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I am currently in the process of making a 3S 18650 battery pack using a BMS board that I purchased from Amazon. The image of the board can be found below:

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Yesterday, I successfully connected all the wires and charged the battery pack using an adjustable DC power source set at 12.6V. It worked well, and the battery pack was fully charged.

However, during further research today, I discovered that my BMS board consists of three DW01A components and some MOSFETs. These components are responsible for protecting the battery from overcharging, over-discharging, over-current conditions, and so on. What I learned is that 18650 cells should be charged in a specific way, involving Constant Current (CC) and Constant Voltage (CV) charging methods, among others. It appears that the DW01A alone does not provide such charging functions. Consequently, people usually use a TP4056 charger along with a DW01A to charge a single 18650 cell effectively.

Now, I am wondering whether it is safe to charge my battery pack using the adjustable DC power source at 12.6V or a fixed 12.6V charger. Alternatively, would it be necessary to use a charger specifically designed for Li-ion batteries, like the B6 charger?

I am a little bit confused. Based on my understanding, the TP4056 is a charger IC, while the DW01A is a protecting IC, correct? If that's the case, do I need to use both of them together for my battery pack? Any clarification on this matter would be greatly appreciated. Thank you in advance!

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    \$\begingroup\$ You MUST use a proper charging circuit for a Li-ion battery. There are plenty of ready-made modules available that combine the TP4056 and DW01A. Charging using a fixed voltage can cause overcharging, destroying the battery or worse. \$\endgroup\$
    – Finbarr
    Commented Jul 20, 2023 at 19:16

2 Answers 2

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I am wondering whether it is safe to charge my battery pack using the adjustable DC power source at 12.6 V

If it is current-limited, yes. Otherwise no.

or a fixed 12.6 V charger.

If it is truly a charger, yes. But be aware that some people mistakenly call an AC adapter "a charger". An AC adapter is not a charger.

Alternatively, would it be necessary to use a charger specifically designed for Li-ion batteries, like the B6 charger?

Ideally yes. In practice, any current-limited supply with a top voltage of 12.6 V (or adjustable to 12.6 V) will work. Just make sure to disconnect it when the battery is full.

A Li-ion charger may include a shut-off function when the battery is full, something that a power supply doesn't have.

the TP4056 is a charger IC,

Yes, but for a single cell. It can't be used for a 3S battery.

while the DW01A is a protecting IC, correct?

Correct.

do I need to use both of them together for my battery pack?

Yes, you do need both a charger and a BMS. But, no, the TP4056 is not a charger for a 3S battery. You need a 12.6 V charger.

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  • \$\begingroup\$ Thank you very much! Now I have a much better understanding of the situation. Yes, the fixed 12.6 V charger I mentioned is, in fact, an AC adapter. So, I believe I can use my battery pack (3S + BMS) as a regular battery pack. I just need to be careful during charging and it would be better to use B6, right? Thanks. \$\endgroup\$
    – Defisher
    Commented Jul 20, 2023 at 20:07
  • \$\begingroup\$ > right? -- No, wrong., I will say it again: "An AC adapter is not a charger." It is not current limited. \$\endgroup\$
    – Davide Andrea
    Commented Jul 20, 2023 at 21:45
  • \$\begingroup\$ yes, I understand, what I mean is I will use a B6 charger, then everything should be fine, right? @Davide Andrea \$\endgroup\$
    – Defisher
    Commented Jul 20, 2023 at 21:52
  • \$\begingroup\$ Yes, right. (Comments must be at least 15 characters in length.) \$\endgroup\$
    – Davide Andrea
    Commented Jul 20, 2023 at 23:46
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No, it is not safe to randomly plug power supplies directly to batteries.

And a BMS is not a charger. It's a BMS. It can't be used as a charger or instead of a charger.

When lithium-ion cells are mishandled (charged incorrectly, discharged incorrectly), they degrade and may get enough damage to be unsafe to use. Unsafe meaning they may internally short circuit, heat up, burn and start fires or explode under internal pressure.

Always use a proper charging circuit. Proper charger determines when battery is full enough and stops charging before the battery overcharges.

The charging circuit is used to charge the battery safely, and the protection circuit protects the battery from various situations that may happen, such as overvoltage during charging, undervoltage during discharge, and overcurrent in both situations.

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  • \$\begingroup\$ Hi, thank you for your explanation. Based on your answer, the charging circuit can protect the battery from overcharging, over-discharging, etc. However, these are also functions of the BMS. In my test, when I charged the battery using BMS and an adjustable DC, the charging process automatically stopped at 12.6V. I believe there must be some differences between DW01A and something like TP4056, but I don't know what they are, which is why I am confused. Could you please provide more details about this point? Thank you very much. \$\endgroup\$
    – Defisher
    Commented Jul 21, 2023 at 8:53
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    \$\begingroup\$ No the charger won't protect from overdischarge when you are using the battery, i.e. discharging it instead of charging. The charger safely charges the battery until it is full with correct current and voltage profile so under normal conditions. The protection circuits are there to be the last line of safety if the charger happens to fail, or the battery has been incorrectly connected to something like a power supply, so the protection circuit can disconnect the battery before things are so much over normal operating conditions that they soon reach critical limits. \$\endgroup\$
    – Justme
    Commented Jul 21, 2023 at 9:09
  • \$\begingroup\$ thanks, now it's clear for me! \$\endgroup\$
    – Defisher
    Commented Jul 21, 2023 at 10:07

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