Take an educated guess!

*Update: this thread has gone OT with discussion of cells to help in my project. You are still welcome to guess without reading anything! So far we have 26%, 35% and 40%. I harvested 460 untested cells from those 80 batteries.*

I finally have my first 80 laptop batteries to harvest. Who wants to take a guess as to the number of good cells I'll end up with? Good means >2000mah, >80% SoH and IR <5% off spec.

Any other predictions?

Probably less than 40% would be my guess...

If they are all OEM packs I will take a stab at it.

After recording and testing 6269 cells here is what I came up with:

First a bit of background I first started testing cells with several testers and if the cellwas over 2000mAh I was happy and it went into my pile.
Well then I found out just because its 2000mAh does notmean its a good cell if it is a 2800mAh original capacity cell.
So the first 1000 or so cells where tested again but all the <2000mAh cells where not included as I was looking for cells with at least 2000mAh to begin with.
From ~ the 1000 cell mark up to 3500 cells I just looked for ?2000mAh cells checked the IR and tested them.
Here are the results in percentages with cells ?2000mAh ?80% SOH and ? 55m?.




After cell 3500 I started to take IR seriously and really only tested cells that I believed the IR was good enough to actually test the cell.

Here are the results of that.




So from busting open laptops and just testing cells without an IR test I got ~31% of reasonably good cells.
After starting the IR check the percentage went to almost 50% of reasonable cells. The problem with these numbersof course isI never recorded the high IR cells and have no idea how many I gave away but I am guessing around 3500.
Lets say out of 9500 Cells here are the results of that calculation.




So my guess is 26%

Wolf

Wolf, what are your personal target IRs ?
Do you consider the official specs for each cell type or you just set a general target and stick with that ?

i would say 35% is above 2Ah and useable for most of us.

Overmind said:

Wolf, what are your personal target IRs ?
Do you consider the official specs for each cell type or you just set a general target and stick with that ?

Click to expand...

I have an IR cheat sheet that lists the IR of most popular models we see in the laptops that we break down.It was refined to average out the IR of well performing cells. I then took the average of that and55m? was the sweet spot.
I personally built my PW with IR of cells between 40m? and 55m?
I do consider the Official specs If they are published andI have them incorporated into my spreadsheet but I do find that some of them are opportunistically high and referto ? XXm? a lot.



That being said if you follow myIR cheat sheet you will getgood results.





Wolf

Wolf, I only took a quick glance at your IR test results, but it seems that you consider IR that's within 5% of spec to be okay. Sound right?

If you think 5% is okay for a PW is 10% okay for certain applications? What about 50-100% over spec but still below 100mQ? Maybe low drain or maybe frequent cycling or maybe limiting the number in series or parallel.

Initial cells will go into a 36v 10s3p ebike pack powering a 500w motor. I'm not yet in the packing planning stage of the cells. That's about 13 amps at max draw. That's 4.3 amps per 10s1p cell. If I build my packs with 2200 mAh cells that's, about 2c discharge, right? Anyone have tips for packing for a 2c discharge rate?

Sed6,

I built my personal spec sheet from experience and have found if I stick to the values that I have in my IR cheat sheet I have good end results.
One thing I have done on occasion is violate my cheat sheet by a couple of m?. Soifmy sheet says ?55m? and I try a cell with 58m? just to find out that it does not pass the muster. There are some cells that have a high IR from the get go and are quite good but the highest IR I have found on those is 80m? anything above that is usually either a heater or a sub par cell at far less than 80% SOH. There is one exception I have found ant that is the Sony US18650GR G* series. Just a weird battery and I wont use them unless I have enough to make a pack just with them and never mix other cell in with them.

10% deviation from spec IR is your choice as well as 50-100%. Would I use them in certain applications I don't know as I have given all those with high IR away and someone in Canada and other places are really happy but they are also building 200p to 300p packs so the draw is very low and they can get away with it. I am a little more picky. As I have a great source for cells whenever I need themI can afford to be choosy. I no longer go after laptop packs but am always on the lookout for power tool, medical, scooter, andebike packs.

If you are going to build an ebike pack my suggestion is going to be power tool packs not laptop packs. Laptop packs generally have ICR chemistry for longer lasting at a low discharge rate. ~500mA tops. Can they do more? Sure but at a price of heat and longevity.Power tool packs generally have IMR INR and sometimes NCA chemistry. This allows for higherdischarge rates and still keeps the battery relatively cool. Also you will find that the IR on these cells tends to be in the 12m? to 35m? range. and added benefit is faster charge times.
Pulling 13A from a 6600 mAh pack gives you tops an hour of max ride time. More of course if you draw less If you are OK with that great.

