I have a 4-cell Li-ion battery pack, purchased from RS Components (code: 144-9416).

Link :


It integrates a BMS, as you can understand on the datasheet (and I feel the PCB too).

So my question is: How can I recharge?

  • Do I have to design my own battery-charging PCB (with a IC from TI, for example)?
  • Or can I just apply, let's say 24V, and the BMS will do the CC/CV up to 16.8V?

Thanks in advance for your answers.

Good day to you all.


1 Answer 1


Do I have to design my own battery-charging PCB? Or can I just apply, let's say 24V?


  1. Buy a ready-made 4S Li-ion battery charger (14.8 V nominal, 16.8 V constant voltage, and no more than a 1.3 A constant current). For example.
  2. Connect it to the battery through its BMS.
  • \$\begingroup\$ The linked charger is incompatible with OP's battery pack as it requires a balancer connection, which the pack in question doesn't have. The pack balances itself via its internal BMS and only requires external 16.8V CC/CV to be applied. \$\endgroup\$ Commented Nov 18, 2023 at 18:31
  • 1
    \$\begingroup\$ "The pack balances itself via its internal BMS". There's no BMS in that battery. \$\endgroup\$ Commented Nov 18, 2023 at 18:57
  • 2
    \$\begingroup\$ You're right... I managed to track down the exact PCM used: power.tenergy.com/… I really didn't expect RS to sell battery packs that literally can't be charged safely at all, so given that the pack doesn't have balancing leads, I expected it to balance internally. It's quite strange to me that RS would sell a product that's dangerous by design. I guess I'll have to delete my wrong answer. \$\endgroup\$ Commented Nov 18, 2023 at 19:40
  • \$\begingroup\$ @JonathanS. I was also trying to track down the circuit used. The RS datasheet shows a picture of a PCB with the label cl-s04-019-a01. A search found the datasheet S-8254A Series which doesn't mention cell balancing. Whereas BQ29330 is a datasheet for a different device which does mention cell balancing for S41P cells. \$\endgroup\$ Commented Nov 18, 2023 at 19:53
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    \$\begingroup\$ It does have per-cell voltage monitoring - the pack can be charged safely. But it won't last as long as a pack with balancing, because eventually one of the cells will get out of sync and the protection circuit will cut off early. \$\endgroup\$
    – jpa
    Commented Nov 19, 2023 at 8:44

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