Forum Discussion

juano's avatar
juano
Explorer
Oct 20, 2021

Coach battery bank not working

Hi,

Fulltimer with a wife and 2 years old baby trying to troubleshoot an electrical issue for almost a week without luck, need to be able to run furnace and the rest of the equipment as its getting really wet and cold here in the mountains of Northern California.

Got a 1995 Bounder and loving it, original 6v Interstate batteries were from 2005 so totally dead, replaced them with brand new 6v Interstate deep cycle connected in series as the original. Starter battery replaced too.

After 3 days coach batteries died.

Alternator or shore power by charger/converter not able to recharge coach battery bank. I got a big wheel Napa battery charger and recharge them to 12.8v.
If I'm running engine I've 12v power but few minutes after I shut it off I lost all 12v power after a relay click. Looks like coach battery bank is not being recognized by the system.
I already cleaned the two grounds from each bank at the chassis until I got shiny metal, nothing changed.

With the engine off if I click both battery disconnect switches I can hear a click, but maybe I should go further and check it with my meter, any guidelines of how to proceed step by step? I'll take notes and update the post as requested.

My electrical skills are not great but I've 2 multimeters available, voltimeter light, wires, and the whole day to take readings and hopefully fix this annoying issue.


Thanks you!
  • BFL13's avatar
    BFL13
    Explorer II
    Oct 21, 2021
    You know the battery fuse is ok because the battery powers the 12v things. so the open is not that. You want to know if the converter 13.7v is reaching the DC fuse panel so it can run the 12v stuff. Should see 13.7 at the individual fuses at the panel.

    If only 12.x (battery voltage) at the panel, then the open is in the converter to DC panel which is also where the converter to battery goes.

    The battery lugs and the converter connections to the DC meet there. You could have the battery wires on their lugs but one of the converter wires not in its lug.
  • obiwancanoli's avatar
    obiwancanoli
    Explorer
    Oct 21, 2021
    MT BOB wrote:
    Generally most coaches will not use chassis battery, but gets power from chassis when vehicle is running.
    Just because a relay clicks does not mean it is good, the internals could be poor/bad.
    Here is a basic 3 relay system,the "isolation" relay would be your emergency start relay.
    I suspect a bad house battery relay,or it is not being turned on, or a bad positive connection somewhere from the house battery(s) to the relay.


    I recently had a problem with my solar, and on-board generator not recharging house batteries. Used an external generator to recharge back to 100%, but it pretty much destroyed generator's ability to work after that, as it revved up a lot, in spurts, while recharging over a period of about 5 hours.

    Had a mobile tech come out, and he completed thorough diagnostics, during which he found two items of concern... first, there's an on/off switch at the top of the on-board generator that was in the off position, although it charged batteries for 3 weeks prior with no issues. No idea how it was flipped to "off", but flipped back on, and then generator charged batteries.

    Second issue was that solar was not recharging house batteries, and diagnostics showed the "battery disconnect" module (housed in the electrical cord bay) showed 1V difference between chassis side (14.2V) and coach side (13.1V), and this, he said, was the problem, as they should both be reading same voltage.

    So, am about to have this module replaced, and hope this resolves the charging dilemma...
  • juano's avatar
    juano
    Explorer
    Oct 21, 2021
    enblethen wrote:
    What is the exact model number of the converter? is it a 9100 or 9200?
    Does it supply power when connected to shore power?


    I've the 9000.
    Yesterday I followed the troubleshooting guide and I got every reading well like 120v input, 13.7v output, no blown fuses and the two 30amp breakers at the BCC reset but coach batteries still not charging and converter fan not starting.

    Does I have a failed converter?

  • fourthclassC's avatar
    fourthclassC
    Explorer
    Oct 21, 2021
    All good recommendations and discussion above. Just wanted to add, while not likely to be the specific situation here, the battery isolation solenoid can click but still not do it's job disconnecting/connecting. The magnet and plunger actuate but the contacts are worn and not working. Need to check this with a multimeter and 12vdc supply to actuate the solenoid.
  • enblethen's avatar
    enblethen
    Nomad
    Oct 21, 2021
    What is the exact model number of the converter? is it a 9100 or 9200?
    Does it supply power when connected to shore power?
  • juano's avatar
    juano
    Explorer
    Oct 21, 2021
    I found my issue, a cleaned ground that apparently was not clean enough so testing conductivity through the chassis I got bad connection.

    I'm happy to say that my brand new coach batteries are giving power to my house.

    Now I'll need to figure out why after followed the troubleshooting guide positively my Inteli Power 9000 is not charging my batteries.
  • MT_BOB's avatar
    MT_BOB
    Explorer
    Oct 20, 2021
    Generally most coaches will not use chassis battery, but gets power from chassis when vehicle is running.
    Just because a relay clicks does not mean it is good, the internals could be poor/bad.
    Here is a basic 3 relay system,the "isolation" relay would be your emergency start relay.
    I suspect a bad house battery relay,or it is not being turned on, or a bad positive connection somewhere from the house battery(s) to the relay.
  • juano's avatar
    juano
    Explorer
    Oct 20, 2021
    Thanks enblethen and BFL13 for the comments.

    Before I pass to converter/charger testing I need to know why my coach battery bank is not being used by my house. So went from battery banks positive to BCC and found that I was getting full voltage from the chassis battery at the solenoid but only 3v on the coach battery bank.

    This morning I decided to jump the automatic charging aux start relay (a.k.a. solenoid) to see if I can find some changes. Before I jumped it I took readings with my multimeter on each battery bank:

    Chas bat 12.21v
    Aux bat 12.68v

    Using ground around the BCC and positives entering into it and connecting to solenoid I read:

    Chas bat: 12.21v
    Aux bat: 3v (??)

    Then I proceed to disconnect everything and jumped the solenoid and measure again on solenoid sides:

    Aux bat 12.18v
    Chas bat 12.29v

    I turned on 12v lights at the coach and I measured again after 5 minutes:

    Chas bat 11.8v
    Aux bat 12.68v

    So it’s clear that my house is not using the power from the coach battery bank and draining the chassis battery.

    So that's why I want to keep converter aside until I get this step solved.
  • BFL13's avatar
    BFL13
    Explorer II
    Oct 20, 2021
    When plugged in and you see 13.3v at the converter output, you should also have about 13.3v at the battery posts. If only 12v there, check your "battery fuse" or DC circuit breaker near the batts somewhere. If it is open, the alternator charging won't reach the batteries either.

    However, if your batts die after running things for a while, that means that battery fuse is ok since the 12v from the batts can get to the lights and fans etc. Some other "open" would be between the converter and the battery bank.

    You are getting 12v in the house with alternator running so it is not the DC CB by the isolator, but could be the DC CB at the other end of the wire from the isolator near the batteries (which might be in addition to the "battery fuse")

    Some MH have some of this in a compartment next to the battery location instead of at the engine battery and house battery locations. I don't have that so others can help there--also with whatever a BIRD is, if it is not the same thing.

    You need the PD booster control if not fitted so you can put 14.4v to those 6s to charge them properly.

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