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I'm planning to use 9 or 10 of 12V 7AH (or possibly up to 35 AH) SLA batteries in series to power some LED bulbs.

Can I charge these in series, and if so, is it safe to assume that I just multiply the charging voltage times the number of batteries? Are there any other considerations I'd have to take other than as if I was charging a single battery?

Thanks in advance!

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    \$\begingroup\$ A battery fault (one shorted cell) would mean replacing one battery... and would imbalance the whole ensemble. Unless there's an extraordinary reason for it, fewer is better. \$\endgroup\$ – Whit3rd Mar 5 '17 at 5:02
  • \$\begingroup\$ And when you Googled "battery charge algorithm" what did you get? \$\endgroup\$ – WhatRoughBeast Mar 5 '17 at 5:21
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    \$\begingroup\$ All batteries in a series-connected bank should be identical - same make, type, usage history, etc., for best results. \$\endgroup\$ – Peter Bennett Mar 5 '17 at 7:16
  • \$\begingroup\$ Yes, you can, but see Peter's comment. Make sure you pay attention to safety. That is a high enough voltage to do some bodily harm, and there will be enough power available to do some serious sparking, arcing, etc. You can't use AC switches, fuses, etc, unless they are rated for DC also. Automotive fuses may not be rated for the voltage. Etc. \$\endgroup\$ – mkeith Mar 5 '17 at 7:22
  • \$\begingroup\$ Also, make sure the batteries are at the same state of charge before you put them in series. \$\endgroup\$ – mkeith Mar 5 '17 at 7:23
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I knew about voltage safety and making sure the batteries matched/equalized charge, etc. At any rate, I'll probably use a larger AH battery and an inverter (probably more economical), or if I can get the batteries cheap enough, charge them in parallel and run them in series using relays to switch which "mode" they're in.

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  • \$\begingroup\$ I believe that off-the-shelf chargers are readily available up to 48V. After that, I am not sure. If you plan to go higher, make sure you can source a charger. \$\endgroup\$ – mkeith Mar 11 '17 at 1:55

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