How can I discharge a battery to certain voltage?

robocam

10 kW
Joined
May 29, 2014
Messages
773
I have batteries of several voltages, and I want a way to discharge them to 40% (3.8V per cell) when I'm not using them (other than draining them in the devices they power). Is there a circuit I can use to discharge them to that voltage automatically? Right now, I'm using a voltage booster/regulator to charge them up to 3.8V per cell, but I also want to be able to also discharge them to that voltage. I don't mind buying/making one for each battery voltage. It'd be nice if there was a circuit like the regulator that I can buy that can serve this function.

If someone has a circuit idea, I'd love to hear about that as well. I just need something to open the circuit when a preset voltage has been reached.
 
This is listed as a charge limiter not discharge, but perhaps it can be used either way?


https://endless-sphere.com/forums/viewtopic.php?f=14&t=87562
 
Battery medic will discharge cells down slowly.

Or CellLog 8M has an output for an alarm that can be modified to trip a discharge like a bank of globes. Will stop when the lowest cell hits the trigger point.
 
Not only Cell Log. There are some blue Battery Medic clones that discharge into halogen bulbs. Search "Battery Balancer Discharger 150w" on ebay or aliexpress
Instead of using the native discharge device which only works for 2S-6S batteries, try to use the 2-wire plug on the top of the LCD display to trip your discharge device (e.g. several 12v bulbs in series, or a 110V hair dryer) through a mosfet or relay.
 
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