Battery disconnect on house battery?

[tekrsq]

Can I put a disconnect on the house battery without screwing up the converter when plugged into 110 v?

The reason I ask: I think my converter may be overcharging the house battery when I'm plugged into 110v. I've had the rig plugged in for the last few weeks while I've been working on it, and I've noticed when I move it, the alternator is charging higher than it should, and when I checked the "panel" it shows the battery at only half charge. I haven't had a chance to put a volt meter on the system yet because of the storms, but I've heard about converters overcharging the house batteries and frying them if plugged in for extended periods. I don't need the 12v battery when plugged in, correct ?

[tomwalt]

I'm not an expert, my OEM cheap-o converter provides 13+V to the coach when plugged into 110VAC and provides a trickle charge to the house batteries. If I disconnect the batteries, I still have 12VDC in the coach. I don't think this harms anything. I recommend you figure out the 1/2 charge issue raather quickly. A bare bones cheap-o converter doesn't overcharge, just too much constant charging. This constant charging causes battery low water and I must add water to the batteries every couple months. The panel should read full charge when plugged in or the engine is running. The panel showing 1/2 charge is a concern - weak battery or shorted cells. I would disconnect and figure this out soon. I just had a weak house battery explode and I suspect the constant charging and hot weather contributed to the water level going down and pow (see the recent post "Battery be gone").

[tekrsq]

I got a chance to put a volt meter on my batts today. I think I have a bad panel gauge, and possibly a bad battery isolator. Since I'm totally new at this, I still have a lot of research to do. Is there a way to adjust the panel ? Or is there something I can test and/or replace to make it read correctly ?

Here's what I found with the volt meter:
House battery- 12.2v at rest, 12.5v on the shoreline, 16.6v with the engine running (alternator)

Chassis battery- 12.3v at rest, 12.3v on the shoreline, 12.0v with the engine running. I'm a little confused the voltage went down with the engine running.

[Wanabee FTer]

Originally Posted by tekrsq

Here's what I found with the volt meter:
House battery- 12.2v at rest, 12.5v on the shoreline, 16.6v with the engine running (alternator)

The House batteries are being charged quickly by the engine alternator @16.6 volts, but they are not being charged enough by shore power (the converter) @12.5 volts. A full charge on a 12 volt battery is 12.7 volts, charging at 12.5 volts will never fully charge the batteries. Check the converter fuses, output voltage to see if there is a problem there. It also would be a good idea to check your batteries with a hydrometer to see if there are any dead cells.

Originally Posted by tekrsq

Chassis battery- 12.3v at rest, 12.3v on the shoreline, 12.0v with the engine running. I'm a little confused the voltage went down with the engine running.

At 12.3v the chassis battery is appx 60% charged. 100% charge would be 12.7 volts.
Because of the high voltage reading from the alternator on the house batteries I would say the alternator is working. The low alt. reading on chassis battery leads me to suspect there is a problem in the battery isolator circuit. See if the MH is equipped with a BIRD (Bi-Directional Isolator Relay Delay) the BIRD charges batteries when either one is being charged. When the coach is being driven, batteries will be charged from the engine's alternator. When the coach is plugged into shore power, batteries will be charged from the converter. If neither battery is being charged, the batteries are fully isolated. The BIRD controller also senses heavy loads on either battery to prevent the wrong battery from being inadvertently discharged.

On my coach the converter charges at 13.6 volts when on shore power, 14.5 volts when running from alternator. MY coach is equipped with a BIRD.
The other suggestion I have is to physically inspect all of your ground connections in and around the battery circuit.

One more thing, the alternator gauge on the dash reading high and voltage reading over 16 volts could mean the alternators built in voltage regulator is faulty.

If your coach has a Bird it looks like this...