Need some opinions about salvaging batteries

Hi people
Need some advice?? Let start off by saying I just hate throwing thinks away!!! Now I have had a dead laptop lying around for around five years. Its an old IBM Thinkpad. Now, nothing wrong with it that a new battery pack wouldn’t fix. Too dammed expensive and realistically to old.

I just got bored tonight and decided to have a cleanout of all the crap I have accumulated over the years. You know the type of stuff that may come in useful but has been taking up space in the shed for years. Those of you who are married will understand where the urge came from!!!

Recently I came across a website dealing with Lithium rechargeable batteries. To try and cut a long story short, the majority of mobile phone batteries returned to telcos under warranty, have nothing wrong with them, even though they will not take and hold a charge a charge. The protection circuit is the issue, and all they do is reprogram the circuit, and send them back out.

Having seen this, I decided to dismantle the computer battery. Before starting I did a voltage check at the terminals and the result was zero. As you would expect after five years. I managed to eventually get the batteries out of the case. Checked the charge again and zero. Now the protection and control circuit is a separate board, not on each cell. I snipped the two wires connected to the batteries, completely removing the board from the equation. Checking the voltage again, it was indicating 10.9 volts. I didn’t feel like doing a complete load test at that point. The battery pack consisted of six 18650, 3.7v lithium, which equaled two lots of three in series and the two lots connected in parallel. Any way the soldered tabs were peeled from the terminals of two of them, and they are now in the charger. If these batteries turn out to be good, what is the general feeling about using them in mods, based on the fact they are not protected, although I am using a regulated charger.

 

I am using old 18650 dell lappy batterys in my prototype mod, internal resistance is up a bit from what a new cell gives, i can tell from the charge current I get at fixed 4,2v current limited supply, good batterys are 3.5A and these do not hit current limit and charge at 3A or so.
Apart from that I would assume Iwould get reduced life in the provari if i was to use em in that due to higher voltage drop at peakcurrents. I have no intention of doing that though.
I personally would be very hesitant to use them in a mod with no electronics, due to the risk of a shorted atty or similar hitting 20A plus, grab some grab some 'ego' electronics and a atty connector from JW, solder to the tags, make a dodge case with resin putty and bobs ya uncle with a long life unregulated mod with blue led.
I would also not use the cells in series at all as balance with old cells will be an issue.
I would run some tests to get a good idea of mAh rating of the cells and only use the best ones. An imax B5 or B6 charger can run a charge or discharge sequence and give a good comparison of capacitys.

 

Hi Stoney
Yes thanks for that. No I don’t intend to try and run them in the Pravari!! To bloody expensive to screw up! It just seems a shame to dump them if more life can be squeezed out of them. The intention is just to use them for a cheap power source for anything I will be nailing together. I wouldn’t dream of carrying them in my pocket at this stage. Funny, I was looking at JW site yesterday and saw the circuits, and at a reasonable price. Need to have another look to make the postage worthwhile.

 

Hi Stoney
I found the site I mentioned earlier. Maybe you have seen it and maybe not. Lots of information
http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

 

yes read it before .. the IMR info there is really good .. http://batteryuniversity.com/learn/article/types_of_lithium_ion
The AW IMR is the LiMn type as opposed to LiCo used in the normal 18650 batterys.
The battery will not harm the provari by the way, it will likely have a reduced life per charge due to the voltage drop being slightly more.
More efficient to leave the tags on and solder to them though than bother with it in a provari, need a nippled battery to work with the provari anyway.