Troubleshooting 12V Trailer Power to Charge Dump Trailer Battery

Question:

I just bought a 2020 chevy 2500hd diesel and the dump trailer i tow all the time isnt getting the battery charged to dump it all lights and trailer brakes work but wont charge the battery i went back to dealer because i wasnt sure if there was a wire that needed to be connected like in my last truck but the mechanic had no idea what i was talking about is it just the wire i need to connect to the fuse box terminal again or do the 2020s not have a wire that does that?

asked by: Jory

Expert Reply:

The 12v power output on your 7-way trailer connector at the 1 o'clock position should be tested. There is not a wire like in the older models that needs to be installed for that function, but if you aren't getting power when tested with a circuit tester like # PTW2993 or a multimeter like # PT89ZR then you will know there is an issue. You can check the connections for bent pins or the fuses and relays as outlined in your owner's manual.

If you have power at that pin, then it is likely your dump trailer needs assistance in charging the battery which isn't uncommon. The battery will only get about 2 amps charging (whatever the vehicle isn't using that is put out by the alternator) while being towed so that couldn't charge a low battery unless you were literally driving hours between using the dump trailer. Newer vehicles often have a "smart alternator" to save creating too much energy (saving fuel) but that actually works against charging trailer batteries. My recommendation is to add a battery charge line like the Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp # 331-BCDC1225D. This will charge your battery much faster and ensure your trailer will be able to dump when needed because the battery will be charged and maintained on the go.

expert reply by: Jason S