make 12 volts from li ion batteries

monterino

Reputable
May 8, 2014
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Hi- Trying to use 3.6v Li-ion batteries to make up 12v, but....
4 (series Li-ion cells) x 3.6 = 14.4vdc, 3 (series Li-ion cells) x 3.6 = 10.8vdc.
And no... the series of 4 and the series of 3 cannot be put in parallel-
There's a difference of potential between the strings which will allow the high to flow to the low.
(boom)...
I can reduce 14.4v to 12v using diodes in series, each of which drops the voltage a smidge...
But, I hate bringing a battery, which is a portable energy store, then killing it's output with a voltage reducing, power sucking device like a diode.
WTF?
 
Most devices have a fairly large operating range. "12V" SLAs typically run from 14.8V all the way down to ~11V (depending how much you want to destroy the battery).

Li-ion batteries tend to want to stay between 4.2V and 3V per cell. I'd suggest four in series, but make sure that you've got an undervoltage cutoff around 12V.

Other option is to go for 5-6S and get a buck converter.