Is it possible to charge an 3s (3-cell wired in series) lipo battery with a balanced charger (and using the balanced charger port of the battery ofc) and connect a load to the discharge port of the battery at the same time?

For example using:

Charger: http://www.hobbyking.com/hobbyking/store/__7637__Turnigy_12v_2_3S_Basic_Balance_Charger.html

Battery: http://www.hobbyking.com/hobbyking/store/__92447__Turnigy_700mAh_3S_30C_Lipo_Pack_XT30_.html

My concern is that the charging is done by wiring the cells in a semi parallel way (all ground are tied together and each positive are going to the charger) and drawing is by connecting the cells in series - wouldn't it short circuit the battery?

  • \$\begingroup\$ Is "all ground are tied together" something you have read in the documentation, or is it just an assumption? If so, based on what? \$\endgroup\$ – Dampmaskin Jun 24 '16 at 8:05
  • \$\begingroup\$ Assumption based on the charging connector that has one black lead and 3 red leads and the understanding that a balanced charger charges each cell independently to achieve a similar voltage/charge for all cells. \$\endgroup\$ – Uriel Katz Jun 25 '16 at 9:22

While 'charging while using' is possible for a LiPo battery, it is not recommended, as it may compromise the battery safety and lifetime.

This is because the charger measures its own output current, but it does not know about the load current. The battery voltage is also lower than it would otherwise be. This means the charger incorrectly estimates both its state and rate of charge.

The idea of a standard charger charging in parallel is overwhelmingly unlikely, and can be dismissed.

  • \$\begingroup\$ The idea of a standard charger charging in parallel is not just "unlikely", it's fundamentally impossible: In order to charge the battery with the cells in parallel, the cells would first have to be disconnected from their series configuration, otherwise the cells would be shorted out. \$\endgroup\$ – jms Jun 24 '16 at 12:47
  • \$\begingroup\$ Yes, I guess a charger is overwhelmingly unlikely to do that, but a standard charger will not. I did say the idea could be dismissed. More to the point, a standard 3S battery pack has the cells hard connected in series, so cannot be charged the freaky way. \$\endgroup\$ – Neil_UK Jun 24 '16 at 13:29
  • \$\begingroup\$ @jms There are in fact some series packs that charge in parallel (I recall a flashlight pack that did so), but they are relatively rare. \$\endgroup\$ – Bill Dubuque Jun 24 '16 at 19:37
  • \$\begingroup\$ About parallel charing, so how is the balanced charging done? as far as I understand each cell is charged independently via the balanced charger port, right? how the wiring looks like inside the battery pack? \$\endgroup\$ – Uriel Katz Jun 25 '16 at 9:24

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