It is a single-cell battery so no onboard bms would typically be present - a look at the terminals confirms this. The charge and protection logic is built into

It is a single-cell battery so no onboard bms would typically be present - a look at the terminals confirms this. The charge and protection logic is built into the device which charges the battery itself. edit: http://forums.sonyinsider.com/topic/29187-lip-4wm-battery-rebuild/ http://forums.sonyinsider.com/topic/29187-lip-4wm-battery-re... A review of the original pack teardown reveals it has a small pcb with what looks like some voltage cutoff or thermal fuse.