0

I've created a device where up to 24 AA batteries can be connected in series, with a rotary switch determining how many batteries supply the combined output voltage. If all batteries are at full strength, this output voltage is as low as 12V and as high as 36V, with 3V increments. I created the device to burn through a multitude of AAs I've collected out of devices that didn't completely use up their charge.

I would love it if I had a circuit on there that could regulate the output voltage to 12V, and when it falls below this I can dial in more power and still put out only 12V. What parts and schematic would i need for such a circuit? I would use it primarily to power an LED light bank. Many thanks...

Eric Eggers
  • 1
  • 1
  • A series string of cells will be limited by the weakest cell in the series. If you're using it to use up cells at random states of charge, age, and original quality, then you're going frequently run into situations where the whole string fails because one or two batteries are refusing to generate current. You'd need to either regularly check each cell when the device is on with a voltmeter, or make yourself some way of monitoring each cell's voltage. – TimWescott Mar 02 '24 at 19:04
  • There's a good reason that recommendations like "don't mix old and new batteries" exist (1, 2)... I'd recommend against your approach here, especially if you intend to "add batteries to the string, as others in the string discharge" - it won't compensate for the lower voltage, it'll just cause you issues. – Attie Mar 02 '24 at 23:44
  • So, the dead cells in the string won't just be 0V added to the other, non-0 sources? They wouldn't just act like shorts? – Eric Eggers Mar 03 '24 at 00:15
  • The voltage across dead cells will change polarity and produce heat in those cells. Schottky diodes parallel to the cells, cathode connected to +, can mitigate this to a degree. – Jens Mar 03 '24 at 18:07

0 Answers0