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Need help setting up charging system!

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I'm getting ready to build a light weight trike and need some good advice on what's already going to be an unconvential project. I've got 2 deep cycle 12v Optimas coming. I plan to use them in parallel with a pedal powered generator that will generate more than 48V pretty easily. Yes, I know It's definately outside the box, but I'm going for it. Ideally, I hope to set it up so that the generator charges the batteries and any excess voltage is automatically dumped to the brushed Etek style motor I'm using. Would it be possible to have battery A only engage when charging voltage is reached and battery B only engage when charging voltage is reached for it? Can I do this without a charging system? Am I just dreaming? I know that a slider throttle could do part of this but, I'm hoping to make it all work together seemlessly. Any advice would be grealy appreciated.
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Well I agree totally with what Major says on the efficiency of it. But if you are going to do it anyway then here goes.

You dont necessarily need a charge controller. I really wouldnt worry about overcharging your batteries. Simply pass the AC output of the generator through a bridge rectifier, then the output of this straight to your batteries. The faster you pedal, the more current will go into the batteries. You may need to experiment with gearing to get a comfortable pedal speed and torque to your liking.

Then connect your motor controller straight to your batteries, and control the motor speed/current via a handlebar mounted throttle.

With this setup, depending on how much effort you put into peddling and the demand on your motor, any excess current you generate will charge the batteries, likewise if you dont generate enough current, then the batteries will supply the rest.

Is this how you see your setup working?
 

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Thanks. Yes except the generator is already putting out DC. So generating say 48v to the batteries would send approximately 20V straight to the motor? Sounds good to me. Only problem is I had no idea motorcycle wheels cost so daggon much! Can a person run a car wheel on a motorcycle chain? I don't really want to go that big though. Any suggestions?
OK so in that case you dont need the bridge rectifier. You may still need a blocking diode.

Er no im afraid it wont really work like that. As Major says, probably best to post up a circuit diagram and some parts. Basically if you attach your generator to your batteries and start peddling, the generator output voltage will be held at your battery voltage, say 26 - 28 volts. Then depending on how hard you pedal, will determine the charge current into the batteries. This may not be the most efficient way of doing it - would have to see datasheets of the generator. It might be better to use a DC-DC / charge controller to better match the voltage / current of the generator and batteries.

Am I right in thinking that you want to control your motor power output based on your generator input? Thats harder to do. What capacity (Ahrs) are your batteries? Because unless they are tiny, you are probably never going to generate more power than you can use to charge the batteries.
 

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Will
It doesnt matter what generator you use. You could get a super-super efficient 50kW alternator, but if the engine (You in this case) can only produce 100W, then thats all you will get out of it (-losses of course)

These power numbers on alternators/motors doesnt mean that you will automatically get that power out if you spin the alternator, or hook the motor up to a battery. All those numbers mean is thats the power that the motor was designed to run at, and so running at that power will ensure that the thing does not overheat and fail.

Anyway, back to pedalling. If you still really want a pedal powered electric trike, then you have to be thinking in terms of bike weights and sizes. So it needs to be super light and built with bicycle wheels, not motorcycle/car wheels. Forget the generator, connect the pedals to the wheels via a chain drive, then use the batteries and electric motor for extra power (And yes you will need a controller, not that death trap slide switch thing on that webpage). Accept that you will only get about 10 - 20mph from peddling (depending on what you build and your fitness). As for how fast you go with the motor, that depends on a lot of things, including how fast you would feel safe going. Also don’t know what the laws concerning electric bikes are where you are.

If you want something more robust and faster, ie motorcycle style trike, then forget about peddling, as Major says, it will get you nowhere.
 
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