My new-to-me 2014 Coachmen C (21QB) has no 12 V juice without the generator running. As in, the lights won't even come on. The battery is a cheapo, previous treatment unknown. When I looked at it prior to buying, the generator was running, because it was a really hot day & I wanted to make sure the AC was working.It's possible a light was left on inside the first day I got it home, too. That may have flat-lined the battery in a couple of days.If the 12 V systems work when the generator is running, does that mean the converter is working?If the 12 V systems work when plugged in to 110 V, does that mean the converter is working?The generator hour display has a tiny battery icon and as best as I can see it shows a symbol of a battery charging (zigzag in the icon.) Does that mean that the generator is charging the battery?What battery does the generator use to crank up? It starts just fine.

Sounds like the converter is workingTry this testWith the generator on and you have 12v powerFlip the the battery disconnect switch several timesThe latching relay might be stuckOr if the batteries are discharged the latching disconnect relay might not have enough power to engageCheck to see if the batteries are getting charge voltageSomebody will post where the relays are locatedAnd any fusesGenerator can be wired chassis or houseThe Onan in my RV is wired to the engine battery

1ST. Remove the battery and have it load tested at any auto parts store. 2nd disconnect the output wires of the converter and check the voltage of the 12 volt output terminals.Converter should operate with shore power or generator. It is on it's own 15 amp breaker.

find some body close to you that has a rv get them to walk you threw things. better than throwing money at it. then finding out it was a simple fix.

Dead BatteryTripped circuit breaker or blown fuse. this breaker or fuse should be near the battery and likely is not part of the main fuse panelBad connection battery or ground end of negative cableDisconnect switch in the disconnected position. Defective disconnect solenoid.

does sound like converter is working.There is commonly a circuit breaker or fuse adjacent to the battery(ies). It could be bad. The battery disconnect could be in the off position. Cycle it. You should hear a click out of it. That means the control circuit is good. No click would indicate a bad control circuit power or a bad relay.

No 12 V juice--battery or converter? | Good Sam Community

coolmom42
Explorer II
Sep 06, 2020
MrWizard wrote:
Sounds like the converter is working
Try this test
With the generator on and you have 12v power
Flip the the battery disconnect switch several times
The latching relay might be stuck
Or if the batteries are discharged the latching disconnect relay might not have enough power to engage
Check to see if the batteries are getting charge voltage

Somebody will post where the relays are located
And any fuses

Generator can be wired chassis or house
The Onan in my RV is wired to the engine battery

Thanks!

More questions:

OK does the battery isolation switch totally disconnect the battery from the RV? For some reason, I thought the disconnect was between the house battery and the chassis battery, so you couldn't run down the chassis battery and be stuck. I googled around and found differing info. Can you clarify this for me?
MrWizard
Moderator
Sep 07, 2020
The disconnect
Is for disconnecting the house from the batteries when the RV is stored and Not being used and not on Shore power to maintain the batteries
The connection between chassis and house is normally open and connects automatically only when the engine is running,
From your description the house/RV is completely disconnected from the batteries, they are not being charged, you need to put the disconnect switch back in use mode, it should not drain the engine/chassis batteries
The generator or a large inverter are things that would be connected directly to the batteries and not go thru the battery disconnect relay
coolmom42
Explorer II
Sep 08, 2020
MrWizard wrote:
The disconnect
Is for disconnecting the house from the batteries when the RV is stored and Not being used and not on Shore power to maintain the batteries
The connection between chassis and house is normally open and connects automatically only when the engine is running,
From your description the house/RV is completely disconnected from the batteries, they are not being charged, you need to put the disconnect switch back in use mode, it should not drain the engine/chassis batteries
The generator or a large inverter are things that would be connected directly to the batteries and not go thru the battery disconnect relay

You were correct. The switch was turned to the OFF position! DUH.

I was previously a partner in a TT that did not have a disconnect switch.
MrWizard
Moderator
Sep 08, 2020
Problem solved ... Learning experience acquired
enblethen
Nomad
Sep 09, 2020
Thanks for the update!
coolmom42
Explorer II
Sep 09, 2020
MrWizard wrote:
Problem solved ... Learning experience acquired

Definitely. It doesn't help that the switch labelling is in microscopic letters in a poorly lit location. But now I know which position is for disconnect.
jaycocamprs
Explorer
Sep 10, 2020
But be aware that there are likely still a few things (like the propane detector) that draw electricity even with the disconnect switch "OFF". So for long term storage, disconnect the negative battery cable.
bikendan
Explorer
Sep 10, 2020
jaycocamprs wrote:
But be aware that there are likely still a few things (like the propane detector) that draw electricity even with the disconnect switch "OFF". So for long term storage, disconnect the negative battery cable.

Or install a battery disconnect switch right on the battery. I did and my dual batteries were still nearly fully charged after 4 months of storage.
mchero
Explorer
Sep 10, 2020
bikendan wrote:
jaycocamprs wrote:
But be aware that there are likely still a few things (like the propane detector) that draw electricity even with the disconnect switch "OFF". So for long term storage, disconnect the negative battery cable.

Or install a battery disconnect switch right on the battery. I did and my dual batteries were still nearly fully charged after 4 months of storage.

Good idea!

Forum Discussion

No 12 V juice--battery or converter?

About Technical Issues

Related Content

Not Enough Juice! (Need Help with Coach Battery)

LiFePO4 Converter Change?

Upgrading converter

Replacement catalytic converter

How to test Converter voltage