Should the engine alternator charge the house batteries while under way ?

[Cwalther]

2023 Thor Miramar 35.2
I drove several hundred miles today with the refrigerator on, and each pit stop I made, I checked the house battery voltages. The voltage slowly dropped from 13 to 12.6, to 12.1, to 11.x, which was flashing red on the xantrex panel. Should the engine alternator be charging the house batteries while under way ? I could barely get the generator started, but once I did, the house batteries were reading 13.x volts again. After driving with generator running, the house batteries are still reading 12.7.

 

[Jimbo57]

Yes engine should charge both house and chassis. How old are batteries because if they lead acid( cheapest per battery) and RVis 2023 then batteries are probably 2022 so end of life. LiFeP04 are better in the long run as they have a 10 year life

 

[Cwalther]

Yes engine should charge both house and chassis. How old are batteries because if they lead acid( cheapest per battery) and RVis 2023 then batteries are probably 2022 so end of life. LiFeP04 are better in the long run as they have a 10 year life

There are two 6v batteries for the house hooked up in tandem, is this the preferable setup , or could I replace them with 2 x 12v batteries.

 

[Jimbo57]

There are two 6v batteries for the house hooked up in tandem, is this the preferable setup , or could I replace them with 2 x 12v batteries.

I would check prices on LiFeP04 on Amazon prices are way down from 2 years ago. 100 ah maybe cheaper then the golf cart batteries, no maintenance and longer life

 

[16ACE27]

hould the engine alternator be charging the house batteries while under way ?

Yes

 

[16ACE27]

There are two 6v batteries for the house hooked up in tandem, is this the preferable setup , or could I replace them with 2 x 12v batteries.

Don't replace them at all until you troubleshoot and resolve your charging problem. The fact that they're holding a charge after being charged by the generator shows they are NOT you current problem.

 

[Jimbo57]

Checking voltage while generator is running aren’t you just seeing charge sent by generator then it dropped to 11volts. I trust Ace’s word more

 

[16ACE27]

Checking voltage while generator is running aren’t you just seeing charge sent by generator then it dropped to 11volts. I trust Ace’s word more

After driving with generator running, the house batteries are still reading 12.7.

11 volts was without the generator running. He ran the generator while driving after the batteries dropped to 11 VDC and they got charged up to 12.7 VDC. I assume that is after he stopped and turned off the generator.

 

[PS89]

Factory schematic for the OP's coach show a BIRD/Trombetta arrangement for the charging of the house batteries from the alternator.

It isn't working while driving.

Don't get sucked down the path of alternate batteries at this time, the subject simply clouds the issue at hand.

 

[Mark54]

There are two 6v batteries for the house hooked up in tandem, is this the preferable setup , or could I replace them with 2 x 12v batteries.

I know that in my RV the 'master switch' has to be ON to charge with UHG underway- check that.
Might be called "USE/STORE" switch in yours?
Trace system and schematic to see where the connection is.
As for GC6 batteries- I would swap out for 12V LFP's- much lighter and higher energy density. GC6's are very heavy and usually quite tall.
Also opposed to GC6 batteries, LFP's give you 100% of the amps (watts) delivery instead of 50% with lead-acid types. Just don't let either get to 0% for any length of time- charge them back up asap.
20-80% SOC gives longest life if you can catch it them at those times...

 

[16ACE27]

I know that in my RV the 'master switch' has to be ON to charge with UHG underway- check that.
Might be called "USE/STORE" switch in yours?

Not in Class A or C. The USE/STORE is not in the path between the battery banks.

 

[ipburnout]

Sounds like a dead battery. If it's gel or lead acid, take it to an auto part store to have tested. Most will do it for free.
I bought an cheap ancel battery tester a while that will test CCA and Alternator charging. I always use it as my first test when I suspect a battery issue.

 

[ipburnout]

Not in Class A or C. The USE/STORE is not in the path between the battery banks.

You say this, but Thor claims otherwise. I have not seen any circuitry that would back Thor on my 2017 Windsport 34J. I recently had BIRD issues and the first thing they suggested is to be in STORE mode to break the battery banks.
From what I understand, as soon as either of the battery banks go over a certain voltage the bird will join the two banks.

 

[16ACE27]

what I understand, as soon as either of the battery banks go over a certain voltage the bird will join the two banks.

Yes it will; REGARDLESS of the position of the USE/STORE switch.

 

[PS89]

Just a reminder (for those who need it) that the USE/STORE (aka MAIN POWER) switch controls the BATTERY DISCONNECT RELAY's connection between the coach batteries and the converter/interior fuse panel/12V bus.

 

[rudyhehn]

Yes, the engine should be sending a charge from the alternator to the house battery bank, as well as to the chassis battery. When the engine starts there is a relay that closes a circuit so that a charge is sent to the house battery bank. Depending on your rig is it will probably be a BIRD/Trombetta relay device. You need to run some diagnostics. The Trombetta relay looks similar to a starter solenoid. Trace the large red wires coming out of it. When the engine is running the one going from the motor alternator to the relay will show 13v. Mine has a 2-minute delay before the relay closes. If your relay is working properly the red wire leaving the relay will then show 13v also. That wire goes to the house battery bank. My Trombetta went bad 3 years ago and I replaced it with an upgraded one with silver connections and it has done fine. The repair was not difficult but it depends where your BIRD is located.

 

[ipburnout]

Yes it will; REGARDLESS of the position of the USE/STORE switch.

View attachment 1314182

Yup. That's how I understand it also. USE/STORE disconnects the converter and the house circuits. Nothing with the two battery banks.

 

[tedh]

2023 Thor Miramar 35.2
I drove several hundred miles today with the refrigerator on, and each pit stop I made, I checked the house battery voltages. The voltage slowly dropped from 13 to 12.6, to 12.1, to 11.x, which was flashing red on the xantrex panel. Should the engine alternator be charging the house batteries while under way ? I could barely get the generator started, but once I did, the house batteries were reading 13.x volts again. After driving with generator running, the house batteries are still reading 12.7.

Yes they should charge while driving. On my Hurricane, the inverter needs to be turned on. While running the engine tho inverter voltage shows 13.9V

 

[Chateau_Nomad]

Yes they should charge while driving. On my Hurricane, the inverter needs to be turned on. While running the engine tho inverter voltage shows 13.9V

Hmmm... my inverter shows 120 volts.

 

[16ACE27]

Yes they should charge while driving. On my Hurricane, the inverter needs to be turned on. While running the engine tho inverter voltage shows 13.9V

Why do you think the inverter needs to be turned on?
What do you think an inverter does?