Search found 272 matches

by docware
Feb 20 2020 10:58am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

I use cheap 2 - 3 USD voltmeter on ebike for battery voltage/SOC. For regular checking of the paralel groups voltage I use single purpose instrument with precise voltmeter. 0,1 mV voltmeter.jpg Precise voltmeter has resolution 0,1 mV up to 4,3 V. There is also built-in precision 0,02% voltage refere...
by docware
Feb 20 2020 1:46am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

.... and on most of my ebikes the only gauge I've used of any kind is a $2 digital voltmeter. Thanks for confirming that once you become accustomed to your pack's voltage as a measure of its SOC, that doesn't change with time despite the change in capacity. Just to confirm, that 50% SOC point is th...
by docware
Feb 19 2020 7:43am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

Yes, those are rest voltage values. Testing protocol consist of 20 discharge 2 amp pulses , each pulse equals 5 % of the cell actual capacity (measured as a first step). 20 min rest time between discharge pulses. LG MJ1 SOC mapping 2A 292 s pulses.jpg In this example was LG MJ1 discharged by 2 A for...
by docware
Feb 19 2020 4:33am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

SOC comparative table.
It´s obvious that SOC voltage distribution has no significant change after 700 cycles.
SOC% versus voltage - after 700 cycles  18.2.2020.jpg
SOC% versus voltage - after 700 cycles 18.2.2020.jpg (193.68 KiB) Viewed 224 times
by docware
Feb 17 2020 11:52am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

New batch of pictures : Samsung 30Q 472 cycles, LG MJ1 435 cycles, SONY VTC6 200 cycles, Samsung 21700 50E 165 cycles, Samsung 35E 125 cycles, LG HG2 64 cycles. 50E curve is obviously influenced by the ZKETECH failure. Samsung 30Q 472 cycles.jpg LG MJ1 435 cycles.jpg SONY VTC6 200 cycles.jpg Samsung...
by docware
Feb 11 2020 4:55am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

flippy wrote:
Feb 11 2020 2:51am
doc, how do you impelement the IR on the table?
viewtopic.php?f=14&t=103092&p=1513811#p1513811
by docware
Feb 09 2020 1:35pm
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

Yes, it´s very probably an instrument issue.
by docware
Feb 09 2020 7:35am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

All my certainties about Li-ion cells are disappearing step by step, ….. :) Thanks Pajda for sharing your experiencies. Not only these HG2 issues, something strange happened to 50E and 35E testing channels. I contemplate if continue with those anomalous data, or finish them and start with new cells....
by docware
Feb 08 2020 8:33am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

LG HG2 No2 production date November 2017. Purchased fom nkon September 2018. In December 2018 capacity 2 909 mAh at 3 A discharge, measured at ZKETECH EBC-A10H. In September 2019 measured with Maynuo M9712/ GW Instek GDM 8351 : LG HG2 No2 September 2019.jpg Storage at 3,5 - 3,7 V / 16 - 18 °C. LG HG...
by docware
Feb 08 2020 4:45am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

LG HG2 started yesterday with the same parameters as 30Q and VTC6.
LG HG2 No2.jpg
LG HG2 No2.jpg (208.86 KiB) Viewed 565 times
LG HG2 DCIR.jpg
LG HG2 DCIR.jpg (170.69 KiB) Viewed 565 times
by docware
Feb 07 2020 4:57pm
Forum: Battery Technology
Topic: Spot welding tesla 21700
Replies: 7
Views: 722

Re: Spot welding tesla 21700

Since aluminum foil is used as a cathode current collector, aluminum positive pole make sense.

http://budgetlightforum.com/node/60883
http://budgetlightforum.com/comment/149 ... nt-1492629
by docware
Feb 07 2020 4:23pm
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

Another charts delivery. Samsung 29E7 700 cycles, Samsung 30Q 407 cycles, LG MJ1 370 cycles, SONY VTC6 134 cycles, Samsung 50E 112 cycles, Samsung 35E 63 cycles. Samsung 29E7 700 cycles.jpg Samsung 30Q 407 cycles.jpg LG MJ1 370 cycles.jpg SONY VTC6 134 cycles.jpg Samsung 21700 50E 112 cycles.jpg Sam...
by docware
Feb 06 2020 7:00pm
Forum: Battery Technology
Topic: Spot welding tesla 21700
Replies: 7
Views: 722

