li ion battery connection trouble

Projects Discussion and Showcase Robotics
1

Hi guys, i was making a robot this week. And suddenly i came to think about the batteries. I was planning to use 2 li ion cells from old nokia cell phones. I happened to read about handling these cells and it says that u have to drain them bfore soldering. It also says that we have to use a balance charger. So heres what i had done so far.

  1. I took two 3.7v cell phone batteries ( to make 7.4v)
  2. I drained them using the phone and a couple of bulbs

Now what shud i do? Here r my questions

  1. How shud i wire the two batteries so that i can charge it again with a balance charger?
  2. Shud i take the current limiter out?
  3. Is it safe to solder?

Please help

2

Draining a battery to 0V destroys it. Draining it to 10% charge won't help you solder anything
to it. Soldering may start a fire, dont do it, you need mechanical sprung contacts to safety connect.

If you modify the batteries they become as unsafe as a bare LiPo battery, so treat them as such.