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How can I tell when my SLA batteries are charged? Answered

I have three, 12v, 22ah SLA batteries wired in series to make a pack that is 36v and 22ah.  The charger I have is the very crude kind which is essentially just a transformer.  It says it outputs 36v at 1.6a. The batteries are empty, this will be the first time I am charging them.  How can I tell when then are finished charging?  Can I use a multimeter? If not, then what? Thank you in advance for your help.

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mpilchfamilyBest Answer (author)2012-04-21

Yes you need to use a multimeter and measure the batteries. But in order to charge the batteries you need a power source that can give each battery about 13.5V or in the case of charging the batteries as a single unit you will need.closer to 40V to fully charge them. If you only have 36V going into it then you will only get them up to about 34V or 35V.But you have to remove the charger then test the batteries with the meter.

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___ (author)mpilchfamily2012-04-21

Thank you for your fast response! How do I test them with the multimeter? Should I measure voltage, current, or what?

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mpilchfamily (author)___2012-04-22

Measure the voltage. Turn off the charger and measure the voltage on the batteries.

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___ (author)mpilchfamily2012-04-22

OK, that's what I thought, but just making sure. So I will stop charging when it reaches 34-35v? Thank you so much for your help!

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