# Charging batteries connected in series

Discussion in 'General Electronics Chat' started by kudapete, Mar 23, 2015.

1. ### kudapete Thread Starter New Member

Mar 23, 2015
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I am connecting 3 12v batteries in series to produce 36 v for powering a 36v LED Module. Can I charge the 3 batteries with a 12 v charger connected to the + & - of the first battery ?

2. ### nycokello Active Member

Aug 10, 2009
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the solution is to use 12v by 3 charger. but if you cant get such a charger ,you may only be left with another option of charging one at ago...as long as you dont violate laws of nature.....

3. ### blocco a spirale AAC Fanatic!

Jun 18, 2008
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No.

Did you notice how, if you were to do this, there would be no charging current flowing through the other two batteries?

4. ### kudapete Thread Starter New Member

Mar 23, 2015
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That's what I was thinking too, I guess the only way would be to have a dedicated charging switch that changes the serial configuration to a parallel when connected to the charger Thanks for your response.

5. ### R!f@@ AAC Fanatic!

Apr 2, 2009
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1,111
Parallel charging is tricky.
All depends on the battery capacity and type of batteries

6. ### ScottWang Moderator

Aug 23, 2012
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1. What is the LED Module?
2. What kind of the battery(datasheet)?
3. How much current of the battery?
4. You may using a 12 V charger to charging three in parallel batteries, but this way must be disassembly the batteries, some 12V batteries can be charge by a voltage about 13.7V, so that's why we need to know more about the battery.

5. Using a 36V battery charger, but at least the charging voltage can be using a 12.7V voltage for each one, so the charging voltage should be 12.7V*3=38.1V, some batteries maybe could be charging for 13.7V*3=41.1V.

7. ### #12 Expert

Nov 30, 2010
18,076
9,691
R!f@@ just said, "Yebbut...you can't just flop a switch and connect a bunch of batteries together". They aren't necessarily matched in charge quantity, and it gets worse as the batteries age. You should account for this by using about an ohm in series with each battery so they aren't very successful at trying to equalize each other when they are suddenly in parallel. A few fuses will protect you if one of the batteries becomes internally shorted and the others try to equalize its voltage.

Trying to charge them all in series will eventually end with the weakest battery causing the others to be overcharged.
The best you can do is separate them for service and be vigilant as they become less like their new condition.