no transmission losses). It just makes for easier comparisons in my eyes. Of course, peak power is immaterial. What's important is the average power/torque in the rev range used. This is where electric motors win as they have a flat torque curve. Compare that with a bike engine!
Stick to a SAFE, affordable and reliable battery choice, at least to start with. A Hawker (Enersys) Genesis or Oddysey would be a good choice. As I recall the 26Ah size has the best peak power (measured at half the nominal voltage). http://www.enersys.com/
Thanks for that. I've had a look through the data on the Odyssey batteries. It seems I can get almost 150KW from a bank of 14 PC1500 batteries weighing almost 340KG. That'll give me a voltage of 168v which isn't ideal for most of the motors I've seen. Of course, I could run at half that voltage (84v), but I may struggle to find motors that produce 40KW @84v.
If I lose the weight of the engine/gearbox and the rear discs, then that'll help offset the weight disadvantage. There should be no issues with the run time of this setup as I should be able to run at full throttle for over an hour! Another solution is to run 48 PC625 batteries, which would save another 60KG but would cost a little more (just under £100 each). The PC1500 batteries are just under £220 each which brngs the batteries in at around £3000.
Cheers,
Andy