Zero power in coach unless connected to A/C

[Boosa]

I have a 2012 Airstream Interstate

I am trying to determine if my batteries or inverter or possibly a fuse may be causing my problem.
The fuses I’m aware of all checked ok.
Nothing in the coach works unless connected to shore power but everything works fine when connected to shore power.

[Aircruiser]

I am assuming you recently purchased the rv and are learning its systems. If you already know what I'm mentioning here, my apologies. First, open the compartment above the rear tv. there is a battery condition monitor on the bottom right. What does it say without using the switch and then while pressing the switch? If you get low or no voltage on one of the two readings, your house batteries are probably dead. Two things to check--When you open the panel below the back seat, there is a large red knob to the left. Is it turned clockwise as far as it will go? Also, the inverter is located all the way to the right. There is a small slide switch at the top. Is it slid all the way to the left position or right position?

[uncle_bob]

Hi

Ok, first some terminology:

A converter / charger takes shore power and turns it into 12V power to do things like charging your batteries.

An inverter takes 12V from the batteries and turns it into 120V to run thing like hair dryers and TV sets.

You may also have a generator in your MH that creates 120V from fuel.

With a few exceptions, most things these days run on 12V. The lighting in the vehicle is a good example. A fantastic fan (if you have one) is another good example. Do these things only work on shore power? The microwave is an "exception" it will only operate on shore power or off a generator.

You should have two 12V systems in the vehicle. One starts and runs the engine to move you down the road. The other runs the gear you use when parked. Normally the part that runs the engine gets called the "chassis" system ( as in chassis battery). The part that runs the camping side of things gets called the "house" system (as in house battery).

Since there are two 12V systems, each with it's own battery, it's quite possible for one battery to run flat while the other is charged enough to be useful. If the vehicle is stored for a few weeks without power, this is a likely thing.

The most basic way to troubleshoot electrical systems is with a multimeter. These days, you can get an adequate one for less than $20. You can get a really good one for a bit more. Adequate is plenty in this case. First thing to measure are the battery voltages. Depending on what you find, there are a lot of branches to the troubleshooting tree.

Bob

[Boosa]

Battery condition shows 13.68 main
13.85 Aux

House red battery knob turned all the way clockwise

Tripp-lite inverter switch turned to the left

All this With shore power connected.

Unplug from shore power and the compartment above rear TV is completely dead.

[uncle_bob]

Hi

When on shore power your "house" system gets it's power from the converter / charger. If the battery has a disconnect switch *and* it's disconnected, it's out of the act. As soon as shore power goes away the house system goes to zero. Yes, this assumes the override is not engaged and the two systems are separate.

Simple check still is to grab the multimeter and see what the house battery reads with no shore power / no engine running.

Bob

[Aircruiser]

You have good (great) battery power, so the typical suspects would be a breaker, but you've checked all of those. I recall that some on this board doing a remote battery shutoff modification so the house battery could be disconnected at the door via an added switch somewhere on the shower wall near the other switches. Also, some owners had the Service Bulletin 164 mod done, which involved installing a solenoid that acted to completely disconnect the house batteries while the rv is in storage. Maybe both were the same modification. I didn't do the mod on my 2012 Interstate. Bottom line, something has disconnected the battery from the power busbar.

[Boosa]

My coach batteries are located under the rear lounge in this RV Difficult to access I can see the heavy gauge red/cable coming from the battery box. I checked for voltage at the 125amp fuse between the battery and the inverter. Had 0 volts. Is there a fuse in the rear battery box?

[uncle_bob]

Originally Posted by Boosa

My coach batteries are located under the rear lounge in this RV Difficult to access I can see the heavy gauge red/cable coming from the battery box. I checked for voltage at the 125amp fuse between the battery and the inverter. Had 0 volts. Is there a fuse in the rear battery box?

Hi

It sounds like somebody has put in a battery disconnect switch or the batteries are (manually) disconnected. It's possible that they are totally toast as well ....

Bob

[Aircruiser]

I don't recall seeing a fuse in the battery box. Hopefully someone else here can provide some insight.

[Boosa]

Ok thanks I will keep plugging away and figure it out. Soon o hope.

[Boxster1971]

Originally Posted by uncle_bob

Hi

It sounds like somebody has put in a battery disconnect switch or the batteries are (manually) disconnected. It's possible that they are totally toast as well ....

Bob

Agree - these conditions will give you the symptoms you are seeing. No battery power, but 12VDC only when plugged into shore power which puts 12VDC on system from Inverter/Charger.

[Boosa]

I think my problem ....no power when not connected to shore power is with the Tripp-Lite inverter.
I have DC volts going into the inverter but nothing coming out

Any ideas other than replacement Thanks

[uncle_bob]

Hi

The only thing the inverter powers are 120V items. It has no impact at all on stuff that runs off of 12V. If we are just talking about 120V to the inverter outlets when you are off shore power, that's a very different thing than "no power at all".

The inverter does not come on automatically, you need to turn it on. First thing to do is to check that switch and make sure it is working / in the right position. Next, there is a fuse or breaker on the output of the inverter. Check it to be sure it is not blown / tripped. It is over by the inverter and not part of the normal breaker panel / fuse box.

Assuming all of this checks out and indeed the inverter is dead - how fancy do you want to get? How much of an upgrade do you want to do? Victron makes some nice stuff, but you have to be pretty serious to make it worth the money.

Bob