Look what I found in the recycle bin

Very interesting discussion.
It really is a shame that there is usually no datasheet available for 18650 cells. It would be so nice to be able to find some good data, maximum ratings and a quick description of each cell… That would eliminate the need for us to speculate like that.
Anyway, if someone is interesting and wants me to test something specific on these cells I’ll be happy to do it! (But I opened the pack and separated the cells as 2 were shorted)

It’s hard to turn down free but aren’t 1300mah and 1600mah batteries a bit small? That’s before throwing in the unknown condition of these very old things. Would they only be suitable for running things in low mode?

Hi battery.

I don't know anything about these particular cells, but most high current cells have lower capacity. They tend to be hardier and can handle more charge/discharge cycles though. Some users may have special applications that the compromise is necessary trade off.

Separately,

This whole self-balancing thing is way over my head. I didn't know it existed and am still skeptical in the case of these particular cells.

Hmm, have you considered the NiMH example I gave earler? Or maybe I didn’t. In that case: Think about NiMH series packs. They don’t get balanced, ever. That’s actually the whole story. Those cells store lots of energy, just like Li- chemistries, but they didn’t need to be balanced. Why not?

NiMH cells (as well as NiCd and Pb batteries) transform the excess energy into heat once full. That’s why they can balance on their own.
Lithium cells on the other hand, act almost like a capacitor. The voltage increases as long as you charge it. Of course, it’ll destroy itself at some point. The termination voltage (4.2V for most batteries today) is just a trade-off between capacity and security/longevity.
That’s why lithium cells (and capacitors) need to be balanced charged, to avoid any deviation that would cause one cell to be charged/discharged higher than the others.
No with the sony US18650V/VT, I noticed a very strange phenomenon, the battery “self discharges” down to about 4.1V. That also causes a battery of cells to balance by itself.
Example: 2S pack: Cell1: 3.95V Cell2: 4.05V
When charged to 8.4V: Cell1: 4.15V Cell2: 4.25V
After some time, both cells will self discharge to 4.1V. So they are balanced again.
I’m pretty confident with my observations, but it would be great if someone else could test this characteristic.

I guess you already know all that, but I just wanted to give all the facts so that we are all talking about the same thing. :slight_smile:

These are new cells and are IMR’s which are a different chemistry that ICR, which are the ones most commonly found in laptops.
IMR’s generally are of lower capacity (mAh) than ICR’s but are more suitable to rough treatment and can deliver higher current levels.
As in most things, there are trade offs. For very high powered flashlights, one may prefer to use IMR’s. There have recently been improvements in the capacity of IMR’s and 2000 and even 2500 mAh versions showing up.

I know that but 1300mah 18650s must be pretty old. The Sony VTC3’s are 1600 and those have been around for a while.

I would have figured for high power higher capacity would be more useful because the voltage drops pretty quickly within the first few minutes of high power discharge even on IMR.

They could be old, or they could be even higher drain. Frequently it’s a trade off between size, capacity, and drain rate. Since we’re stuck with a specific size we are left balancing capacity and drain rate. To get even more drain rate than the “usual” numbers, more capacity can be sacrificed. That’s what I would assume is going on here, but you could be right - it could just be a cash grab go get rid of some NOS cells, or maybe process advances have made the 1300’s really inexpensive to manufacture.

@ lagman - that all sounds fine, but what happens when one cell is somewhat more out of balance than in your example? I agree 100% that Ni- stuff burns off excess charge as heat. I do not remember for certain whether A123’s LiFe cells burn off excess charge that way, or simply take a high charge voltage and then settle in the way you describe with the Sony cells.

I think the 13Q’s are just a cheaper low end cell. I see them a lot in Ryobi packs, as Ryobi is a discount line of tools sold by HD. The upgraded drill packs have some of the Samsung 15M’s (1500 mAh) cells.
A couple of months ago, HD had a special buy on 18V, 4Ah drill packs that had 20R’s in them. They were a good deal, a set of 2 - 10 cell packs were $99. That works out to $5 per cell. Almost made sense to buy the packs to harvest the cells.
I bought a pack and sold one and gave the other to a friend. Everybody’s happy.

I’ve only ever been questioned once and I explained that the likely destination for the vast majority of the cells inside the packs I was taking was in a hazardous waste dump but that I would take them home for private use, disassemble them myself (not some chineese kid for $.02 a day) and the cells would be used on my personal equipment and the plastic trash recycled. They were more than happy with that answer and I’ve never so much as been approached again.

