Charging trailer battery

mthiker33 · 04-20-2014, 05:38 PM

My tow vehicle (2014 Jeep GC) has factory tow package with constant 12 volt pin in the 7 pin connector for charging trailer battery. Problem: my 2014 Fun Finder 189FBS shows no voltage getting to the trailer battery from my tow vehicle. Jeep is wired correctly (checked with voltmeter). I checked the wires to the battery + side while the tow vehicle was plugged into the trailer and trailer battery was removed. With tow vehicle running, shouldn't there be voltage on one of the wires that is normally attached to the trailer battery + side? This a new (2014) trailer that we've only had two weeks. I think the trailer wiring is messed up but before I take it back for service I want to see if my assumptions are correct.

Citycamper · 04-21-2014, 07:12 AM

Make sure that your battery cut off switch is turned on. If not you will have no voltage from the tow vehicle to the RV.

mthiker33 · 04-22-2014, 09:28 PM

Citycamper:
I checked and the battery disconnect switch is in the ON or Connect position.
No juice to battery when connected to tow vehicle.
Thanks for responding.

profdant139 · 04-23-2014, 11:21 AM

I realize this is kind of basic, but when the trailer is hooked up to the tow vehicle, and you turn on the turn signal, do the lights on the back of the trailer blink? Sometimes, the plug does not seat well into the socket, and no power flows to the trailer.

mthiker33 · 04-25-2014, 05:54 PM

Today I hooked up my tow vehicle to the seven pin connector on the trailer. I checked voltage on the trailer battery before and after hookup to tow vehicle. There was no change to trailer battery voltage when the tow vehicle was connected and running. I disconnected the tow vehicle from the trailer and removed the battery. With my voltmeter set on ohms I traced the +12 volt wire from the trailer connector to a junction box on the trailer tongue. This wire is attached to a wire that runs back and is attached to the Battery Disconnect Switch. This doesn't seem right to me but hopefully someone out there can tell me if this is correct wiring. Why would the +12 volts wire from tow vehicle go directly to battery disconnect switch? I would think the battery disconnect switch disconnects the trailer battery from all circuits.
By the way, with the trailer battery connected and tow vehicle disconnected, I plugged in the 120 volt plug and the trailer battery voltage went from 12.1 volts to over 13.4 volts so the battery is being charged when connected to shore power. Just trying to figure why the tow vehicle isn't charging the trailer battery when towing.
Thank you.

Kafn8td · 04-25-2014, 06:47 PM

What you are describing sounds correct to me. The battery disconnect needs to be on to charge from the truck, so that sounds correct.
If I get a chance tomorrow I will hook mine up and see what the voltage change is.

looking4fun · 04-27-2014, 08:18 PM

I believe you would want your battery disconnect in the connected position no matter what while towing. Because if its not on you will not have any power to the break away switch if your trailer ever became uncoupled. I don't see an issue with the power feed going to the battery disconnect because it should be on while towing. Atleast thats how my trailer is set up.

Eagle · 04-30-2014, 03:48 PM

I leave my battery disconnect switch in the 'on' aka pulled out all the time.

What is the purpose of turning it off aka pushed in? Why not just eliminate it all together?

LINERGUY · 04-30-2014, 08:50 PM

I turn mine off when I'm not using the trailer to stop parasitic draw from draining down the battery.
I put a plastic "turn" type cutoff switch in after something shifted in the cargo area and pushed in the disconnect switch shutting off the refrigerator.
LINERGUY

Eagle · 05-02-2014, 03:56 AM

Yea, never thought about that as when mine is at home, it's hooked to shore power and when stored for the winter, the battery is removed.

DiverRick · 05-16-2014, 01:11 PM

Since your vehicle is new, maybe you have the same problem I ran into.

I found out the hard way that my then new GMC pick up was delivered without the fuse installed that powers the line to the trailer for charging! Went through three replacement batteries over two summers until my trailer dealer suggested the fix!

Everything else working fine (lights, signals, electric brakes) and the trailer battery charged fine when I was hooked up to 110v. But it would mysteriously not charge while driving & hooked up to our vehicle. $4 later problem solved.

Is it possible your Jeep is missing the same fuse? Will be easy to check at least. Good luck.