Beginners Guide to Processing 18650 Cells | Cell Database


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I love Li'ing. Is that bad? Missouri, USA
#1
I've been doing research, watching videos & I am starting to salvage cells out of my old laptops. I also got a decent deal on ebay for a few laptop batteries. I am starting off small. I'm going to build small packs for a few things. Then a 24 or 48v inverter pack for my welding trailer to run grinders & other tools without having to run my generator.

I have only tested 12 cells so far from 2 of my old laptops. The Dell had better cells than the HP. I have been using a SKYRC B6 AC V2 http://www.skyrc.com/index.php?route=pro...uct_id=217. I use the ChargeMaster for Windows to log the discharge curves. The ones form the Dell are red with green tops. They discharge at 1A for about 2hrs then for about 20 minutes it ramps the amperage down after getting to 3.2v. The cells from the HP are Panasonic. They discharge at 1A for about 1hr then ramp down the amperage for another 2+hrs. The total capacity is only about 200mAh different. But the red ones deliver alot more at 1A.

Is there a cheap program that will log multiple chargers on the same computer to be able to compare the curves & not just the total capacity to better match the cells in smaller packs?
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#2
For your charger i dont know. I use LogView with my iCharger duos and they log each test with its own curve and all.
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#3
(09-13-2017, 03:19 AM)osweld Wrote: ...

Is there a cheap program that will log multiple chargers on the same computer to be able to compare the curves & not just the total capacity to better match the cells in smaller packs?

I have read that the B6 needs Cheali firmware if you want to log data using LogView Studio, I have not tried this myself so you'll have to google the procedure.
Not sure if you can have multiple instances of LogView open, each logging a different charger.
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#4
Since I really only need a voltage curve to know when the cell gets to 3.2v I decided to get a CellLog 8s to log with. I have it set up with a 2s holder that only one cell is connected to the charger. The other cell is to keep voltage high enough for the CellLog to stay on since it needs a minimum of 4v. I have successfully logged a couple cells now & compared the results with ChargeMaster. My calculations are within 3mAh of what ChargeMaster shows when voltage hits 3.2v & starts dropping amps.

Its also nice that I can log without being connected to a computer & has the capability to log up to 8 cells at a time for up to 36 hours.
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#5
If you want to run powertools from these laptop batteries you need a lot of them. Logging and comparing discharge curves is going to be hard and tedious work when you have to do it for several hundred cells. Bigger packs follow statistical effects, there will be an average across the pack and if it is designed properly there is no need to log and compare discharge curves.
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#6
(09-24-2017, 09:29 AM)DarkRaven Wrote: If you want to run powertools from these laptop batteries you need a lot of them. Logging and comparing discharge curves is going to be hard and tedious work when you have to do it for several hundred cells. Bigger packs follow statistical effects, there will be an average across the pack and if it is designed properly there is no need to log and compare discharge curves.

The pack for my tools will be somewhere around 24 or 48v 5kWh with about 600 - 700 cells.

I'm not planning on logging all the cells I process. I mostly want use it for smaller packs I build. I want to be sure the cells have a similar curve, so I don't stress any cells.
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