I got one pack similar to your link, also ACER, but is 5800mah, from another vendor. It contained grey Panasonic NCRs, lowest at 1.72V out of the pack but I have all of them discharge-capacity tested in my iCharger and all even exceeded its 2900mah rating. (if indeed they are 2900mah cells)
I have incoming 2 packs from this OP’s item, will be tested when it arrives.
Just got the pack.
How and where do you start cracking it open?
If you’ve got a Swiss knife, use the CAN opener’s squared edge by pressing it in-between the halves of the pack, then twist. When you do it right the two halves will slowly split. When the halves are a little bit opened, you may use the CAP opener’s flat edge to split it wider. You may start at either side of the left or right side of the pack.
You should always see is peeling the labels off first helps .Some packs have just a thin plastic covering cells on one side and peeling back the label that has all the writting on it reveals the cells . i'm probably thinking of a dell pack or something else .. but since ubehebe said they were an easy pack to open maybe I just made that assumption ....wait and ask "the king of pulls "
>>>>>How and where do you start cracking it open?
.
This is how I do it —- VERY carefully. The batteries are thin and the plastic is sharp. It isn’t a race. Just take it slow, and it’ll be a breeze. Feel any battery getting hot during the process; toss the whole thing outside and leave it alone for at least 15 minutes or so. If you feel heat, you probably short circuited it and that’s the end of it. But fortunately this rarely happens.
I sorta think of it like defusing an IED. Someone on BLF said this — not me. But they’re pretty close to the truth.
Get some needle nose pliers and some leather work gloves. Tear the label off. There is also a long thin piece of plastic down a seam. Pull that off. Then start with the tabs. Sometimes, you can get a good grip on one of those and pull back the shell enough to get a gloved finger in. I suggest gloves because this plastic can have edges like razor blades. Trust me on this. I have got some NASTY cuts pulling apart packs without gloves. A couple almost deep enough for stitches.
Okay after the tabs break off and you do all you can do there, start peeling back the edges under the label. Just keep peeling and trying to get the plastic off in as big a pieces as possible. Finally you will get a pretty big hole going in the center. Now go to the rounded ends with the needle nose and sorta grab an edge and see if you can break the ends off and then you can pretty much diassemble it.
It’s not exactly easy, but it’s not exactly hard. These acers are about a 5 in difficulty. There are FAR worse. It is better to twist off little pieces of plastic then to twist a big piece and dent a cell. Once dented, even a small dent, to me the cell is usless and I’ll toss it. If you can cut the label, I’d never use it without a shrink tube over the original label. These cells can arc in a millisecond and tack weld themselves to whatever the arc is jumping to. Once they’re welded to something, you are not going to separate them, and the reaction will continue to its messy smoky and fiery end.
Once you get the battery tree out, twist and pull the tabs off the terminals. Be really careful around the neg poles. The cell-can metal is thin and can be deformed easily, another cause for tossing a cell.
Once you get all the batteries separated, use a chop stick edge to wipe off the crunchy glue. dremel off any weld remnants, especiall VERY carefully on the neg ploes again. The metal is thin and you do NOT want to weaken it. You need a super light touch to do this.
Then use clear 18650 shrink tube — cut to size — to cover any nicks and the whole cell, like a second clear label. Some people don’t do this and I can’t figure out why. The shrink tube costs like 2 cents a cell and protects the label and prevents shorts. Plus it looks totally pro and factory installed. The original label is a stretchy plastic and doesn’t hold up well to use.
I also write battery info on the battery before covering it with the shrink wrap. If you’re using it in a light like the S5 that has a tiny tube, don’t use a second shrink tube. It won’t fit.
Stand cells upright and QUICKLY put an even solder blob on top. Do NOT heat the battery. Once again, you have to be super quick. There’s a thin plastic bag jelly-rolled inside, and if that melts, you’ll get a vent with flames for sure. But you can do the solder so fast that the postive terminal barely gets warm. If you’re unsure of your soldering skills, practice on something first. Magnets will work in a pinch if you’re feeling lucky, but they can migrate and short out. Not a chnace I want to take. Obviously no preheating the tab when soldering. Flux will help it stick better.
Then charge em up.
Maybe there’s a better way to crack a pack, but this is the way I do it. Once you do it a couple times, you’ll do it much faster and be able to do a six-cell pack — from cracking to solder — in about 15 minutes. Charging these in an intellicharger takes about 4-5 hours. Like any new and unknow battery, charge it OUTSIDE. I have had a li-ion blow up inside, and believe me, you don’t want it to happen to you. Not only is it life-threatening dangerous, it leaves a toxic-nightmare mess that will take you and another person DAYS tp clean up.
Oh —- Be careful about twisting the whole pack in a gorilla grip with Hulk strength, thinking your superhuman prowess will bust all the glued plastic seams, and the cell tree will miraculously tumble out unharmed. I have never succeeded in doing anything better than twisting 5 out of 6 cells completely out of round and bulloxing the whole pack. And DON’T use the cells for leverage against your needle-nose pliers. You will dent them for sure. Tear the plastic in peces AWAY from the cells, with a twisting tearing action.
I have also used a dremel cutting wheel to get into some packs, but these acers don’t really have any clearance between plastic and cell, so there’s a good chance you’ll cut the battery AND the plastic.
This all sounds much worse than it is.
