Search found 372 matches

by Pajda
Nov 13 2020 2:27pm
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 483
Views: 54220

Re: Li-ion cells cycle ageing

If this is to be trusted can be had by around $150 https://www.aliexpress.com/item/4000465060713.html?spm=a2g0o.productlist.0.0.39a1c515QIsXAf&algo_pvid=53a00069-433e-44bb-8cf2-a17666e54be9&algo_expid=53a00069-433e-44bb-8cf2-a17666e54be9-1&btsid=0bb47a1a16052917948615783ef6be&ws_ab_...
by Pajda
Nov 13 2020 12:52pm
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 483
Views: 54220

Re: Li-ion cells cycle ageing

Padja, do you recommend a tester that can do more than 5 A charging and doesn't break the bank? I want to play with fast charging profiles and thermal control in the future Good question, yes there is a solution from ZKE model EBC-A40L with internal 35A charge and 40A discharge current, but it is w...
by Pajda
Nov 10 2020 10:54am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 483
Views: 54220

Re: Li-ion cells cycle ageing

multifrag wrote:
Nov 10 2020 10:13am
The next cell I want to test is K-Tech INR18650P. As it's extremely cheap and would suit my UPS battery rebuild very well.
Teaser warning: I believe that you will be pleased with its performance (25HCCG model), particularly in cycle life. :wink:
by Pajda
Nov 10 2020 9:54am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 483
Views: 54220

Re: Li-ion cells cycle ageing

I've adjusted the post. Sorry for bothering you, but the cut-off current is in mA, not mAh. :wink: But more importantly I would like to present your work as excellent example of how easily with more than satisfactorily accuracy you can verify your favourite cell parameters. I think that 120-150 USD...
by Pajda
Nov 09 2020 12:28pm
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 483
Views: 54220

Re: Li-ion cells cycle ageing

Great work Multifrag :thumb: I can confirm that your test results are valid. Your setup, methodology and test equipment are correct. Do I understand well to the yellow course "100% Dis. Datasheet" that it is a simple linear extrapolation of datasheet value, where the cycle life should be >...
by Pajda
Nov 08 2020 10:59am
Forum: Battery Technology
Topic: How IR is affected when doing the not topping thing for prolonging life?
Replies: 5
Views: 252

Re: How IR is affected when doing the not topping thing for prolonging life?

So the question is, how does this rule apply to IR? Good question, it should be noted that the declared cycle life is only one part of the cell quality warranty. The second should be DCIR rise. So common warranty wear level of 70% should be connected with DCIR rise of 100% (twice the initial value)...
by Pajda
Nov 08 2020 7:59am
Forum: Battery Technology
Topic: How IR is affected when doing the not topping thing for prolonging life?
Replies: 5
Views: 252

Re: How IR is affected when doing the not topping thing for prolonging life?

I read alot about the thing that for every 0.1V (per cell) that you shave off your top charge voltage you double the cycle life of your pack. This statement is now generaly outdated and so useless for evaluation of modern cells released after ca 2015. It is because a huge progress in development of...
by Pajda
Oct 31 2020 10:42am
Forum: Battery Technology
Topic: EBC-A20 Cell Cycler Question
Replies: 6
Views: 183

Re: EBC-A20 Cell Cycler Question

You need a computer. The cycler itself store only one step final parameters: total capacity and energy.
by Pajda
Oct 31 2020 8:43am
Forum: Battery Technology
Topic: EBC-A20 Cell Cycler Question
Replies: 6
Views: 183

Re: EBC-A20 Cell Cycler Question

Just got my ZKE Tech EBC-A20 for doing cycle tests on single cells. Question is, if I run it without being connected to the a computer using the software, just the device itself, does it log the data on the unit for me to download via the usb cable later or do I have to leave it for days connected ...
by Pajda
Oct 26 2020 2:06am
Forum: Battery Technology
Topic: Recommended Cell Supplier from China?
Replies: 11
Views: 462

Re: Recommended Cell Supplier from China?

Thanks for informations. This manner definitelly does not look good. :?
by Pajda
Oct 24 2020 10:41am
Forum: Battery Technology
Topic: Recommended Cell Supplier from China?
Replies: 11
Views: 462

Re: Recommended Cell Supplier from China?

Even when I ran into heavily dented cells (of course didn't use them), the IR was within spec and consistent. Good for you I just googled Queen Battery and it seems that they are not a supplier on Alibaba but in AliExpress which is where the all the junk grades and old stocks are dumbed in so I wou...
by Pajda
Oct 24 2020 8:53am
Forum: Battery Technology
Topic: Recommended Cell Supplier from China?
Replies: 11
Views: 462

Re: Recommended Cell Supplier from China?

Try QueenBattery or Vapcell.

And small remark to battery quality grades. You are right that it is important to get cells clean without scratches or dents. But crucial is also the consistency of cell internal parameters, particularly (DC)IR and capacity. This is unfortunately much harder to evaluate.
by Pajda
Oct 22 2020 12:32pm
Forum: Battery Technology
Topic: good 30Q/141 cycle test
Replies: 12
Views: 743

Re: good 30Q/141 cycle test

newbs like you :lol: i hear what youre saying, im not a computer guy or a battery guy its a learning curve and i get distracted with bunk cells or self healing batteries so it is all over the place and then i only have 1 tester. i could put my results in one thread when im done like docs. how does ...
by Pajda
Oct 20 2020 3:02pm
Forum: Battery Technology
Topic: good 30Q/141 cycle test
Replies: 12
Views: 743

Re: good 30Q/141 cycle test

Have you ever thought that the results which you achieved could be presented, how to say, less chaotically?

