Search found 52 matches

by docware
Mar 16 2019 9:01am
Forum: Battery Technology
Topic: DIY HI POWERED PACK: First time, General questions
Replies: 43
Views: 776

Re: DIY HI POWERED PACK: First time, General questions

Yes, you are missing the fact that your expectation regarding both 18650 and 21700 is unrealistic. care to explain? I am afraid that your project is unrealistic. Warming of LG HG2 and Samsung 30Q in the closed battery pack even at 5A discharge is too high. Samsung warming 30Q 2A v 5A.jpg At 5A disc...
by docware
Mar 15 2019 2:25pm
Forum: Battery Technology
Topic: DIY HI POWERED PACK: First time, General questions
Replies: 43
Views: 776

Re: DIY HI POWERED PACK: First time, General questions

Yes, you are missing the fact that your expectation regarding both 18650 and 21700 is unrealistic.
by docware
Mar 15 2019 1:21pm
Forum: Battery Technology
Topic: DIY HI POWERED PACK: First time, General questions
Replies: 43
Views: 776

Re: DIY HI POWERED PACK: First time, General questions

Well, I didn´t catch you mean aged cells estimation. I understand that better DCIR doesn´t ensure better lifecycle.
by docware
Mar 15 2019 11:56am
Forum: Battery Technology
Topic: DIY HI POWERED PACK: First time, General questions
Replies: 43
Views: 776

Re: DIY HI POWERED PACK: First time, General questions

SamRich wrote:
Mar 15 2019 9:18am

I included it with a best guest of IR.
The IR you included seems to be out of reality. Real values should be around these values ( ± 1 miliohm ) :


ACIR v DCIR.jpg
by docware
Mar 08 2019 8:32am
Forum: Battery Technology
Topic: LiFePO4 in 18650 format?
Replies: 64
Views: 2105

Re: LiFePO4 in 18650 format?

No, I was nearly all the time speaking about capacity measurement. Unfortunately I didn´t differ enough the questions to cycle test. (" Let´s make a summary. Cycle test consist of : charge 1,3 A to 4,05 V, discharge 2,75 A to 3 V. Cut off current ? Rest times between cycles ? ") flippy, flippy, from...
by docware
Mar 08 2019 6:24am
Forum: Battery Technology
Topic: LiFePO4 in 18650 format?
Replies: 64
Views: 2105

Re: LiFePO4 in 18650 format?

Flippy, I consider cycle testing really important. So I am thankful to any information. Hope I´m not bothering you too much. 😊 Probability that any cell have only 0,5 % capacity loss after 500 cycles between 4,05 and 3 V is very very low. Value 0,5 % seems to be rather accuracy of the equipment. Loo...
by docware
Mar 07 2019 6:16pm
Forum: Battery Technology
Topic: LiFePO4 in 18650 format?
Replies: 64
Views: 2105

Re: LiFePO4 in 18650 format?

Did you check the current during whole first and final measurement ? I mean checking the current during the whole discharge time to see the variations of the current.
by docware
Mar 07 2019 5:40pm
Forum: Battery Technology
Topic: LiFePO4 in 18650 format?
Replies: 64
Views: 2105

Re: LiFePO4 in 18650 format?

the sawtooth shape is due to the temperature changes in the room over time. once you average out those changes you are left with no measureable differences in usable capacity. even if you take in any percentages in measuring error you are still left with a cell that has basically the same usable ca...
by docware
Mar 07 2019 4:37pm
Forum: Battery Technology
Topic: LiFePO4 in 18650 format?
Replies: 64
Views: 2105

Re: LiFePO4 in 18650 format?

I own ZKETECH EBC – X510, believe me I know what I am speaking about. If you measured 0,5 % difference, then accuracy of the equipment has to be at least 0.1% or better. Frankly, achieve 0.1% accuracy at capacity measurement is not easy. You need to have voltage and curent calibrated to values bette...
by docware
Mar 07 2019 3:05pm
Forum: Battery Technology
Topic: LiFePO4 in 18650 format?
Replies: 64
Views: 2105

Re: LiFePO4 in 18650 format?

the unit that does the current batch of 29E's is a 8 channel tester from EBX capable of pushing and pulling 10A per cel. temperatures were pretty equal between 15~20c depending on the other loads in the room. temperature is not a measureable factor in these tests as the test duration is meastured i...
by docware
Mar 07 2019 12:19pm
Forum: Battery Technology
Topic: LiFePO4 in 18650 format?
Replies: 64
Views: 2105

Re: LiFePO4 in 18650 format?

this is LESS then 0.5% loss in capacity.
so no, you are NOT going to wear out these cells anytime soon if you stick between the lines.
[/quote]

Can you please specify your test equipment and conditions (temperature) ?
by docware
Feb 26 2019 5:33am
Forum: Battery Technology
Topic: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?
Replies: 28
Views: 1867

Re: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?

This data is excellent. But... I see a real dilema.... In order to ensure a low current per cell, you would have to increase the battery capacity, size ,weight, and cost. All of those factors are oposite to the fundamental ideal of an Ebike battery,...lightweight, compact, and low cost Also, therma...
by docware
Feb 25 2019 7:37am
Forum: Battery Technology
Topic: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?
Replies: 28
Views: 1867

Re: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?

