[RockyMtnRay]

Originally Posted by hingarfi

Ray said:


Ray I surely agree it sure sounds Rube Golberg. However, even if you had a dedicated separate #8 wire from the TV battery to the TM battery, with NO CONNECTORS, the 12A feeding the refrigerator would cause about 0.5 Volt drop (assuming 60 feet of wire round trip) If TV battery fully charged is 12.7 V, this would put the TM battery voltage at 12.2 V which is about 60% charged battery. I agree running separate 110VAC is bad idea. A separate 12V #12 gauge circuit from TV battery to run the refrigerator would solve the problem since the TM battery would then see the full 12.7V of the TV battery. The refrigerator would see about 12.5 V which should be OK. Again, this is a kluge. There seems to be no easy answer. Fun to discuss though.

Concur that there will be roughly a .5 volt drop from the connection under the TV hood to the TM battery (will vary a bit depending on whether the TM battery is on hitch or in the rear). And your values for the TV battery are correct when the TV engine/charging circuit are not operating.

However, really BIG however, the voltage at the TV battery is NOT 12.7 volts if the TV engine is running and the alternator is spinning. It will in fact be around 14 volts (probably anywhere from about 13.5 to nearly 15 volts, possibly as high as 16 volts). Most TV charge regulators are voltage/current sensing and increase the charging voltage anytime they sense high drain...which is exactly what will be happening with the trailer hooked up and its refer running on DC. Using a nominal voltage of 14 volts at the TV battery, that means the TM battery will be seeing at least 13.5 volts which is at least .8 volts higher than a fully charged battery...and more than enough excess voltage to provide a good rate of charge.

Ergo there is any easy answer and no kluge is required...just run a heavy gauge conductor from the TV charging point back to at least the bargmann connector.