RV.Net Open Roads Forum: Tech Issues: Battery Disconnect positive or negative side?

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Topic: Battery Disconnect positive or negative side?

Posted By: SFVdave on 05/28/16 07:19pm

My battery disconnect on the positive side only kills the light, fridge and furnace. Still have lots of parasitic drain, probably from 1 or both of the 2 other positive battery cables. Can I add a battery cut off switch to the negative side and kill everything or is that not recommended with certain components like levelers and slideouts?

Posted By: MudChucker on 05/28/16 07:37pm

strange, the entire idea of a cutout is to "cut out" or disconnect completely. Perhaps the switch, or batteries are not hooked up in the correct order ?

are you able to take a photo of your setup and post it ?

2017 Cougar
2015 Ram 3500 Megacab 6.7 Cummins Aisin transmission

Posted By: 2oldman on 05/28/16 07:39pm

As long as there's no electricity flowing it doesn't matter which pole it is. Obviously your 'disconnect' isn't wired up right.

Posted By: YC 1 on 05/28/16 07:47pm

It is not uncommon to leave things like steps connected. Or to keep radios programmed. Disconnecting the negative is just fine.

H/R Endeavor 2008
2013 Ford Edge toad
Full Timers

Posted By: CA Traveler on 05/28/16 07:51pm

Yes.

It may be wired as intended by the mfg. It's common for the salesman switch to not disconnect everything. And my manual disconnect switches also don't disconnect everything on either battery bank.

I did install a disconnect switch on the house battery negative terminal and will probably do the same on the chassis batteries.

2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
750 Watts Solar Morningstar MPPT 60 Controller
2014 Grand Cherokee Overland

Bob

Posted By: Bobbo on 05/28/16 08:03pm

"Danger Will Robinson!"

If your RV is a trailer or 5er, disconnecting the negative also disconnects the breakaway brakes. Not recommended. If you forget to reconnect the negative to the battery and tow, there is no emergency braking.

If your RV is motorized, disregard this post.

Bobbo and Lin
2017 F-150 XLT 4x4 SuperCab w/Max Tow Package 3.5l EcoBoost V6
2017 Airstream Flying Cloud 23FB

Posted By: SFVdave on 05/28/16 10:18pm

CA Traveler wrote:

It's a Class C MH so no 5er or TT issues.
The battery system has the BIM Battery Isolation Manager on a separate fuse and relay panel. This BIM monitors both house and engine batteries and charges both or either when needed (Bi-directional). So it's always powered. It's wired correctly. I either have to add a cutoff for that cable (also has generator, awning, levelers and more on it) or all the negative.

Posted By: wa8yxm on 05/29/16 01:29pm

Some things really need power all the time.. Steps if they are automatic need to extend when door is opened... Explosive Gas, Smoke and CO detectors,, Really should never be disabled.

But yes. you can add a 2nd switch if you wish and kill EVERYTHING.

Depending on where the switch is.. You may also be able to move the positive leads to the switched terminal instead of the battery.

Home is where I park it.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times

Posted By: SFVdave on 05/29/16 01:42pm

Would something like this work?
Inline circuit breaker
I could cut the cable at the battery and insert this.

Posted By: CA Traveler on 05/29/16 02:32pm

Won't work - it must handle the maximum amps, consider inverter or emergency start, etc. Consider something like this switch:

[image]

Posted By: RJsfishin on 05/29/16 05:10pm

Quote:
Some things really need power all the time
----------------------------------------------
Oh no they don't either,....and especially not any memory held items !!! DUH??
The reason for a batt cutoff, is to illuminate any possibility of the batteries being drained. Have to wonder what ever gave you that idea.
And I don't care whats common, or what the factory does, or anything else. I just know whats right.

Oh, to answer the question,...whichever cuts the entire 12v circuit, bar nothing.

Rich

'01 31' Rexall Vision, Generac 5.5k, 1000 watt Honda, PD 9245 conv, 300 watts Solar, 150 watt inv, 2 Cos 6v batts, ammeters, led voltmeters all over the place, KD/sat, 2 Oly Cat heaters w/ ox, and towing a 2012 Liberty, Lowe bass boat, or a Kawi Mule.

Posted By: MEXICOWANDERER on 05/30/16 10:26am

LIFT the negative battery cable from the negative post/

ALL LIGHTS GO OUT
Batteries are wired correctly

ALL LIGHTS DO not GO OUT
Are there wires running to the other 12 volt battery negative? WIRED WRONG

Posted By: Boon Docker on 05/30/16 10:58am

SFVdave wrote:

Would something like this work?
Inline circuit breaker
I could cut the cable at the battery and insert this.

That is what I use for a disconnect, works fine. I use a 150 amp.

Posted By: time2roll on 05/30/16 11:02am

Do you have more than one positive wire coming off the battery?
afaik there should be one wire that goes to the cut-off switch.

If there are other wires I would discover what they are connected to and verify no current flow.

Next is the switch. Again need to discover what is connected to the battery side and what power does it use.

I would tend to rewire and adjust so that the OEM switch does as you expect. Or why have it at all.

2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
675w Solar pictures back up

Posted By: MEXICOWANDERER on 05/30/16 12:14pm

Flooded batteries corrode anything connected to either post.

Connect lots and lots of wire and cables to the two posts

Have lots and lots of corrosion.

Connect one, single cable to battery post and run cable to multiple connect buss bar.

A fraction of the problems

Now which method appeals to you?

Posted By: pianotuna on 05/30/16 12:20pm

I'm a buss man myself. (and balanced, too!)

Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

Posted By: SFVdave on 05/30/16 04:54pm

Here's my battery compartment. Originally, all 4 red cables were on one post. I added the adapter so I could attach the positive for solar and battery monitor from shunt.
">] [image]

* This post was edited 05/30/16 05:06pm by SFVdave *

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