Wolf

Sed6, even a relatively bad shape 3.6V cell / high current cell will handle 4-5A with no problem.

That of course if they are original; if not, they will overheat like hell.
Here's a fake example of HG2s:
Basically if they are too cheap they are fakes. They may have the full capacity but will not sustain the stated current and take damage at high current.

Wolf said:

Power tool packs generally have IMR INR and sometimes NCA chemistry. This allows for higherdischarge rates and still keeps the battery relatively cool. Also you will find that the IR on these cells tends to be in the 12m? to 35m? range. and added benefit is faster charge times.

Wolf

Click to expand...

Great info, all of it! But ugh! I thought I finally had my head wrapped around everything and up comes nickel vs manganese vs cobalt

Sounds like I also need to separate or label the chemistries of my cells if I plan on making batteries for different uses like a PW or ebike battery that have different drain requirements? OR is IR and capacity good enough? Any reason to not mix ICR and IMR/INR cells in a battery if I use packer software and pay attention to IR and mAh?

All my tool batteries so far are low capacity, 1300-1600. Even the 40v, they mostly had 1300's. Best I found so far is a 40v with Sanyo 2600's. Any certain tool packs you've found with higher capacity?

I do have a R2 Recycler around the corner and they are willing to let me dig thru their huge pallets. At $2/lb that's $.23 per cell approx. I'm happy to pay that especially if I can target my haul to appropriate batteries.

Given what you and others have shared; I should target laptop batts for IMR/INR cells for low drain use like a PW and powertool/ebike/scooter batts for ICR cells for higher drain apps like my DIY ebike batt?

Maybe I will get this...
Thanks!

Sed6 said:

Given what you and others have shared; I should target laptop batts for IMR/INR cells for low drain use like a PW and powertool/ebike/scooter batts for ICR cells for higher drain apps like my DIY ebike batt?

Maybe I will get this...
Thanks!

Click to expand...

Its the other way around ICR are your high capacity low drain cells.( Laptop)
YourNCA are your middle of the road, great capacity with mediumdischarge current (Some Laptop mostly Medical)
Your IMR and INR are your high drain cells. (Power tools) (You wont find any of them in laptop packs at least I haven't)

Look at my posts on IR and how parallel cells react to each other.In a 10s3p you do need to have ALL your cells very close (IR and mAh),the same brand, type andif possiblemanufacture date. That is if you want a successful pack.
Here is some reading material that will keep you awake at night.
https://secondlifestorage.com/showthread.php?tid=7873&pid=53600#pid53600
https://secondlifestorage.com/showthread.php?tid=7846&pid=53209#pid53209
https://secondlifestorage.com/showthread.php?tid=8857&pid=60625#pid60625


Wolf

Wolf said:

Sed6 said:

Given what you and others have shared; I should target laptop batts for IMR/INR cells for low drain use like a PW and powertool/ebike/scooter batts for ICR cells for higher drain apps like my DIY ebike batt?

Maybe I will get this...
Thanks!

Click to expand...

Its the other way around ICR are your high capacity low drain cells.( Laptop)

Look at my posts on IR and how parallel cells react to each other.In a 10s3p you do need to have ALL your cells very close (IR and mAh),the same brand, type andif possiblemanufacture date. That is if you want a successful pack.

Wolf

Click to expand...

Thanks Wolf! If I bump it to 4p or 5p then I have a little more wiggle room and/or the pack will be more successful?

Let's define success; for this ebike battery I would be happy with one year, maybe 50 complete discharge cycles, 100 partial discharge cycles before the battery is no longer serviceable (let's say 75% of original capacity). This battery is "disposable" and replaceable and I don't expect it to last forever. How would that change any recommendations? I would almost guess that I could slap together almost any cells and get 50 cycles. Or am I wrong?
Thanks all!

I'd go with 25-35%.
I've had some hauls that were amazing and had 60%+ good cells, but I've had other hauls too that only yielded 5%.

Since adopting the Wolf methodology I've had much better results, with over 95% of my tested cells proving good. However I am now weeding out loads more cells that before I would have consigned to the recycle bin once I'd wasted time testing them.

chuckp said:

I'd go with 25-35%.
I've had some hauls that were amazing and had 60%+ good cells, but I've had other hauls too that only yielded 5%.

