Scavenging for Used Battery Cells: My Mission and the Booty!

[theyerb]

I have recently been inspired by some of the posts by Doctorbass in the EV Battery forum. From what I understand, he has been getting A LOT of used and broken Makita power tool packs from some source, and as I understand it, for FREE! The Konion cells in the Makita packs are what I was after since they require no balancing when put in series. I called up a few battery service places in my county to see what I could find. Here's what I found:

One of the shops gave me two boxes like this full of all kinds of different batteries. Each battery was in a little plastic bag- protects the batteries from shorting out on one-another.

Here's all of the batteries on my table with some of the better finds in front.

And here's what I'm after: these beautiful little neon green gems.
[img]http://farm4.static.flickr.c...00 worth of cells out of it, so I'm happy :)

 

[John in CR]

I prefer to leave as much of the tabs on and keep good cells attached together, as long as they are balanced. This includes leaving the tab of the bad cell still attached to the good cells, as well as cutting the metal leading to the electronics of the pack as long as possible. That way when I'm stringing the cells together I can solder tab to tab instead of the cells themselves. Lithium cells don't like heat, so I try to avoid soldering directly on the cells as much as possible.

You might try a recycling center for used packs too.

John

 

[theyerb]

Thanks for the advice, John. I am going to leave the leads on the cells for the next few extractions in order to simplify the eventual soldering. I am also bought a Bosch bat836 tonight to play around with. Cheers-

 

[pwbset]

I don't know.. I just finished tearing down and charging up a couple hundred single konions and am going to start a 14s10p pack soon. I built a 10s2p test pack with the "pairs" and ran it for a bit and it was fine (happy to put out 20a sustained in only 2p!) but I can already tell I'm going to like building a copperstrap/spring GaryPackâ„¢ better than soldering. I don't have a CBA anymore and am too lazy to match resistances anyway so I figure with single cells I'll be able to repair the pack on the trail on the fly if a cell duds on me. I'll just carry a dozen charged extras in my backpack at all times. These konion recovery cells are cheap and plentiful and so tolerant of abuse that soldering them to me is just too much extra effort unless you're going to the extremes that DocBass does - then it makes sense 'cause his pack is matched and will last forever. At this point I'd rather just recycle and replace the ones that die.

What's the deal with those Emolis? Those are good cells if they are relatively new!

 

[pwbset]

Oh.. and by the way.. investing in a $5 T10 security bit will make you the happiest person in the world. :wink:

 

[theyerb]

T10 security bit- so that's what I need?! I'll have to pick one of those up some time. I'm going to open up the rest of the packs tonight with a hack saw... carefully. Where do you get your cells, pwbset?

And the Emolis... I am not familiar with the type of battery (I'm building my second ebike at the moment. This time, I'm using Li-ion rather than SLA, so I'm slowly educating myself). I was going to discard the emolis to be honest, but if you say they're worth something, maybe I'll have to do some research on their possible use. I have about 5 of the Milwaukee packs with Emolis in them.

 

[pwbset]

There are ES members here that post sales of reject Makita packs from time to time... keep your eyes peeled in the Items For Sale forum. I got mine from 'marty' a couple months ago.

Emolis are what.. like 26700A or whatever that format is called. A safe-ish LiMnO2 chemistry like the green konions. Both charge to 4.2v/cell and the emolis are typically 2.6-2.9ah depending on how low you take the voltage... wouldn't go lower than 2.7-3v though. The emolis are fine in the 5-8C discharge range... 15-20A. A good strong, long lasting cell with a proven track record. The konions have a bit flatter discharge I think and definitely discharge more consistently.. the emolis would definitely need a BMS to balance the cells. Anyway... a lot of people have emoli based kits, but usually leave the cells in the Milwaukee cases to maintain the warranty and use the Milwaukee chargers. I wouldn't throw them away... there are always people here that could use them if you don't want them and they are in decent shape. Do you have a single cell Lipo/LiMn charger? I highly recommend a couple of those and if you have the money get a CBA battery analyzer so you know capacities and resistances. I'm jealous of people that can get reject packs 'cause you can make some extra cash and it's for a good cause. Not everyone can afford new batts... even Pings, but these reject packs are getting people on the road to ebiking affordably for sure!

Good luck and keep us posted!

 

[John in CR]

pwbset,

How are you going to identify a dead cell on the trail?