For newbies like me, will be fine to present your tests results also in simple "capacity fade" graphs
by Pajda
Sep 28 2020 4:47am
Forum: Battery Technology
Topic: Question about "Maximum Momentary Pulse" for an 18650 cell
Replies: 27
Views: 608

Re: Question about "Maximum Momentary Pulse" for an 18650 cell

It is always a good approach to do a simple math with DCIR. From the presentation sheet it should be about 20mR for Samsung 25R. This DCIR value gives an instantaneous voltage drop of 2.2V at 100A load. If you use simple BMS with instantaneous 3V cut-off voltage, you can get only up to 60A from full...
by Pajda
Sep 28 2020 3:29am
Forum: Battery Technology
Topic: MJ1 vs 30Q for my needs?
Replies: 18
Views: 764

Re: MJ1 vs 30Q for my needs?

Samsung 30Q feature is that it wears fast with the very little impact of discharge(charge) rate or DoD. If I should be more specific the wear level when cycled at 1C or 3C at 100% DoD is practically the same. So with this behaviour it is suited for powertools but definitelly not the traction app (ma...
by Pajda
Sep 27 2020 12:07pm
Forum: Battery Technology
Topic: Tesla battery day announcement
Replies: 48
Views: 1522

Re: Tesla battery day announcement

Perhaps Tesla will actively cool only the tops and bottoms of these 4680 cells? Actually I am very interested in presented Tesla CTV (cell to vehicle) design. They showed us that they would like to remove side cooling (cell cans will be glued together and acts as a supporting structure). But this a...
by Pajda
Sep 27 2020 4:22am
Forum: Battery Technology
Topic: MJ1 vs 30Q for my needs?
Replies: 18
Views: 764

Re: MJ1 vs 30Q for my needs?

anyone have a cycle test of the mj1 at 7 or 10 amp discharge? Of course we have :wink: Those cells have quite different parameters and so their operational life depends on their usecase. Unfortunatelly Rizeblader (and many others) give us not enough informations. From the information about using 45...
by Pajda
Sep 27 2020 3:58am
Forum: Battery Technology
Topic: Tesla battery day announcement
Replies: 48
Views: 1522

Re: Tesla battery day announcement

I would be more impressed if they were making at least a little improvement in cell energy density ! This is very good point. actuaIly if we look at the presented gain values for the new 4680 cell we can easily translate that "5x more energy" actually mean lower energy density than its pr...
by Pajda
Aug 30 2020 1:44pm
Forum: Battery Technology
Topic: Continuous Charge Amp vs Continuous Discharge Amp
Replies: 60
Views: 1646

Re: Continuous Charge Amp vs Continuous Discharge Amp

eMark it is good to realize that the information given in the datasheet may not be directly related to the theoretical laws of operation of the cells. So as was previously mentioned, it is very likely that the value of 0.2C for standard discharge was historically "shot from the side". The ...
by Pajda
Aug 29 2020 2:01pm
Forum: Battery Technology
Topic: Continuous Charge Amp vs Continuous Discharge Amp
Replies: 60
Views: 1646

Re: Continuous Charge Amp vs Continuous Discharge Amp

eMark I hope you finally find the dependency or law what you looking for. I gave up this search a long time ago simply because I cannot find any generel rule. Maybe you noticed common policy that in "product specifications" from all manufacturers there are very few information. I think tha...
by Pajda
Aug 09 2020 9:32am
Forum: Battery Technology
Topic: What's the longest period of time you can store a Li-Ion pack?
Replies: 31
Views: 784

Re: What's the longest period of time you can store a Li-Ion pack?

Matador thanks for your comment. I'm trying to warn against generalizations of evaluation of the cells by some significant parameters like chemistry, and right now I am doing the same thing. :D Both me and docware measured excellent cycle life results of LG Chem HG2 which is definitely a contender o...
by Pajda
Aug 09 2020 8:43am
Forum: Battery Technology
Topic: What's the longest period of time you can store a Li-Ion pack?
Replies: 31
Views: 784

Re: What's the longest period of time you can store a Li-Ion pack?

I agree with Matador, a poor BMS design he describes causes a lot of issues and I guess that this is also that case. Just remark to the cell ageing itself: The recent tests (for example docware`s work here at ES) proven that modern HE (high energy density) cells, shows significantly better cycle lif...
by Pajda
Aug 08 2020 4:14am
Forum: Battery Technology
Topic: What's the longest period of time you can store a Li-Ion pack?
Replies: 31
Views: 784

Re: What's the longest period of time you can store a Li-Ion pack?

Do you know what particular cell was used in this pack?
by Pajda
Aug 08 2020 4:08am
Forum: Battery Technology
Topic: ZKE-TECH Cell Cycler Question
Replies: 4
Views: 137

Re: ZKE-TECH Cell Cycler Question

the ebd-a20h i believe doesnt charge. Yes, some of ZKEtech testers does not include "internal variable charger" but they support external charger input. The intended appliation is for example e-bike battery pack testing, so you connect the battery pack to the EBC-B20H together with your s...