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Old 10-20-2015, 01:13 PM   #10 (permalink)
thingstodo
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Quote:
Originally Posted by Alex77tj View Post
the alternator setup is to generate enough juice so i dont drain the battery to quikly.
not to power the dc motor
You take energy you take out of the battery to run the car. Say it takes 30 HP to run your car at 55 mph (which should be close)

If you run an alternator as well, the power it 'generates' is less than the extra power you use. Say the high output alternator 'uses' another 5 HP OUT of your batteries. elhigh was trying to explain that you will only GET BACK 3.5 HP worth of power to put back into your batteries.

The Controller on your car, that takes the accelerator input and puts out power to your motor, ramps the power up and down to get the speed you want to drive.

I can only think of one way that your configuration of using an alternator to 'put back' energy into the battery will sorta work - if you have NO controller at all, on a DC motor that you just TURN ON (no throttle ramp) and you use the alternators to load the motor heavily so that it goes slower. This does not work well on a series DC motor (it has more torque as it slows down) and it is horribly inefficient (reference elhigh's explanation of the alternator efficiency) as well as kinda dangerous (it's easy to have a contactor fail closed when you are switching such high currents).

Every time you take energy and convert it - mechanical to electrical, chemical to electrical, etc - there are losses. Most of it shows up as heat.

You posted your ideas and asked for feedback. You have received the feedback. It is your choice to listen to it or not. In my opinion, you will not convince more experienced people that you are right.
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