Puzzling Battery Disconnect Polarity - Printable Version

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+--- Thread: Puzzling Battery Disconnect Polarity (/showthread.php?tid=6142)

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Puzzling Battery Disconnect Polarity - [email protected] - 06-28-2021

I am replacing a failed engine battery manual disconnect switch. The faulty one is on the positive side of the batteries. Everything I read says it should be on the negative side. Any idea why Newell put it in the positive side? Perhaps it is someone's after market modification but the house battery disconnect is also on the positive side leading me to believe it came from the factory that way.

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RE: Puzzling Battery Disconnect Polarity - Tf175 - 06-28-2021

Our '86 also has both battery disconnect switches on the positive side . I would think it was born that way . Presume you have  two 8 D batteries for starting , one on each side forward of the rear wheels ? Switch for those mounted in passenger side engine compartment .
Chris

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RE: Puzzling Battery Disconnect Polarity - encantotom - 06-28-2021

this is a very interesting question. and if you do research online you will get a long variety of answers. my 02 has them on the negative.

for instance the for a long time, the NHRA mandated them on the positive side. alot of marine builders do positive side.

others have discussions on current flow direction etc.

when i put a new magnum inverter in my 99 i put a positive cut off switch at the inverter making sure all lugs were 100 percent covered.

i think one of the reasons the cut off switches have moved on the newell to negative is just safety. there is a thought that if it was on the positive and there was a crash near the switch that it could short to ground.

when i was putting the 6 agms in my coach i had a helper. on the very last terminal connection of those mazes of cables he had the wrench touch the side of the coach. at that point all the amps from 6 8 d batteries shorted. he screamed, it arc'd, melted a chunk of the wrench and left a nice black mark and mild burn on his hand.

also use common sense if you change the cables on that cut off switch. to make sure that there is no current to them.

bottom line is cut off switch on positive or negative, either is ok. with caveats

tom

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RE: Puzzling Battery Disconnect Polarity - encantotom - 06-28-2021

btw, what has puzzled me on my 99 i had and the 02 is that the positive cables from the batteries to the inverter were hot all the time. that is why i put a cut off at the inverter just in case of needing to work on the inverter.

tom

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RE: Puzzling Battery Disconnect Polarity - [email protected] - 06-28-2021

Interesting to say the least. Wondering now if the logic is to leave the negative connected so that the batteries would charge even if the battery disconnect was thrown since the inverter is always connected?

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RE: Puzzling Battery Disconnect Polarity - kyleb - 06-28-2021

Tom, Was there a fuse or circuit breaker in the positive lead to the inverter?

As for shorting out the battery - with the amps an 8D can deliver - I am extra cautious when I'm anywhere near the battery terminals !

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RE: Puzzling Battery Disconnect Polarity - encantotom - 06-28-2021

no cb but there is a fuse.

tom

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