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Author Topic: RV deep cycle system problem  (Read 438 times)

AKRhino

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RV deep cycle system problem
« on: May 30, 2017, 04:49:30 PM »
Hello all, I recently purchased a 1972 Dodge Sportsman RV.  At the time I purchased it, we hooked up the deep cycle battery and tested it (the lights worked).  We also hooked up the exterior power and tested that (the other lights worked, and the fridge worked).  After we tested it I unhooked the battery system, and set about repairing an issue with the roof.  I also threw a solar charger on the deep cycle (which was still disconnected).  Last night I put everything back together but now the 2 lights that operate via the deep cycle don't work.  I traced the wires from the battery forward.  The negative goes to a ground on the transmission, the positive goes up to a black box with a red light on it mounted on the firewall at the back of the engine compartment.  My assumption is that the problem is there, but I have no idea what that thing is.  I figure someone here might be able to point me in the right direction.

TLDR:  My deep cycle battery positive cable goes to a black box with a red light on it (light is off) mounted to the firewall at the back of the engine compartment.  What is it?

Thank you!

Alfa38User

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Re: RV deep cycle system problem
« Reply #1 on: May 31, 2017, 07:08:59 AM »
By any chance, you didn't miss a wire when reconnecting  them at the battery, did you?? Any "spare" wires hanging around there??
Stu
Montréal, Canada 🍁
Snowbird, Naples Florida
Alfa Gold 38 (2000) 5ver (parked!)

"Of course I talk to myself, sometimes I need expert advise!!!"

Gary RV_Wizard

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Re: RV deep cycle system problem
« Reply #2 on: May 31, 2017, 10:01:35 AM »
The black box is may be some sort of isolation solenoid or diode, intended to keep the house deep cycle separate from the chassis 12v system. That assumes this rig has two batteries and isolated 12v systems, which you did not mention.

Dodge didn't build RVs (just the Sportsman van chassis), so it's unclear just what you have. Is it a Class C or class B, and can you identify more about the RV body on it? Photos would help, e.g. the black box and wiring.

Since it worked before, it seems something got messed up when the battery was removed and disconnected. Recheck your wiring, and get some voltage readings on the battery and that black box to help determine what is working and what is not.
Gary
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Kevin Means

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Re: RV deep cycle system problem
« Reply #3 on: May 31, 2017, 10:05:54 AM »
The first thing I'd do is disconnect the battery, let it sit for at least 30 minutes, then measure its voltage with a VOM/volt meter. How old is the battery, what Group is it (24, 27, 31 etc.) and have you checked the water level in its cells?

Kev
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ or an Acura MDX
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AKRhino

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Re: RV deep cycle system problem
« Reply #4 on: May 31, 2017, 11:42:58 AM »
A bit more information, I tested it, and it's got power on either side of the box.  I did find a blown fuse in a different spot where the wire splits, so that may be it?  Still curious what the heck this thing is though.  I took some pictures. 

AKRhino

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Re: RV deep cycle system problem
« Reply #5 on: May 31, 2017, 11:46:33 AM »
The motor home is a 20 foot class C.  It's got some...  issues, but it runs great and drives great, and all the appliances work.  The little stuff can be worked out over time (leak around the A/C, turn signal switch "issues", someone lost the water system drain plug at some point, the radio is only AM...) 

AKRhino

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Re: RV deep cycle system problem
« Reply #6 on: May 31, 2017, 11:50:01 AM »
The black box is may be some sort of isolation solenoid or diode, intended to keep the house deep cycle separate from the chassis 12v system. That assumes this rig has two batteries and isolated 12v systems, which you did not mention.

Dodge didn't build RVs (just the Sportsman van chassis), so it's unclear just what you have. Is it a Class C or class B, and can you identify more about the RV body on it? Photos would help, e.g. the black box and wiring.

Since it worked before, it seems something got messed up when the battery was removed and disconnected. Recheck your wiring, and get some voltage readings on the battery and that black box to help determine what is working and what is not.

Yes, you are correct that there are 2 batteries, and the deep cycle is isolated from the regular vehicle wiring system!  Sorry, I'm extremely new to RV ownership, so I just kind of assumed that's how all systems are, but I guess there's no reason why that would be the case.  I'm extremely new to deep cycle systems, but I'm very familiar with 12V wiring/electronics, so I'm trying to figure it out.  It's tough to find wiring diagrams for systems this old, unfortunately.

NY_Dutch

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Re: RV deep cycle system problem
« Reply #7 on: May 31, 2017, 12:21:19 PM »
I think if you trace the two heavier wires, you'll probably find that one goes to the "house" deep cycle battery, and the other to the "engine" battery. On the right is a relay that likely connects the two batteries together when the engine is running so both can be charged by the alternator. The small silver item with the two terminals is an auto resetting circuit breaker.
Dutch
2001 GBM Landau 34' Class A
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John From Detroit

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Re: RV deep cycle system problem
« Reply #8 on: May 31, 2017, 04:58:41 PM »
Black box with red light,, I can think of several possible answers but "Disconnect" is the primary one that comes to mind... Often operated by a switch just inside the entery door aor a switch marked AUX Battery.
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AKRhino

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Re: RV deep cycle system problem
« Reply #9 on: May 31, 2017, 07:20:41 PM »
Thank you everyone!  You've all been alot of help! 

Utclmjmpr

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Re: RV deep cycle system problem
« Reply #10 on: June 02, 2017, 10:07:56 AM »
 The black box is an old fashioned  relay and in that relay is a circut breaker, it could be used for many different things.>>>Dan
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mel s

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Re: RV deep cycle system problem
« Reply #11 on: June 02, 2017, 02:19:12 PM »
A bit more information, I tested it, and it's got power on either side of the box.  I did find a blown fuse in a different spot where the wire splits, so that may be it?  Still curious what the heck this thing is though.  I took some pictures.

AKRhino
On my Safari coach a relay similar to the one in your picture is wired into the solar charging system.
That relay automatically switches the voltage produced by the roof mounted solar panel FROM the house batteries TO the chassis batteries whenever the coach is plugged in.
(However that is not something I have ever seen, or heard of, on any other coach).

 

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