Some New Preliminary testing of 21700 Tool battery cells to 2.00

[sam_sam_sam]

I decided to try a new approach to testing unbalanced battery cells with my battery testing machine that has more graph curve information and it looks like if you discharge them to 2.00 volts if the battery voltage does not come back to over 3.something volts you have some kind of issue with that battery cell

I going to do more testing and see if is the case or not

More to come later

[sam_sam_sam]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

I am testing the second battery pack the same way it does take a while for the battery cells on the battery cells rail on the one you load tested several hours to stop with gradual voltage increasing to see where it finally stops at to get an idea if those cells are going to be any good

[sam_sam_sam]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

Here are the results from one battery cell that was at 4.00 as you can see in the graph it takes about 10 hours to climb above 3.00 after being load tested to 2.00 volts @ one amp load

Here was the result from the second battery that was at 3.15 the same test was run I going to compare them as far as how long it takes to climb above 3.00 volts

One thing you will notice is that the battery cell that started at 3.00 volts has a much steeper roll off rate than the one that started at 4.00 if the battery cell that starts 3,00 volts if it were as good as the 4.00 battery cell it just would be tighter together time wise but would still have basically the same voltage roll of rate

But what is interesting is that voltage recovery curve is basically the same rate of recovery rate at the beginning but I wonder if the voltage recovery will continue to be the same as far as the amount of time that it takes to recover to above 3.00 if it does recover to that point

I checked the voltage on the first battery pack that I tested and the voltage range is 3.1something to 3.2something but did not leave them on the battery testing machine until the battery voltage went above 3.00 volts so do not have those results to share unless I rerun the test again

But I think the issue with these two battery packs is that the battery cells that are low in voltage is because they are self discharging over a period of time ( which takes around about a month or so ) and or battery cycles which in either case they are not suitable for tool use anymore unless the battery cells that have been discharging by themselves are removed and replaced with battery cells that are not self discharging this is what my next step is going to be and see if these battery cells are still usable with the same discharging rate

I will post more information about this issue when I have more data from more battery testing

Stay tuned for updates as they come available

[CapLeaker]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

I’ll be keeping an eye on this thread and see how this progresses.

[sam_sam_sam]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

Here are the final results of the second battery cell rail failed for two reasons see the picture below

I will be testing the next battery cell rail sometime today

[sam_sam_sam]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

I have a new shed and I going to have a battery testing station that will be able to test BMS protection board for functionality and weather or not it is functioning properly or not I have a couple of battery testing machines that have issues that are NOT easily fixed so I have modified them so that they can be used as amperage testing machine instead of what it was designed to do I more work to do to make the testing jig for my setup more to come when I finish putting up the drywall and putting in the electrical wiring and workstations tables stay tuned more to come later

[sam_sam_sam]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

Update on the shed I have 75% of the drywall up now I still have the drywall the ceiling and running the electrical wiring and lighting and the work tables that go around the hole shed on the walls except for the wall that has the doors and the windows still have to put a room air conditioner in there as well

When I get it completely done I will post some pictures of the inside of the shed

[CapLeaker]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

I’ve looked at your results and they kind of look similar like other battery chemistry when they get high internal resistance. Drop fast and don’t recover properly and also get hotter compared to good cells. Interesting to see it on a graph like that. I use a graphing DMM to get results like this.
Do these Milwaukee cells have battery protection built in like some other 18650 or 21700’s?
Good luck with the new shed! I am building a new shop in the basement. Got most of it done, but I am still lacking on shelves and drawers and I don’t think I am getting them before fall. Too many other outdoor projects and too much work at my work place.

