Battery/power issue

Electrical issues, both 12 volt and 120 volt
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lwrider20
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Battery/power issue

Post by lwrider20 »

I have a 91 b190 and on our last trip I noticed the engine battery is going dead while the house battery seems to stay charged. From what I can tell it seems everything that is supposed to run off of the house is actually running off of the engine battery. We ran the heat on and off throughout the night and by the morning the fan would barely turn and the water pump wouldn’t even turn on. This last trip the engine battery finally gave up and won’t even take a charge anymore. Any ideas why everything would run off of the engine battery? I did remove the original generator and just run an external generator when needed. Was there something that should have been done with the original generator wires that would cause this?
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skater
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B190 Year: 1991
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Re: Battery/power issue

Post by skater »

lwrider20 wrote:
Sun Jan 29, 2023 4:39 pm
I have a 91 b190 and on our last trip I noticed the engine battery is going dead while the house battery seems to stay charged. From what I can tell it seems everything that is supposed to run off of the house is actually running off of the engine battery. We ran the heat on and off throughout the night and by the morning the fan would barely turn and the water pump wouldn’t even turn on. This last trip the engine battery finally gave up and won’t even take a charge anymore. Any ideas why everything would run off of the engine battery? I did remove the original generator and just run an external generator when needed. Was there something that should have been done with the original generator wires that would cause this?
I have a few possibilities off the top of my head.

1. You mentally have the batteries swapped. In the 1991, the coach battery is on the driver's side, and the engine battery is on the passenger. This is swapped in later model years, so there appears to be conflicting information, but that's how it works for the '91. The coach battery running down while parked and using coach things - especially the furnace, as that draws a lot of 12 volt power for the fan - would make sense.

2. The engine battery is weak and dying unrelated to using the coach. When you go to start it, the two systems are connected, so you might be starting off the coach battery.

3. Someone changed the wiring for some reason. This one is going to be a lot harder to diagnose.

My first suggestion would be that you disconnect the battery on the passenger side by removing the negative terminal, then see what works and what doesn't. Then reconnect that and disconnect the other one to confirm that the opposite things work.
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
lwrider20
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Re: Battery/power issue

Post by lwrider20 »

Im positive the batteries are on the correct side. I just disconnected the engine battery and confirmed nothing inside the rv will work. So the engine battery is the only source of power. So now that my question is could I have a bad battery isolator switch? I don’t know much about how they work but I’m assuming when the key is turned on that switch makes it so the engine battery provides power and then when the key is off it should switch over to the house battery?
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skater
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Re: Battery/power issue

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lwrider20 wrote:
Fri Feb 03, 2023 11:44 pm
Im positive the batteries are on the correct side. I just disconnected the engine battery and confirmed nothing inside the rv will work. So the engine battery is the only source of power. So now that my question is could I have a bad battery isolator switch? I don’t know much about how they work but I’m assuming when the key is turned on that switch makes it so the engine battery provides power and then when the key is off it should switch over to the house battery?
That's the idea for how they work. If the isolator switch was bad or even bypassed, the engine battery could be supplying the coach all the time. In mine, I THINK the isolator is mounted just in front of the engine battery, but I'm not sure about that.
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
lwrider20
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Re: Battery/power issue

Post by lwrider20 »

In mine it’s just in front of the house battery. They are cheap enough that I’ll probably just replace it and hope for the best.
lwrider20
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Re: Battery/power issue

Post by lwrider20 »

So switched out the battery isolator and still the same problem. When I turn the key on I can hear a click coming from the isolator but with the key on or off it still only runs off of the engine battery. I’m starting to think it’s something to do with the generator missing. Anyone have any suggestions?
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skater
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Re: Battery/power issue

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lwrider20 wrote:
Sat Feb 25, 2023 2:26 pm
So switched out the battery isolator and still the same problem. When I turn the key on I can hear a click coming from the isolator but with the key on or off it still only runs off of the engine battery. I’m starting to think it’s something to do with the generator missing. Anyone have any suggestions?
Anything is possible, but in mine the wiring for the generator has nothing to do with this functionality. The wire for the generator in mine splits off the circuit breaker that is next to the coach battery.

