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ricelake922's avatar
ricelake922
Explorer
May 18, 2017

Replacing chassis battery with group 27 batteries

I have a 1996 Monaco Dynasty that has a 8D chassis battery. I have a new 200 amp alternator and battery isolator. On the drive back home from Florida I stop to get diesel and turned the engine off. The engine would not start after refueling. I turned on the generator for 5 minutes and the engine started. Took RV for an hour ride a couple of weeks ago to heat up engine and exercise and when I brought the RV home turned off engine, went to restart 5 minutes later and the RV would not restart. It has been suggested to me that I should replace 8D battery with group 27 batteries. Don't want to spend money if it is not going to fix starting issue. Any opinions would be appreciated. Thank you in advance.
Class A
  • MrWizard's avatar
    MrWizard
    Moderator
    May 18, 2017
    Let's See
    New alternator, new isolator
    You drive, then it won't start,
    You start generator and then it starts
    Shut off engine and it won't restart, with out generator

    Providing it started find, before the new parts where installed
    I would guess that something is wired wrong
    If the reason for the new parts was the starting problem
    Then I would have the battery tested
    A new 8d will be stronger than any pair of group 27s

    Although my 5.9 Cummins isb uses 2 grp27 batteries for the engine/chassis
  • time2roll's avatar
    time2roll
    Nomad
    May 18, 2017
    For superior starting performance consider a Lifeline AGM 8D starting battery.
  • pianotuna's avatar
    pianotuna
    Nomad III
    May 18, 2017
    By going to two jars you double the number of cells which means each cell only needs to produce 1/2 as much current. I would get two of the biggest starter batteries that will fit the available space.
  • wolfe10's avatar
    wolfe10
    Explorer
    May 18, 2017
    What will start a Cummins B will not necessarily start a Cummins C.

    Either go with two group 31's or another 8D.

    BUT, at this point, we don't know for sure that the chassis battery is bad. Need to confirm:
    1. That it is getting a charged from the alternator (voltage 13.5+ with engine running at 1000 RPM).

    2. That after being fully charged, that it passes a load test (free at any place that sells batteries).

    When you have the "no start", does using the boost switch allow it to start?
  • Triker33's avatar
    Triker33
    Explorer
    May 18, 2017
    I replaced my 2 OEM group 31 chassis batteries that were 7 Years and 9 months(just thought they were getting old and time to replace) old for group 24 930CA@0º

    And they lasted 9 Years(still working but cranking speed had slowed some) and then I replaced with group 31 950CA@0º 2 years ago.

    So any group will fit and start the MH if they are around 930-950 CCA
  • dougrainer's avatar
    dougrainer
    Nomad
    May 18, 2017
    Group 24/27 batteries are NOT starting batteries. You need 2 group 31 Chassis batteries to replace your D battery. Doug
  • Gjac's avatar
    Gjac
    Explorer III
    May 18, 2017
    How old are the batteries? If your charger has these functions I would equalize then desulfate and see if that makes a difference. You can also take your batteries to Walmart or most auto parts store and they will run a load test to tell you of the condition of the batteries. You need a certain minimum CCA to turn your eng over which is higher than a gas engine. Someone with a DP can tell you that. For example my 454 needed 700 CCA to start it was turning over slowly and when I load tested it it had 500 CCA, so it was replaced with a battery that had 810 CCA.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    May 18, 2017
    8D is 230 amp hour if I redcall correctly. Group 27 is roughly 100, so for capacity you'd need 3 of 'em.

    But for starting I have no idea of the Cranking amps.. You need to either match or increast the cranking amps.. that varies from brand to brand of battery.

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