battery disconnect switch

If you have 2 batteries, check for another ground on the other battery. I had this issue on my chassis batteries last winter. There was a ground to the ECM on the inside battery that wasn't attached to the terminal I put the knife switch on. I had some kind of parasite load that ran that battery down.

On a side note, if I had tried to start the coach with the knife switch open, the starting current would have (tried) to go through the ECM ground and it would have fries the ECM.

I'm not familiar with your rig so it's hard to give specifics. Just to check on a possible connection between the house and coach, while the coach is disconnected, disconnect the chassis negative.

If all drops off when you disconnect the chassis negative, there is a charging circuit that is cross feeding.

Some, maybe many,, rigs have a B.I.R.D OR Bi_Directional Isolator. The BIRD determines when the chassis battery is about 90 percent of charge and then the relay pulls in and chatges both the house and floats the chassis to full charge.

It could be that.

Write back on what you try and lets us know what happens.

If you have a Winnie, it has a different charging system.

If the Aux switch circuit or solenoid is stuck it would do the same as having the BIRD fail.

I got tired of parasitic loads so I ran new 4/0 cables placing Chassis and House Battery disconnect switches inside our MH. This also allows me to shut down both battery banks while in my driveway and I just connect a dual Battery tender to keep it all top off. OH....sorry, I do have mine the positive leads.

Could be a defective switch. I put a new one in our last TT and it quit working after only a couple of uses. Bought a different type / brand and all was good.

billysurf wrote:
Also, the switch bolt and nut were very hot.

This suggests defective or undersized switch. What switch did you use and for what sized batteries? In addition to the above comments perhaps the switch is not wired correctly.

Some units have an emergency switch that allows the house battery to supply power to the engine battery via a solenoid, if that unit welds shut or lacking the solenoid the switch it self has broken you might have a hot lead that way, the other thought that I have is through the alternator, but that is way off.

navegator

No, just the positive side to the batteries will not keep everything on. In fact, it won't keep anything on.
So, if you have physically removed the negative lead on the battery, and still have power to everything, then try this; at the same time the negative lead is off, take the positive lead off. If everything is still on, power is coming from something else other than the battery.

Nope, just doesn't work that way. You have to have a complete circuit for the battery to supply electricity. If you've isolated the negative terminal from the positive terminal wiring, you won't have power from that battery.

Did you have power when the wiring was totally disconnected from the negative terminal to install the battery disconnect switch. Maybe the switch itself is defective.

Are you hooked up to shore power? Maybe that's supplying your 12 v power through the converter.

navegator wrote:
Are you sure it was the house battery and not the engine, there might be more batteries and or you have the unit plugged to shore power and the battery charger is on.

navegator

Definitely house batteries, not starter. 50 amp plug (or any plug for that matter) was 100% disconnected.

Would just the positive side of the batteries keep everything on?

Are you sure it was the house battery and not the engine, there might be more batteries and or you have the unit pluged to shore power and the battery charger is on.

navegator