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Subject: Charging batteries?

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steveVa    Posted 01-13-2018 at 18:07:33 [URL] [DELETE]        [Reply] [No Email]  
  • Charging batteries?
  • If I charge a new battery up to 12.8 volts when sitting off the charger, how long should it stay at 12.8 volts or at least 12.6 volts? That is while it just sits not connected to anything. I would guess that outdoor temperature would make some difference, but lets just say it is kept above freezing. Thanks for any input.

    Jack - Iowa    Posted 01-15-2018 at 07:40:49 [URL] [DELETE]        [Reply] [Email]  
  • Re: Charging batteries?
  • Looks like I was low! Found the following on a manufacturers website.

    The truth is, most 12-volt batteries need to measure at least about 12.6 volts before they are considered fully-charged. That is because each of the six cells in a 12-volt battery should measure at least about 2.1 volts when fully-charged. Multiply that number by six cells and you arrive at 12.6 volts. Battery chemistry can vary from one battery to the next, so we say "about 12.6 volts," because a battery could be fully-charged at only 12.5 volts or 12.8 volts and some batteries may be fully-charged at even higher rates.

    steveVa    Posted 01-15-2018 at 23:30:37 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Charging batteries?
  • Thanks Jack. Looks like my batteries are staying at 12.7 volts. I also bought a charge meter that shows volts and percent of charge. 12.7 volts shows as 88% charge. 12.8 volts shows as 92% charge. 12.9 volts as 96% and 13 volts as full. I am making a solar bank and only want to discharge to 60% in order to keep the batteries healthy.

    Island Mike    Posted 01-14-2018 at 01:24:38 [URL] [DELETE]        [Reply] [Email]  
  • Re: Charging batteries?
  • Good batteries will sit at 12.75 for quite a while, possibly a week or more. Some even a few weeks in warm weather. Some like the new battery in my Dodge, that got drained, level off at 12.6. Fully charged is 12.75. Half charged is 12.25 and the point where they should be charged.

    Island Mike

    steveVa    Posted 01-15-2018 at 23:43:44 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Charging batteries?
  • Looks like you are right on the money. Mine sre staying at 12.7 volts.

    Jack - Iowa    Posted 01-13-2018 at 19:59:32 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Charging batteries?
  • Steve,

    I think it will balance out at 12.4 volts once it has cooled off.


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