Interior lights won't stay on.

[Airboutique]

I replaced the battery thinking that was the problem but they don't stay on very long. The converter also has to be off as when it is switched on the lights go off ??? What else should I check??? The lights use to work regardless of whether the converter was off or on. Any suggestions?

Thanks!

[overlander63]

Check all the fuses. Also, if it's the original Univolt, I'd consider replacing it as well. Even if the original still works, it's hard on the battery, and the new ones are so much lighter you will actually gain 25 or so pounds of cargo capacity.

[Inland RV Center, In]

Originally Posted by Airboutique

I replaced the battery thinking that was the problem but they don't stay on very long. The converter also has to be off as when it is switched on the lights go off ??? What else should I check??? The lights use to work regardless of whether the converter was off or on. Any suggestions?

Thanks!

If the lights worked before and all you did was change the battery, then most likely you wired the battery "backwards".

Andy

[Rebee]

Look for corroded ground wires, probably in a terminal block. Make sure you have a good ground to the trailer chissis. Wiggle ground wires and see if lights flicker.

[Inland RV Center, In]

Originally Posted by Airboutique

I replaced the battery thinking that was the problem but they don't stay on very long. The converter also has to be off as when it is switched on the lights go off ??? What else should I check??? The lights use to work regardless of whether the converter was off or on. Any suggestions?

Thanks!

Possibly the light switches are now bad.

Andy

[edglenn]

I think Andy's right. (He usually is, that's why he's the "Airstream Guru".)
The battery is installed backwards, or was charged backwards. When you turn on the Univolt, it's fighting against the battery, making zero volts and the lights go out.
With the Univolt OFF, the battery is operating the lights, but probably in reverse voltage (batteries CAN be charged backwards), so it drains right away, and the lights are probably dim. Can be hard on switch contacts, too.
You may have other, hidden damage, including a fried refrigerator board, furnace, and hot water heater, if the voltage were indeed reversed.
Please let us know what you found.

[overlander63]

Originally Posted by edglenn

I think Andy's right. (He usually is, that's why he's the "Airstream Guru".)
The battery is installed backwards, or was charged backwards. When you turn on the Univolt, it's fighting against the battery, making zero volts and the lights go out.
With the Univolt OFF, the battery is operating the lights, but probably in reverse voltage (batteries CAN be charged backwards), so it drains right away, and the lights are probably dim. Can be hard on switch contacts, too.
You may have other, hidden damage, including a fried refrigerator board, furnace, and hot water heater, if the voltage were indeed reversed.
Please let us know what you found.

If a battery was charged backwards, what would happen is it would be discharged really fast, then charged back up with positive post now negative. The effect would merely make the charge (and the life of the battery) a lot shorter. It would not do as described.

[edglenn]

Originally Posted by overlander63

If a battery was charged backwards, what would happen is it would be discharged really fast, then charged back up with positive post now negative. The effect would merely make the charge (and the life of the battery) a lot shorter. It would not do as described.

Well, let's back up and review. This was the origianal post:
"I replaced the battery thinking that was the problem but they don't stay on very long. The converter also has to be off as when it is switched on the lights go off ??? What else should I check??? The lights use to work regardless of whether the converter was off or on. Any suggestions?"

So, maybe there was a problem with the wiring PRIOR to replacing the battery (note: "replaced", not re-charged), but the lights DID work before, with or without the Univolt. They just didn't last very long (SO THAT problem hasn't gone away), from what I infer from the original post. That would seem to indicate a bad battery (or a high discharge/wiring short). So, the only change to the equation was a new battery. Now the lights only work when the Univolt is turned OFF. I'm thinking zero voltage differential (reversed battery) with the Univolt ON, and battery voltage with the Univolt OFF.
I agree with you that the battery would be charged backwards and wouldn't last as long, but unless there's something else not mentioned, the only thing different is a new battery.
So, what else can cause the Univolt to "drop out" and not provide 12 vdc to the cabin lights when it's plugged in? Also, can the battery operate the lights with the Univolt turned off, more than once? The battery has to become discharged sooner or later, so how does it get recharged?
If the Univolt is bad, then the battery can't get recharged, and the lights won't go on for a second time.
I don't know, but I still suspect a reversed battery.
I could be wrong. I've been wrong before, and I'm sure I'll be wrong again.

[Hibby]

Perhaps a stupid question, but can I assume that you are leaving the battery switch ON when plugged into shore power or towing? Otherwise, your battery may not be taking a charge, and drains quickly when you turn on the lights.

I had a friend who thought he was supposed to leave the switch off all the time unless going "off the grid". When I got to where I was going, everything was dead. I mean he.

The reversed battery sounds probable, but the original problem (before replacing the battery) might be attributable to this...

[overlander63]

There's also a large (usually 40 or 50 amp) fuse going to ground. If something got connected backwards, that fuse should have blown. Now, that fuse could also have a bad connection, allowing the small draw from some lights, but when the converter kicks on to charge with a much larger load, the connection (say from corrosion) could fail until that "load" is removed.

[edglenn]

Airboutique, I'm not sure we answered your question at this point.
You've been pretty darn quiet, too !
Maybe we need a little more information and background.
What WAS the original problem?
Have you examined all the connections, and fuses?
Did you check all the switches? Breakers?
Do you have a digital multimeter? A test light won't suffice. You need to be able to check polarity, and resistance. Amperage, possibly.
Do you have a second set of eyes, like maybe an electrician friend who might be able to spot electrical issues? You probably need to check for a leak to ground (maybe not a direct short). Maybe there's a light left on somewhere or a circuit board that's draining the batteries. You might have to do a load test, too.
A little more info, and we can steer you in the right direction.
Or, onto the rocks!