Disabling 12v charging to trailer

[kipkohl]

I want to disable the 12v charge line to my trailer in order to protect my alternator. I have plenty of solar and a converter so I don't really need the charge from the truck, nor do I want to spend MORE money on a DC-DC charger. I've looked through the fuse diagrams and don't see anything that is specific to the 12v pin on the 7 pin connector. Can anyone point me in the right direction?

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[Dgc333]

Why not disconnect it on the trailer side?

 

[mtbikernate]

on my trailer, that 12v wire doesn't do much. just power to the brake system (the signal to engage the brakes is a different wire). it does not send anything to the trailer's battery. the manufacturer strongly recommends against wiring it that way because the wire gauges aren't large enough to send a terribly useful amount of power.

that's not saying that the mfr of your trailer didn't wire it that way, though.

I'd start by looking at the junction box for that 7 pin connector to see what's attached to that. then try to trace the wires to see if one of them heads to the trailer's power system at all.

 

[airline tech]

Pin 5 of the trailer connector (7-Pin) is for charging. This wire is direct from the TRM

Now, power feed (Fused) to the TRM , for battery charging is Fuse 73 in the Eng Bay fuse box.
In looking into the troubleshoot for the system (Trailer Charging) it has you check Fuse 73

Now, I am not sure if pulling that fuse will create faults.
Plus I cannot see where the TRM gets the information that a trailer is connected / disconnected.
It is through the Data network, and may be looking for power from that fuse (communication)

 

[kipkohl]

Why not disconnect it on the trailer side?

Well that might work if I can figure out the rats nest of wiring in the junction box. Thanks

 

[Fawnbuster]

Well that might work if I can figure out the rats nest of wiring in the junction box. Thanks

Can't you just unplug it at the rear bumper of the truck?

 

[dmeyer302]

Pin 5 of the trailer connector (7-Pin) is for charging. This wire is direct from the TRM

Now, power feed (Fused) to the TRM , for battery charging is Fuse 73 in the Eng Bay fuse box.
In looking into the troubleshoot for the system (Trailer Charging) it has you check Fuse 73

Now, I am not sure if pulling that fuse will create faults.
Plus I cannot see where the TRM gets the information that a trailer is connected / disconnected.
It is through the Data network, and may be looking for power from that fuse (communication)

I would try pulling this fuse first. I don't think it should cause any faults, but it would be a good idea to verify that everything else is working before you take off down the road.

 

[Old Red Replacement]

The TCM will sense your battery is charged, and not send power back there,
your overthinking something already controlled by trucks computer.

It also only works in tow mode with trailer connected activated by being in gear and stepping on brakes.

I check mine is connected to the truck charges batteries to run 12 V fridge in route to campsite. Easy to do if your camper has 12V meter.

 

[Dgc333]

The TCM will sense your battery is charged, and not send power back there,
your overthinking something already controlled by trucks computer.

It also only works in tow mode with trailer connected activated by being in gear and stepping on brakes.

I check mine is connected to the truck charges batteries to run 12 V fridge in route to campsite. Easy to do if your camper has 12V meter.

I have a volt meter in my truck and when towing my camper the battery management systems quite often turns down the charge voltage to low 13s so even with the alternator charging the camper batteries the alternator is not being over worked.

 

[Nellieg]

Would advise against. Would be precautionary for a battery failure while camping... You would have trouble towing if trailer batteries/power system failed.

 

[Dgc333]

You would have trouble towing if trailer batteries/power system failed.

Other than during an emergency where the trailer separated from the truck and the batteries were needed for applying the trailer brakes the trailer batteries aren't used during towing.

 

[kipkohl]

I have a volt meter in my truck and when towing my camper the battery management systems quite often turns down the charge voltage to low 13s so even with the alternator charging the camper batteries the alternator is not being over worked

I keep reading that the LIFePO4 batteries might try to draw too much from the alternator if they are at a low charge state. So I'm really confused about whether I need to worry about this or not.

 

[Dgc333]

I don't know anything about LIFePO4 batteries, I just have deep cycle marine batteries in mine. They hold their charge between uses and during the winter I keep them in the garage on a battery tender.

 

[mtbikernate]

LiFePO4 batteries definitely need different charging protocols than other battery chemistries.

I definitely wouldn't want to be sending juice into one without the right kind of charge monitor.

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