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Old 05-24-2012, 01:29 PM   #15 (permalink)
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Originally Posted by mechman600 View Post
Sounds like a great project!
My advice is that you go as high with voltage as possible within your budget. The higher the voltage, the less efficiency is lost to heat in your cables and whatnot. You can go quite high before a Warp9 turns into molten lava - something like 192V is still within reason.

Controllers do get quite pricey above 144V but many people say it is worth the investment. Keep searching the EV trading post for parts. [EV Tradin' post] - Electric Vehicle Classifieds
You can register to get alerts emailed to you when something you are looking for goes up for sale.
Best of luck!
I disagree, a DIY EV for the purpose of saving money and not creating a money hole is best operating at a LOWER voltage at LOWER amps using more or less common off the shelf parts.

Generally speaking you want your vehicle at the max reasonable speed you want to travel to draw under 200amps, preferably near 100amps.

Ideally with your pedal to the metal cruising at about 3500-4500rpms you should be at your top speed you want, have a gear or two below for mud and a gear above for special circumstances.

Every EV I have dealt with runs most efficiently (in terms of power in power out) with the pedal at WOT. AC systems and DC systems become rather inefficient at low throttle positions, enough that on a lithium setup you are loosing at least 25% out the window on PWM if you drive in that region often with a typical controller. You normally still gain range because of better aero at low speed but its still worth knowing.

Other factors such as using lead batteries is when amp draw and rate become more important than controller losses, lithium this isn't the case.

So the most effient and lowest cost EV is typically the same car. Less volts, costs less, and is less to maintain, has more parts available off the shelf new and used, but also will have less performance but be taylored to drive a specific speed most of the time and do so most efficiently.

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