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When I look at 18650 Li-po cells with built-in cell protection (either the small disk type fitted to the top of the cell, or the side-mounted ones with straps that that run to the battery top and bottom) I notice that at C/10 currents the protection board runs the cell between 4.3 and 2.8 V.

These voltages seem to be at the extreme range of what a Li-Po can tolerate with a range like 4.0 to 3.4 V being more appropriate for maximum battery life.

Does anyone know of an off-the-shelf 18650 protector that's a bit kinder to the cell?

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  • \$\begingroup\$ Recommendations are off-topic. \$\endgroup\$
    – pipe
    Oct 14, 2020 at 12:03
  • \$\begingroup\$ Consider either building your own or modifying commercial ones, armed with the datasheet for the chip they use, specific to your requirement. \$\endgroup\$
    – user16324
    Oct 14, 2020 at 13:26

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As for the charging side, the "kindness" should come from the charger, not the protection board; it's not what it's for.

Modifying a protection board to block the charging current when 4 V has been reached will also likely throw off most chargers' algorithm (CC trying to reach 4.2 V before CV), so I doubt a "friendlier" protection board can be bought off-the-shelf, as it wouldn't play nice with chargers.

Setting your charger to a lower end voltage for the CC charging stage and using a separate circuit to switch off the load at a voltage of your choice would be a better way forward; the protection board is meant to be a last-ditch safety device for when things go wrong, and not a charger or a charger second-guesser.

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