Look what I found in the recycle bin

This tube inspired me to take a stop by our local Best Buy, Home Depot, and Lowes in search of cells. So… Best Buy had not a thing that we cared about(I went with a friend I got into flashlights). It was filled to the brim with AAs and a little rummaging revealed a shoddy flat power bank so it was a bust…. Next was Home Depot, and after asking several employees we almost thought they didn’t even have a battery bin. It is marked online that they have a bin, but it isn’t a traditional one, but just a series of cardboard boxes filled with various drill battery packs… I had a friend that worked there ask someone if we could just take them all and he said sure so we walked away with 2 boxes of assorted batteries. Lowes had the most conventional battery bin, probably because they had just built it. This time we hit the employees with an educational shtick that we were looking for cells in order to help with our educational robotics program and they said sure take whatever we have, SCORE. Sadly all they had were these Motorola NIMH packs, but as I suspected they each contain 6 NIMH AA sized cells.

Onto the haul:

Unfortunately only one of the drill packs was Li Ion and had 10 of these 18650s

They all registered at around .5 volts so pretty dead. From battlebots in high school we used A123 and other Lithium cells we would often have cells drop below the “safe” voltage and just force charge them until they hit the required voltage. I have managed to get 1 of the 18650s up to 4.2v, but they all seem to have this problem where they are constantly discharging so I expect either a protection has blown internally or maybe they have external circuitry to blame? The one cell I charged was the one that discharged the slowest, the rest would discharge at a rate near 0.01volt per second so I didn’t even fiddle with them. I’ll see if the one that I charged holds a usable charge over the course of a few days, otherwise it’s not really worth keeping around. I did not take any pictures of the NIMH AA cells, but they all seem usable I’ll try to charge a few and test if they hold onto it or can power stuff. I’m not well versed in NIMH do they have a voltage they shouldn’t drop under?

All in all, it was a great first time haul. Anyone have ideas for all the nicad cells I got? A lot of the 14v packs measured in at around 13.3volts and seemed healthy. I just didn’t tear into them because I was only really interested in the 18650s, which incidentally we got the least of.

edit: also got what looks like a brand new never used electric scooter lead-acid battery along with a very-used lead acid battery. We have plenty of fodder to give us an excuse to start frequenting the bins…

With all the packs I have opened, I have NEVER come across one A123 cell that was any good. Their cells are not as good as the modern ones from Samsung, LG, or Sony.

Maybe you got away with charging up dead Li-ion cells in high school, but that is something you definitely should not do. There is too great a chance of a catastrophic failure. Look for batteries that are in the bin for reasons other than that they are worn out, or have been discharged to unsafe levels.

For instance, of the 3 NiCad packs I described above, one pack was discarded because it was simply worn out. The individual cells have lost over half of their storage capacity.
BUT, the second pack I described above was in the bin, I think, because just one of it’s cells failed early on, rendering the whole pack useless. After disassembling that pack and separating the cells, I have netted 9 good cells out of 10. Those 9 cells still function at near full capacity.

Bottom line is be fussy with what you pull out of the bin, most of it will be trash.
But there are some good finds, if you are willing to be patient. :wink:

Aw, that’s a shame. I’m not really worried about catastrophic failure, I took necessary precautions. I will put my safety above all else, I don’t take these things as lightly as I used to. The best part was that in high school we would solder tabs onto each of the cells, then over discharge them, force charge them as nicad, have them near punctured in battle, and continue using them. In all my years never have I seen a cell do anything dangerous. There was one time a 21volt lipo that was huge got short circuited and it didn’t have a protection board so it fused the wires together and started a fire. The cell got puffy after, but never vented. Just a few horror stories from high school and most were due to our instructor neglecting safety, I don’t take after those bad practices.

Home Depot was all or nothing, they made us take everything. A lot of the drill packs were just returns, but they don’t restock the packs if they’ve been used. I’m certain I have a lot of usable nicad cells, some of the packs have leaky cells and read flat so there’s no use fiddling. I’ll just return those to the bins. I get my chances are slim, but it’s all about the gamble right?

Let me make just one last point.
Say the probability of a new, perfectly good cell of venting and catching fire is 1 in 10 million, let’s just suppose that.
And let’s just suppose that discharging it all the way to 0 volts and then charging it back up increases the probability of a problem occuring by 10,000 times. There would still be a 1 in a 1000 chances of something going wrong. Just because nothing ever happened doesn’t mean the danger hasn’t increased.
Because of this, I strongly believe that it is very easy to become complacent and careless. For that reason, we must draw a line and say do not use after a certain discharge voltage is reached. I would recommend the numbers generally discussed in all the literature on this subject.
What you do is your own responsibility.
BTW, I store all of my scavenged battery packs outside in the shed, away from the house.
I am nervous about the new ones I buy as it is.

