I have a motorolla Razr v3I but unfortunately, the battery does not charge. I suspect it it due to a non compatible charger. I decided i could create a diy external unti like a camera battery charger to charge thes batteries.

The question is

  1. battery has 4 terminals, 2 with +,- which are obvious. There are 2 unmarked terminals. What's the use of those terminals?

2)how to proceed with a BMS?

An image of the battery. There is nothing on the front side.

enter image description here

  • \$\begingroup\$ If you don't know what you're doing, I strongly suggest you don't mess with lithium ion batteries. If you insist on doing so anyway, look for as foolproof a charger IC as you can find, and follow every recommendation on the datasheet to the letter. \$\endgroup\$
    – Hearth
    Oct 4 at 1:31
  • \$\begingroup\$ Also be aware that there is a difference between a BMS and a charger. You cannot charge a battery with a BMS alone. \$\endgroup\$
    – Hearth
    Oct 4 at 1:36
  • \$\begingroup\$ @HearthI know I can use things like the TP4056 but I don't think this as direct as pluging the charger terminals to the battery. Batteries are dangerous that's why I asked what the other terminals do. I'm guessing they are related to balance terminal? \$\endgroup\$ Oct 4 at 1:38


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