No problem :) , I now how the results will look like. It will be a good example for community that designing battery pack for more than 1C continuous discharge rate is problematic even with HD/HP cells in 18650 format like 30Q or HG2. Well, we are in agreement. Designing battery pack for more than ...
by docware
Feb 22 2019 4:32pm
Forum: Battery Technology
Topic: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?
Replies: 28
Views: 1867

Re: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?

Sorry Pajda, I´m not about to do 5A comparison test.
by docware
Feb 22 2019 4:09am
Forum: Battery Technology
Topic: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?
Replies: 28
Views: 1867

Re: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?

And last postcript - simulation of cell warming in the closed battery pack during normal e-bike running. 2 Amp discharge was chosen as an average current per cell representing standard e-bike operation. All cells were treated at the same conditions: - charging 1A to 4,1 V, 0,1 A cut off, 1 hour rest...
by docware
Feb 17 2019 4:25am
Forum: Battery Technology
Topic: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?
Replies: 28
Views: 1867

Re: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?

Just small addition. I simulated cell warming in the closed battery pack with help of standard plastic material fixture and expanded polystyrene isolation. The plastic fixture was trimmed to decrease mass by cca 30 - 40%. Temperature was again measured by thermocouple K, wires diameter 0,127 mm, fix...
by docware
Feb 15 2019 12:13pm
Forum: Battery Technology
Topic: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?
Replies: 28
Views: 1867

Re: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?

Thank you Pajda for sharing your info. As LG 18650 M36 seems to be interesting cell, I also have made some measurement. LG M36 specification : - standard charge 1 A , 50 mA cut off - standard discharge constant current 0,2 C 670 mA is giving capacity 3350 mAh - nominal energy 12,5 Wh and minimum ene...
by docware
Jan 23 2019 4:07am
Forum: Battery Technology
Topic: Samsung 50E capacity testSamsung 50E capacity test - 5000mAh or not?
Replies: 12
Views: 1027

Re: Samsung 50E capacity testSamsung 50E capacity test - 5000mAh or not?

I have to correct my previous statement that ZKETECH equipment is OK to measure capacity and energy with reasonable accuracy. The cooling fan of my equipment is switched-on according the manufacturer algorithm depending on the immediate power and internal temperature. At 1 and 2 A discharging mode i...
by docware
Jan 18 2019 7:51am
Forum: Battery Technology
Topic: Samsung 50E capacity testSamsung 50E capacity test - 5000mAh or not?
Replies: 12
Views: 1027

Re: Samsung 50E capacity testSamsung 50E capacity test - 5000mAh or not?

Hi thunderheart, here are my results from Samsung 21700 - 50E measurement : Testing conditions : ambient temperature during testing 24 – 25 °C, charge 2,45 A to 4,2 V, 0,1 A cut-off, rest at least 60 minutes. Equipment : ZKETECH EBC-A10H, BF-2A fixture Samsung 21700-50E disch capacity test b.jpg As ...
by docware
Jan 15 2019 2:04pm
Forum: Battery Technology
Topic: Samsung 50E capacity testSamsung 50E capacity test - 5000mAh or not?
Replies: 12
Views: 1027

Re: Samsung 50E capacity testSamsung 50E capacity test - 5000mAh or not?

I appreciate that you involve DCIR in your measurement as it is important characteristic of the cell. Just if you are going to measure according to IEC 61960-3 standard, we can compare apples to apples. ZKETECH equipment is quite OK to measure capacity and energy with reasonable accuracy. But defini...
by docware
Jan 15 2019 12:58pm
Forum: Battery Technology
Topic: Samsung 50E capacity testSamsung 50E capacity test - 5000mAh or not?
Replies: 12
Views: 1027

Re: Samsung 50E capacity testSamsung 50E capacity test - 5000mAh or not?

BF-2A sad story - you always have some surprise, I am curious 😊 Unfortunately, it is not possible to get correct DCIR values with „EB Tester Software“ automatic „Resistance Test“. You need to have some external voltage logger, fast and precise enough to get acceptable results and do measurement „man...
by docware
Jan 11 2019 11:36am
Forum: Battery Technology
Topic: Samsung 50E capacity testSamsung 50E capacity test - 5000mAh or not?
Replies: 12
Views: 1027

Re: Samsung 50E capacity testSamsung 50E capacity test - 5000mAh or not?

Hi thunderheart, wish you all well for this year. And wish many interesting cells like Samsung 50E to test. Hopefully you finish BF-2A modification early. Still don´t understant why you need to test more than 10 amps, we are not vaping here. 😊 As DCIR 26,5 miliohm you measured seems to me little bit...
by docware
Jan 07 2019 6:19am
Forum: Battery Technology
Topic: Cap cooling of 18650, thermal output graphs?
Replies: 10
Views: 539

Re: Cap cooling of 18650, thermal output graphs?

Even not very effective heat transfer at measuring fixture BF-2A from cell axial surfaces plus and especially minus pole is sufficient enough to cool the cell to some extent. Heat transfer from shell to minus pole is enough to cool down the cell as it is all part of one can. Temperature measured by ...
by docware
Dec 28 2018 4:55am
Forum: Battery Technology
Topic: Samsung 40T - 35A 21700 Li-ion battery's capacity test
Replies: 13
Views: 1011

Re: Samsung 40T - 35A 21700 Li-ion battery's capacity test

Well, gentlemen, HKJ started to use true 4-wire measurement for some reasons: https://lygte-info.dk/info/batteryTestImprovement%20UK.html "Any test done with the improved test stations will be marked with an asterix* in the comparator." Look at these pictures. It is a comparison of Samsung 25R and S...