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Archive for March 7th, 2018

Baofeng BL-5 Battery Pack: Disassembly

Not much to my surprise, both Baofeng BL-5 lithium batteries went bad on the shelf:

Baofeng BL-5 Packs - Final Failure - 2018-02-21

Baofeng BL-5 Packs – Final Failure – 2018-02-21

The longer traces show their original capacity, back in the day.

Whacking a chisel into the obvious split lines broke the solvent glue bonds holding the case sections together, after which some slow prying defeated the double sticky foam tape on the cells:

Baofeng BL-5 battery pack - innards

Baofeng BL-5 battery pack – innards

A closer look at the (dis)charge controller PCB:

Baofeng BL-5 battery pack - protection PCB

Baofeng BL-5 battery pack – protection PCB

The other side of the PCB has no components, so what you see is what you get. The larger IC proclaims FS8205A EP050C, which may indicate a vague relation to an S8205 protection IC. The datasheet shows a 16 pin TSSOP package containing an IC for four or five cell batteries, completely unlike the 8 pin package on the PCB, but when you buy enough of anything, you can get anything you want.

In common with all cheap lithium batteries around here, the “thermistor” terminal connects to a 10 kΩ SMD resistor steadfastly maintaining its resistance in the face of all temperature variations.

Some probing shows one feeble cell in each pack. Perhaps a Frankenbattery built from the debris will have enough capacity for a standard ride around the block.

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