Bad Battery Disconnect Switch?

gwillor · 01-12-2023, 05:53 PM

After a wonderful summer of traveling all over the west I put my baby to bed for the winter (time to go skiing). I always winterize the coach, then plug in to a 120V 15 amp plug and once a month start the generator, and charge and start the coach. Well this last time I ran the generator it didn't charge the house batteries and I discovered the only charging of the coach was from the solar panels. During the summer we were dry camping and we lost all our 12V power and at that time I called a tech and he walked me through some trouble shooting. It turned out that after repeating to click the battery discount switch it 12V turned back on. He told me that I probably had a bad Battery Isolator relay but he would just continue using the old one until it craps out. Well I thought that that it was probably the cause of my current troubles so I changed out that device but still no 12v. I went through old threads and found someone who had what I thought was a similar problem (jneum525) in 2020 and he solved his problem by finding a bad circuit breaker under the seat. Well I pulled the seat and the breaker was fine. The only thing that I can think of is an actual bad disconnect switch. I could not find a thread on that and I was wondering if anyone has dealt with that. Please let me know if you have experience with replacing the switch.

thanks

gdw
2018 Istata 3 FW on 2016 MB

SeaDog · 01-13-2023, 10:20 AM

Not sure I follow all the past trouble shooting with that said put a meter on the disconnect switch and test it.

gwillor · 01-13-2023, 11:18 AM

Thanks SeaDog for replying. I was hoping that someone has already done that and if they had any suggestions on the best way of doing it. The toggle switch is on the main panel which I have never dove into and I am sure it is a spider nest of wire.

SeaDog · 01-13-2023, 11:27 AM

the switch on your panel is not the disconnect it simply puts power to disconnect to open or close it. Find the actual disconnect (likely in the battery bay) and start there. JMHO

gwillor · 01-13-2023, 11:44 AM

Thanks I will start looking.

**bclemens** · 01-13-2023, 01:12 PM

A 2018....I think the solenoid is in the BCC (panel on the left of the stairwell). Diagram is likely printed on the back of the metal cover plate.

gwillor · 01-13-2023, 02:52 PM

Thanks Brian,

The diagram shows the battery isolation manager, the battery isolator relay (which I replaced with a new one) and a converter breaker. I check the breaker and it does not appear to be tripped. I also checked all of the fuses in the fuse box inside the BCC and all appear to be okay. There is not a separate solenoid that I can find.

Thanks so much for your time,

gdw

**bclemens** · 01-13-2023, 04:43 PM

Quote:

Originally Posted by gwillor

Thanks Brian,

The diagram shows the battery isolation manager, the battery isolator relay (which I replaced with a new one) and a converter breaker. I check the breaker and it does not appear to be tripped. I also checked all of the fuses in the fuse box inside the BCC and all appear to be okay. There is not a separate solenoid that I can find.

Thanks so much for your time,

gdw

solenoid/relay

BCC I think might have a relay solenoid on the M2. The only other part of the equation is the actual charger in the convertor.

gwillor · 01-13-2023, 06:16 PM

M2? I am sorry I am not sure what that?

**bclemens** · 01-13-2023, 06:39 PM

Freightliner M2.

gwillor · 01-13-2023, 06:45 PM

thank you.

mnoland30 · 01-27-2023, 07:44 AM

Modern RVs are so much more complicated. I just have a Harbor Freight manual disconnect that unscrews to disconnect the battery cable. I only need to do it once a year, so no need for a special switch and a relay.

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