Now I'm feeling bad about not sharing more, because you guys are going to feel terrible about separating your cells all the way. Here's my version of a 24V15ah pack of Konion V's sitting on top of the Bosch36 sixpack I shared in December. It was made using 3ah Makitas from Doc. You'll notice that there are only 2 tab-on-tab solder connections on this side and 3 not as pretty connections on the bottom side, to connect these 70 cells together and form a pack. This method enabled me to connect 6 or 8 matched and balanced over the long term together at a time. Plus, the long tabs left by the removed cells gave me plenty of surface area to safely glob solder on at more than one point for each connection without heating up cells at all. The battery leads were a lot more work than connecting the cells.

See that black cell bottom left? He's a tough one that still works fine, but is a reminder to be very careful after using your multimeter to measure current. Don't leave your meter leads plugged in that way and try measuring voltage on your pack later. It's not just sparks, it's welding without eye protection.

Note that this pack has over 500 miles exactly as is (no cover or anything, just bungees holding it down and in place, obviously not the pack that went to the beach) with great balance maintained, but it's theoretically better to parallel at each cell level. That's why the pack is still open, to some day add that parallel structure along with taps to monitor and balance.

John

 

[pwbset]

How are you going to identify a dead cell on the trail?

Well.. I'll be the first to admit it may take a few minutes to identify a dud, but I'll be adding a multimeter to my tool/trail repair kit this summer for just that purpose. Your pack looks great, but I don't feel bad about breaking up into individual cells at all because there is so much variance in these reject cells that you "just never know". Plus I'm saving on "packaging" by removing the tabs and that hideous white plastic crap that I hate to deal with. I really, really don't want to have to solder on the trail.. did that last summer twice for some diode repairs and it's kind of a pain in the ass. I'm just going to take the time to build a decent compression pack of 1s10p subpacks out of single cells. Worst case scenario is that a dud takes out all 10 of a 10p and that's why I'll carry a dozen charged in the backpack ready to replace. I seriously doubt that will ever happen. I just don't have the time, equipment or desire to resistance/capacity match 140+ konions so I'm going the guerilla route and will just abuse them until they die and replace them on the fly. They are certainly cheap enough after all. 10p will ensure at least decent self-balancing of voltages and having personally charged these puppies to 4.35v+ by accident (oops) without ill effect and having revived 0v cells to 1ah+ I'm not too worried about it over all. I'll at least "match" to resting voltages the best I can.

Bottom line is that I can't stand soldering. :wink:

 

[John in CR]

Also note that if used cells in the original packs are in balance with each other when they arrive, then they are perfectly matched. Separating them only increases your work. I got lucky with this pack, but with all my many more to process, I will match pack capacities to combine into the series strings. That should give me good balance over a fairly long term, which I will monitor at least on a monthly basis at first. Conservative charging and discharging should also decrease the chance of problems.

BTW, my capacity matching of 200 good and balanced in the original pack "Marty cells" will be to first parallel all of the 4 cell packs (160 cells) after charging them to within a volt of each other. Then fully charge them in one shot together, so they have identical voltage at rest. Then I'll string them all together in series, along with 6 regular 110V light bulbs in series, and run them a little more than 50% of nominal capacity. I'll need to be extra careful with that 600+ voltage. Then I'll just sort them by resting voltage afterward, and those with matching voltages obviously have matching capacities, since they started at the same voltage, and the same current was run thru them for the same amount of time. The good Dr Bass signed off that it should work, and that's good enough for me.

If you come up with an easier and quicker way that doesn't require $1k of equipment, please let me know.

John

 

[John in CR]

Bottom line is that I can't stand soldering. :wink:

I don't like it either and I'm no good at it. Don't those springs you plan to use each need soldering? That sounds to me like 2 solder connections for every cell in a pack. I do like the ability to easily swap out cells though.

John

 

[Doctorbass]

Hey.. I saw extreme pack made of konion!! Bikeraider just beat my battery pack size!! it have 600 cells that i sold to him!! 3000Wh!!

Nice job he did too!

15s 40p!!

http://endless-sphere.com/forums/viewtopic.php?f=12&t=8622

Doc

 

[pwbset]

Don't those springs you plan to use each need soldering?

Not planning on soldering any springs.. a single screw per spring is what I'm thinking so far... ES member leamcorp is working on some 18650 cells holders that could prove really useful, but would bulk up the pack a lot. Trade offs.. ain't they a bitch. Nice work matching your cells there with the lights and what-not.. that's creative thinking!

The one thing that also led me to decide on single cells is that some of the packs I tore down would have a single cell where the two little tab welds blew apart and the top of the cell is black/scorched etc. It wasn't the same positioned cell either... randomly placed within the pack. The good news is that I'd get 9 good cells instead of 8 though! Ha!

