Alternator not charging house batteries- Axis 24.1 with BCC

[Mo_Mike]

Originally Posted by tjyap

Here is the latest:

Plugged into shore power: 13.1V House, 12.5V chassis (I believe this should be the same. It seems the relay is not working in the other direction either (house system not charging the chassis system).

Tried holding down aux start button: No change from above (no audible sound of the relay working either).

Unplug from shore power and start engine: 12.9v (and falling) House, 14.5v chassis. Wait 5 minutes and no change to the above. Try holding down aux start button and still no change.

My next step: after starting engine try cycling the Use/Store switch as I saw where that worked for some other person.

Don't have the BCC on our 2016 VEGAS, but on our coach the BIRD was wired wrong, with the COACH BAT and IGNITION leads reversed. Took a lot of checking and double checking to prove to myself that THOR did wire it wrong from the factory.

After I bit the bullet and wired it the way I thought it should be, everything has worked exactly the way it should

[Oneilkeys]

You don’t say if this is a new problem that you never had before? Did the system work correctly and now you have an issue or is this a new coach? My BIRD was also wired incorrectly at the factory. The wire to the coach batteries went somewhere - just not to the coach batteries. After cutting that wire from the BIRD and rerouting it to the coach side of the Trombetta (with an online fuse) it worked perfectly. There have been numerous reports of misfired BIRDs.

[javelin]

tjyap, the BCC does have contain an interconnect relay (also called emergency start relay) that connects the chassis and coach batteries together under certain charge and emergency start scenarios. You have diagnosed the typical failure of this interconnect relay......converter charges the coach battery OK but not the chassis battery and the reverse when engine is running and alternator is charging things (chassis battery charges but coach battery does not. So I suspect the interconnect relay has failed (no audible click when emergency start switch is operated). The issue is getting into the BCC and repairing this relay.....can be a hair puller depending on where the BCC is mounted. Start by killing all power in the coach (batteries, shore, no gen, no alternator).....after obtaining a replacement relay. Picture of the BCC showing the silver colored interconnect relay is attached. The other two relays are the coach and chassis battery latching relays.

[tjyap]

You guys nailed it! Thanks for all the help especially Javelin. I was able to purchase a replacement relay and dig down into the BCC to pull out the old one. Don't understand why the old one doesn't work, looks perfectly fine. Anyway, took me about 75 minutes yesterday, but the end result is that everything works great! Thanks again.

[javelin]

Glad to hear you got your BCC charging system working again. I think you had said before that the old interconnect relay did not click when you operated the emergency start switch by the driver seat. If true, then the coil sounds like it went open (or is intermittant). If you have a 12 volt charger you could briefly touch +/- to the coil terminals on the old relay and see it it clicks. An ohm meter would also work to show continuity (with some resistance) when connected across the relay coil. The bonus is that the cct board in the BCC is not damaged.....that would put a small dent in your wallet.

[SANDDOG]

And alternator with almost all commercial vehicles should charge 13.5 V anything more than that or anything less than that the alternator is not doing its job. It will fry the batteries or deplete them buy a new alternator or have it rebuilt

[tjyap]

Whoa... you had me worried for a moment! Until I did some research online to determine that 14.4V is the when gassing may start to happen, but still within the range of normal. From what I have read, more than 14.6V and you should start to be concerned, though many suggest 15V is the cutoff. I think my 14.2V should be ok and definitely not worth me going down that rabbit hole. I keep my unit plugged in and working off the converter all the time, so I monitor the Volts constantly. They rarely remain above 13.2 for more than 24 hours. I also monitor my Deep Cycle Lead Acid water levels. So far they haven't dropped at all in 9 months.