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I have a 3 cell Li-Ion battery connected in series and want to charge them with a single battery charger IC. What I found is BQ24105, a Stand-Alone Battery Charger with following schematic for charging 2 cell battery. BQ24105 2 Cell Application

Problem

  1. Does this battery charger IC, handle cell balancing?
  2. Is cell balancing required, I ask this because this IC claim to charge multicell battery, but dont seems to handle cell balancing
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  • \$\begingroup\$ All the magic for balancing is in the dashed box labeled "Battery Pack". \$\endgroup\$ – Ignacio Vazquez-Abrams Aug 24 '17 at 8:05
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    \$\begingroup\$ And if the battery pack does not have the balancing circuitry, then there cannot be any balancing. Does the BQ24105 mention "balancing" in its features ? I didn't see it so very likely it doesn't. \$\endgroup\$ – Bimpelrekkie Aug 24 '17 at 8:16
  • \$\begingroup\$ So are there any battery pack that handle battery balancing? or any IC probably \$\endgroup\$ – pazel1374 Aug 24 '17 at 8:50
  • \$\begingroup\$ My other question will be if the battery have protection and each cell are the same does I have to care for battery balancing? \$\endgroup\$ – pazel1374 Aug 24 '17 at 8:53
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The BQ24105 can handle multicell battery charging as stated in the datasheet. The IC just takes care of the charging of the batteries but assumes that the battery pack (the dashed box in Figure. 1) has all the necessary protection circuit.

A battery pack with multiple batteries in series should have a protection circuit that monitors battery voltage, temperature and current. A balancing circuit is also necessary to monitor each cell in the pack to equalize the voltage for all cells.

Even if you buy the same type of batteries from a single manufacturer, each cell has small variations causing them to charge and discharge differently which makes it necessary to have a balancing circuit.

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  • \$\begingroup\$ My batteries already have PCM so i'm worried only about if I really need a balancer or not. Thanks for clearifing that. \$\endgroup\$ – pazel1374 Aug 24 '17 at 12:53
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BQ24105 will not handle cell balancing, But it should be take cared as suggested by Oskar Persson Answer. Note that battery balancing can be implimented passively or using active components.

Fortunately in a system with a fully integrated battery charger(like in my case), circuit comes with a Battery Fuel Gauge IC like BQ40Z50-R2 to measure state of charge(SoC) in the battery pack.

This seems a miracle to me, as these Fuel Gauge IC comes with an integrated battary balancer. So as long as you have a Battery Fuel Gauge in your system, that thing will handle cells balancing for you.

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