[sam_sam_sam]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

When I get all of the testing done with the way I am testing them I plan on testing the battery cells that have issues I will put them on the other battery testing machine that has the temperature sensor build on it and see if they are the ones that I seen running warmer than other battery cells the two might go hand in hand with why I see on some battery cells

The type of battery cells that are used in power tools do not have individual BMS protection boards on them these are known as unprotected battery cells ( some 18650 batteries do have BMS protection board on each cell but these cells are a few mm longer than battery cells that are unprotected ) one note I personally have not found 21700 with BMS protection boards not meaning that they do not exist I just have not run across them yet

Actually I have come them I got some when Radio Shack was carrying them for some kind product that is out there that used this type of battery cell I should round them up and put them on some better brand battery cells because the ones that they are on the batttery cell are not very good quality

[sam_sam_sam]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

Here is the story about how I came across this type of battery testing machine that I have been using for several years now

I was buying some pouch battery packs from a EBay seller for a device that I wanted to improve its running time and some of the battery packs cell did not test properly so I decided to return them but before that I had took pictures of the results from the SkyRc battery tester that I first bought for battery testing but it graph results are very primitive in nature and the seller said that they would have to run the tests on there battery testing machine

So of course I had to ask what brand of testing machine are you using and they gave me the product information so I ordered one and installed the software and started running different types of testing on battery cells and getting use to the way this testing machine behaviors are and what to expect and how to interpret the results from brand new good quality battery cells

Some of the battery cells that I had gotten from that ebay seller were replaced but once I got my own battery testing machine like they have I just had to send them the results and they refunded some of money back for the low preforming battery cells ( these were used battery cells that were in a product that was discontinued for battery life issues )

The Battery Hookup where I get most of my battery cells from they uses the same battery testing machines that I have so I have to do is send them an email with the results of the battery under test

I take a picture in such a way that I show the battery pack or battery cell that I am testing and show the battery testing screen and the second picture shows the graph results and no other information is needed except if I have more than one of the same item then they want to know how many of them that I have issues with

This is the reason why I from time to time mention some of items that they offer that I have tested and are happy with the results that I got from my own testing

[CapLeaker]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

I’ve got one 21700 with a built in BMS that came with a crazy @$$ flashlight that I use for work. Actually you plug in any USB-C cable to it and it will charge. No specific charger needed. I’ve just got an older OPUS Li-Ion charger and I’ll do my 18650’s with it, but these 21700’s I’ve got do not fit in there, because they are extra long. Many times I though I’ll buy the SkyRC charger, but then on a second thought, only for 2 batteries? Umm, no!
Yesterday I went to the store and got me a Milwaukee framing nailer. It came with a 5Ah battery and a 4Ah charger. I’ve tried it out on a small job yesterday afternoon and was pleasantly surprised. That think got some power, repeatedly too driving 3 1/2 inch spikes like no problem. Usually I’d be sitting afterwards with a hammer in the hand and pound the nails down that didn’t get enough oomph. Hopefully that will speed up my work list considerably. I am getting towards the end of my tool purchase list now.

[sam_sam_sam]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

This might work for 21700 button type battery cells you have to measure the length of the battery cell and look at the drawing for the battery holder

https://www.digikey.com/en/products/.../1042P/4286267

With this item

https://www.ebay.com/itm/25598432129...Bk9SR5KRi-b-YQ

Which then you could use the ( SkyRc MC3000 battery testing or your OPUS Li-Ion charger ) machine on them and other battery size

I have some of these dummy 18650 testing pins for just that purpose to be able to use the SkyRc MC3000 battery testing machine when I do not need more accurate test results ( one note I have not personally used them yet because I have done anything with my pouch battery cells yet but this is because I have not found the right enclosure for them yet )

[sam_sam_sam]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

Well the testing on the 21700 battery was sidelined because of the battery pack that I ordered for the battery operated air compressor came in and I wanted to get the battery testing done on this battery pack soon because if there is any issues with it I want to send them an email about the results soon so I will will not have lost the warranty on them because I think it 30 days if I remember correctly

[sam_sam_sam]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

But hopefully I can get back to doing some more testing on the rest of the battery cells that are still have not been tested yet

[sam_sam_sam]