Don't mind at all,,, here ya go.

JACKPOT...!!!

Ego 56v tool pack, = 42cells, Samsung 25Q
Ryobi 40v tool pack, = 20 Samsung 13Q

Well, I've tried to get into the recycle bin at my local Home depot to no avail, for months now. Every time into it, a employee questioned me and more or less stopped me from any further exploration of their bin...
This all changed last week.

HD moved the recycle bin to a out of the way, kind of out of sight location. So,,, last week was my first bin pick. No more questions from employee's that now don't see me dropping off my recycles and exploring whats in their bin...

Got a couple tool packs last week out of HD recycle bin. No good. All the cells were 18650, LG1100mAh, but had 1.1v or less. Tossed them all in my recycle ammo box after a wrestling match with the packs disassembly.

Yesterday morning got lucky. Got a Ryobi with 20 Samsung 13Q, all cells 3.1-3.3 volt.

Now for the Ego, a massive tool pack, chock full of 18650, got to be the recycler's JACKPOT.. 42 Samsung 25Q all cells 3.2-3.4v. Yes, I know they aren't 30Q or Sanyo 3600mAh, but for free, not bad.
They seem to be hi drain cells. Power my highest amp lights as good as any of my best high quality batteries, says my trusty amp probe. And the ones I charged so far, charged up great, didn't even get warm in the lii-500, and took a full charge.

Getting good at taking these tool packs apart, a slight art to it. They sure don't make it easy.
Haven't got them all charged up yet, but dang, more cells then I know what to do with,,,lol

This is getting fun, thanks BLF for showing me the light, to the recycle bin...

Going to start to get picky on what I take from the bin. What tool packs have the best cells..?

Oh, by the way, 56v does pack a nice wake up shock, wear gloves, be careful with the ego...

Opened my 2nd to last battery pack from ebay. Supposedly some Chinese 2200mAh cells. Not bad! Better than the rest of the bunch! Accidentally pulled off some heat shrink around the casing of a cell and connected the positive nickel tabs to the negative on a battery…BAM! huge thing of sparks and the entire nickel melted away…lol! Fortunately all the batteries are still good! Good thing I got a 2nd heat shrink wrap for my batteries! Save them from possible shorts!

Would you still have that 40V Ryobi pack from the original post? i’m interested to reverse engineer the BMS board in that pack and wondered if you could post the part numbers of the 2 big IC chips seen in the pictures. i would guess that the square one is a microcontroller (TI?) and the rectangular one is a cell monitoring chip (LT?).

If we could hack the BMS then it might be possible to figure out why the packs are shutting down and how to repair them and then re-use the entire pack.

thanks, kenny

I maybe able to help soon. I still have one I havnt taken apart yet. My 4th one. In 3 months I’ve found 4 they seem to fail a lot. But the cells are still almost at original capacity. I’ve been putting it off being is highly disappointing they are 1300mah cells. When other brands have much better cells in them. A lot of people say there’s have Samsung 13q. All of mine so far have lg 25 amp 1300 cells not samsung. I’ve just been using them mostly for vaping since they are high drain. Or night lights. Each pack had a few cells that were shorted out. In 60 cells 18 were completely dead. The other 42 perfectly fine. Just low capacity. Figure I’ll hang on to them for hurricane season. In case power is out for a few days or a week

On a positive note I found a brand new pack a display I believe in the bin still had new plastic smell and the battery light worked on it. Had 5 Samsung 20q inside. At 2200 capacity roughly. So those are my batteries for the Q8 I’ll put solder blobs on 4 of them

ok i can answer my own question now.

There are two versions of BMS boards made by TTi in the ryobi OP4026 40V packs.

model # board # date
13086012 280146 jan 6, 2011
13086045 280296 dec 17, 2013

i had guessed just opposite for the two chips on the board: the square quad pack U3 is the battery monitoring chip by O2 Micro, OZ8940ATN; and the rectangular 28-pin SSOP designated U2 is a PIC16F1786-1/SS microcontroller.

i had found a 40V and a 18V pack in the recycle bin at HD. The 40V is completely dead, the cells have been totally drained. The other pack indicates 9V when reading from the outside terminals, but all the cells read 4.0V when opened up.