From this I conclude that some of these konions are clearly potential duds (out of millions manufactured it's reasonable to conclude some will pass through QC and still suck) and if that happened mid-ride in the middle of a soldered/taped up/boxed up battery pack I'd be walking a 70lb ebike for miles out of the mountains and potentially up or down a thousand feet (preferably down!)... not something I'm willing to do. I broke enough crap on the trail last summer that I'm not willing to build a battery pack that can't be fixed in the field. Pesky me. :wink:

If I was in a city I wouldn't even think twice about this and the pack would already be done and I'd be riding again. Haha.

 

[John in CR]

pwbset,

The potential for new cells that are duds or weak cells definitely exists. In that way these used packs are more valuable to me, because if the cells are used and still well balanced, then I know they are good matched cells. Plus I know the connection to them is better than I can achieve myself. I especially like the 3ah packs, since they typically give me 6 or 8 matched cells already assembled and connected, with nice excess tab that make connections easy. I'm saving the oddball cells from packs with bad ones in the middle to use later.

I just feel like you've created yourself extra work, given up already good connections, and lost the good cell matching that existed straight out of the used packs. Since 2 of you posted having done the same thing, I thought I should share that there's an easier way.

John

 

[John in CR]

I think I found a flaw in my discharge test. I'm only going to run 50 cells in the series strings and use 2 lightbulbs as my resistors. I'll use the same 2 lightbulbs and connectors and wires for each discharge run for consistency. Even though I'm only going to run less than an amp, the high voltages of the very long strings I was planning, I believe posed a significant risk of something jumping a gap or not contained by cheap thin wire.

Back to processing packs and getting all of my cells up to the same voltage. I think this pic explains why I probably have no business messing even with 200VDC, much less 600V or more. This is 21 4packs getting parallel charged up to 16.4 volts. It's a case where it look much worse in person. I need to make another Radio Shack run, because I need a lot more wires, so I can double the number of packs that I'm parallel charging. Yes I really have bikes too. That's Big Blue's frame in drydock for some upgrades, after which she should jump right to 45mph carrying me, and pull me and 2 kids up the 25% grade hill leaving our house without pedaling.

John

 

[pwbset]

I just feel like you've created yourself extra work, given up already good connections, and lost the good cell matching that existed straight out of the used packs.

You may well be right. I never claimed to be the brightest bulb in the room. :lol: Having said I'm still totally okay with the extra work of dealing with individual cells. You just wait until I get all my parts together and build this pack... you'll see! :wink:

 

[theyerb]

I've removed the rest of the Konions and left the tabs on for the latter batch. You're right, now I am bummed I peeled the tabs off of the first 25! lol. I still have to remove some emolis from the Milwaukee packs- should have about 18 or so of them once that's done.

Here's the goods:

Not bad for FREE

I'm going to call up a recycling center tomorrow to see if they have any other tool batteries. In the meantime, I'm waiting for my Bosch 36v pack to arrive so I can start playing with it.

I plan on using these cells in a 10s4p configuration for my current eCruiser- should get me around the block a few times. They will be replacing 40 lbs of SLA. Here's the current setup:

Cheers!

 

[John in CR]

Anyone processing the Makita 1.5ah packs, the thin 1p packs, don't throw away the black rubber mats contained in the bottom. If you don't want them, I'll take all that you have. They are absolutely ideal for Konion pack building to allow spacing for ventilation and to support and hold cells securely in place. You do need the proper tool for cutting them. I use tin snips, which I find to be an invaluable tool for processing these packs. I'll try to post some picks later, once I assemble some 17s 60V strings.

John

 

[John in CR]

Call me lazy, but I like figuring out the easiest way possible to do things. Here's a 10p17s "Martypack" of matched VT cells. Notice it just takes 3 tab-to-tab solder connections to make a 60V battery. I hate soldering because it requires 3 arms (recruit a helper to press tabs together with a pointed metal object, while you solder, and then it becomes quite easy). 3 legs I got, just not 3 arms.

John

Here's what I do with those rubber mats. A bit of RTV silicone on the flat side to secure them to previous level, then they become a perfect holder for the next. I cut them in strips not only to make them go further and have some for my 3ah packs, but there's plenty of air space left. That way I cant put rigid sides (I'm going to epoxy 3mm plywood directly to it for a permanent pack, once I verify all my connections are good. That's the kind of thing I think I can get away with on the bargain used cell packs that I plan to run at very low C rates due to the large formats), and still get cooling airflow right through the pack from one end to another. sorry about the poor picture quality, but I think you get the point. The pack will end up 2.75" x 12.25" x 8.5" plus 3mm for each side panel and a bit on the ends or bottom depending how I decide to run the wires and the ventilation duct entrance and exit. Not bad for 63V nominal 15ah pack. I may decide to forget the plywood and ventilation in favor of 2 layers of duct tape on the sides + 1 layer of fiberglass cloth saturated with epoxy + a thin sheet of aluminum. It would give me a way to take it apart later, but I worry about the rigidity of the pack to vibrations long term. I guess I could go permanent and forget the duct tape, and let one layer of fiberglass/epoxy cure before going a second layer of fiberglass with the aluminum sheet.

