Need the solar/power pros to weigh in

[dreadlocks]

30A is what most have as over-current for on trailer brakes from Vehicle side, I doubt it uses that much and its going to depend on the number of axles.. quick googling says about 4A per brake max, so ~8A for a single, ~16A for a tandem, ~24A for a triple axle. These are usually not fused but have a thermal PTC breaker, so it could self reset if the short was of the intermittent variety.

The brake circuit is going to be variable voltage from the brake controller output, the AUX output on the trailer plug is mostly for battery maintenance (all trailers w/e-brakes have batteries).. due to voltage drop and other things you often dont see more than 5-8A at the trailer battery, and sometimes as much as a half a volt under what the alternator is outputting.. good enough to run your fridge, but rarely does much for the battery, even after a long day on the road.

 

[shade]

30A is what most have as over-current for on trailer brakes from Vehicle side, I doubt it uses that much and its going to depend on the number of axles.. quick googling says about 4A per brake max, so ~8A for a single, ~16A for a tandem, ~24A for a triple axle.

Usually not fused but has a thermal PTC breaker, so it could self reset if the short was of the intermittent variety.

I dug around the eCFR site and didn't find anything about power minimums for the brake or aux circuits. As long as the breakaway system can lock up the trailer brakes for 15 minutes, they don't care how it's powered or charged. I wonder if the Aux circuit shares circuit protection with the brakes.

 

[dreadlocks]

on mine the brakes are always hot (the brake controller is always on) and the aux output is keyed to the ignition.. they wont be on the same circuit on any vehicle unless its wired wrong.. all brake power goes through the brake controller and those usually dont come factory installed.. so it'd be in the manual of brake controller proper connectivity..

I had an OEM harness, just had to make an adapter.. its wiring was same heavy 10 gauge as the controller.. but it was dark wiring until I hooked up brake controller to it.

 

[shade]

on mine the brakes are always hot (the brake controller is always on) and the aux output is keyed to the ignition.. they wont be on the same circuit on any vehicle unless its wired wrong.. all brake power goes through the brake controller and those usually dont come factory installed.. so it'd be in the manual of brake controller proper connectivity..

I had an OEM harness, just had to make an adapter.. its wiring was same heavy 10 gauge as the controller.. but it was dark wiring until I hooked up brake controller to it.

Looking at e-trailer's 7-pole kit, they ship 10 gauge wire for the brake circuit. Iirc, the OEM wiring on my truck was 10 gauge, or a metric equivalent.

Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires e

If your vehicle already has a 4-way flat, this kit includes everything you need to install an electric trailer brake controller and 7-way connector. I

www.etrailer.com

That doesn't answer what gauge is commonly used for the Aux, though. Lighter than 10 AWG, no doubt.

 

[TantoTrailers]

Looking at e-trailer's 7-pole kit, they ship 10 gauge wire for the brake circuit. Iirc, the OEM wiring on my truck was 10 gauge, or a metric equivalent.

Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires e

If your vehicle already has a 4-way flat, this kit includes everything you need to install an electric trailer brake controller and 7-way connector. I

www.etrailer.com

That doesn't answer what gauge is commonly used for the Aux, though. Lighter than 10 AWG, no doubt.

If I'm not mistaken its all 18# for the Aux like the lights.

 

[shade]

If I'm not mistaken its all 18# for the Aux like the lights.

I'm wondering if you're going to reach the minimum input voltage for the Mean Well power supply. If I'm reading the specs right, it requires a minimum of 9.5V input. If your tow vehicle is using 20' (a guess) of 18 AWG at 7A, that will deliver barely more than 10V. Add in voltage drop from connections and circuit protection, and it may be a near thing.

Voltage Drop Calculator

Voltage drop calculator to choose what size wire or cable based on amps, distance and voltage. Marine wire cable amperage and ABYC allowable amps per cable gauge.

www.genuinedealz.com

https://www.meanwell-web.com/content/files/pdfs/productPdfs/MW/SD-100/SD-100-spec.pdf

Try testing the voltage at the input of the Mean Well tomorrow and see what you have to work with.

 

[TantoTrailers]

When I stopped for firewood I checked the voltage at the plug going into the DC converter (12" from the device, 14' from the 7 pin connector) and it was 14.something with the truck running.

 

[shade]

When I stopped for firewood I checked the voltage at the plug going into the DC converter (12" from the device, 14' from the 7 pin connector) and it was 14.something with the truck running.

That's good. I hope a quick adjustment at the power supply is all that's required to set it right.

 

[TantoTrailers]

Testing some solar this morning. Winds are crazy so my portable panels are a challenge but they seem to be doing ok on the awning.

 

[luthj]

Obviously the photos may have been taken at different times. But they show different voltages. I would double check the voltage at the solar controller matches the BMV, and that matches the batteries terminals. Within reason, 0.1V at 10A of charge current is fine at the solar controller. The BMV should show battery voltage accurate to withing 50mv.

I have seen poor wiring connections (and bad solar chargers) which result in lower than desirable voltage at the batteries.

 

[shade]

How about the Mean Well output at the battery?

 

[TantoTrailers]

14.6 at the MPPT, 14.45 on the BMV and 14.57 at the terminals.

 

[TantoTrailers]

How about the Mean Well output at the battery?

Havnt tested the Mean Well yet since it actually uses the same wiring to the battery as the mppt for testing. Everything is on Powerpoles. Seems like I have a bunch of testing to do!

 

[TantoTrailers]

Now were cookin w electric!! Adjusted the little knob till I saw 14.25 on my multimeter in the output of the DC converter and looks like Im generating some power back to the battery! 1 hour drive home should show me any progress.

 

[shade]

Iirc, you have a thermometer in your electrical bay. Have a look at that as soon as you're home, and feel around the gear to see if anything feels particularly hot, including the battery. I doubt one hour in cool temperatures will push anything very hard, but you'd probably rather find a problem now than in June.