Near Heart Attack from Laptop Pulls

Batteries and Chargers Rechargeable Batteries
1

I am fairly new to 18650s and just did my first laptop pull, and also just bought my first good multi-chemistry charger, an Opus BT-C3100. I tested all 8 of the laptop pulls and while their internal resistance was a bit high, I decided they worth saving. They all charged up to about 4.18 to 4.22 according to the Opus, and only lost about 0.02V after 4 days.

So I decide to discharge them down to 3.7V for storage and put the first 4 back on the Opus and set it to discharge at 500 mA, and set a timer for 30 minutes to check their voltage. The timer goes off, I look over to the charger display and see numbers like 489, 490, etc. and my brain is processing this like 4.89V and 4.90V and I start freaking out til I realized I had not reset the display from reading current to reading voltage.

I won’t make that mistake again!

2

Hahaha with a title like this I am glad you are OK!

3

I’ve done that too!
It’s good not to be complacent and congrats on the pulls. Holding voltage is a good sign. It the final test is the capacity compared to new original

4

I was expecting something involving smoke and toxic fumes. Glad it was nothing serious. I can’t tell you how many fuses I’ve replaced in my DMM after forgetting to move the leads from V/Ohms over to A.