But if your engine battery really is on the driver's side, then your wiring is very different than the normal, so all bets are off.
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
lwrider20
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Re: Battery/power issue

Post by lwrider20 »

The engine battery is on the passenger side like it’s supposed to be. As far as I can tell all of the wiring is original. Could the converter have something to do with it?
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skater
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Re: Battery/power issue

Post by skater »

lwrider20 wrote:
Sun Feb 26, 2023 2:10 pm
The engine battery is on the passenger side like it’s supposed to be. As far as I can tell all of the wiring is original. Could the converter have something to do with it?
Sort of. If it's bad, which often happens to the original ones, it wouldn't be charging the battery (whichever one it is), so it would be running down overnight. I have no idea how the engine battery (only) would be powering the coach though.

So if you disconnect the intended coach battery, nothing stops working? I can't figure out why someone would make that change...maybe an emergency to keep the coach working if the deep cycle battery failed in the middle of a trip. But I'd hope they'd revert the change.
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
lwrider20
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Re: Battery/power issue

Post by lwrider20 »

Ya exactly. If I leave the coach battery hooked up and disconnect the engine battery then I have no lights, water pump, etc. that’s with the key on or off. I’m assuming the coach battery is directly wired to that stuff somehow? Does it go through a breaker or fuse first that I should be checking?
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skater
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Re: Battery/power issue

Post by skater »

lwrider20 wrote:
Sun Feb 26, 2023 3:09 pm
Ya exactly. If I leave the coach battery hooked up and disconnect the engine battery then I have no lights, water pump, etc. that’s with the key on or off. I’m assuming the coach battery is directly wired to that stuff somehow? Does it go through a breaker or fuse first that I should be checking?
Yeah, there's a circuit breaker next to the coach battery, mounted on the fender. It doesn't look like a traditional circuit breaker though. Here's the culprit.

Sorry I misunderstood what you meant about the batteries being swapped!
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
lwrider20
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Re: Battery/power issue

Post by lwrider20 »

Ok I’ll check that out. Also do you have a photo of how the battery isolator switch is connected? I’m thinking it might have been wired backwards. I swapped the wires around and I could get everything to work off the coach battery if the key was turned on
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skater
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Re: Battery/power issue

Post by skater »

lwrider20 wrote:
Sun Feb 26, 2023 6:00 pm
Ok I’ll check that out. Also do you have a photo of how the battery isolator switch is connected? I’m thinking it might have been wired backwards. I swapped the wires around and I could get everything to work off the coach battery if the key was turned on
I don't have a picture. Honestly I'd have to look for mine - I've never needed to touch it, so I wasn't even sure where it was.

But...I don't think it could be wired backwards. It'd be hard to do, let me put it that way. The way it should be wired is that the "sense" terminal would get 12 volts when the ignition is on, which triggers the isolator to connect the batteries (and it shouldn't matter which side each battery is wired to). That's relatively easy, because lots of circuits are wired to ignition power. To make it work in reverse, you'd have to have a wire that goes "hot" when the ignition is off...which isn't really a thing vehicles need often, so I can't even think of any circuits that would normally fall into that category. So it would require some special wiring, and I'm struggling to understand why someone would go to that trouble.
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
lwrider20
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Joined: Sun Jan 31, 2021 2:27 pm

Re: Battery/power issue

Post by lwrider20 »

Finally figured it out. I had a new engine installed and when they wired the isolator they put the wire that comes from the engine battery on the same side as the wire that goes to the coach. So all I had to do was put the engine battery wire on one side of the isolator and the coach battery cable and the coach cable on the other side and it works now. Thanks a bunch for the guidance
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