Harvesting Lithium Ion batteries

But there are a number of risks that need to be clearly understood and managed. Some cells should be immediately discarded. Any cell with a voltage below 2.5 volts is unsafe to recharge. Some say 2.75 volts and perhaps even a higher rejection voltage should be chosen. but we are getting ahead of ourselves.

After doing this for a couple of years and getting some experience, I have developed some preferences in brands of cells. Panasonic and Sony seem to be the best. Samsung and LG can be good also. I have seen varied results from the red Sanyo cells. Some are fine, but I have had quite a few get really hot when being charged, much more so than other brands.

Unbranded cells from China have been quite variable. Some are terrible with a short life after which they refuse to take a charge. I have seen some sit forever at 3.6 volts and never charge. Some are fine. The good ones are marked "ASO" -- whoever "ASO" is seems to be making a good product.

Disassembling a laptop battery is a somewhat hazardous process. You probably have no idea what the state of charge of the pack is, and it is very likely to be holding a significant charge. This means if you short out any cells, or puncture a battery, very bad things can happen.

• My laptop pulls - early 2017
• My laptop pulls - late 2017
• My laptop pulls - 2019
• My laptop pulls - 2020
• My laptop pulls - 2021
• My laptop pulls - 2022
• My laptop pulls - 2023

Also, any cells harvested from a laptop (or any other) battery will be unprotected cells. You can read a lot about this elsewhere (and you should), but the main issue here is that you must take care to avoid excessively discharging the cell. The circuitry in a laptop battery takes care of this, but once you take a cell out of this managed environment, you are responsible. If you discharge a cell below a certain point (lets say 3.5 volts) it becomes dangerous and unstable.

Overcharging is equally bad, if not more so, but if you are using a reputable charger, this is not an issue. If you are going to use unprotected cells, you absolutely should invest in a quality charger like the XTAR I use.

Here is how one guy does it:

• Recover 18650 cells safely and reliably
• A local copy of the above

Another fellow says he uses the following guidelines. I used them for a while, but have started recovering a lot of batteries that measure less than 2.5 volts. It is certainly safe to follow his first guideline, but you will miss some treasures.

1. measure cell voltage. if it's less than 2.5v, throw it away.
2. charge the cell. if it gets hot during charging, throw it away.
3. measure cell voltage off the charger. verify it's between 4.1 and 4.2v.
4. wait 30 minutes
5. measure cell voltage. if it's fallen to less than 4v, throw it away. Otherwise record the voltage.
6. store cell for 3+ days in cool, dry place.
7. measure cell voltage. if cell voltage has fallen more than .1v from the recorded voltage, throw it away.

• Laptop 18650 extraction
• Reusing old laptop batteries (check this!)

My procedures and policies

I am tempted to say that any unbranded cells may as well just be discarded. I have now learned to (given a choice) only harvest batteries from brand name packs like Dell, HP, Compaq and such -- avoid generic replacement packs, both for harvesting cells, and for replacing the battery in your laptop!

Where to get them

• Suburban Miners
• SIMS recycling

Suburban Miners, 3820 E. Blacklidge, 520-406-7446
SIMS Recycling solutions, 820 S. Euclid, 520-622-7600