I have been looking at several 2S LiPo batteries for my project. The charger that I have has a balancer output to balance the cell voltage in batteries, but a lot of 2S packs on the market don't include a balance connector at all. For example, this one:

enter image description here

Why is that? Isn't it unsafe to charge a 2S (or any multi-cell battery) without proper cell balancing?

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    \$\begingroup\$ Why do some <x> come without <y>. The answer is always: it is cheaper. \$\endgroup\$ – PlasmaHH Dec 4 '17 at 10:14
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    \$\begingroup\$ @PlasmaHH of course, it is cheaper, but no one produces cars with no seatbelts for that reason. LiPos that aren't charged properly can incur some serious damage, so why not include the balancing connector? \$\endgroup\$ – Egor Tamarin Dec 4 '17 at 10:17
  • \$\begingroup\$ You can get cars with the minimum required by law. There is no law requiring LiPos to contain any balancing or protection circuits. \$\endgroup\$ – PlasmaHH Dec 4 '17 at 10:19
  • \$\begingroup\$ @PlasmaHH I suppose you're right, although it surprises me, given that I've seen 3S batteries without balancers and most chargers will refuse them. \$\endgroup\$ – Egor Tamarin Dec 4 '17 at 10:27
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    \$\begingroup\$ @OlinLathrop Indeed, painfully obvious. OP claims to be an embedded systems apprentice, however, in the light of this inquiry I must deduce that he must be merely a charlatan. A rascal, if you will. The audacity to be this pretentious is beyond the norms of civilized behaviour. We shall banish him at once. \$\endgroup\$ – Atizs Sep 8 at 19:42

If a lithium-ion battery with more than one cell has no provision for balancing, it's a blatant safety risk. As a battery ages, one cell will drop in capacity faster than the other, causing the lower capacity cell to eventually overcharge (risk of fire!) during charging. Nobody but the very cheapest, least reputable sellers will sell you one.

That said, this battery brings three wires to the combined charging/discharging/balancing connector (3-pin female JST-PH).

It's just hard to see because one of the wires has white insulation, and the image background is white, so I manipulated the image a bit to change the background colour.

While a separate balancing connector is better (it reduces the effect of the voltage drop caused by the charging current on the balancing measurements), a charger can still balance charge this pack, since it does have a connection to every series cell in the pack.

  • \$\begingroup\$ +1, and now the question went from "quite obvious" (cause its cheaper) to "doesn't make sense"(premises are wrong) \$\endgroup\$ – Wesley Lee Dec 4 '17 at 14:12
  • \$\begingroup\$ Great answer! I understand I will need a special charger for those kind of batteries then (compared to mine, which has the balancing and charging separate)? \$\endgroup\$ – Egor Tamarin Dec 6 '17 at 9:07
  • \$\begingroup\$ You can make (or buy, e.g. this or this) an adapter harness for it, as long as you have a balancing charger where you can set the right charging current, battery chemistry (3.7 V li-ion/lipo) and cell count. \$\endgroup\$ – jms Dec 6 '17 at 10:44

You can clearly see this battery has a balance lead (red, white, black) It just uses one set instead of two sets of wires due to size and weight. I have these for a plane the balance lead plugs into battery charger as usual and plugs into pos/neg leads on plane without using middle(white lead). Simple.

  • \$\begingroup\$ This answer has already been given. \$\endgroup\$ – Bort Aug 30 '18 at 19:43

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