I use this ready module for 3S battery group.

Due to high charge rate (pull about 2-3A from power supply) a high current power supply also needs.

I want to reduce charge rate up to 0.2C or 0.1C. No problem charging slowly.

Is there a way adjust this charge rate and making slowly charge on the module?

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  • 1
    \$\begingroup\$ what does the schematic have to do with the board? They might represent the same thing, but since the ports on the board are differently labeled, I'd at least be careful. \$\endgroup\$ Dec 15, 2021 at 18:14
  • 4
    \$\begingroup\$ It's not the BMS' s job to set or regulate the charge current; that's the charger's job. The BMS is a security measure to make sure the cells aren't charged/discharged with out-of-spec voltages/currents; some also do cell balancing. Charging current should be set by the charger. \$\endgroup\$
    – ocrdu
    Dec 15, 2021 at 18:24
  • \$\begingroup\$ Thank for the answer. How battery capacity effects this charging rate? Can we say 1200mAh batteries draw less current then 2000mAh while charging? Also i use standart wall type power adapter, how can i set rate? \$\endgroup\$
    – berker
    Dec 15, 2021 at 18:44
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    \$\begingroup\$ The charge rate is determined by what rate the charger wants to use to charge. But now you talk about standard wall type power adapter, and ask how to set the rate, so you are not using a charger, you are using a power supply? A power supply is not a charger, you need a charger. \$\endgroup\$
    – Justme
    Dec 15, 2021 at 18:52
  • \$\begingroup\$ Actually, I want to use it in a closed box with an enclosure and powered by an adapter. There's no way I can take the batteries out of the box and put them on charge. But although the circuit does not draw much current (<0.5A), it draws about 3A while the batteries are charging. Can I charge it with an adapter? instead of charger. \$\endgroup\$
    – berker
    Dec 15, 2021 at 18:57

1 Answer 1


A BMS is not the device that decides the charging current.

Neither is the power supply.

It is the lithium charger that defines the charging current. The charger is the device that takes power from power supply and safely charges the lithium batteries.

The BMS, even if it has overcurrent and overvoltage protection, is only the last line of protection if the charger has failed to prevent further damage.

Do not connect a power supply directly to the BMS or batteries. The batteries or the power supply may be damaged, and damaged batteries are dangerous.

You need a charger which can charge the batteries with the current you want.


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