Here is a pic of the older Makita Li-Ion pack, the one I believe you have. There is no BMS and no leads to each cell. This is a 10 cell, 3Ah pac that was not used very much when apparently a pair of cells failed.


The 8 cells that were still good are in excellent condition and each test at over 1500 mAh each.
This next pack is also a Makita, but one of the newer improved packs. It also is a 3 Ah pack. Notice this pack has a BMS circuit and leads going to each individual cell. These newer packs can be identified by the star.


Now the 2 different packs side by side. The newer pack is on the right.

Tool batteries seem to work just fine in my lights at the beginning of the use cycle. In other words, 1250, 1400, 1500, etc samsungs/sonys are the exact same brightness with most of my one-emitter lights that are not high demand or direct drive —— compared to testing the same light with a 2400-2* cell. Even tested a bunch with my light meter. The tool batts don’t just last as long at full brightness, which is just fine for me for around-the-house lights. And they seem to charge faster.

I find so many of the Ryobi, makita and other tool packs that I sure wish they used 2800 samsungs or 2900 panasonics!! I did see some new packs that said they contained 2400 and 2600 mah batts. They are just too new to make it to the recycle bins yet, so I don’t know what’s in there. When I do find one, BLF will be the first to know what they contain!!!

Tool pack cells are IMR type and generally have lower capacity, but can deliver more amps. For very high powered lights with multiple emitters in parallel, they may be preferred.

I somehow missed your post…
Thanks for the pictures! The first pack looks exactly like mine… no balance leads.

That second Makita pack, with the star, has the same cells and the balance circuits. 2 weeks ago I charged and discharged each pair of cells individually with my B3100 and some alligator clips. Each pair of cells measured in the 2900’s mAh. Almost as good as new! When I was finished with my tests, I fully charged them each to 4.20V. Now 2 weeks later they are each sitting at 4.15V. I don’t know why that pack was discarded, the cells are healthy, maybe the BMS circuit is faulty and it will not charge on a Makita charger. Maybe the pack is bricked.
I am not yet ready to believe that the Sony’s self balance. On the other hand, how does that Ridgid and older Makita pack get away with not having one?

I guess the self-balancing is fine when new - it’s when the resistance levels of the cells vary that it would possibly become a problem -> try not to bang my batteries around.

I had an old 5 cell Makita pack go bad with less than 10 charges (one cell reportedly will self drain and then the pack will not recharge you don’t regularly recharge them). Perhaps the balance updates help avoid the non-recharge problem? Anyway, took it by one of their factory shops where they can read recharge info on their packs - they did a free exchange with a 10 cell - happily I now know it has the star and new wiring - thanks for that info! Will be interesting to compare old and new 10 cell packs as they age.

I just read through this thread and wanted to say that I have some Sony US18650GR 18650 laptop pulls (N.O.S. HP 9 cell Pack) that seem to discharge down to about 4.1V after I charge them up to 4.2V. I just noticed this behavior a week ago. I wonder how much capacity I'm losing with them self-discharging down to 4.1V. I did a capacity test (from 4.2V) on my new OPUS and got about 2600mAH on two of them. Interesting that others are seeing the same behavior on similar Sony's.

-Garry

I’d definitely like to hear the results of your capacity test from a rested 4.1v.

Nice of you to join the thread Garry.
I must point out though that the Sony’s we’re talking about are drill pack IMR’s

wight you asked me earlier how I handled rummaging through the recycle bins and I gave you my answer. However, a couple of days ago I got caught off guard. While I was poking around in one at HD, I heard one of the girls behind the returns desk ask me what I was doing.
I looked up and dead panned “I’m looking for an old sandwich or something, I haven’t eaten in a couple of days!” She looked at me and laughed and said “Oh there was a half in there earlier, but I already ate it” We both laughed and I went back to my business. :bigsmile:
I pulled out these 2 brand new Ryobi packs, thrown in the bin by HD. I haven’t taken the 10 cell pack apart yet, but it reads 17.65V or an average of 3.53V per cell. The 5 cell pack had 1 dead cell, the other 4 at 3.61V. I don’t know if it was just a bad cell, or that channel on the BMS leaks. I see either all the time.

2 days ago at Lowes I found an unopened 8 pack of Duracell AAA’s. The date on the pack was 2012 and they are 7 year cells. The only thing I can think of is that someone thought that date was an expiration date, like on food. Got them just in time, yesterday 2 of my remotes needed new cells’ :slight_smile:
That is Lowes parking stripe in the background, shot this outside in the lot.

Wish I knew of places in ga I could go thru these bins