I have just opened a Parkside X 20v Team 4AH battery ( PAP 20 A3 ). There are some very small low-power SMD components on the internal PCB. They look adequate for cell monitoring, and possibly for top balancing at very low current. There are no large heatsink-mounted MOSFETs, and so I do not think that the battery has any internal low-voltage-cutoff capability. It may be able to signal an attached Parkside power tool to shut down, but that option would not be implemented in this 3D printed adapter & light. Therefore I think that the supplier, and @Onoff , are correct to warn against over-discharge.I've had a few Parkside packs apart, I'm pretty sure they have discharge protection in them.