Chassis Battery Issues

[BC-ClassC]

Hi All,

I went to start my 2019 Four Winds 28E which I do monthly over the winter and the battery was dead (showed just 3.4V) despite being connected to the house in our driveway via a 30amp outlet and running fine the month previous. The house batteries were still charged albeit ready for a replacement as we purchased this as an ex-rental and these batteries were well used. Oddly enough the solar control module was blank where it usually shows the level of the house batteries. I checked all the fuses (they were fine) and checked to ensure power was still going to the motorhome from the house (also fine). Using a battery charger I tried to charge the chassis battery but it would show the battery had a fault and could not be charged.

I replaced the battery and also reset the solar control module (which now showed the house batteries as being 13.4V). The MH started great and reads 14.5V while running. I then replaced the house batteries with 2 new AGM batteries. With the MH plugged into the house the solar control module shows 13.7V and with the MH running it also shows 14.5V. The problem is after a couple of weeks of sitting in the driveway plugged into the house the chassis battery is reading about 12.3V while the house batteries are reading 13.7V. The alternator can charge both the chassis battery and the house batteries but the converter is only charging the house batteries and not the chassis battery. When running the generator, again only the house batteries jump to 13.7V while the chassis battery stays at 12.3V. What could be the issue? Thanks for any advice!

[Lt Keefer]

Is you dash radio on? What is the power source for your propane detector?

[RunnerJim]

Not sure if this will be your situation, but I fought a dead truck battery for a while. I discovered that the house master had to be turned on before I plugged it into the house.

[craigd853]

Originally Posted by BC-ClassC

Hi All,

I went to start my 2019 Four Winds 28E which I do monthly over the winter and the battery was dead (showed just 3.4V) despite being connected to the house in our driveway via a 30amp outlet and running fine the month previous. The house batteries were still charged albeit ready for a replacement as we purchased this as an ex-rental and these batteries were well used. Oddly enough the solar control module was blank where it usually shows the level of the house batteries. I checked all the fuses (they were fine) and checked to ensure power was still going to the motorhome from the house (also fine). Using a battery charger I tried to charge the chassis battery but it would show the battery had a fault and could not be charged.

I replaced the battery and also reset the solar control module (which now showed the house batteries as being 13.4V). The MH started great and reads 14.5V while running. I then replaced the house batteries with 2 new AGM batteries. With the MH plugged into the house the solar control module shows 13.7V and with the MH running it also shows 14.5V. The problem is after a couple of weeks of sitting in the driveway plugged into the house the chassis battery is reading about 12.3V while the house batteries are reading 13.7V. The alternator can charge both the chassis battery and the house batteries but the converter is only charging the house batteries and not the chassis battery. When running the generator, again only the house batteries jump to 13.7V while the chassis battery stays at 12.3V. What could be the issue? Thanks for any advice!

Sounds like your charger /inverter is not charging the batteries. You will need a volt meter to test both the house batteries and the engine battery. Should be at around 13-14 volts if its charging the batteries. I'm sure someone will be along here shortly with the exact numbers but this is definitely what it sounds like. Hope this helps

[BC-ClassC]

The radio in the dash, which is off, only works when the house battery switch is turned on. The propane detector works off the house batteries. Thanks.

[BC-ClassC]

Originally Posted by craigd853

Sounds like your charger /inverter is not charging the batteries. You will need a volt meter to test both the house batteries and the engine battery. Should be at around 13-14 volts if its charging the batteries. I'm sure someone will be along here shortly with the exact numbers but this is definitely what it sounds like. Hope this helps

So the house batteries are reading 13.7V when plugged into the shore power or when the generator is running, so all good there. The chassis battery is only ready 12.3V when plugged into shore power or when the generator is running so not being charged by the converter or the generator. There seems to be something that is not allowing the charge to go from the converter or the generator to the chassis battery. However the engine will charge both the chassis battery and the house battery. Weird...

[BC-ClassC]

Originally Posted by RunnerJim

Not sure if this will be your situation, but I fought a dead truck battery for a while. I discovered that the house master had to be turned on before I plugged it into the house.