Depending upon the model, there are either one or two big FETs (IRF1404Z) on a heatsink on the bms board that switch the low side of the pack closed/open that functions like an ON/OFF switch. Something must be causing this to stick ON and draining the packs—there are a huge number of dead packs for sale on ebay, plus lots of posts from folks with problem packs. These cells should last 10 years—something is killing them early…

These packs, like nearly every other power tool brand, are built under patent 7554290, invented by Todd Johnson et al, and assigned to Milwaukee Electric Tool Corp. The BMS has no shutoff or low-power mode, and it gets it’s power from the pack—so it is constantly draining the pack. Too bad we have to pay these guys royalties for a POS system, there are better solutions out there e.g. Texas Instruments

^

Thanks for the info kennybobby. Not sure what it means, but it seems like good info for those that know about such things. I just pulled my 5th or 6th one from a recycle bin today. So far, 2 of them had completely dead cells and the others had cells that acted as if new (Low resistance, full capacity, stay cool when charging and discharging a 1 amp, normal warming under high current loads, etc.). So it seems the bms has some other issue that prematurely ends its usefulness. I heard (don't know if it is true) the internal bms disables the pack and intentionally fully discharges the cells when it deems the pack unsafe.

Great cells for around the house lights that don't need long run times.

i think you are right—the controller can disable the pack by opening the FET, which is device 480 is this simplified patent schematic image (440 is the microcontroller).

^

Interesting. Are you thinking those resistors may be used to do a controlled discharge of the cells when certain parameters are met?

If that is the case, it is best one break down a found pack as soon as possible to hopefully liberate them before getting below 2 volts/cell (IIRC what the 13Q can safely discharge down to). I will try to open up my pack tonight and measure cell voltage and voltage drop across those resistors.

The 40V ryobi are very difficult to desolder without shorting and arcing. They put a huge amount of solder on each cell connection and it requires a very high wattage solder iron and lots of solder wick to disassemble if you want to preserve the circuit board. If you don’t care about the board then it should be easier. i wanted my board for reverse engineering purposes.

Here is another patent schematic showing the cell draining/balancing resistor circuits [460’s], which could be used for draining all the cells in the event that a safety feature is triggered (out of range for temperature or voltage, defective temperature sensor, blown fuse, etc). i hope to trace the actual board circuits and identify all these components, probably in another thread so as to not hijack too much here…

^

I can send you my best board if your wanting one still. Just PM me the address you want it sent to and I will have it off to you. As you stated, they are difficult to tear down. So I don't think I have one without some damage.

I opened the pack and the cells were down to about.48v. I didn't have time to follow traces and try to find the resistors you diagrammed above. There are about 12 510ohm resistors and they are the biggest ones on the board. 10 of them are probably the ones in question. I tests voltage across some of them and got a reading of about .01 (IIRC). So it appears the pack is actively discharging the cells. When the "test" button is pressed, the 4 LED's that normally show level of charge all flash off and on.

Yes those 510 Ohm resistors are designated RF1 - RF10 on the board and connected to each 2-in-parallel Cell as shown in the schematic above where they are connected to the - end of each pair. If those were removed it would isolate that pair from the drain circuit. i don’t know how long it would take to drain a pack, best not to wait to salvage the cells. (EDIT note: The 18V ryobi packs have 5 cells and use 51 Ohms for the RF resistors)

i think RF11 and RF12 are in circuits that provide power for the digital section so those could be removed as well to just turn off the controller and stop the bleeding. i ended up taking them all off the boards.

i have 3 packs that indicated bad, one was actually overcharged at ~42.8 V, the others were around 3 to 4V, with cells at .2 to .4. i put them on a power supply and slowly stepped up in 1V increments while monitoring the current and temperature.

The 4V pack immediately took current at 50-90 mA and then it tapered back to about 25mA, then i incremented 1V and repeated this until the voltage got up to ~23 V for the pack. At that point the current draw was increasing with each 1V increment, , e.g. 200 to 300 mA. Again i let it hold at that voltage until the current dropped to ~25mA, then increment. Got the pack up to 32V and stopped, will see how it is in the morning.

The 3V pack didn’t seem to draw any current like the other one did—i stepped it up from 3 to 23 in 1 V increments with little to no current flow, then at 23V it started to draw/charge at 25mA, and after a few more increments it soon started behaving like the pack above until reaching 32 Volts, will check it tomorrow.

