Building a Lithium Ion Battery Pack with S-8254A Protection IC

Encouraged by my earlier success buying somebody’s implementation of an IC reference design off Amazon, I went looking for more. The previous project used a MP1584 chip to regulate the variable voltage of a battery to a constant level for a Raspberry Pi 3. Now I want to improve upon the battery side.

The battery pack had three 18650-sized lithium-ion battery cells in series. These cells were salvaged from an old Dell laptop’s power pack. Since they were ten years old, there’s a bit of a question mark hovering over them. A battery pack that simply wires them in series risks over-charging or over-discharging the weakest cell. This abuse of lithium-ion cells usually ends in a fire.

I searched for a battery management circuit board to help me avoid setting my projects on fire. I settled on this item which is built around the Seiko Instruments’ S-8254A IC. This circuit board will monitor individual cells. If any of the voltage levels exceed safe limits for lithium-ion cells during either charging of discharging, the chip will disconnect the whole pack.

Once everything was connected according to instructions, I have a battery pack that I can use with much higher confidence.

BatteryManager

Using my Astro-Flight power meter, I put this battery pack through a full charge and discharge cycle. Something I was squeamish to do before the battery protection board. Upon completion of the cycle, the power meter counted 1.65 amp-hours. The text printed on the cells say LGDA2E18650, which had a nominal 2.25 amp-hour capacity when new. Ten years old and 73% of nominal capacity is not bad, and perfectly usable for a wide range of future projects.

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