Thanks, I did check this and you're right that the switch has to be in the on position before plugging into shore power, however this did not resolve the issue unfortunately.
Could it be a problem with the BIRD that I heard others have spoken about? Thanks!

[16ACE27]

Originally Posted by BC-ClassC

Thanks, I did check this and you're right that the switch has to be in the on position before plugging into shore power, however this did not resolve the issue unfortunately.
Could it be a problem with the BIRD that I heard others have spoken about? Thanks!

You may not have a BIRD or a BIM. Some Class C MHs are setup from the factory so that the house does not charge the chassis battery. Log into the Thor Owners website, create an account and download the electrical diagrams for your RV so you can determine IF you have a problem before chasing your tale (or radio or propane detector or working converter).

[Trkyte@msn.com]

My 2017 class c doesn’t charge the chassis battery when on shore or generator.
It has a timed delay control that only operates one way from engine to coach.
It also has a emergency start switch that will manually tie the coach and chassis battery in case of a dead chassis battery

[BC-ClassC]

Originally Posted by 16ACE27

You may not have a BIRD or a BIM. Some Class C MHs are setup from the factory so that the house does not charge the chassis battery. Log into the Thor Owners website, create an account and download the electrical diagrams for your RV so you can determine IF you have a problem before chasing your tale (or radio or propane detector or working converter).

Great advice, thank you! I signed up and downloaded a lot of useful information. Turns out this model does charge the chassis battery when on shore power, using the generator and solar. I also found a Trombetta solenoid and a battery isolator behind the coolant reservoir. Could one of these have failed? Thanks,

[simidrm]

Had the same issue chassis wasn’t being charged when plugged in and coach not charging with engine running found the bird relay was bad, replaced relay and all is good

[simidrm]

Use a volt meter and check the solenoid white wire is ground purple wire is power or signal

[16ACE27]

Originally Posted by BC-ClassC

Great advice, thank you! I signed up and downloaded a lot of useful information. Turns out this model does charge the chassis battery when on shore power, using the generator and solar. I also found a Trombetta solenoid and a battery isolator behind the coolant reservoir. Could one of these have failed? Thanks,

If the Trombetta is actuated when the engine is running and tieing the two systems together then the Trombetta relay is good. Need to look at what controls that relay; normally a BIRD. Maybe you'll get lucky and find a loose/bad connection or a blown fuse (see the diagram below):

[Trkyte@msn.com]

This this what you saw? This is a one way only that I talked about.

[BC-ClassC]

Originally Posted by Trkyte@msn.com

This this what you saw? This is a one way only that I talked about.

Yes, this is what I see beside the Trombetta. Thanks!

[camperguy99]

Hearing the Trombetta clank is not sufficient to say it is working. My Trombetta actuated just fine but the contacts were so covered with god knows what that no current would pass. Best to measure the voltage across the Trombetta contacts (big wires terminals) and it should be close to zero volts when actuated.

[BC-ClassC]

Originally Posted by 16ACE27

If the Trombetta is actuated when the engine is running and tieing the tywo system together then the Trombetta relay is good. Need to look at what controls that relay; normally a BIRD. Maybe you'll get lucky and find a loose/bad connection or a blown fuse (see the diagram below):

Great diagram, thank you! I will try and find what is controlling the rely (i.e. BIRD). Would it be up in the engine compartment near the Trombetta?

[BC-ClassC]

Originally Posted by camperguy99

Hearing the Trombetta clank is not sufficient to say it is working. My Trombetta actuated just fine but the contacts were so covered with god knows what that no current would pass. Best to measure the voltage across the Trombetta contacts (big wires terminals) and it should be close to zero volts when actuated.

Thanks, I'll measure the voltage on the Trombetta and see what it says. The contacts look pretty clean as the MH is only a couple of years old. Unfortunately it is located on the inside fender behind the coolant recovery tank, so not very easy to access.

[16ACE27]

Originally Posted by Trkyte@msn.com

This this what you saw? This is a one way only that I talked about.

Originally Posted by BC-ClassC

Yes, this is what I see beside the Trombetta. Thanks!

If that's what you have to control the Trombetta the system is operating as designed. That is an IRD, not a BIRD. The IRD allows charging in one direction only. The "B" in BIRD stands for Bi-directional.