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KATOOM's avatar
KATOOM
Explorer
Jul 10, 2013

Need a quick answer from the battery guru's

I thought I remember this being talked about, but knowing that the battery chargers in the RV/trailer tends not to deliver enough amps to bring the batteries up from a low charge (say like overnight usage) when just firing up the generator. So it was advised to get a separate battery charger and use that to charge the batteries instead. So with that said, my question is, how many amps and for how long is it normally required to bring the batteries up to a decent charge? I thought there was a formula for battery size per amps per hour, or something like that. I know that was just asked in layman's terminology so bear with me. Also, the charger I have is a 6 amp / 2 amp charger. Thanks.

23 Replies


  • If you have a RV manufactured within the last 10 yrs you most likely will have a more modern converter which uses a switching power supply. These converters can supply the FULL rated amperage into the battery.
    Unless it's a WFCO converter, then odds are it will never go into boost mode.
  • KATOOM wrote:
    I thought I remember this being talked about, but knowing that the battery chargers in the RV/trailer tends not to deliver enough amps to bring the batteries up from a low charge (say like overnight usage) when just firing up the generator. So it was advised to get a separate battery charger and use that to charge the batteries instead. So with that said, my question is, how many amps and for how long is it normally required to bring the batteries up to a decent charge? I thought there was a formula for battery size per amps per hour, or something like that. I know that was just asked in layman's terminology so bear with me. Also, the charger I have is a 6 amp / 2 amp charger. Thanks.


    Somebody has given you some very bad advice.

    If you have a RV manufactured within the last 10 yrs you most likely will have a more modern converter which uses a switching power supply. These converters can supply the FULL rated amperage into the battery.

    Old style Linear converters which used a big heavy transformer often only would trickle charge the battery(ies) at a measly rate of 6A or less. Then on top of that once the battery(ies) were charge the voltage was to high and boiled the batteries to death.

    Your 6/2A portable charger is like using a KNIFE at a gun fight, not worth the effort :S It will take DAYS if not a week to fully charge even a group 24 battery from full discharged to fully charged with 6A..

    If you take a look at your power center (this is were you find the 120V breakers and the 12V fuse panel), you should be able to get the name and model number of the converter. Post that here and someone will be able to properly interpret it and give you a better idea as to what you have.
  • Here are the times for a 220AH bank using 70, 55, and 35 amps smart chargers (Vector portables)

    Double the bank doubles the time at the same amps, but double the amps does not halve the time on the same bank size.

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