| Off topic but don't know where else to turn [message #371356] |
Sun, 21 May 2023 17:52  |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Need just a couple of quick answers to my problem. I'm headed to Canada fishing after Memorial Day. We will be using a trolling motor that operates on 24V. For that we are using two 12v RV type batteries hooked in series for 24v. This typically gets us about 6hrs of normal use taking us to mid afternoon. We would like to extend that so that we could fish all day without having to exchange for fully charged batteries in the middle of the afternoon. So instead of changing batteries in the middle of the afternoon, could I hook up two 24v sets in parallel and get twice the hours out of the batteries? So, two sets of 12v batteries in series. Each set is now 24v. The two 24v sets hooked in parallel for a total of 24V but with twice the AH capacity. Is my thinking right? Seems like the same thing we are doing when we hook up two 6v in series to make a 12v set in our coaches. Then charge all 4 batteries over night for the next day fishing. Would 12ga wire work for the parallel hookup?
Again, sorry for the off topic. A simple yes or no if appropriate is all I need.
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: Off topic but don't know where else to turn [message #371357 is a reply to message #371356] |
Sun, 21 May 2023 18:33  |
Melbo
Messages: 144
Registered: August 2018
Location: Albuquerque NM
Karma: 0
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Senior Member |
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Connecting four batteries for 24 volts is tricky. I ruined a pair of batteries trying to do the four battery thing. If it were me I would just run the two and when they need to be charged switch to the other pair. Keep each pair as a set or they won't charge and drain properly. The 12 guage wire is good for 25 amps if memory serves me but in most applications is limited to 20 amps.
HTH
Melbo
Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
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| Re: Off topic but don't know where else to turn [message #371361 is a reply to message #371356] |
Mon, 22 May 2023 05:38 |
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RF_Burns
Messages: 2276
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Larry,
Your initial thinking is correct, two 12V batteries in series will give you 24V. If you put two sets of these in parallel, you will increase your capacity.
BUT... each set of batteries are likely to be very different in capacity. So I agree with Melbo, use the first set of batteries, then when that set is discharged, disconnect them and connect the second set of batteries.
Better yet, get a set of LiFePO4 lithium batteries. More usable capacity, much less weight, very fast recharging time and no dealing with acid, off-gassing and terminal corrosion.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: Off topic but don't know where else to turn [message #371363 is a reply to message #371356] |
Mon, 22 May 2023 07:45 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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I would make 2 bigger 12V batteries first by putting 2 12s in parallel and 2 12v in parallel creating two larger 12v batteries. Then put those in series. That way you have only 2 larger 12V to recharge. You could also use A/B batt switches between the 12s to not have to parallel them. You’d then have main and “get me home” bank. Wire gauge depends on the motor spec max Amp draw. Maybe go up one size from min recommended so more energy turns prop instead of heating the wire. Put a self resetting breaker right after the final battery out to protect the wire.
John Lebetski
Woodstock, IL
77 Eleganza II
[Updated on: Mon, 22 May 2023 07:52] Report message to a moderator |
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| Re: Off topic but don't know where else to turn [message #371377 is a reply to message #371356] |
Fri, 26 May 2023 21:44 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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Thanks to all that commented. We decided to keep the banks separate and installed a A-B switch. When we run out of power on A bank, simply switch to B. After I got all the wires replaced with 4ga, and wired in the A-B switch, a test found that it did not work. ARGGGG! Traced it to a bad connection at the front of the boat between the trolling motor and the boat outlet. Bent the connections back to normal and every thing works again. Thanks again people. Lots of good ideas/solutions to a potential GMC problem.
Larry
78 Royale w/500 Caddy
Menomonie, WI.
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