Thor Tellaro Batteries not Charging

[chrisb]

Hello - I have a 2021 Tellaro KT with the standard AGM batteries. We are on a 2 week trip through the southwest and the batteries have stopped charging via the engine alternator and generator. I do get a slow trickle charge via the solar panels. With just the frig running the mornings start off with about 12.1v and below about 10ah. By late in the day (if sunny all day) will be at about 12.6v and around 60ah. That’s after driving all day thus I know it should be much better than that. With the engine running I do see the chassis battery is charging as the battery voltage is around 14.2v, but the couch battery remains at around 12.5v. With the generator running I can bump the coach battery up to around 13.3v but several hours of it running does not boost the available amp hours. Based on all this it appears only the juice from the solar panel is actually making it to the batteries.

Does anybody have any idea what is going on? I suspect there is a bad gizmo somewhere that is keeping power from making it from the alternator or generator to the batteries. I’ve checked all the fuses and have done a complete shut down and restart but still having the problem.

[DavidEM]

The alternator not charging the house batteries may be due to a faulty BIM, battery isolation manager. You probably have one of two types, the Precision Circuits BIM 160 which has been pretty reliable or the Intellitec BIRD/Trombetta which is known for the relay failing.

I am not sure why running the generator doesn’t charge faster. On my 2021 Axis I replaced the slow charging WFCO 9855 charger with a Progressive Dynamics charger and saw a significant improvement in charging current, particularly as the batteries got close to full.

David

[chrisb]

Thanks for the info, this will be helpful info when I take it in for service. Today after a full day of driving I noticed sometime the coach batteries were getting the normal 14.2 volts from the alternator, then at times only 12.4 and then oddly enough 14.9 for awhile. I’m now adding loose wiring and/or inaccurate sensors to the list of possible causes.

[chrisb]

I’ve done some research and talked to Thor and I suspect the problem the BIM. Thor was thinking it may be located in the engine compartment on the back fire wall or side walls. I can’t seem to find it. Does anybody have a clue where it may be? Thanks

[djkeefe922]

I have a Sequence 20K with Onan and AGM. Mine is under the coach about midway or back a little on a cross member facing to the rear. Exact location might be a little off. I haven't been under there for a while. If that dosen't help I'll crawl under and get a pic for you.

I had the same issue and it was lose connections on the BIM.

[chrisb]

Thanks for the info…I finally found it exactly where you said it might be. It never occurred to me that it would be exterior. I’m betting on the loose connection also but such an awkward location, couple with my limited knowledge, makes me nervous to redo the connections. Based on the location I think I’ll let the service folks mess with it.