# laptop 18650 - mixing?



## RIPPERTON (Jan 26, 2010)

Jehu's Kombi has these.

http://www.diyelectriccar.com/forums/showthread.php/1958-vw-bus-panel-1st-ev-80329p13.html


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## mecanum (Jan 8, 2015)

Thanks, I have just seen the first video of the series but it seems he's using all the same ones (from lenovo?)
I tested the batteries and all of them report promising voltage. I don't have a charger yet, thinking using my school's power supply and using a chip to shut the current for every cells hitting 4.2V.


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## eldis (Sep 3, 2013)

mecanum said:


> Thanks, I have just seen the first video of the series but it seems he's using all the same ones (from lenovo?)
> I tested the batteries and all of them report promising voltage. I don't have a charger yet, thinking using my school's power supply and using a chip to shut the current for every cells hitting 4.2V.


Don't worry too much about the manufacturer/code. I've been building packs from "dead" notebook batteries for quite some time. As long as you measure the capacity of each cell, you will be fine (you don't want almost empty cells in your pack, as they add weight but not the capacity).

Some general advices:
- Fully charge each cell and make sure that the current goes to 0 at the end. Some older cells will heat up instead of charge.
- When characterizing the capacity, discharge them at constant current that you expect they will see in your application (no need to test at 2C per cell if you need 0.5C!)
- Leave the fully charged cells (mark their resting voltage on them) for few days without touching them. Throw out those that show self-discharge


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## rwaudio (May 22, 2008)

eldis said:


> Don't worry too much about the manufacturer/code. I've been building packs from "dead" notebook batteries for quite some time. As long as you measure the capacity of each cell, you will be fine (you don't want almost empty cells in your pack, as they add weight but not the capacity).
> 
> Some general advices:
> - Fully charge each cell and make sure that the current goes to 0 at the end. Some older cells will heat up instead of charge.
> ...


I'm doing exactly the same things, the only difference I'd suggest is a brief test at full rated current. I've found that cells that still have decent capacity and don't have self discharge can have rising internal resistance which make them poor performers under less than ideal conditions (Cold/high current loads/etc.)
I've also found that different brands age differently (or had different initial quality). I get a lot of very good LG cells out of packs, that's not necessarily a good trait as it means the rest of the pack likely died early, but these survivors may last a long time. On the other hand Panasonic, Sanyo and Sony's have been more consistent and I don't typically get as good a cell out of a "dead" pack. Samsung is somewhere in between but closer to LG.

This is just my experience based on about 1500 Cells, half of which have been good enough for my application.


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