Trailer Battery runs down

Airstream uses a WFCO inverter that draws power even when it is supposedly turned "off." I put a separate disconnect switch on the hot wire between the battery and inverter for this.

If your Bambi has an inverter, disconnect its hot wire from the battery and see if that makes a difference. If it does, a Blue Sea disconnect will fix the problem.

Thanks for the replies. The batteries discharge in about a day; they are a few years old and they lasted about a week just last month with minimal use. “Store” is supposed to be the battery disconnect, except for the CO alarm, which I suspected was the problem and disconnected, but they seem to discharge faster in that mode! I was curious if anyone had had a similar problem/could help me think of what else might be drawing current. I have an Airstream Bambi.

2 things draw a Trailer battery down
1. The TV antenna power booster----out of sight and mind if ON Probably 99% of my customers with this complaint have left the Booster ON in storage
2. The LP/CO detector which has no ON and OFF switch. Doug

As BFL13 said first find out how big the draw is. What I would do is to disconnect the positive cable and set your HF multimeter to 10 amps and read the amp draw between the pos cable end and the pos terminal on the battery. Is it more than one amp? If more than 2-3 amps something is left on. Pull each 12v fuse one at a time to see which one reduces the amp draw then you will know which circuit is the problem. If your amp draw is less than an amp say .2-.5 amps and your battery goes dead quickly I would suspect a bad battery.

As others have indicated, it could be any number of items. The only way to know for sure is to verify the current consumption of each wire going from the battery.

You don't indicate how long it takes for the battery to discharge or what "store" mode means. If store mode means a battery disconnect in the disconnect state, then there are obviously things that aren't being disconnected. This may or may not be "normal."

There are a couple of ways to tackle the problem. One is to trace each wire connecting to the battery, if possible, to see where they go. If they are all connected through the battery disconnect, then perhaps it's defective. You can get a clamp on DC amp meter similar to this one. and learn to use it to see which wire(s) are using battery power. If the internal power center is still powered while in storage mode, you can use the amp meter to check each wire coming from it. The inside power distribution center should definitely be disconnected by a disconnect switch if one's installed. Be aware that a lot of the clamp on current meters are AC only and won't be of help. When set correctly, you can clamp the meter around each wire to see how much current is flowing through the wire at the time.

Assuming there is any way to get power to the unit while its in storage, I would definitely recommend a purpose built battery maintainer similar to this one. Lead acid batteries will eventually self discharge even if disconnected.

If you can't get power to the RV during storage, I would look at completely disconnecting the batteries either by making sure the battery disconnect switch is set up correctly or by physically disconnecting them. If it's going to be in storage for months at a time without power, I would pull the batteries and take them to where they could be plugged into a battery maintainer.

BFL13 wrote:
How big a draw?

Exactly.

How big a draw? How long does it take to run down to what voltage?

If no ammeter, at least check voltage difference from when disconnected to connected. Report the numbers please. A bigger voltage diff would indicate a higher amp draw that might help with identification.

When connected, you can pull DC fuses one at a time to see if that makes the voltage go back up. That would identify which circuit is the draw.

Can I join the nagging?

Battery switch
Disconnect switch
Kill switch

A battery maintainer/charger will vastly lengthen the life of a battery

install a kill switch at the battery then you know theres no draw ,

Unless you disconnect the battery, the CO/LP detector, radio and other loads will draw down the battery. The trailer probably did not come with a disconnect switch, and if it did, it was likely wired to not disconnect everything. Get a switch and wire it correctly. Turn it off as soon as the trailer is disconnected from the tow vehicle or power, unless it is being used.