Battery Disconnect Warning 2020 3740BH

[mridgewayii]

Hello everyone. Putting this out as a public service message of sorts to check your battery cable wiring.

I recently decided to take out the poor Marine batteries and install two 6v strings of cart batteries as we do a great deal of off grid camping. Long story short, our unit has a DC junction strip in the front as well as a battery disconnect that is actually operated from the storage compartment. I unplugged the ac to disable the rectifier and turned the battery disconnect to off.

Low and behold, I had 12.4 V on both sides of the disconnect. I had to pull the cables and trace it out but they had the battery positive connect to the distribution / buss bar directly and a cable from the buss bar to the disconnect then a cable from the disconnect going into the fuse panel in the camper. So, battery was being applied to the camper before the disconnect was introduced.

We all hope fires due to shorts don’t happen but this could be a life or death situation or at least cause a total loss should a short occur and you can’t disconnect the power source.

Please check your voltage on both sides of your battery disconnects with it turned off. If you have 12V on both sides with it turned off - something is wrong!

Stay safe and happy camping

[ad4645]

I have the same trailer and the 2 marine batteries were discharged to 50% in 2 weeks with the battery disconnect engaged. I am not sure why they even have that since it defeats the purpose of having a battery disconnect. I even contacted GD to see what was draining the batteries and they could not give me a definitive answer. They need to change the battery disconnect to be a true disconnect and not there for window dressing.

[FT4NOW]

This is very common and not isolated to GD. There are parasitic loads that come off the battery before the disconnect (Propane detector, radio memory, leveling system, brake away switch, sometimes some other loads). If you want a true disconnect you will have to either add one yourself or re-wire it. Regardless of that fact, whenever working with electricity you should always check it dead to be on the safe side.

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[mridgewayii]

In my case it was definitely a design issue in the wiring or they just connected it wrong at the factory.

FT4NOW, I agree with regarding parasitic loads and you will never get away from those but to wire anything before the battery disconnect is completely defeating the purpose. The disconnect is there for safety reasons first and convenience second (not having to manually disconnect your batteries in storage).

[FT4NOW]

In my case it was definitely a design issue in the wiring or they just connected it wrong at the factory.

FT4NOW, I agree with regarding parasitic loads and you will never get away from those but to wire anything before the battery disconnect is completely defeating the purpose. The disconnect is there for safety reasons first and convenience second (not having to manually disconnect your batteries in storage).

You know, I re-read your initial post and now see what you are talking about. Yes, in your case I think they miswired the disconnect switch. Either way, at least you realized and it didnt shock you. GD's wiring isnt exactly setting an industry standard for anything, wait until you see under the coroplast or behind the walls in the basement. Once you see that you will see why your disconnect switch wasnt wired properly.

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[TNFSolitude]

Once we learned the disconnect was not absolute many of us bought quick disconnect adapters for the negative cable at the battery.

[traveldawg]

Once we learned the disconnect was not absolute many of us bought quick disconnect adapters for the negative cable at the battery.

Ditto... I've actually put the negative lead to a disconnect switch in some of the RVs I've owned. It's is about the only way to be certain the batteries are disconnected.

It looks like in this case GD messed up.

I rewired my rig so the disconnect turns everything off except the break-away switch.

[315RLTSinPA]

Not sure why so many people add another disconnect. There's nothing wrong with the factory disconnect. It's just the way things are wired. Switch a few wires around and all is well. The only things live on ours are the breakaway and I made the tongue jack live in case the trailer is in for some type of service and they need to hitch it up.

[pmonte77]

Hi ad4645,

I have ordered a 3740BH and while I'm waiting, I downloaded and read the owners manual. On page 92 they state to in order to disconnect the auxiliary power (battery) turn the Battery Disconnect Switch to the OFF position and REMOVE key. They then state that all 12-Volt safety items WILL REMAIN OPERATIONAL. They then state if the RV will be in STORAGE: Also DISCONNECT the battery cables from the auxiliary battery terminals. See page 178, Winterizing/RV Storage Preparation #12 . Step 12 states DISCONNECT the battery cables from the auxiliary battery terminals & REMOVE all batteries from the RV. Store batteries in a place where they will not freeze.
If a battery is frozen, it will no longer hold a proper charge.
So not sure what components make up the 12-Volt safety items but for some reason they discharged your batteries. Maybe you can call them back and site these references in their User Manual and see if they can shed any more light on this topic for you. Hopefully this helps.

[SoberRider]

I recently had an opportunity to purchase a 2015 Momentum 385th. I could not understand why the battery kept going dead. The previous owner had put in an AGM battery. I would charge the battery and it would be dead the following week. I could not figure it out. I was then perplexed when I lost all power from the battery and could not get any systems to operate without the unit plugged into my truck. The generator would not even power up the systems. I thought something was going on with the disconnect. I thought I had left it on when the battery went dead. I was at my wits end with the unit. I decided to dig into the issue and find out why the battery kept going dead. I pulled the battery, charged it, and reinstalled it. I left it unhooked at the negative terminal. A week later, I had a full charge on the battery. I found the main breaker that the battery hooked to on the junction strip was bad. I began to research this problem, and agree that the disconnect should disconnect all systems (less the breakaway switch) for safety reasons. I will rewire it this week and I WILL USE THE DISCONNECT SWITCH as it should be. I agree with 315RLTsinPA that the switch that is there should be adequate for the disconnect. I see no reason to reinvent the wheel.