Since adopting the Wolf methodology I've had much better results, with over 95% of my tested cells proving good. However I am now weeding out loads more cells that before I would have consigned to the recycle bin once I'd wasted time testing them.

Click to expand...

Fingers crossed for more than 5%!!! My Yr1030 will be here any day. I've been putting off testing any but a few until I can do it the Wolf way.

Not including rusty cells, self-dischargers, heaters, unrecoverable cells (0 Volts), etc. based on your criteria of >2000mAh and >80% SoH, the cells that I was able to test, I got about 24%, so if you include the cells I didn't track, it would probably be between 15 and 20% for genuine used laptop batteries.

If you are making an ebike battery, try to stick with the INRs as the ICRs degrade quickly at high discharge rates.

Milwaukee 6AH and 9AH batteries will have Samsung and LG 3AH cells. I'm getting a lot of these.

Basically this is what they use...
1.5AH = 5 x 1.5AH/1.6AH cells
2AH = 5 x 2AH cells
3AH = 10 x 1.5AH cells
4AH = 10 x 2AH cells
5AH = 10 x 2.5AH cells
6AH = 10 x 3AH cells
9AH = 15 x 3AH cells
12AH = 15 x 4AH 20700 cells

Will be the same in all 18v packs where they offer those capacities - Mlwaukee, AEG, Makita, Hitachi, Bosch etc.

Hilti is different. Their packs are 22v and 36v, and their older packs use 1.6AH and 2AH. More recent packs use 2.5AH. These are a pain to disassemble to - I need to brush Acetone on the ends and just under the plastic holder to dissolve the glue. This damages the cell wrapper as well. I'm told their newest packs are higher capacity, but we won't see those for a while. I suspect they are 20700 cells, which means higher drain and less failures, so could be a while, and when we do, they'll be EOL.

I also have 1.3AH cells. I think they might be out of Makita 2.5AH packs.

Dewalt Flexvolt uses 10 x 4AH 20700

EGO uses 2.5AH and 3Ah, from what I've seen so far, but I haven't opened every type yet.

I've got around 2,000 cells. All from power tool batteries with cells 1.5-3AH. I have capacity tested around 1,000 and am concentrating on the 1-2AH cells for smaller test projects like UPS and camping packs. I'm actually hoping to get enough 3AH to use those exclusively in my home system in about 2 years. But will need around 2,000 of them! I think that's achievable.

[quote="Wayne']
Milwaukee 6AH and 9AH batteries will have Samsung and LG 3AH cells. I'm getting a lot of these.
[/quote]

Great info, all of it, thanks! Where are you finding these batteries? Targeting at a recycler, buying used, recycle bins, other?

Unfortunately my first 2 dozen 3AH batteries have only 21-2200mAh capacity left. Well below the 80% I'd like to see. I have over 650 cells now and I'm really hoping for 100 or more a 2AH.

I've got a couple of local tool shops on the hook.

I haven't done any serious %ofOEM calculations yet as I've only got around 300 SD tested, with only about 3 fallen below 4.15v after 3 weeks, which is an incredible result.

Of the Samsung 3AH cells, unless they are 0v, are testing between 2.8AH and 3.2AH. An excellent result really.

I've done all this with 1 tester for 2 months, then a second for the last month. I've got 6 testers enroute, and a DELL server PSU ready to roll... Well, I just have to rig up a power rail with the DC pigtails along a frame that I'm yet to make... but all in good time!

@Wayne's World, you're right about Milwaukee.
There's also an 8Ah now which uses 21700s.
Anyway, most have samsung Q, Rs, RMs or newer.

I did not see too much 6Ahs in circulation, the most spread seem to be the 5Ahs.

Anyway, the cells from big brand power tools (MW, dewalt, bosch, makita, etc) are all premiums, worthy of being recovered.

[quote="Wayne']
I've got a couple of local tool shops on the hook.

I've done all this with 1 tester for 2 months, then a second for the last month. I've got 6 testers enroute, and a DELL server PSU ready to roll... Well, I just have to rig up a power rail with the DC pigtails along a frame that I'm yet to make... but all in good time!
[/quote]

Local tool shops, thanks! So lemme ask, why are you and others using a PS to power your testers instead of the wall plugs? I too have 6 Opus and a 6 outlet power strip works for me.