Podmods, Maintenance, Tips and Tricks: Dual Battery Cutoff Switch

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Dual Battery Cutoff Switch

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Forum Name: Podmods, Maintenance, Tips and Tricks
Forum Discription: Ask maintenance questions, share your podmods (modifications) and helpful tips
URL: http://www.rpod-owners.com/forum_posts.asp?TID=7382
Printed Date: 21 Jun 2025 at 9:22am
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Topic: Dual Battery Cutoff Switch

Posted By: ronahue
Subject: Dual Battery Cutoff Switch
Date Posted: 24 Jan 2016 at 9:48am

I am installing dual batteries in my 179 I have decided on dual 12 volt batteries with a 1,2,both and off switch. Every article I have seen says install the switch on the negative side, however the switch instruction says to install the switch on the positive side unless you have a positive ground system. Is their really a compelling reason to install it on the negative side if not I prefer to go with the manufacturers recommendation.

PS: I have already considered the 6 volt verses 12 volt possibilities and decided on 12 volt.

Thanks in advance

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Ron & Sharon
2015 R-Pod 179
2022 Nissan Frontier

No trees were harmed in the sending of this message but a billion electrons were really agitated

Replies:

Posted By: CharlieM
Date Posted: 24 Jan 2016 at 11:05am

No reason at all. Convention says put the switch in the positive leads and that's where it should be. The only reason to disconnect the negative side is (hold over from eons ago) if you leave the lead connected to and dangling from the battery terminal. This would allow the dangling wire to contact the frame which would be dangerous if it was the positive lead. If you disconnect from the battery terminal itself there is really no difference. Stay with convention and your switch manufacturer's recommendation.

That said, if you do physically disconnect the positive lead, and if you are connected to shore power, do not let the dangling lead from the trailer contact the frame.

BTW, you will get more capacity if you leave both batteries connected during both charge and discharge due to Peukert's law. The only reason to use only one is in a failure situation.

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Charlie
Northern Colorado
OLD: 2013 RP-172, 2010 Honda Pilot 3.5L 4WD
PRESENT: 2014 Camplite 21RBS, 2013 Supercharged Tacoma 4L V6 4WD

Posted By: Podster
Date Posted: 24 Jan 2016 at 11:06am

Well, yes and no. As far as functionality... it doesn't matter what side you put the switch on. Now, ALL of the electrical schematics seem to show switches, fuses, breakers, Etc, on the power side. Some will argue that providing a cutoff on the power side reduces the slim chance that other legs could still short to ground. Ground is common and if you cut the ground with a switch you can still have a short to ground from the power side because it's still connected. However, if you cut the power side at the source, the battery in this case, the chance of shorting is reduced. Doug will remind us from time to time that NASCAR rules dictate that battery cut-off switches be placed on the power (positive) side, presumably for a good reason.

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Cliff & Raelynn
Ranger 4.0/178
(1/2 ton 5,800lb tow capacity)

Posted By: ronahue
Date Posted: 24 Jan 2016 at 12:01pm

Thank you both.

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Ron & Sharon
2015 R-Pod 179
2022 Nissan Frontier

No trees were harmed in the sending of this message but a billion electrons were really agitated