I've decided to take apart my old android phone, and since I've been in a great shortage of batteries for my high energy requiring protable projects, I was wondering If I colud use my phone batteries, that are quite capable in terms of Ahs.
I know the hazards of li ion batteries, and the difficulty in charging them, and I've attempted a solution by using the phone very charging circuit, or actually the pcb containing the usb port and the battery terminals.
My question is, is this safe? I've connected the load in parallel with the battery and charging circuit, and whereas the battery should be 3.7V it remains a costant 4V, even without the charger; When I connect a motor, the voltage drops down as expected, but when the running speed is reached it's still 4 V.
I somehow managed to get the batteries to 0V, but i suspect it was some protection, but connecting the charger brings the battery to 4V immediately, whereas obviously he phone woult take hours to charge.
Also, do you think there is some cheap IC that could replace the phone pcb? I would also need to use these batteries in series or parallel, but I don't know hot to treat them tho.