Quick dumb question - vehicle battery

[dg0603]

Am I correct in understanding that the coach battery under the hood does not get any kind of trickle charge from any of the charging systems?

It's just under there like any other vehicle battery.

I know you can get a boost from the house batteries if it's dead.

[DavidEM]

I think you meant chassis battery in the post above. Newer coaches with modern BIM's do charge the chassis battery while the coach battery is being charged. The Precision Circuits BIM 160 in my 2021 Thor Axis does this. I have measured the voltages and I am sure that it does.

Older BIM's like the Intellitec BIRD/Trombetta were built originally to do this, but their relays have often failed or contacts got dirty so it doesn't work that way any more.

David

[16ACE27]

Originally Posted by dg0603

Am I correct in understanding that the coach battery under the hood does not get any kind of trickle charge from any of the charging systems?

It's just under there like any other vehicle battery.

I know you can get a boost from the house batteries if it's dead.

Where did you get that understanding? What do the electrical drawings in your Thor Owners Resource say about your RV and it's ability to "cross-charge"?

[dg0603]

Yes sorry, chassis battery. Thank you.

Didn't think to look at the owner's site.

Was hoping for a fast lazy answer for my 2022 Tellaro.

[16ACE27]

Originally Posted by dg0603

Yes sorry, chassis battery. Thank you.

Didn't think to look at the owner's site.

Was hoping for a fast lazy answer for my 2022 Tellaro.

Well, you can get fast, lazy answers; off topic answers; answers that don't apply to your RV; or the correct answer.

[dg0603]

Ok....I really like you Ace. True.

[16ACE27]

[DavidEM]

Originally Posted by dg0603

Yes sorry, chassis battery. Thank you.

Didn't think to look at the owner's site.

Was hoping for a fast lazy answer for my 2022 Tellaro.

Look around for the BIM on your coach. It is sometimes in the engine compartment like my 2021 Axis. If you have the Precision Circuits BIM 160 which I suspect most newer Thor coaches have, then you will have chassis battery charging from the coach DC system.

If you have something else, then maybe it is working, maybe not.

David

[Pillbox]

Turn everything off. Disconnect shore power.
Measure chassis battery voltage.
Plug in shore power, measure chassis battery.
If different, then most likely your genny and shore power
Charges your chassis batteries.

[LawrenceofPA]

I downloaded the manual for the BIM from Thor, and it's very clear that the BIM allows charging from both alternator and shore power. It's a pretty smart device.

[RonRM]

Originally Posted by dg0603

Am I correct in understanding that the coach battery under the hood does not get any kind of trickle charge from any of the charging systems?

It's just under there like any other vehicle battery.

I know you can get a boost from the house batteries if it's dead.

You are correct, only from the engine alternator: BTW the chassis battery in the Ram is under a panel at your feet on the drivers side.

And yes, again correct...if the 'chassis' battery dies, you can start the engine with the switch to the left of the steering wheel.

To be sure it will work, with everything off (ie. quiet), so you can hear it...push the switch/button - you will hear a 'click', when you release it you will hear another 'click'...that's the relay under the coach which connects the coach batteries to start the engine.

edit: added pic for clarity - that round thing is the relay, it only connects the chassis battery to the coach batteries when the e-switch is pressed. And it properly identifies the fact that the chassis battery is NOT charged from the inverter/charger nor the generator or Balmar alternator (units without generator). The two battery chemistries are incompatible to charge from the same source...Thor did that right

Ron