Re: Some New Preliminary testing of 21700 Tool battery cells to 2.00

Well I sold 10 of the 21700 battery cells that I bought from Battery Hookup from a very large robotics battery pack that I removed all of the tabbing from all battery cells ( have a listing on EBAY for them )

One note the robotic battery packs are still available at Battery Hookup new or slightly used and they test like they are slightly used

The buyer is making a scooter battery pack that is going to be 72 volt battery pack out of the same robotic battery pack that is 36 volt about 54 amp hour the buyer is going to cut the traces so instead of 10S 11P
is going to be 20S 6P that is why the buyer needed 10 more batteries from me because he saw that are the same battery cells that I have for sale so the battery pack would be about 27 amp hours instead of 54 amp hour in it’s original configuration ( I tested 16 of them and put 10 of them together that have very close amps hours results not more than 0.100 amp hour difference and the charging/discharging curves are very similar in results )

This is the same battery pack that I mentioned in another post where I made it two separate packs 5S 11P configuration for my battery operated air compressor

[sam_sam_sam]

Battery Hookup has a new 21700 @ 3 amp hour @ 35 maximum continues load these battery cells are made for high current demand power tools these are brand new battery cells never have been used the sitting voltage is 3.5something volts they are individually in boxes in a case of 20 they are $2.00 each

I have put a battery on the battery testing machine to see how close are they to the specs according to the data sheet specifications

https://batteryhookup.com/products/n...-power-battery

[sam_sam_sam]

Battery Hookup has a new 21700 @ 3 amp hour @ 35 maximum continues load these battery cells are made for high current demand power tools these are brand new battery cells never have been used the sitting voltage is 3.5something volts they are individually in boxes in a case of 20 they are $2.00 each

I have put a battery on the battery testing machine to see how close are they to the specs according to the data sheet specifications

https://batteryhookup.com/products/n...-power-battery

I tested eight of them already and they tested at a range from 2.90 to 3.03 so they are testing at what the data sheet shows so I bought 4 boxes of 20 but I going to test all of them before I put them in battery packs that I plan to put new batteries in them for best results

[sam_sam_sam]

I have to replace some batteries in my Milwaukee 18 volt battery pack collection because they are failing to charge properly and I want keep using them and re-use the ones that have not gone completely bad yet

I have some Ryobi 18 single row battery packs that have charging issues as well and new barely used or new battery cells are called for to bring them back to life again

I have stopped buying replacement battery packs for the ones that are failing because the cost of high current battery packs have really gone up in price and they do not have the special buys like they used to so I going to rebuild them instead of buying new ones unless the BMS protection boards go bed

Plus the job that I have now they provide battery operated tool and battery packs so I do not use them as anymore like I used to

[sam_sam_sam]

Well I have two Milwaukee m18 @ 8 hour battery packs that are suffering from self discharging battery cells and I getting ready to put some 3 amp hour cells that are rated for 35 load continuously that I bought new from Battery Hookup which they still have the last time I looked at there website

https://batteryhookup.com/products/n...-power-battery

I have new battery pack enclosures but everyone of the BMS protection boards did not work and I bought several different ones from different eBay sellers and I had to get a partial refund from the sellers these were repairing kits that would have the enclosure , tabbing , screws for the enclosures , BMS protection boards

So as long as you have a way to weld the tabbing to the battery cells you are in business and replace battery in the battery pack

[sam_sam_sam]

I checked the two Milwaukee m18 / 8 amp hour battery packs and both of them are suffering from self discharge but I do not 4 amp hour high current battery cells to replace them right now but I have some 4 amp hour battery packs that need replacing I have 18650 battery cells to repair some of them but the 21700 battery cells I only have 3 amp hour cell that I interchange them in the 4 amp hour battery packs that have 21700 battery cells in them

In the 8 amps hour battery packs there is enough battery cells to make one 8 amp hour pack because they have a battery voltage of about 4.00 volts and some of them around 3.8 volts and this enough to cause the battery charger to refuse to charge them up fully