"desulfate" 40T and 30Q and VTC6 and P42a

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"desulfate" 40T and 30Q and VTC6 and P42a

Post by goatman » Dec 16 2020 12:11am

checking to see if any battery experts can tell me what is happening with these batteries. i dont know the word for it to do a google search.

if i do a capacity test on 30Q or 40T

ill get a curve like this

Image

if i repeat the test a couple times the curve smooths out

Image

and step 1-4 will jump from 183mah to over 300 mah

Image

you can see the testing here

viewtopic.php?f=14&t=106550&start=25#p1604360
Last edited by goatman on Feb 24 2021 7:12pm, edited 2 times in total.

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Re: "desulfate" 40T and 30Q

Post by john61ct » Dec 16 2020 5:29pm

Cell getting warmed up?

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Re: "desulfate" 40T and 30Q

Post by john61ct » Dec 16 2020 5:29pm

PS sulfation is a lead thang

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Re: "desulfate" 40T and 30Q

Post by goatman » Dec 16 2020 6:41pm

yes sulfation is a lead thing, thats why i put it "desulfate" and asked if anyone knows what this is

kind of click-baity

rg12 has 40T batteries and the same tester i have, be nice if he could verify what im seeing

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Re: "desulfate" 40T and 30Q

Post by Hillhater » Dec 16 2020 9:13pm

Lygte test results show a similar , if less pronounced, profile......but they will be from multiple test runs
Image
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Re: "desulfate" 40T and 30Q

Post by goatman » Dec 16 2020 10:15pm

its good to see the same profile but im wondering why, while testing i can increase the mah by doing a capacity test

its like the deep discharge to 2.5v brings mah back into the cell for a dozen or so cycles
thats why i used "desulphate" but lithium gets dendrites? not a clue

it takes 2 capacity tests to straighten out the discharge curve

heres the 30q before capacity at #100-2395mah, it took 56cycles to reach 2395 discharge mah

#100 d-2395, c-2355
0.6amp capacity test, #1-3170mah, #100- 3092mah. 78 mah loss
#101 d-2542, c-2501 i dont know whats happened with these numbers, im going to shut down and restart in the morning
#102 d-2528, c-2486
#103 d-2517, c-2472
#104 d-2501, c-2456
#105 d-2489, c-2445
#106 d-2479, c-2435
#107 d-2470, c-2427 shutdown and restart
#108 d-2463, c-2421
#109 d-2458, c-2416
#110 d-2455, c-2413
#111 d-2450, c-2408
#112 d-2446, c-2405
#113 d-2442, c-2401
#114 d-2440, c-2398
#115 d-2438, c-2396
#116 d-2436, c-2393
#117 d-2432, c-2391
#118 d-2431, c-2388
#119 d-2429, c-2386
#120 d-2427, c-2387
#121 d-2428, c-2384
#122 d-2424, c-2384
#123 d-2426, c-2385
#124 d-2425, c-2382
#125 d-2423, c-2382
#126 d-2421, c-2380
#127 d-2420, c-2377
#128 d-2417, c-2376
#129 d-2416, c-2373
#130 d-2413, c-2370
#131 d-2413, c- usb cable was pulled from computer at 2100 mah, gave it a charge top up
#132 d-2418, c-2371
#133 d-2414, c-2373
#134 d-2411, c-2370
#135 d-2410, c-2367
#136 d-2407, c-2366
#137 d-2408, c-2366
#138 d-2406, c-2364
#139 d-2405, c-2364
#140 d-2405, c-2362
#141 d-2406, c-2365
#142 d-2405, c-2363
#143 d-2404, c-2364
#144 d-2404, c-2363
#145 d-2404, c-2362
#146 d-2401, c-2361
#147 d-2400. c-2359
#148 d-2400, c-2357
#149 d-2399, c-2358
#150 d-2399, c-2359
#151 d-2398, c-2355
#152 d-2397, c-2355
#153 d-2396, c-2355
#154 d-2396, c-2354
#155 d-2393, c-2352
#156 d-2395, c-2353
#157 d-2395, c-2352
#158 d

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Re: "desulfate" 40T and 30Q

Post by Hillhater » Dec 16 2020 11:21pm

?? ..are you suggesting you are only getting 2400mAh from that cell now ??
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Re: "desulfate" 40T and 30Q

Post by goatman » Dec 16 2020 11:31pm

under 10/7.5/5/2.5 amp discharge, its the 30Q im showing there. it gained 147mah from #100 to #101 because of the capacity test

if you go to #200 of the 30q test it happens again

#199 d-2371, c-2330
#200 d-2372, c-2329
#200 d-3026, c-2863 capacity test
#201 d-2497, c-2453

im just going to keep cycling the 30Q and do the 0.6amp discharge capacity test every 50 cycles to see what happens

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Re: "desulfate" 40T and 30Q

Post by neptronix » Dec 17 2020 9:35am

What temperature are you running these tests at? because temperature will influence the internal resistance a lot.

