First: IF the batteries are disconnected.. In "Store" mode. they WILL NOT CHARGE and in fact the generator should not start either.
If the batteries are not being charged by the generator first check the breakers on the Genny. Should be two. if your rig is 50 amps one runs half the RV the other the other half ONE runs the converter. (It is on one or the other halves)
On a 30 amp RV one runs most everything the other one A/C.
Then check the breaker box. Make sure you don't have a tripped CONV breaker (I've had that)
IF like mine your converter is a "plug in" model. Make sure it's plugged in (YES I've had to do that several times)
Now we test the converter itself. And post the results.
Measure output voltage
There may also be a fuse or trippe circuit breaker in the line.
IF you have a big INVERTER/CHARGER.. Well post that and we will modify the sequence.
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