Can 7-Way 12 Volt Accessory Circuit be Used to Power Dometic PerfectPower Battery Charger  

Thank you so much.

Hi Mike, I recently installed a Dometic charger. This charger is capable of doing so much more than limiting amperage draw from your vehicle. It does take some understanding of how the electrical system works. The charger does require 2 positive power wires feeding the charger, one for load, one to turn the charger on and off. Depending on your vehicle, you may be able to use one power wire for both. The reason I say this, is some vehicles 12 volt auxiliary in the 7 way are turned on and off with the ignition switch, others stay on constantly. The vehicle I used happened to be constant power supply, so I did some rewiring. I also really needed 2 power supplies from the truck, because the trailer has electric over hydraulic brakes and breakaway that I needed to be on an isolated circuit from all the other 12 volt things being supplied by the battery being charged by the Dometic (I did use the factory wire to turn the charger on and off, but that’s very minimal amperage draw). I installed a relay on the factory 12 volt supply to turn it on and off with the ignition switch, and I ran a fused power supply directly from the vehicle battery through the center terminal of the 7 way. So far so good, I’m very happy with the results.

As Mike said in his 01/30/26 reply, this is a great 12 volt Battery Charger. It will take the 12 volts coming from the tow vehicle and regulate it so you don't overcharge or damage your "trailer" battery . He points out correctly that the 12 volt auxiliary feed from the tow vehicle is up to the job of feeding your battery charger. I just ran a jumper wire from the 12 volt input at the back of the charger to the 12 volt "switching" input at the front of the charger. On my truck this works well because the factory 12 volt setup on my truck is only hot when the truck is running. this way the charger can't discharge the tow vehicle battery when the engine is not running. My truck is a 2016 Chevy with the "smart" charging system . This means that the alternator is turned on to full charge when the truck is first started, but minutes afterwords the computer controls the charging rate (voltage at the battery) based on the truck's battery need. You have to be very careful when adding a second battery to this kind of charging system. This battery charger solves this problem because to my truck computer, this second battery just looks like a regular 12 volt load. Also, when the battery charger is not turned on it does not seem to drain the auxiliary battery.