If comparing to cell spec sheets, you need to be at ~70F.
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Re: "desulfate" 40T and 30Q

Post by goatman » Dec 17 2020 10:37am

capacity tests are done at room temp/75f

while doing the life cycle testing with the 10/7.5/5/2.5 amp discharge testing

10amp reaches 97f
7.5amp 102f
5amp will stay at 102f
end of 2.5amp will be 90f
start of charge will be 89f
end of charge will be 75f
next cycle starts at 75f

temperatures will be the same discharge temp at #100 and #101 but the mah increased 147mah because the 0.6amp discharge happened inbetween the cycles

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Re: "desulfate" 40T and 30Q

Post by neptronix » Dec 17 2020 11:25am

Don't you love high capacity cylindrical cells and how they over promise and under deliver on discharge efficiency...
..there's a reason why the voltage curves and max capacity graphs are generated at 0.000001 amp.. :lol:
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Re: "desulfate" 40T and 30Q

Post by goatman » Dec 17 2020 4:02pm

i thought it was doing really good, the cycle testing is 4.2v to 3.2v :D

the capacity test is 4.2v to 2.5v

im just wondering if every 50 cycles you should do a 0.6 amp discharge to 2.5v to double the lifecycle of 30q and 40T

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Re: "desulfate" 40T and 30Q

Post by Hillhater » Dec 17 2020 5:46pm

Cycle life testing,..no matter how well thought out and conducted,.. can never replicate “real world” applications.
... Discharges are rarely continuous, mostly at uneven rates, to random end voltages.
...And charging, whilst often continuous and at steady known rates, is rarely from the same initial voltage start point.
... Rest time between cycles is also very different and variable.
I suspect all this would result in very different “real life” actual life span outcomes.
But controlled tests, such as yours , is the only practical way of assessing and comparing cell performance before putting them into service.
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Re: "desulfate" 40T and 30Q

Post by john61ct » Dec 17 2020 6:10pm


goatman wrote: every 50 cycles you should do a 0.6 amp discharge to 2.5v to double the lifecycle of 30q and 40T
Sounds like something from a different chemistry family

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Re: "desulfate" 40T and 30Q

Post by john61ct » Dec 17 2020 6:15pm

I'm feeling more certain the increased performance from subsequent test runs is tge result of increased internal temperatures.

You could test that by letting them settle an hour before each run,

ideally pre-warming cells to say 30°C every time (whatever so long as well above ambient)

bet that will show greater consistency

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Re: "desulfate" 40T and 30Q

Post by goatman » Dec 17 2020 7:14pm

temps are the same as always, if there is a difference it recovers in 2 or 3 cycles
this was the fridge test

charged battery placed in fridge for 18 hrs at 5 celsius and restart the test
#213 d-2366, c-2332
#214 d-2374, c-2332
#215 d-2376, c-2334
doing 0.6amp discharge capacity test to see if lost mah can be recovered
#216 d-3042, c-2867 capacity test


ill show the test im doing right now and 2 pictures

first picture is cycle 225
second picture is cycle 234 and youll see the mah change at 1-1 and 10-1
at cycle 250 ill do the capacity test, resume testing and the mah will be brought back up

Image

Image

Image

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Re: "desulfate" 40T and 30Q

Post by john61ct » Dec 18 2020 6:14am

The **internal** temperature is what matters, not the outside.

Why are you cooling the cells down?

25°C / 77°F is the standard for controlled testing.

Hotter is better in actual usage for performance and longevity.

Cooler is good only for storage longevity, with no cycling.
Last edited by john61ct on Dec 18 2020 6:14am, edited 1 time in total.

