how do i connect DC devices to my DC generator?

I got an old treadmill with a blown board, stripped out all the electronics ( kept it) with the intention of using the treadmill as a generator only - knowing that the engines are good - the engine is rated to 180VDC, and i have so far at a nice easy walk noted 100VDC on my multimeter hooked directly up to the terminals.

it seems clear to me when i plug my 24v fan in and walk that while it spins well and faster the faster i walk - it doesnt need 100vdc and will probably blow eventually - so i must need a voltage regulator?>> or the like....

1.) how to make / buy one easily?
2.) can i charge car battery from it - do i need any kind of regulation/ charge controller  if i was doing that

- am i correct in believing the more load i wire in ( perhaps on a sliding scale or some kind of switch) the more resistance will be generated to the walker?

thanks - will



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frollard4 years ago
You either need a regulator or a buck transformer to convert the high voltage to a usable dc voltage, probably that will go into a battery if you want primarily usable power.

As for the voltage output - attach a beefy wire between the motor terminals and see how hard it is to walk. Energy out = energy in, and a short circuit (for a short time) will demonstrate how much work your system can actually do (with you as the power source). Try hooking up the fan AND the multimeter at the same time. Open circuit you can get high voltage, but as soon as there is any load I bet the voltage drops to something reasonable (hence the fan doesn't explode).
agatornz (author)  frollard4 years ago
thanks for that answer - any chance of explaining that in even more laymans terms for some one that doesnt know the subject.. ie: open circuit.

... so 100 volts is considered high voltage??? like dangerous stuff? and while it will run gear its better to reduce it...

so the more motors you add across the circuit . the more it has to share the power so the speed drops on all items? is that what you are saying - so that would kinda self regulate the fan...
Open circuit = nothing connected to it.

100V from a generator like that can kill easily.

I think a fan is a very small load for the 500W motor in a treadmill, and so you will blow it up quickly. Try measuring motor volts with the fan, like frollard says
agatornz (author)  steveastrouk4 years ago
thanks every one - great to know i can get good answers here;-)
You should check the voltage when you have a load on the generator - You should find it much lower then the off load voltage.

Yes as you load the generator the effort to move it will increase - Quite dramatically. I have a hand cranked generator producing 50 volts off load, with a 12 volt bulb attached it is almost impossible to crank.