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freewayrandy's avatar
freewayrandy
Explorer
Oct 07, 2019

How many volts....

Asking for my neighbor who recently got his first Class A, a used one, when plugged in to shore power, how many volts should we be seeing going to the coach batteries? Assuming there is a trickle charger built in to this unit.

26 Replies

  • Thanks for the replys and to 'set the stage' for the issue here, he went to the rig for something and when he closed the door the step would not retract all the way back in. Then he heard a clicking from near the steps, apparently from not enough voltage to retract them all the way. I went over and told him we need to check the batteries. The coach batteries, 2 6 volters, 1 was way low on water in all 3 cells the other was way low as well. We topped them off with distilled water then plugged it in to shore power. I checked the terminals with a multimeter and had only about 6.5 volts between the two. I thought there would have been at least 12 volts. Another issue here? Perhaps the batts. are toast?
  • 13.4V (float) to 14.8V (bulk charge) depending upon the charger and battery SOC. And there is some variation based on battery type if the charger has that option. Plus it will vary if the charger is temperature compensated. It will not drop below the float voltage unless the charger has a standby no charge option.

    Or a trickle charger may take a long time to reach the float voltage and above. Or never if there are house or chassis battery loads.
  • 2oldman wrote:
    Depending on the soc of the batteries, anything from 12.7 to 14.1


    Both those numbers are a bit low.
    At 12.7 volts, the batteries will NOT be charging.
    IF it is in boost mode, 14.3 to 14.5 is more likely.

    IF.....you have a "simple" converter/charger, it might read in the mid 13's all the time.
    IF.....you have a multi-stage charger, it likely will start out in the mid 14's and then drop back to the 13's after an hour or two.

    IF.....it never goes above 13.0, it likely is not working right.
  • The "trickle charger" would be either a converter or an inverter charger. It should put out 13.6 volts approx. unless it is in "boost" at 14.4 approx.

    The voltage you see at the battery posts depends on how far up in charge they are at first, but it should rise from there to that charger voltage. Same as in your own RV.
  • Depending on the soc of the batteries, anything from 12.7 to 14.1

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