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Re: "desulfate" 40T and 30Q

Post by goatman » Dec 18 2020 9:24am

im not cooling down the cells, they do it on their own

i set discharge voltage cut off by temp so the battery doesnt exceed 104f/40celsius during the discharge test, if i go hotter like 105f it will lose more mah/cycle than 104f or less.

i used to think a fatter battery like a 21700 or 26650 would trap the heat inside it but they dont, they run cooler than a 18650 at 10 or 7.5 amp discharge

when i saw Tesla switch to a fat cell i figured heat was part of the reason they went fatter.

a 40T can put out 2370 mah before reaching 102f

Image

a 30Q can put out about 1170mah before reaching 102f

Image

the mnke 26650 can be discharged at 7amps putting out about 4200mah? (cant remember) without ever reaching 102f f

i couldnt set discharge cut offs for cycling by temperature like i do other cells, its runs too cool
viewtopic.php?f=14&t=107191#p1569263

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Re:

Post by goatman » Dec 18 2020 6:56pm

john61ct wrote:
Dec 17 2020 6:10pm
goatman wrote: every 50 cycles you should do a 0.6 amp discharge to 2.5v to double the lifecycle of 30q and 40T
Sounds like something from a different chemistry family
went googling and came across an article on the SEI layer

https://circuitdigest.com/article/what- ... erformance

i also went looking for an exchange between docware and another es member about endothermal and exothermal but havent found what im looking for yet, here it is

viewtopic.php?f=14&t=102891&p=1505696&h ... c#p1505590

heres Pajda trying to find the new 141 30q for testing

viewtopic.php?f=14&t=103092&start=225#p1525408

has pajda tested them yet?

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Re: "desulfate" 40T and 30Q

Post by goatman » Dec 19 2020 3:28pm

had a power outage while doing the capacity test, the test was stopped at about 3.6v and then resumed 2 hours later when the power came back on, that interruption caused the capacity test to fail to provide the capacity or straighten the curve

here it is to 3.6v

Image

and resumed

Image

so i did it again

Image

heres a picture of cycle #242 before the capacity test, look at steps 18-1, 18-2,18-3, 18-4 and then compare to cycle #243 after the capacity test and youll see how the mah gets redistributed in the second picture, 1-1, 1-2, 1-3, 1-4

#242
Image

#243
Image

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Re: "desulfate" 40T and 30Q

Post by 999zip999 » Dec 19 2020 4:40pm

Desulfate samgsung 40t cells in brick bunker 100ft from all building and tree's find the 220 outlet and make sure POS and Ned is right and give it the juice.
Will guarantee No more worries of desulfation ever again. Oh stand back 100ft. Behind blast sheilds.

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Re: "desulfate" 40T and 30Q and VTC6

Post by goatman » Dec 21 2020 11:42am



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Re: "desulfate" 40T and 30Q and VTC6

Post by goatman » Feb 24 2021 6:49pm

going to desulfate some salvaged 30Q from bad packs

these were in a hot glue pack

5 cells at 1.97v 1s5p
IMG_20210223_081939.jpg
IMG_20210223_081939.jpg (2.61 MiB) Viewed 1219 times
charged to 4.2v at 3amps

then discharged to 2.5v at 3amps (0.6amps) curve looks fine

Image

charged to 4.2v at 3 amps

Image

then i discharged them a little bit and theyre sitting at 4.02v . now just put them on the shelf and see what happens

had another 20 that were 3.28v to 3.03v, taped them together to equalise
IMG_20210224_155200.jpg
IMG_20210224_155200.jpg (2.37 MiB) Viewed 1212 times
theyre sitting at 3.22v right now, in a couple days ill make a 2s10p pack and desulfate at 5amps

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Re: "desulfate" 40T and 30Q and VTC6

Post by eMark » Feb 25 2021 2:12pm

goatman wrote:
Feb 24 2021 6:49pm
going to desulfate some salvaged 30Q from bad packs

5 cells at 1.97v 1s5p

charged to 4.2v at 3amps

then discharged to 2.5v at 3amps (0.6amps) curve looks fine

charged to 4.2v at 3 amps

then i discharged them a little bit and theyre sitting at 4.02v . now just put them on the shelf and see what happens

had another 20 that were 3.28v to 3.03v, taped them together to equalise

theyre sitting at 3.22v right now, in a couple days ill make a 2s10p pack and desulfate at 5amps
Had you previously determined if all these 25 cells ("5 cells at 1.97v 1s5p" and "20 that were 3.28v to 3.03v") were suffering from moderate to high self-discharge?

When you say they (all 25 cells) need "desulfating" you imply that they all suffer from an unacceptable degree of self-discharge. Do you know for a fact that all 25 cells suffered from unacceptable self-discharge? For all you know maybe 15, or only 8 out of 25 suffered from unacceptable self-discharge.

You first need to determine how many suffer from unacceptable self-discharge and only then perform your "desulfate" routine on just those cells suffering from unacceptable self-discharge to see if a partial "fix" is in and for how long ... experimental research parameter :wink:

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