Author Topic: Battery cell balancing technique, review it?  (Read 543 times)

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Offline HSPalmTopic starter

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Battery cell balancing technique, review it?
« on: September 17, 2019, 12:06:59 pm »
Hello,
I have reviewed some different circuits for balancing battery cells, but I have not seen any using the technique I propose here. Would like to discuss any downsides and benefits, maybe if you see some obvious errors that I don't see.

Each cell can be individually connected to either VDD or GND, except the top or bottom cells of course.
When charging the full pack, you close the top and bottom switch and operate VDD in constant current mode. When one (or more) cell(s) reach full charge voltage, you start the constant voltage charge mode until charge current is equivalent to a complete charge. If any cell is out of balance, you adjust VDD output and charge it individually as shown in the one screenshot.

VDD or the charge voltage/current will be controlled by a fet in linear mode, so the switches can actually remain switches (relays or fets operated as switches).

This is a list of downsides and benefits I've discovered so far.
:-+ You can charge the unbalanced cell(s) with the full current of the charger. Balancing current is often limited in other chargers.
:-- You can only balance one cell at a time, unless the unbalanced cells are adjacent.
:-- You must wait to balance until the full pack is charged.
:-- Transistor count is high.
 


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