How to check protection circuit in lithium battery

Question

I've recently bought a single cell, 600 mAh lithium battery (like this one) and a TP4056 battery charger module, which I intended to use with the battery. The charger has an integrated protection circuit based on a DW01 IC with a 8205a dual MOSFET IC. I have already replaced the resistor connected to the TP4056 to limit the charging current to 500 mA.

I'm not sure if the battery has its own protection circuit. The guy that sold it to me didn't have a clue and I have found contradictory info in several websites. Is there a way to check if the battery has its own protection circuit (hopefully without having to push the battery to a condition where this protection would trigger).

My main concern is what would happen if I connect a battery with a protection circuit included to a second protection circuit. Would it work correctly?

Answer 1

If that battery has a protection circuit it will be where the leads are attached to the pouch. One of two things happens there. Either the wire is soldered directly to the pair of metal tabs that are directly connected to the battery's anode and cathode. Or they're soldered to a PCB that carries those protection circuits and is also soldered to those tabs. If you feel two largish lumps in there, it's likely to be unprotected, and if you feel a PCB with a bunch of smaller components it is likely to be protected from some situations. (You would do well to think of how to protect it from:

• Overcurrent
• Overvoltage
• undervoltage
• overtemperature
• undertemperature charging

whatever protection circuit is in there might not protect the cell from those events, or might cut off the operation of the battery permanently.

More than one protection circuit there, connected through only those two wires shouldn't be a problem at all.

Answer 2

All my RC airplanes use unprotected batteries. The charger does many protections and the circuit in the airplane disconnects the battery if the current gets too high or disconnects the motor when the voltage gets too low.