Yeah usually it's only some of the cells that have died, and a few will be marginally usable. But the 'good' ones are just as old as the dead ones and have been worked just as hard, it's really not worth the work to get cells with so little lifespan left.
It's like driving your car 120,000 miles until it starts misfiring, and then only replacing the spark plugs worn enough to cause the misfire. The others are just as old and just as worn and the labor to replace one is the same as the labor to replace all of them...
After having just done that with an ancient Inspiron 6000 and a somewhat-old Latitude D620, both of which made error lights and could not keep their laptops ON for a moment w/o AC power, I can say YES!!!
Rip the pack apart carefully (I managed to hit 3 (three) shorts simultaneously on the Inspiron pack, but the smoke was just from the red plastic covers melting — I won’t use those) because they weren’t made so solidly back then, and measure the V. If any have a full charge, use it/them, down to the point the charger would bring them back up (3.something depending on the charger) then charge them.
Most won’t have a full charge. Charge them, but in any case pull them and toss them if they get “hot” (YBTJ) while charging. Some will count the V down as you read it (weird to watch) to some ‘undervoltage’ that doesn’t seem to hurt anything. Just recycle those without further concern, they’re toast. If it reads some 4.x V but won’t light your light, it’s probably one of these. Oh well. Sometimes your local recycler will get whole packs & will be happy to trade… Just thinking out loud…
If you get one or two (or 9 total, out of both packs) decent batteries, guess what? It’s all free! I honestly don’t concern myself with anything more than “is this one charged, or has it been used?”… It’s fun (to me, but I’m weird), when we’re out and my friends’ flashlights run dim, to be able to just produce a battery from a pocket for them…
Likely scenario: You’ll get most of them working, they’ll have some decent-but-short runtime, and you’ll give them away.
Worst-case scenario: You make a bad short, cause a fire, post a viral Youtube video! What’s to lose?
Dim
PS: Be sure to turn on a camera! I have only memories of this:
I’ve harvested several packs now and the hardest part has allways been getting the two halves of the outer casing separated, especially at the beginning, when trying to get the crack started. That has just gotten much easier with the suggestion to use outside ring pliers. Thanks for the tip Comfy!
One or more of them is bad, in this case bad meaning different from the others. The protection in these packs is very picky. It has to be to protect the manufacturers from liability claims.
The two at 4.15 should be treated as a group, and the other four as a different group - don’t mix the two groups. If you test them you will likely find a difference in capacity and internal resistance between cells in the two groups. That is what tripped the pack’s protection. I think you will find that all of those cells are usable.
Amazing, I just cleaned them up and they all work in my S3! I see what you’re saying P1K, I’ll mark them to denote the groups. This pack is dated 12/2010 so they’re coming up on 3 years old, with a cheap meter and an i4 is there any way to discern capacity or anything else that might be useful?
As bad as the tears on those wraps look I want to suggest you strip the wrap and apply new shrink-tube over the cells. That looks like a short waiting to happen.
95% of those nicks will all but disappear with a few passes from a heat gun. I wouldn't strip & re-wrap just for the damage shown in that pic.
The silicone caulk junk in the white Acer packs is a lot tougher than what I've run into in other packs and a few of my cells had the wrap stretched out pretty bad but not torn. I went over them gently with my hot-air-blowing butane pencil iron and all the bad spots went away.
edit: OK, 4th one down from the top I would re-wrap, due to the nick at the top corner. The others will be fine after a little heat.
"A short" in this case will only be between the - and the light body which is the exact same 'short' the tailcap switch creates to make light come out the shiny end. Nicks in the wrap on the sides of the cell body will never be able to make electrical contact with the body of the light unless there's a corresponding burr on the ID of the tube, highly unlikely.
Unfortunately an i4 won’t help you measure discharge capacity. A bit tedious, but you can measure relative capacity by discharging them down to a particular voltage in a light — a lot of work for very little information. With a DMM and a resistor you can measure internal resistance.
I agree with Comfy, the battery body will only contact the part it is supposed to contact anyway. However, I would already have them rewrapped if my FastTech order wasn’t sitting in Hong Kong waiting for the bomb squad!
FYI, all the black and white gunk came off no problem. The gooey double-stick tape was harder, but it’s gone now too.
If you are into this old/new laptop battery pack adventure like me, I strongly suggest not only a good DMM, but also a good hobby charger. It takes out the guess work. A good voltage reading out of the pack is not enough statistic, but more importantly its discharge capacity, which a hobby charger can give. In my case I keep cells that retain at least 75% of its nominal capacity for my nicer lights.
A hobby charger’s digital readout of the growing voltage rise (abnormally fast) of a cell during charging can also give you another symptom of an unhealthy cell. A cell with a still high voltage reading after a charge will collapse when subjected to a hobby charger’s adjustable discharge rate, usually manifested at 2A or higher.
Oftentimes I got disappointed from cells that read good voltage readings out of a pack, only to show it ‘tiredness’ due to heat and cycles in its lifetime when subjected to hobby charger tests and readouts during after the tests.
The good new is I have not yet encountered a bad cell from a brand-new pack, regardless of its individual cell voltage when taken out of its shell. (some as low as a 1.78V pair)
Okay, I can’t stop calling them “smart” chargers, but I agree! But wait, there’s more!
It’s also takes out the “work” work! Just drop the batteries in and Know. Leave the dangly VOM leads and fiddly calculations in the box for “serious work”.
Recycling laptop packs gives you a slightly different ‘view’ on battery-related things. Smart chargers clarify that view.
I use the cheap-o chargers which I test as thoroughly as anything else, but I also don’t really care about capacity since I have packs of extra batteries (if I don’t pun it, who will) lying around. But I believe in knowing. If your time is worth money, smart chargers are actually revenue-positive, even if just to cull dying cells without having to carry them around…
Just trying to draw some attention to some Really Good advice…
Nominal Capacity* 2,250mAh
Nominal Standing Voltage* 3.60V
Charge Method* Constant Current-Constant Voltage
Charge Voltage* (V) 4.20 (MAX)
Charge Current* ( C ) 0.5 (MAX, above this may cause damage)
Discharge Voltage* (V) 2.75 (Below this, internal damage will be irreparable)
Discharge Current ( C ) 0.2
*
You have to remember these were not ment to be used as singular cells, they are supposed to be in a pack chargerd together, this is why the charge amps and discharge amps are low.
Apparently not. It’s like breaking into a wild-found honeycomb… You can tolerate a lot of waste and still come out with something sweet.
If you’re in OK, you know about ice. Specifically, Ice TRAYS. The modern plastic kind only release their bounty when you grab both ends and twist.
That twist motion works GREAT to break the welds on laptop pack shells, so you can see where to pry them open. Twist more and more welds break. The pack inside can take a surprising amount of this, but be careful. I’m not bragging a bit to say lately I don’t seem to need tools until I get to the nubs where the buss strips were welded to the batteries.
BUT… Full disclosure, I just wasted 3 batteries (awww) by grinding them together (not on purpose) until they shorted out and melted parts of the covers with smoke. I was able to solve it by dumping the pack out of the shell & pulling the ends apart. So now I only have SIX new (-ish) batteries to play with.
Anything above 3 volts is usable, I’ve revived cells below 2volts, and they are happily being used daily In my own lights(single cell), as mentioned above pick up a hobby charger if you want to harvest laptop batteries, then you determine the available mAhours in each cell and then accurately group them in batches.
No need to charge them in pairs in the i4 , the charger will simply finish the lower capacity cells first.
I’m using cells with 800mAh quite nicely (originally 1600Ah and 2200mAh), toss any that don’t keep their voltage above 4 after a few weeks.
