Battery Ground Disconnect Switch

[PARAPTOR]

Just came in (yesterday 9th), yes I finally got out, temps reached 50 degrees however, as illustrated in the picture got ~3-4 inches last night. I planned on installing a battery disconnect switch this season so just wanted to check out the current battery wiring. 2 gauge wire was used to connect the two 12 volt batteries in parallel, since battery box covers were on I could only see wires coming out of those boxes. At first glance only seen one white 6 gauge wire coming out of the box and attached to a ground screw in the frame near the battery boxes. Black 6 gauge coming out of battery box terminated on a terminal block with other direct connect circuits, one of these feeding the Raptor power distribution panel etc.

Since the connecting wires were 2 gauge between the batteries, I was expecting a 2 gauge wire also going to ground. After looking closer with a light the lug on the end of the 6 gauge wire attached to the ground screw had barely any marks on the plastic insulation. Grabbed on to the wire and with minimum force it came out of the grounded lug?? Looked like someone had tried to crimp the lug with tweezers. When the wire come off noticed that the light in the battery compartment stayed on ???? OOPs, this wire not ground wire????

After looking around found a couple groupings of wires coming out of the battery box and heading toward the generator, after tracing one of the groupings, a 2 gauge wire came from the bottom of the battery box and the other end was grounded to the generator itself in the generator compartment. This explains why that white 6 gauge wire that came loose had no effect on the operation of the Raptor including that light that stayed on.

Okay having not seen many rigs, here are my questions:

If the Raptor did not have the generator option installed would the normal ground wire be only that 6 gauge wire? ie no 2 gauge ground
Was that 2 gauge ground added to support generator start currents?
Should the 6 gauge battery ground have been removed when generator was installed? Since when this wire came out of the lug, ground disconnected, it had no effect on the Raptor 12V system.

My plan was to install a battery disconnect on the grounded negative side of the battery. Given the battery had two grounds, a 2 gauge grounded to the generator and the 6 gauge grounded to the frame in the battery compartment, I am assuming that the 6 gauge ground wire needs to be removed or in this case not put back on. This wire would basically parallel the proposed battery disconnect switch defeating its purpose. The new battery disconnect switch will be added between the negative post of the battery and the current 2 gauge wire going to the generator frame. The existing 2 gauge grounded wire will be disconnected from the battery and connected to one side of the Blue Sea battery switch and the existing 2 gauge grounded wire will go on the other terminal of the battery switch. May have to lookup starting current on the Onan 5500. Switch spec 900A cranking amps for 30 sec so not much concern there. Plan on adding a 100Amp shunt in series with the this switch so want to no cranking amps of Onan

I am looking for answers to my questions as well as does anyone one see any issues with what I am planning to do. When snow melts again !!!

Thanks

[JRTJH]

You're going to get the "ford/chevy" argument about whether to use the negative or the positive cable to install your cut-off switch. That said, mine is on the negative terminal and has been on every trailer I've owned since 1972 and they all have worked without any failures, so I see no reason to change.

As for "dual cables" from the negative battery terminal, depending on how your specific trailer is wired, you may find two or three cables going to ground. I only have one that physically attaches to the battery terminal, but on the chassis bolt that the other end of that cable attaches to are 4 cables. The one from the battery, one from the running lights, one from the remote control "brain" and one from the converter system (cabin 12 VDC). I'd suspect that if my trailer was "prepped for a generator" there would have to be another cable going to the generator electrical system ground. Depending on the physical location of the "ground bolt", the "battery terminal" and the "generator ground cable", the actual location where those three circuits is grounded would be more from convenience and physical layout. The "electrical circuit ground" would be the same regardless of where the ground cables are attached.

Thinking about it, there are 5 cables attached to the negative terminal on my boat "accessory battery" and there is no "ground terminal strip" . Essentially, I'd suppose that the 4 cables on my trailer ground bolt effectively serve as a "ground terminal strip"...

I'd say that as long as you place the cut-off switch between "all the ground cables" and the battery, it will effectively remove all power drain from the battery circuit. If, however, there's a "phantom cable" that remains physically connected to the battery negative terminal "somewhere".... well you're still subject to "phantom drains" .....

