Forum Discussion

Belgique's avatar
Belgique
Explorer
Nov 12, 2016

Battery/Charging problem checklist?

I know there are a zillion threads on batteries. I've searched.

Is there a relatively simple checklist somewhere on how to fault diagnose house battery problems? I have a digital meter with clamp. I understand basic 12V systems.

My issue is that my 12V house batteries (2ea) drop like a rock when unplugged. They checked good with a hydrometer a few months ago. Today they turned CG power of for 15 min and my inverter was alarming at 11V within 10 minutes. There's water in the batteries. A month ago they lasted for 4 hours before crashing. Nothing was on either time except the usual parasitics.

Thanks in advance
  • mvas's avatar
    mvas
    Explorer
    Nov 13, 2016
    Could there be one bad cell?
    Did you measure and compare S.G. readings in all 6 cells?
  • Belgique's avatar
    Belgique
    Explorer
    Nov 13, 2016
    Thanks to all. Good things to check. Mex, your sequential list is exactly what I was seeking. I'll get to work and report.
  • Belgique's avatar
    Belgique
    Explorer
    Nov 13, 2016
    Thanks to all. Good things to check. Mex, your sequential list is exactly what I was seeking. I'll get to work and report.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Nov 12, 2016
    • CHECKLIST LIKE THE OP REQUESTED
    • Unplug, turn off all loads inside
    • Measure battery voltage what does it say?
    • Report back
    • If voltage says >12.4 you have a batteries themselves problems. Report back
    • If the batteries cannot charge to 13+ volts when plugged in check back you have a charger problem
    • This is a step-by-step troubleshooting procedure and to try and list all the permutations would make the RV.net server, catch fire
    • Take it a step at a time starting with the above.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Nov 12, 2016
    How old are those batteries....???

    What is charging system DC output...???

    What do YOU measure voltage at when fully charged....???
  • Harvey51's avatar
    Harvey51
    Explorer
    Nov 12, 2016
    What Dougrainer said plus remember that chronically undercharged batteries have reduced capacity. Some older converters are not very good at charging batteries and most don't equalize or attempt to desulphate them.
  • dougrainer's avatar
    dougrainer
    Nomad
    Nov 12, 2016
    1. FULLY charge the Coach batteries then check with the Hydrometer
    2. You are assuming your Coach batteries were fully charged when the CG power went off. You may have a problem with your charging system keeping those batteries charged.
    3. One thing people have a hard time understanding----- NOTHING will deplete GOOD fully charged batteries in less than 2 hours. There is NOTHING in an Automobile or RV that can draw enough current to deplete GOOD fully charged batteries in less than 2 hours. Doug
  • Ivylog's avatar
    Ivylog
    Explorer III
    Nov 12, 2016
    You should have a 10 amp setting on your meter so disconnect one battery terminal and put it in series and see how many amps you get. Should be around 2 amps and if so, your batteries are no good. If it's closer to 10 then you have something left on... basement lights are often missed. How many amps with the inverter turned off?
  • time2roll's avatar
    time2roll
    Nomad
    Nov 12, 2016
    What are you running with the inverter? s/b nothing continuous such as the fridge and water need to be on propane.

    Or just turn the inverter off and see what goes.

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