Re: Spot welding tesla 21700

Positive pole is from aluminium.
by docware
Feb 06 2020 12:19pm
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

Well, I again recommend to read all Pajda´s post for understanding the excelent result of LG M36 as also high power cells poor results. LVC 3,4 V …... LG M36, Sanyo GA, LG MJ1, Samsung 50E, Samsung 35E LVC 3,3 V ....... Panasonic PF, Samsung 29E, Samsung 30Q , SONY VTC6 Max. charging current is 5A, ...
by docware
Feb 06 2020 5:52am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

As flippy wrote, contrary to storage mode, in operation mode higher temperature above 30 °C are better for Li-ion cells. Of course, lower temperatures bellow 15 °C mean worse operation conditions. All because temperature has significant impact on the chemical conversions, diffusion of the ions throu...
by docware
Feb 05 2020 3:27pm
Forum: Battery Technology
Topic: Nickel vs Nickel mistery
Replies: 5
Views: 216

Re: Nickel vs Nickel mistery

If you want to be one hundred percent sure, or simply you are curious, find some scrap metal collector shop near you. They usually have handheld spectrometer for metal alloys identification. Strip width 28 - 30 mm and 0,15 – 0,2 mm thickness is more than enough for reliable analyse. https://www.yout...
by docware
Feb 05 2020 11:46am
Forum: Battery Technology
Topic: Nickel vs Nickel mistery
Replies: 5
Views: 216

Re: Nickel vs Nickel mistery

It may be nickel 200 grade different condition (soft, half-hard, hard) or 200 versus 201 grade. Nickel 201 grade has low rate of work hardening.

Conductivity of stainless steel is of one order worse than nickel.
by docware
Feb 05 2020 10:17am
Forum: Battery Technology
Topic: Nickel vs Nickel mistery
Replies: 5
Views: 216

Re: Nickel vs Nickel mistery

The more ductile sample probably had additional heat treatment (annealing) after cold rolling.
by docware
Feb 03 2020 9:54am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

Probably everybody here know negative impact of low temperatures on capacity and internal resistance of Li-ion cells, apart from aging during operation. As I noticed some potential effect of temperature on DCIR during measurements, was wonder to know more. Not having temperature test chamber I made ...
by docware
Feb 02 2020 3:32am
Forum: Battery Technology
Topic: Paralleling uneven voltage cells?
Replies: 43
Views: 1150

Re: Paralleling uneven voltage cells?

The cells after roughly 80 minutes equalizing were within 1 milivolt, after resting another 60 minutes were within 1,5 milivolt. It´s obvious that with proper procedure, taking enough time and starting first with resistor, it´s no problem to have all good cells within 1 milivolt. Just take enough ti...
by docware
Feb 01 2020 12:07pm
Forum: Battery Technology
Topic: Paralleling uneven voltage cells?
Replies: 43
Views: 1150

Re: Paralleling uneven voltage cells?

If I have two identical cells, one at 3.75V and the other at 4.10V and I spot weld a nickel strip to the positive and negative of both to parallel them, how fast will it take the two cells to level eachother? First of all question; why anybody would exercise such crazy thing ? Moreover, how would y...
by docware
Jan 29 2020 2:58pm
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

eMark, stop trolling here and stop sending me personal messsages, I am not interesting in any communication with you.

Can I ask admin for help and ban eMark ?
by docware
Jan 29 2020 2:05pm
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

Alster wrote:
Jan 29 2020 6:49am
@docware

You have started testing 21700 Samsung 50E
Is it Samsung 50E or Samsung 50E2
It´s Samsung 50E.
by docware
Jan 29 2020 2:08am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

Yes, Lipo are off topic in this thread.
by docware
Jan 28 2020 5:23am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 312
Views: 28887

Re: Li-ion cells cycle ageing

Well, here we have New Kid in Town on the testing, or maybe rather the old acquaintance : Samsung 35E. Parameters are standard, 4,1 – 3,4 V 2,5 / 1 A 5 minutes rest. Samsung 35E No2 4,2 - 2,5 V.jpg Samsung 35E DCIR.jpg https://www.youtube.com/watch?v=1mJbk2CuQ0I Always can´t believe to my ears how w...