House Battery Issues

[Fluidone]

I have a 2017 Thor Chateau 31L. Recently I can not turn the house batteries (2, 12 volt deep cycle) on. the DC circuits will not power up ( LED lighting, fridge, ect). If I fire off the generator, all the DC and AC circuits work, so I assume the converter is functioning. Using my multi-meter the resting voltage in both batteries are 12.6 vdc, with the generator running the voltage is the same 12.6 vdc in each battery I should see a charge voltage from the converter. I also assume the generator start is powered by the house batteries and they are on a dedicated cable. Turn off generator and everything dies. Next is to open the electrical bin under the bed and see what I can see .....

So what am I missing and any opinions on troubleshooting system would be would be welcome. Would be most interested in finding the location of the battery cut off relay.

[16ACE27]

Well, is your USE/STORE (Master Power) switch in the USE (on) condition? This is what normally connects the house batteries to the coach's 12 VDC buss (through an isolation relay). If you are confident this is the way it should be then you need to back up to the house batteries and look for a 50 to 100 amp DC breaker that is in the tripped position.

[Fluidone]

thanks for reply
THe use/store switch is pushed to use .... no joy. Both house batteries read 12.6 volts. THere is no charge voltage with generator running. The high voltage surge breaker is no tripped (flag is in) ...

[javelin]

When you operate or release the use/store switch do you hear a relay clunk sound? If not, the use/store latching relay is probably not working (bad relay or bad control wiring which operates the relay) which prevents the converter charging output from reaching the coach batteries......as well as the reverse......preventing the coach battery power from reaching the converter DC bus fuse panel.
If the latching relay is working, then as 16ACE27 says there may also be circuit breakers in series with this battery feeder that may be tripped open also. So it is probably just a matter of finding which item has opened and where it is located. I “assume” all electrical cable connections are good.


Attaching a generic schematic of a typical DC battery control system which may not be exactly what your coach uses, but it helps people visualize what typically is going on. On the right side of the drawing the converter, (use/store) latching relay and a 50amp re-settable breaker are shown connecting to the coach batteries. This is the feed that is likely not working in your coach. Some coaches also have a 100 amp re-settable breaker in series with this feed; usually located at the coach batteries. Sometimes the 50 amp breaker is located behind or close to the converter panel and has a small black reset button than needs to be pushed in if it has tripped.

[Fluidone]

Well folks thanks for all the help and support. The problem is now fixed and all is well. What I did to fix the problem was as follows. First I cleaned up the battery terminals and replaced the corroded terminal wires. That fixed the low voltage issues. I still was not getting any charge voltage from the converter to the batteries. Opened the electrical bay under the bed tested all solenoids and they were working fine, converter was putting out 13.8 DC volts to the battery wires. The battery relay was not putting out anything. I called Thor and talked to tech support. What fixed the problem was there is a small 50 amp potted can type breaker inline from converter to battery relay, after resetting, (pushing the tiny button on side of can) all is well and battery relay works as advertised. Yes it is amazing what happens when an control relay gets the correct voltage/power.

Choke this issue up to a learning experience. I now know a lot more about the working of my coaches electrical systems. Yes all is well and life is good.

John J (aka Fluidone)