RV Battery Isolator?

[MojaveJoe]

I have a 2005 ToyHauler with a dual battery pack. I don't think there is an isolator on the TH to prevent it from drawing down my Ram batteries when hooked up and not running.



Does my Dodge have an isolator in the OEM trailer wiring system to prevent the towed vehicle from draining the truck batteries?



Any and all advice or experiences welcome.

 

[Bob4x4]

No isolator is on the Dodge. If you are concerned just unplug the trailer from the truck

 

[DonFitzwater]

As far as I know, no power should be present unless your truck lights are on or pedal applied. Anyone else want to chime in on that?

 

[Bob4x4]

The 7 way trailer connector ALWAYS has power

 

[Bob4x4]

WIRING-TRAILER TOW 7-WAY - 10 WAY CAV CIRCUIT FUNCTION

1 - -

2 L674 18LG TRAILER TOW RIGHT TURN RELAY OUTPUT

3 L1 18WT/LG BACKUP LAMP FEED

4 A100 14RD/VT FUSED B(+)

5 L678 18BR FUSED PARK LAMP RELAY OUTPUT

6 - -

7 B40 14DG TRAILER TOW BRAKE B(+)

8 Z999 14BK GROUND

9 Z999 14BK GROUND

10 L673 18YL TRAILER TOW LEFT TURN RELAY OUTPUT



Pin 4 always hot... ... ...

 

[Motorhead]

My second gen was also the same way. I just unplugged the trailer if I was concerned about the trucks battery drain. I guess you could install an ignition controlled relay in between the #4 trailer tow plug pin and the fuse panel.

 

[SierraRam]

There is no isolater, the triler plug unplugged is the isolator.

 

[Grizzly]

I have an isolator on my 05 Dodge, as I did on my 95, just in case I forget to unplug. I installed it for my Lance truck camper at the time. It's almost a must with a truck camper. It's just good insurance.



george

 

[MojaveJoe]

Grizzly... where did you install your isolator? Not sure the added resistance in the circuit would be a good idea in my setup. But might be worth a try someday. Right now I usually just disconnect.

Anyone know where the trailer connector power wire hooks into my Dodge.

 

[SBall]

MojaveJoe,
I elected to install a voltage sensing relay which automatically combines batteries when a charging voltage is present, and automatically separates the two batteries when not. Not wanting to mount it on the firewall of the truck, I installed in under the sink of my camper instead where I had plenty of room. I also installed a toggle switch along side the voltage sensing relay to take advantage of the manual functions of the relay which are very handy.

The other advantage of the voltage sensing relay is (unlike diode isolators) that it is relay-based so there is negligible if any voltage drop. The camper batteries have a better chance to reach full charge from the truck's alternator with a relay, than with a diode isolator.

Google "voltage sensing relay" and see what comes up. I bought mine maybe 10 years ago from West Marine.

Steve

 

[jelag]

Experience has shown that we can dry camp for 3-4 days on the batteries with no problem... the key is we don't water manage well enough to dry camp more than that. . so our need to top off the water tank and drain the black water tank exceeds the need of the batteries... If I know we are going to be out 3-4 days without running the truck I will dis-connect the trailer plug...

We've installed an 8 gauge wire from the truck batteries to the trailer connector as well as a 8 gauge ground... we've also replaced the related wires in our 5er... the reason is we noticed that some days, when its really hot and the ECM has reduced the output voltage of the alternator we don't charge the trailer batteries... the larger wire raised the voltage at the trailer batteries during a fast idle by almost 1 volt...

 

[Grizzly]

Grizzly... where did you install your isolator? Not sure the added resistance in the circuit would be a good idea in my setup. But might be worth a try someday. Right now I usually just disconnect.



Anyone know where the trailer connector power wire hooks into my Dodge.

It's on the driver's side near the firewall. It's connected to a #8 wire to the camper plug. It was installed by the RV shop that set up my 05 Dodge when it was new for the Lance camper I had at the time. I still use it with my Arctic Fox 5er. Many time we'll camp without unhitching and unplugging. Some people use a relay switch. I was told that an isolator is much better due to resistance.



george

 

[Bob4x4]

The contact points will build up resistance over time. The electronic isolators generally do not but I have replaced a few that dropped voltage through them as well as a few that shorted out allowing a draw when off.