Hope this helps!
Why a solder blob on the end?
>>>Why a solder blob on the end?
They’re flat tops and won’t work in lights without positive springs. If all your lights have springs for a positive contact, consider yourself one of the luckiest people to ever walk the planet and skip the solder bump (for now …. Until you evetually get a light with a spring-less positive contact.)
Hope this helps.
Yeah………I normally match cells to lights, so the ones that I have that are tight I used the flat tops in. It seems the Convoys tend to be a little tight, so I more often than not use flat tops these days.
Those are some great results. I worry when I see voltages that low upon arrival, but yours seem to have worked out well. After charging and leaving to sit for a week, do they self-discharge any? Have you been able to decode the mfg dates?
My plan is to leave the tabs intact and build a large 24 cell 4.2V pack.
[quote=FlashPilot]
[quote=tatasal]
Usually, packs are 2P, 3S configured. I guess you have to cut off the series part of the connections and re-configure it to make that 24-cell pack while leaving the factory metal parallel connections. Also, leaving the original metal parallel connectors on, you have to to discharge-capacity test them as 2P, 1S connected cells.
In my relatively long experience with used laptop batt pack pulls, I’ve had cells as low as .72V and came out 80% or more healthy cells, and also got some 3.69V cells that came out almost completely useless.
But with brand-new laptop battery packs which is the subject of this thread, (which I’m almost sure that 100% them had a low voltage because of its long shelf storage) chances are they are 99, if not 100, still healthy cells.
I have a hobby charger to test each cell that comes into my possession so I know that the remaining voltage alone of the cells when taken out of the pack has relatively very little bearing on the cell’s health. How much capacity it still holds is the more meaningful figure to find out.
Reading 2.07V to 2.30V
Thanks all for the tips on how to crack/open. The key hint was taking off the label. Once that’s taken off, I see the crack to slide in the cutter and pry open. Long tough process though. (Don’t think I will do any more.)
Initial voltages are: 2.10, 2.11, 2.28, 2.26, 2.41, 2.23.
Going to charge them tomorrow.
Why is the battery pack rated to only 5600mAh when it contains six 2800mAh cells? Does the laptop only charge them to a very low voltage for longevity?
If it has 6 cells, the cells are connected as 3 pairs. Each pair, connected in parallel, hold two 2800mah cells, making it 2800x2=5600mah (that is where the 5600mah figure comes from.
These 3 pairs of parallel-connected cells are again connected in series, making it a 10.8V pack (3.6V X 3 ) and sometimes as 11.1V pack (3.7V X 3)
>>>>>>Long tough process though
It’s like anything, practice is the key. You soon see: “Oh, if I tear here, that will open up the crack over there.” And you’re done ripping apart in 5 minutes.
Then there are packs that just literally fall apart. But there are also packs that take 30 +LONG+ hard minutes for even someone with experience.
It’s not for everyone. I used to do all my own car work, and then I just got bored with it. Now, I’d rather have a root canal than troubleshoot a car electric system. 
>>>>Got mine today!
I can see the double-line date code on yours: More 2009s. (My 2009s all work fine.)
These ebay sellers didn’t just fall off the rutebega truck. They’re selling the packs for so cheep because they know pretty soon that these will be in the below 1 volt dead zone.
Does anyone know if laptop firmware refuses to charge the pack if it falls below a certain voltage?
I think ripping apart laptop packs is sort of addictive ...I have so many form recycling bins buying them off ebay almost feels like cheating ...half the fun is not knowing whats inside ...or if they are going to be any good .
Get some of these if you do a lot of laptop packs
Those are for a thing usually found in auto transmissions called an outside retaining ring, a square metal ring with angled ends that locks into a groove in a shaft. They're different than 'snap ring pliers', technically, though sometimes they're listed as such on ebay. These don't have round pins to fit in the holes of a circlip, they have serrated faces made for the retaining rings. They work great for cracking open laptop packs without cutting or using a screwdriver as a chisel. Just start a small opening near the connector (usually the weakest spot), poke the pliers in, and squeeze.
>>>>>>I have so many form recycling bins buying them off ebay almost feels like cheating
Hahahah. You’re right. It KILLS me to buy cells off ebay when practically every home depot recycle bin has 2-3 laptop packs a week.
But the problem is that even the best used batteries just can’t hold up to the demands of 4-5a drivers. I’ve tried, believe me. Used cells are fine for 3a lights. But with 4a lights, the used batteries quickly spiral down until a high-power light looks like a 3a light. New batteries can barely keep up, but they do keep up.
These are real-time tests using my DMM and a lux meter. Not just shining a light on the wall and trying to see when it gets dimmer.
I can get 15-30 minutes of 4a-5a high power from a new battery like the Samsung 2800s, but maybe five minutes from even my best used cells. There are exceptions of course, but generally speaking. I got two new Samsung 2800s from this three-pack batch that — for whatever reason — have the quick downward voltage spiral and maybe 15 used cells that do “okay” in high-power 4-5a lights.
It will be interesting to see how long it takes for these new batteries to become used batteries, and they start to exhibit the same fairly quick voltage spiral under the load of a 4a-5a light.
Mine arrived today. All 2009 batteries at 2.10-2.15 voltage.
Charging 3 now, the other three have to wait for shrinkwrap due to small abrasions in the wraps from prying the pack open.