Why Cant a Trailer Battery be Charged through a 7-Way Trailer Connector

Question:

With a 10awg auxiliary, can my car maintain the rv full 100ah battery when im driving? Should I stay on propaine? A 8 awg with 40amp breaker be better ?

asked by: Dave

Expert Reply:

The 12 volt circuit in a trailer connector can provide a maintenance charge to a trailer mounted battery but it cannot charge it up. The problem is that vehicle alternators cannot push back the amperage needed to charge up a trailer mounted battery. The wiring is also an issue. You would need large gauge wire, like battery cable. But to go from the front of a vehicle to the back would include too much resistance and again you would need a much more powerful alternator to provide adequate amperage to charge up a trailer mounted battery.

So what I recommend is to provide a charge to the battery when parked with access to AC power using a CTEK battery charger # CTEK56353. This charger will also help recondition a battery and won't over charge it.

expert reply by: Michael H