 

[theyerb]

That 10p17s pack looks nice I don't know where else to get more free Makita batteries. Does anybody have any ideas... nay, *secrets on where to score them? Come on Doctorbass, I won't tell anyone. hehe. I think I've expended the local tool service center supplies.

On a different note, I received a Bosch 36v bat836 this evening- took it apart to take a look at the inner workings. A beautifully designed pack, and "Made in Poland"! It's packed with 20 Konions. You can buy the Bosch bat836 for $46 shipped on ebay- not bad.

Here's the plan for the Bosch packs- maybe I can get some input by the experts. I'm going to purchase 3 more for a total of 4packs. I'm going to make some docking connectors and run the packs in a 2p2s configuration. Is it safe and ok for the batteries in the 2p2s config?- I will check the balancing on the individual packs every once and a while, but there will be no BMS.

Also, is it ok to wire the packs together so that a switch changes the configuration from 72v to 36v for charging, so I could charge all 4 packs in parallel with my 36v SLA charger?

Here's the Bosch pack:

 

[PWJM]

Bump!

Amazon.com is selling these units at 54 bucks a peice!

Here's the plan for the Bosch packs- maybe I can get some input by the experts. I'm going to purchase 3 more for a total of 4packs. I'm going to make some docking connectors and run the packs in a 2p2s configuration. Is it safe and ok for the batteries in the 2p2s config?- I will check the balancing on the individual packs every once and a while, but there will be no BMS.

Also, is it ok to wire the packs together so that a switch changes the configuration from 72v to 36v for charging, so I could charge all 4 packs in parallel with my 36v SLA charger?

 

[TPA]

Nice work on all the batteries, but where's the Booty?

 

[theyerb]

Well, I was going to post a pic of a beautiful young ladies booty in some tight panties... but I'm sorta new to ES and don't know if the moderators would kick me out for it. :? Would they?

I went back to my county's power tool service center and found another box of defective batteries waiting for me. The owners seem to appreciate me taking the batteries off their hands and are pleasant to chat with. This time, I got even more lucky in free batteries! They gave me four Milwaukee V28s, two V18s, and six Makita Li-ion packs- that's about 30 Emoli cells and 35 Konions! Not bad... I am catching up to you, DrBass. lol.

With all these Emoli's, I think I'm going to make an Emoli 13s4p pack soon. That would just about max out the AmpedBikes/9 Continents controller and motor to 52 volts and 12ah (I hear they can go up to 60 volts. We will see...)- that should smoke my current SLA setup.

I would recommend ebikers check where their nearest tool battery service center is and give them a call up.

 

[Doctorbass]

I went back to my county's power tool service center and found another box of defective batteries waiting for me. The owners seem to appreciate me taking the batteries off their hands and are pleasant to chat with. This time, I got even more lucky in free batteries! They gave me four Milwaukee V28s, two V18s, and six Makita Li-ion packs- that's about 30 Emoli cells and 35 Konions! Not bad... I am catching up to you, DrBass. lol.

With all these Emoli's, I think I'm going to make an Emoli 13s4p pack soon. That would just about max out the AmpedBikes/9 Continents controller and motor to 52 volts and 12ah (I hear they can go up to 60 volts. We will see...)- that should smoke my current SLA setup.

I would recommend ebikers check where their nearest tool battery service center is and give them a call up.

Great! 8) That is the greenest way to power your ebike :wink: ..

i've always though that this is rediculous to put battery to the recycling eventhough they still have 80-90% good cells!!

We just help to avoid that to occur and save these great battery for our green use!

But please when you test them, at least, return the bad one to the recycling service!

Good luck!

 

[pwbset]

They gave me four Milwaukee V28s, two V18s, and six Makita Li-ion packs

You really need to get a West Mountain CBA II battery analyzer so you can tell which cells are worth using. They are expensive, but worth it (if it doesn't break on you like mine did). For example the V28 rejects I got couldn't hold a 3-4C discharge and had less than 1ah of capacity. The Milwaukee stuff doesn't have the thermal defect the Makitas have so typically the reject emolis you get typically are junked. Maybe you're more lucky. The Makitas are so awesome because they screwed up the way they are built so they tend to blow early leaving 8+ good cells.

Remember that you can sell your excess batteries here!!