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23hotrodr's avatar
23hotrodr
Explorer
Apr 01, 2021

Old automotive battery charger question

I have an approx. 40 year old 12/6 volt automotive battery charger. When set for 12 volts and not connected to a battery, it reads 12.81 volts. Set to 6 volts and not connected to a battery, it reads 8.1 volts. When I connect to a 12 volt battery, and set for 12 volts and battery fairly well charged I read about 16 volts and the battery starts boiling right away.

Does this seem normal? Should the difference of charger output boltage be that much different when connect to a battery?

Thanks for any info you can provide. -- Mick
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    May 20, 2021
    Don't junk that charger. Send it to someone who understands how to use it. I have sent several hundred pounds of *smart* chargers to recycle centers whom send them to land fills anyway. Transformers in *smart* chargers offer unusable unsalvalvageable voltages.
  • JoeH's avatar
    JoeH
    Explorer III
    May 21, 2021
    Interestingly, on a motorcycle forum I participate in, there was a post yesterday about having a dead battery and that he had a charger on it for a day + and it was still dead. I suggested that he find an old "not smart" charger and try that.... he responded that putting on the old charger worked!

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