Forum Discussion

rekoj71's avatar
rekoj71
Explorer
Mar 17, 2017

12v issues

I have an issue where when I am not hooked up to shore power or have the generator running, I can't turn on many 12v accessories. I'm talking even too many lights without the lights dimming and then maybe even turning off for awhile before coming back on. It kinda has symptoms of a loose connection somewhere but I can't find it yet.

The scenario goes like this. I turn on some lights (5 or 6 LED) and they start off bright. A good 12v showing on the dash meter. If too many are turned on (10 LED or a few incandescents) the lights suddenly dim and the meter shows 8 or 9v. Sometimes they go out completely. When any of this happens 12v show on a multimeter touched right to the house batteries. After turning off some light switches and a bit of time the lights come back on strong.

If I try to start the generator the lights dim or go out and I can't get it started. If I start the engine first, then I can start the generator and I don't notice any light issues, also when connected to shore power there are no issues.

I tried wiggling all the wires I could find from the house battery connections to the distribution power center and from there to the house fuse panel, and even loosened and re-tightened them, but still no change.

I didn't take apart the battery power distribution panel as opening the cover it looks Greek to me, but I suppose I could if I turned off all power. The connections inside seemed secure with just a wiggle test but I couldn't get to all of them without removing a circuit board with gobs of wires and fuses on it.

If you have any new ideas or think I'm on the right track let me know. Thanks.

The rig is a 2013 Bounder classic 36h
  • rekoj71's avatar
    rekoj71
    Explorer
    Mar 17, 2017
    OP here, thanks for the replies and you guys were right on.

    With more troubleshooting it came to a bad cell like Roy had, although there may have been more also. I have a three stage charger so that shouldn't have been the culprit, but it may have just been their time.

    New batteries this morning seems to have fixed it.

    Thanks again.
  • time2roll's avatar
    time2roll
    Nomad
    Mar 17, 2017
    12.3 on the battery should start the generator. Dropping to 9 volts while trying to start the generator is not normal and indicates the battery is shot. The long shot would be a shorted starter motor on the generator.

    LED usually has a voltage regulator so they do not dim the same as incandescent. At around 9 volts would be cut-off to just quit.

    I never have understood why a generator starts from the house battery instead of the chassis.
  • RoyB's avatar
    RoyB
    Explorer II
    Mar 17, 2017
    This is how my batteries did one time resulting from a shorted cell in one of the batteries... This happened when I had my single mode converter/charger going and all of the charging DC voltages was 13.6VDC. This boiled out my battery fluids over time and it eventually shorted out one of its cells inside the battery... The first symptoms was like yours being intermittent...

    Now I am running a multi-voltage smart mode converter/charger and also keep a somewhat close eye on my battery fluids...

    Been going good since 2009 doing this...

    Roy Ken
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Mar 17, 2017
    Bad connection or battery at end of life.. I'd start with the bad connection

    how to test

    you need an automotive test light. This is a device that looks a bit like an old fashion ice pick with a wire out the handle and a light bulb inside

    When the lights dim, hook it to the battery direct.. BRIGHT means battery is not the problem.

    Now moving out

    First move the CLIP to a chassis ground point.. and the tip to battery positive

    now move out connection by connection along the positive line with the tip

    If you move the ground clip re-check last good point

    Problem exists between BRIGHT and DIM/Dark
  • SCVJeff's avatar
    SCVJeff
    Explorer
    Mar 17, 2017
    Just because the battery shows good on the DVM doesn't mean it's a good battery. A battery can go "high impedance" where it will show just fine on a meter (because the meter impedance is several million ohms and presents no "load" whatsoever), whereas drawing any kind of current, even from some of the brighter LED's, it simply cannot do.

    That's why the standard battery test is called a "load test", where you put 50-100A on a battery and see how it holds up. Yours would certinaly fail
  • rekoj71's avatar
    rekoj71
    Explorer
    Mar 17, 2017
    Not wanting to doubt the bad battery suggestions as it could be possible, they are original 6v x2 golf cart batteries, but why would they totally drop power instantly rather than slowly dim?

    Also you were right, I got a better look at my multimeter touched to the battery terminals when we tried to start the generator again (which of course didn't even try) and the power instantly dropped to 9v, and even stayed there with the lights now flickering, then after about a minute the power instantly jumped back up to 12.3v and the lights went bright.

    Guess I might not be used to batteries working that way when they get old, just thought it would slowly dim the lights.
  • time2roll's avatar
    time2roll
    Nomad
    Mar 17, 2017
    When the lights are dim what is the voltage on the actual battery terminals?
    Yes you need a hand held voltmeter.

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