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Old 02-08-2009, 11:10 PM   #5 (permalink)
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Originally Posted by MetroMPG View Post
The EVDL guys have chewed over this before, and the biggest obstacle is that when you go back into PWM mode from Contactor/Turbo mode, you can fry the controller.

There will be back EMF (... if I'm not mistaken ...) in the motor for a short while which will feed back to the controller at a level higher than its rated to handle.
Not only that, your "turbo" batteries will cycle at a different rate than the rest of the pack, resulting in different charge and discharge characteristics, and eventually, earlier or later replacement than the rest of the pack.

Plus, you're better off just going higher voltage to begin with. Put those batteries in the circuit always, and all of the batteries will last longer, because you'll need fewer amps for the same power output, and you'll have longer range, so less depth of discharge in normal driving.

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