Dual Battery Cutoff Switch - R-pod Owners Forum

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ronahue

Senior Member

Joined: 02 Jun 2015
Location: Massachusetts
Online Status: Offline
Posts: 316

Topic: Dual Battery Cutoff Switch
Posted: 24 Jan 2016 at 12:01pm

Thank you both.

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

Podster

Senior Member

Joined: 16 Sep 2014
Location: San Antonio
Online Status: Offline
Posts: 1108

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.

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

CharlieM

Senior Member

Joined: 23 Nov 2012
Location: N. Colorado
Online Status: Offline
Posts: 1797

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.

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

ronahue

Senior Member

Joined: 02 Jun 2015
Location: Massachusetts
Online Status: Offline
Posts: 316

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

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

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ronahue Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 02 Jun 2015 Location: Massachusetts Online Status: Offline Posts: 316	Topic: Dual Battery Cutoff Switch Posted: 24 Jan 2016 at 12:01pm
	Thank you both.
	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

Podster Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 16 Sep 2014 Location: San Antonio Online Status: Offline Posts: 1108	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.
	Cliff & Raelynn Ranger 4.0/178 (1/2 ton 5,800lb tow capacity)

CharlieM Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 23 Nov 2012 Location: N. Colorado Online Status: Offline Posts: 1797	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.
	Charlie Northern Colorado OLD: 2013 RP-172, 2010 Honda Pilot 3.5L 4WD PRESENT: 2014 Camplite 21RBS, 2013 Supercharged Tacoma 4L V6 4WD

ronahue Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 02 Jun 2015 Location: Massachusetts Online Status: Offline Posts: 316	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
	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