Its common for a LiPO battery pack to have a tap in between every cell, so 3 wires makes sense for a 2S pack. Assuming the color codes are typical, where black is 0V and the Red is the full output, check with a voltmeter I'll bet you'll see about 3.5V between the black and white, and about 7V between the black and red.
1) If your battery does not have a protective plate, the three wires are: the red wire is the positive pole, the black wire is the negative pole, and the other color wires are the middle pole of the battery.
If a lithium battery does not have a protective board, the three wires are: the red wire is the positive pole, the black wire is the negative pole, and the other color wires do not serve the function of providing the product motherboard to monitor the voltage of the lithium battery. Instead, these batteries should be handled with extra caution due to the risk of overcharging or deep discharging.
Yes… some battery has three wired (black, red and probably yello)… these kind of batteries may be old models… Yello earth connection. Nowadays Battery has two wires only. (If you tried to connect two pin wire to the 3 pin wired mobile/tab . You can use normally BUT charge can’t be acceptable) Replace the same type of battery is advisable.
A 4s lithium battery has 0, 3.7, 7.4, 11.1, 14.8, and 5 different potentials. If it is a protected version, the two red and black wires should be internally shorted. The white wire is the flag of the protection chip. It is a high battery voltage when it is protected and a low voltage when it is not.
In mobile phones, some Li+ battery packs have 3 terminals. Two possibilities: positive, negative, 1-wire bus. The latter is a digital communication bus that’s connected to a gas gauge IC inside the pack. If you want to explore what’s inside single-cell Li+ battery packs, look-up bq27000 gas gauge IC and associated application notes.