DC side issue Coach Batts not charging

wa8yxm wrote:
There are exceptions but basically here are the switch position explanations and options.

Main = Coach chassis battery, this is the one that cranks up the main engine
AUX = House battery, this is the one that lights and heats your life, cools your food and controls all the stuff that makes you comfortable. It likely also runs the slides in and out.

They must be in the ON or USE position for the house converter to charge them.

NOW: the house converter... IF the original batteries which you were told were good were stone dead.. they may have shorted and popped some fuses on the converter..

OR: the converter may have died for other reasons.. here is a quick check.

Plug in, with the AUX switch off for at least a minute,, Do the house lights still work? NO = Bad converter UNLESS you have a big inverter in which case it depends on how it's wired. (inverters may be wired in before the AUX switch)

But if you do not have such an inverter AUX-OFF they will not charge.

Finally: SOME motor homes... The house will charge the chassis provided it is connected.. Some.. it will not,, Some does not matter if connected or not. As you can see,, OPTIONS... alas, you need someone to look over your coach (Fellow RVer can do it) to figure out this.

1. MOST motorhomes will still operate the 12 volt coach systems on Converter or Inverter/Charger IF the Battery disconnect is off. Some do require the Battery disconnect to be ON before Converter power is supplied, but very few, so your test for the 1 minute is NOT a valid test with the Aux off.
2. NO correct "large" Inverter/Charger will ever be connected thru the battery disconnect. MOST battery disconnects have a 100 amp DC limit. Large (over 1500 watt) Inverter/Chargers will go over 200 amps in Invert mode. You ALWAYS connect the battery cables direct to the large Inverter/chargers thru a 250 to 300 amp DC fuse. Doug