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dave14117's avatar
dave14117
Explorer
Sep 01, 2017

Batteries not charging

05 Cougar fifth wheel, 2 year old Costco batteries.

Today tried to fix problem battery not charging when on AC power. Seems to charge ok when connected to truck; not sure. DC lights do brighten when on AC or truck, dim when no AC or truck.

I think the converter gets AC power, converts to 12v DC for the panel, and somehow also then sends 12v (@ ? amps) to charge the battery. So given that the lights brighten and its fan works, I think the converter must be getting AC power. But somehow the batteries aren’t being charged. Not sure if the charging ckt goes through the panel; if it does, all the fuses are ok, so maybe chewed wiring?

So far:
Checked auto fuses, all ok
Checked ground in basement and in panel area
Added water to batteries

Solution attempts
Removed TV/Stereo 12v fuse (disconnected it a month ago because it was making constant alarm; might still be drawing power)
Removed GFCI and replaced with regular outlet
Added tape to mice-chewed ground wire going from basement to panel

Any ideas appreciated
  • Artum Snowbird wrote:
    Easy fix. Either your positive to the battery, or your negative to the battery both from the converter has a loose connection.

    Cut a short wire and screw it into the negative terminal on the converter, then use your jumper cable to connect to that, and to the negative on the battery. Plug in to power. Do the lights get bright. It's the negative side that has a loose connection.

    If not, do the same, by itself, with the positive side at the converter, and to the positive side of your battery. Do the lights get bright. It's the positive side that has a loose connection.

    In my case, I found the main negative terminal at the converter to be loose, my batteries went down when I was plugged in, and came up when I drove. I wiggled the wire, and bingo, found the problem just like that.

    Start there, at the converter with the main positive and negative feed screw terminals to the battery.

    Your idiot lights on the charging terminal should show full lights when plugged in. When my cable was loose, the idiot lights kept going lower and lower.


    I'll try this tomorrow p.m. Thanks
  • corvettekent wrote:
    Put a volt meter on the batteries with the converter turned off, what is the voltage?
    Now turn on the converter, what is the voltage?


    Converter on (AC power on) - 13.6v
    Converter off (AC power off) - 12.5v
  • ScottG wrote:
    Could be the battery is kaput.
    Or, is there any chance it was hooked up backwards recently? If so then the reverse polarity fuses would be blown. (usually 3 fuses away form the others)


    No changes recently. New batteries 2015.
  • IF battery hooked up backwards...reverse polarity fuses ON converter BLOW....BUT if they are blown the converter has NO DC output.
    Lights work so reverse polarity fuses OK

    Battery in-line FUSE (or a DC circuit breaker) on Battery POS cable to converter.
    If BLOWN.no DC from battery and No charging from converter to battery
    Measure DC Voltage at converter where battery wires connect......with converter OFF and then with converter ON.
    In-line fuse blown...no DC Voltage at converter with converter OFF (S/B 13.2V with converter ON....or converter failing)

    Battery NEG cable not making good ground connection on frame
  • Put a volt meter on the batteries with the converter turned off, what is the voltage?
    Now turn on the converter, what is the voltage?
  • Easy fix. Either your positive to the battery, or your negative to the battery both from the converter has a loose connection.

    Cut a short wire and screw it into the negative terminal on the converter, then use your jumper cable to connect to that, and to the negative on the battery. Plug in to power. Do the lights get bright. It's the negative side that has a loose connection.

    If not, do the same, by itself, with the positive side at the converter, and to the positive side of your battery. Do the lights get bright. It's the positive side that has a loose connection.

    In my case, I found the main negative terminal at the converter to be loose, my batteries went down when I was plugged in, and came up when I drove. I wiggled the wire, and bingo, found the problem just like that.

    Start there, at the converter with the main positive and negative feed screw terminals to the battery.

    Your idiot lights on the charging terminal should show full lights when plugged in. When my cable was loose, the idiot lights kept going lower and lower.
  • Could be the battery is kaput.
    Or, is there any chance it was hooked up backwards recently? If so then the reverse polarity fuses would be blown. (usually 3 fuses away form the others)