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Good thread, Those were my questions also.
andynogo said:What a great thread! I'm in the process of ordering my first hub kit from cellman and was just getting geared up to order the lipos as well... until I saw this thread! Just so happens I have about ten laptops at work which are getting thrown out with battery packs- I will have to rescue them. More will be coming through as well which is good!
Just a couple of quick questions- what chargers are being used to charge the packs and in what configuration? I'd be putting together a 48V 20/30ah pack if there are enough good cells. Is a bms a necessity for these packs?
They sold me the 56Wh Dell packs at $6/each. On average I got 5 good cells out of 6 or 46Wh or $0.13/Wh.darkone040 said:..., do they just give them to you or what is the going rate,
I have disassembled over 15 packs, the worst one had 2 good cells (out of 6), the best ones had all 6 good cells. Average ~4.5 good cells.Red_Liner740 said:of all the laptop bats uve come across, have any ever came with all dead cells? on average how many cells are "good"?
^^ Thats encouraging...now i just have to find a local source that will let me have them for cheap or free...
wonder if the local dump/recycling depots would let you take them away...
SamTexas said:The cells are Lithium-Cobalt, very high energy density, but not so high discharge rate. The cells are best used in lower power application.
That's a very good price.auraslip said:The local computer recycler said they get $3 a pound for battery packs, and they'd be willing to sell them for $4 a pound! Much cheaper than ebay.
liveforphysics said:SamTexas said:The cells are Lithium-Cobalt, very high energy density, but not so high discharge rate. The cells are best used in lower power application.
Lithium Cobalt makes both the highest (practical) energy density cells and highest power density cells (like the nano-tech's and other RC lipo for example.) ...
In other-words, they are perfect for helping your laptop run as long as possible, quite unoptimized for EV duties (unless built into very very large packs).
liveforphysics said:Keep in mind, lappy cells, particularly old and sketchy ones can and do fail explosively if mis-treated.
Very well said.DrkAngel said:"Lithium Cobalt" for notebooks, were specifically designed with lower input-output rates as a safety measure. All Li-ion are capable of dangerous reactions, if "mis-treated", as are LiFepo4, Lipo, SLA, Lead acid ... most any battery type, to some degree.
I too tried to salvage low voltage cells at first without much success. Now I discard everything below 2.0V.andynogo said:Voltages have varied from 0v to around 3.5v so quite a range. One pack of 8 sony cells at 0v take a charge but discharge straight away so they're a bin job,...
Remember tho ... a 40ah Lithium Cobalt pack is about the same size and weight of a 20ah LiFePO4, and same weight as 8ah SLA.
andynogo said:Started pulling apart and charging my first set of laptop battery packs.
...
Worked it out- I"ll need up to 170 or so cells to get my 48v pack up and running. Next challenge will be how to charge the lot!
DT98 said:DrkAngel, Super writeup! Thank you for the info.
I have never done anything like this before but I think I can do it if you don't mind a lot of questions later on.
I asked at work today and jackpot...I got 42 laptop battery packs. 95% Lenovo name on them.
9 packs are labeled 10.8v 7.14AH. I measured the voltage without opening the pack and the low was 11.42, high was 12.49.
10 packs are labeled 10.8v 5.2AH. Low voltage was 10.96, high was 12.45. One pack was 7.17v.
3 packs are labeled 10.8v 7.2AH. They measured 11.5, 11.6 and 12.22.
2 packs are labeled 10.8v, 4.8AH. They measured 12.0 and 12.4v.
18 packs I will have to open to measure the pack voltage...couldn't get a reading or my probes were not making contact.
I just ordered six of the chargers on ebay. Thanks for the link.
It looks like the next thing I need to do is to start opening the packs and separating the individual batteries. Should I leave them in pairs or break into singles? In your picture it looked like some of the batteries were still in pairs unless you did some really cool soldering.
After the chargers arrive I will start charging and testing thanks to your write up.
The only issue I'm trying to figure out right now is how to load test the cells...
Thanks! Excellent thread!!
DT98 said:DrkAngel, Super writeup! Thank you for the info.
I just ordered six of the chargers on ebay. Thanks for the link.
It looks like the next thing I need to do is to start opening the packs and separating the individual batteries. Should I leave them in pairs or break into singles? In your picture it looked like some of the batteries were still in pairs unless you did some really cool soldering.
After the chargers arrive I will start charging and testing thanks to your write up.
The only issue I'm trying to figure out right now is how to load test the cells...
Thanks! Excellent thread!!