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# DC motors as generators in parallel? Answered

Hey guys, im doin a project, ill be using two cordless drill motors with a maximum output of 12v each and unknown amp atm. My question is this: Both the outputs of those two motors will equal 24 volts, but I want 12 volts and increased amperage - this will, for the most part, be used to charge a 12 volt lead acid battery and I dont require the safety police on this one.

So, can I take both outputs of the dc motors and wire them in parallel and have a resultant potental 12v maximum?

Or will I have to use electrickery?? I have only a novice/intermediate skill in electronics and my parts come from re-using old scrap technology.

tx, Sky

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## Discussions

Yes, but unless they are closely matched, you risk getting circulating currents between the generators. Put a very low value resistor, like a 0.1Ohm resistor between each generator and the battery. The resistor needs to be able to handle the maximum expected current. Don't forget you'll damage the battery if you charge is repeatedly at more that C/10 - If its a 100Ah battery, you shouldn't charge it harder than 100/10 = 10 A.

Thats where my electronics knowledge is a little bit fuzzy.
If I put resistors that are able to handle the maximum expected current, then doesnt that mean no current will flow?!?
Also I dont know what "C" stands for in the C/10 equation :(

I would think that I would not need any resistors because its not possible with my generators to charge at a higher rate than 12 volts.

Maybe you are saying..that...im limitting amperage with the resistors? confuzzling!

No, it just means they can take the power without burning out.
C is the capacity of your battery, in Ampere hours.

You're creating voltage drop with the resistors that stops current loops happening.

Trust me.