On the 42+V pack i had removed the fuse between the top and bottom modules (2P5S bricks that make up half-packs). Over just 2 days the bottom module had been drained off to 18 V, whereas the top half was still reading high at 22.8. The digital controls seem to be powered from the upper half, and likely sensed the “blown” fuse and initiated the drain-off for the bottom half. i connected a resistor and bled the top down to 20, and charged the bottom up to 19, will check it in the morning to see how it holds.

So long story short, nothing thermal was noted, but that doesn’t mean they are safe and good to go. Metal dentrites grow inside a cell during any charging that is done after an over-discharge event. These are sharp shards of metal that will puncture the plastic separator sheet in the cell and cause an internal short circuit, which leads to thermal runaway—much heat and eventually fire. So don’t try doing this unattended, recharging after a discharge below 2.5V is not a recommended practice and they can go off AT ANY TIME and burn down your garage, house or trailer. If it happens while you are sleeping, then you might just wake up dead…

My first recycle bin pull as a registered member. Nothing super special but a 20V worx Li-ion pack. Had a piece of blue painters tape with “bad” written on it. 11/2015 mfg date. Every cell measured 4.05v. So maybe the board in it died but every cell in it appears to be good.

http://i.imgur.com/SWot1Uf.jpg

You may be right on a “fatal discharge” circuit being built in to these packs, I don’t know.

I have always assumed that the reason there are so many like new packs in the recycle bin is because the store or customers make the mistake of fully discharging a pack and leave it for an extended time in that state.
With all the monitoring circuits in the BMS board, there HAS to be some parasitic drain, and if there is, it wouldn’t take much time for the pack in a fully discharged state to drain further to a point of no return. In other words a permanently damaged pack.
Take a look at this discharge curve I pulled from the thread

I had to estimate the capacity of an 18V drill pack, here is how I did it.

From that thread, the area under the curve is approximately the same as the area bound by the red lines and represents the Amp-Hour capacity of the pack. The horizontal red dashed line is the cutoff voltage.
Now notice the blue arrow, it points to an area under the curve to the right of the vertical red line that is bounded by the discharge curve.
It is a very tiny area!
The graph only goes down to 2.3V, but as you can see, if you were to continue the discharge curve any further, you wouldn’t increase that area by very much at all. There is very little capacity past the shut off voltage.
What this means is that if there is any parasitic drain in a pack, leaving a fully discharged pack in that state can kill it!

That is why I believe I find so may “like new” packs in the recycle bin that are dead. Most come, I believe, from tools on display in the stores.

I just spent the last 2 weeks in Ohio. Of course while there I checked out recycle bins whenever I could.
At this point I am very fussy and only pull packs that are physically in like new condition.
Here is a picture of my haul. and represents probably 10 different bins over that period.

I have not had a chance to test these yet.

1 - 56V 4.0Ah Echo
3 - 40V 2.4Ah Ryobi
3 - 18V 1.5Ah Ryobi
5 - 18V 1.3Ah Ryobi
1 - 20V 1.5Ah WORX
1 - 20V 1.5Ah Black & Decker
1 - 18V 4.0Ah Makita

I’ve started to get picky as well. One of those 40v ryobi is the 1300mah one. The one on the right op4026 the good ones are the 4040 like on the left. A lot of the ryobi 1.3-1.5 I’ll leave there. Or take to go dig in another bin. I usually walk up with stuff so I don’t draw much attention. The only place I can dig freely is lpwes. Since I worked there for a couple years and still know some people. Best buy only ran me off once. I prefer the 2.0+ tool packs I already have like 70 1300mah 25amp lg cells from ryobi 40volt. I don’t really have much use for such low mah cells besides vaping. And hurricane preparedness.

The battery monitoring chip in the Ryobi lithium packs (18 and 40V) will disable the Pack by opening the large FET (s) if the voltage drops below the LV threshold and not allow further discharging, but it also prevent recharging so the Pack is “bricked”.

Theoretically, if you can open the cover and manually charge up the cells directly from below the LV cutoff, it should be possible to un-brick it and use it once again in normal operation. i did this on 3 packs to test it out and they seem to be holding.

Those older packs with the 1300 mah cells may not be worth the effort since they are selling the new packs online with 2200 mah cells, 20 cells for $145 is ~$7/cell delivered to your door with brand new cells in a pack. That seems really cheap and you don’t have to worry about your garage catching on fire while you sleep because some salvaged cells went thermal. just sayin’