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Old 02-21-2017, 11:30 AM
steveb steveb is offline
Join Date: Jul 2013
Posts: 53
Default Extending my 24v generator line-to-batteries

I'm using a 24v truck alternator on a hydro wheel to provide direct power to a 24v battery bank. The alternator has its own voltage regulator, but I also use a charge controller that has a dump load (I'm using a solar/hydro combo system).

So here is my idea and question: right now, I have the 24v alternator about 3 meters from the batteries, and using a standard size car battery cable for that 3 meter length (which I'm thinking itself is overkill, but....).

What I would like to do is move my batteries away from the alternator to a "better" spot in my storage house, and that distance is 8 meters away.

The 24v alternator never appears to generate more that 10 amps, which is to say the hydro wheel can't turn any faster and I'm already setup with a number of gears, so that won't change.

I've used an online calculator (found here:, and if what its results are true, then for a 24v system with 10amps running up to 10 meters long and only experiencing a 3% drop, I would only need to use a 6mm2 or 9 AWG cable.

Is that correct? And/or should I bump the cable from the alternator to the battery bank to 10mm2 or 8 AWG, just to be sure?

Or, what would be my options to somehow transfer that 24v/10amp power from the alternator at the alternator, to run it a 10meter distance to where the batteries will sit?

Thanks for considering.
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Old 02-22-2017, 08:12 AM
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12vman Male 12vman is offline
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Join Date: Oct 2003
Location: Tuscarawas County, Ohio
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Here's another chart..

In this case, bigger IS better..

8Ga. seems to be fine for a 2% loss at 30 Ft. It's always better to overkill to cover any possible losses in the connections at both ends. Always solder if possible..
"Without Deviation from the Norm, Progress is not Possible".
*Frank Zappa*
"Two roads diverged in a wood, and Ió I took the one less traveled by, And that has made all the difference"
*Robert Frost*
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Old 02-25-2017, 06:41 AM
steveb steveb is offline
Join Date: Jul 2013
Posts: 53

Thanks 12vman! As always, give a helpful reply.

I'm definitely going to go with as large a wire size as makes sense for safety and economy. As well, put a quality fuse in that line. Cheers.
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