First impressions of the battery connection on the BPI M2U led me to think I would just solder a dongle to the back with one lead to Positive and one lead to Ground.
This could work well with most batteries as a trial scheme. But I looked at the provided schematic and there seems to be a third wire going to TS!
I suspect TS represents Temperature Sensor and is intended to attach to batteries that include a thermistor to indicate overheating for a forced safety shutoff of charging.
Considering the Samsung Galaxy 7 debacle, I begin to wonder if Samsung optted to omit the third connection and just go with a 2 wire battery scheme.
With the right thermistor, any battery can be adapted to a thermal cutoff, but that will require some reseach and shopping.
Am I being too cautious to suggest that their might be a fire risk in ignoing the TS feature?
Think this engineering detail through as safe charging is worth the extra cost and effort.
If I have to engineer myself, I might be tempted to try a 10K ohm thermistor first, but the wisest approach would be to test the TS pin with software and a 50K potentiometer to confirm a good resistance value, and only then go shopping. 1/8 watt is likely enough, but analyze the curcuit for TS on the motherboard.
I'm not going to teach basic electronics over the web.