Just curious if there are any good deals on N.O.S. laptop batteries for harvesting 18650 pairs (I want to keep pairs welded together to make a 2S2P bike light battery pack with a protection circuit). Higher the mAh rating the better. I currently have some used pairs of Sanyo UR18650A's (2,250mAh), but wonder if I can do better for a little money.
Thanks,
Garry
Quick search on Ebay and I see this HP 9 cell for $16.99 free shipping which is likely the same Sony "2,550mAh" cells I have from another 9 cell HP pack. Seller seems to be "InandOutComputers" which was a big hit with BLF'ers last year. Ebay link, and same on In and Out Computers website.
So any better options? Any particular search strings I should use to find packs with known good cells?
-Garry
—If its 10.8 volts and 83wh then I’m pretty sure those cells are 2250’s not 2550.
Am I wrong?—
Ooops, I did the math wrong. You are right. They seem to be 2550’s.
One concern I have is the cell layout in that HP 9 cell pack. They don't look "paired" together, or at least they may not be connected as close together as I'd prefer (i.e. your typical pack pulls).
-Garry
In a 9-cell pack, you should expect 3S3P configuration.
Right, sorry I confused things saying "pairs" - should have said "triples". I'm only interested in "pairs" and would prefer they be side-by-side up against each other welded together, as seen in this photo of one of my Sanyo pairs:
-Garry
I don’t have any deals to report, but thanks for starting this thread !
Anybody know if a local battery supplier / warehouse / type store (like "Battery Warehouse") would weld 18650's together if I provided cells? That could be an even better option! (Well the main website shows "custom soldered packs", but they don't list a location near me.) Hmm . . . might have to investigate and get a price.
-Garry
For those interested, I purchased one of these.
It is brand new and genuine HP. Inside it contained 6 gray LG Cells.
Each Cell was around 2.0 volts when pulled.
I charged and then discharged them on my opus and got around 2700 - 2800+ MAH on all of them.
Additionally the Internal Resistance check was very good - all around 90 - 100.
They did not got hot at all and barely even warm while charging.
I have a lot of experience with Laptop pulls and I have determined that there are 3 things that indicate the condition of the cell (besides the actual MAH):
1. How hot it gets while charging. The cooler it stays to the touch the better the cell seems to be. If it gets very hot then toss it.
2. The Internal Resistance Check by the Opus. Anything under 100 is good. Anything between 120 and 160 or so indicates a mediocre condition. Anything above 180 or so should probably be tossed.
3. How long does it take to get from 4.19 to Opus’ Full indicator. I realize this is a weird indication but I have found it to be true. Cells will go from 4.19 to 4.20 and back to 4.19 and back to 4.20 for a while until finally full.
If it takes a very long time to finish (relative to how long it took to charge until that point) then its problematic. I have had cells take hours to reach that point - which indicates a bad cell.
The good news is that these cells - although they were at 2.0 volts - were brand new, held over 2700 MAH, did not get warm at all, and had no problem hitting that magic “Full” indication.
If anyone else buys these let me know how they do.
Could you give the model number those LG cells?
Thanks for the feedback. Yes, please pass to us the model of those cells. I assume they are also welded together in such a way that I could pull "pairs" out of the case (welded tabs across tops and bottoms of pairs)?
EDIT - are they these:
-Garry
That looks like them. I actually re-wrapped them so I don’t have the model number. Every cell was 2600+
They come in pairs welded together.
Hmm . . . I wonder how those LG's will compare (i.e. voltage curve) against the Sony's? Anybody have any idea? I could buy the 9 cell HP pack and probably get 9 Sony cells (which lets me build (2) 2S2P bike packs. I just finished (literally) testing 2 protected Sanyo 2600 FM's against 2 unprotected Sony laptop "2,450's" at 2.5A discharge and they are almost neck and neck:
-Garry
Ok found a similar (?) LG 2,600mAh cell on HKJ's 18650 Comparator:
The Sanyo's (and likely the Sony based on my testing) outperform those LG's easily. So it seems I'm better with the Sony's.
-Garry
Thank you both for the info. I just purchased what turned out to be the last of these packs.
Thats ok, there are several other sellers selling the exact same "genuine" battery for right around the same price. Buy em up! I am...
I decided to order two of the Xiaomi 10,000mAh power banks from Banggood which contain 3 Sanyo NCR18650BF's with welded tabs. I'll build a 2S3P pack and include a balancing lead. See this thread: http://www.budgetlightforum.com/node/40335
-Garry