Can anyone identify the purpose of this circuit board?

This battery is in a small Car DVR video recorder.
The device is USB powered.

The item arrived (from ebay) with an essentially useless LiPo battery as you can see it is puffy and the capacity is about 12mAh.

I would like to replace the battery but I noticed this circuit which I assume to be a buck converter designed to keep providing as close to 5v as possible while running on battery power but I’m not sure.

I measured the voltage coming from the battery
—- at ~empty = 3.99v
—- at ~half charge = 4.14v
—- at ~full charge = 4.21v

So my best guess is it’s some type of buck driver keeping the voltage up even though the battery is depleted?
What would happen if I replace this battery with a LiPo cell without this circuit? Could it damage the video driver etc?
I think I found the data sheet here……

Hmmmm……found this….

High safety: built-in protection board, had overcharge protection,

So maybe it’s an overcharge protection circuit……that would make sense since it’s a LiPo and always charging once plugged into the cars cigarette lighter.

So now the question might become……

Anyone know of an overcharge protection circuit I could add to a small LiPo battery?

Well…I found these….

1S LiPo protection Circuit

Thanks for your help Zebretta !!!

You’re welcome!


this sounds familiar situation to me…

i bought a cheap car DVR at the pawn shop. Battery was smoked. looked like yours… i just cut both wires off as close to the battery as i could, and soldered them to the wires from a different little battery from a different device. worked and charged fine.

your mileage may vary, item sold by weight not volume, some settling of contents may have occurred during shipping and handling, lol

I found the battery on ebay. It was $4.00. Ordered it. Let’s see if I can get the seller to refund me the $4.00