Confused??? Heck now I am too......

ADDED: As for the 6 ga and the 2 ga cables, I'd think that the cable size is dependent more upon length of the cable and amperage draw of the circuit. So, a 1 foot 6 ga cable may run from the battery ground to chassis and be sufficient to carry the load while a 2 ga cable may be necessary to run 10' to the generator and be required to carry the amperage load for that distance, even though it's connected to a "buss bar" which has a 6 ga cable to the battery. "conventional wisdom" is that all cables should be the same size, and that's what I typically see in "home brewed wiring" but in aircraft, where weight and size are considerations, I've seen a number of applications where different size wires are used on the same "buss bar" including those where the "main connection to power" is smaller than some of the longer runs.

[PARAPTOR]

Thanks John
"ford/chevy" discussions much more reasonable than the "I can tow that" ones :D Let me see if I can clarify my question. Have enough snow outside :banghead:

[canesfan]

Let me ask a stupid question. :D Are your 2 12V batteries both coach batteries? I have 2 but one is the coach battery and the other is the genny start battery I had added. They are wired through an isolator I think? So the wiring looks weird from a "normal" setup. I can't remember the wiring size now and it's gotten cold and windy and I don't feeling like going out there after it's been in the 70s. Keep that white stuff up there. :hide:

[PARAPTOR]

Let me ask a stupid question. :D Are your 2 12V batteries both coach batteries? I have 2 but one is the coach battery and the other is the genny start battery I had added. They are wired through an isolator I think? So the wiring looks weird from a "normal" setup. I can't remember the wiring size now and it's gotten cold and windy and I don't feeling like going out there after it's been in the 70s. Keep that white stuff up there. :hide:

I am currently tangled in the undies, but yes I remember years ago you mentioned a genny battery, like your folding ladder I do not have that :banghead: If I recall:confused: from that post you also are charging that dedicated genny battery from your converter?? As you can see from the picture in the previous post few inches snow out there :eek: Soooo this old guy not going out.

I have two coach batteries, genny starts off these batteries. I am going to read over what I wrote in my original post to see if I can clarify what I am trying to say/Ask. Are you sure you do not want some white stuff ???

[sourdough]

This might be oversimplified, but, in a 12vdc system it doesn't really matter how many grounds you have as long as each device is wired with the proper gauge to carry the load that device will use and they all return to the common ground. They will be much larger for the battery because all the load comes back to it (them). If a wire is ran to support multiple devices then the gauge needs to be sufficient to carry the load of all the devices combined. DC is pretty simple; just think of it as battery always searching for ground. Put something in between the positive as it looks for ground and make it perform a function. The ground has to be common back to the battery....ie: frame (or secondary wire).

In your case (if I understand it correctly), I would place a #2 from the battery negative post to a frame mounted cutoff. From the cutoff run the existing wire to the generator and a #2 (properly crimped;) ) to a good frame ground - you should be good.

[Mwoods321]

Sir, if I install a battery disconnect that actually disconnects the battery from all the other stuff will that prevent my battery from going dead during the off season?

[Tinner12002]

I agree with John in that it shouldn't matter which side you put your disconnect on it should work fine, but only if that's the only ground from your batteries. It sounds like you have a grd on each battery instead of the batteries being linked together with only one grd wire. As for your wiring for the gen, I have a separate wire that runs up to the top of my battery compartment through a couple of breakers that powers the level-up and I believe my gen, that's where I added a second disconnect. I have one grd to my top battery and one positive to my bot battery with the 3rd or middle battery connected to both with jumpers. I know I have parasitic drain still so I intend to install a second disconnect in either the pos or neg main cable whichever is easiest to get to but it makes no difference which as long as there is only 1 grd for all the batteries. Hopefully I understood your questions and maybe answered a ques or two.

[notanlines]

Mike, "will that prevent my battery from going dead during the off season? " no it will not, but it will slow it down considerably. You will still need to leave a trickle charger on your rig or remove the battery and bring it home to trickle charge.