Molicel P42a cycle test

4.2v to 2.5v, 0.8amp discharge capacity test



#100




#287 3688mah



wider view



#100



#287

discharge 3516mah, charge 3468mah

setting each discharge amp cut off settings by battery temperature

starting temp was 75f

10 amp cut off at 3.58 volts, battery temperature 94f, 1049mah



7.5 amp cut off at 3.39 volts, battery temperature 101f, 1137mah



5 amp cut off at 3.30 volts, battery temperature 95f, 817mah



2.5 amp cut off at 3.20 volts, battery temperature 87f, 538mah

starting battery temperature 87f

2amp charge to 3.6v, battery temp was 79f at 3.6v, 460mah



when 3.75 amp charge reached 4.2v battery temp was 88f, 2290mah



end of charge temp 78f, 3035mah



cycle #1 combined charge 3495 mah

something goofy happened with the 10 amp/7.5 amp discharge, you can see it in graph below. going to charge back to 4.2v and start again



bad connection, problem solved

peak temp at end of 7.5amp discharge reached 104/5f, going to change cut off voltage to 3.55 volts to lower temperature



volt sag with 10amp discharge

magnets and copper slug tape



battery arrived at 3.527v, charged with 2amps 0.10 c/o



starting 4.2v to 2.5v capacity test at 0.8amp discharge

4.15v, 15mah



4.10v, 95mah



4.05v, 343mah



100 cycles 323mah



4.0v, 799mah



100 cycles 759mah




i just wanted to see where the mah starts

i got this battery from 18650 Battery but had a problem. they shipped the battery and it supposedly left Florida enroute to Canada June.14.

july.15 i sent 1 email with 3 words, Wheres my battery?
next day they replied, It seems to have been lost and weve sent you another battery

2 weeks later i had the battery. Excellent no BS customer service

for cycle 2 i tried to lower peak battery temp from 104f to 101f by changing 7.5 amp c/o to 3.55v from 3.39v, went too far but capacity improved

discharge 3567mah, charge 3516mah



changed 7.5 amp c/o to 3.47v and the discharge is better balanced, peak temp was 100f a little less discharge mah. just going to let it cycle now



#3 discharge 3554mah, charge 3508mah
#4 d-3545mah, c-3499mah
#5 d-3537mah, c-3492mah
#6 d-3531mah, c-3485mah
#7 d-3524mah, c-3478mah
#8 d-3519mah, c-3474mah
#9 d-3515mah, c-3471mah
#10 d-3512mah, c-3467mah
#11 d-3509mah, c-3463mah i changed 3.75a charge to 2.5amps for 12 and 13
#12 d-3506mah, c-3459mah
#13 d-3502mah, c-3455mah- put 3.75a charge back and changed wait time between discharge/charge from 5min to 10min
#14 d-3499mah, c-3456mah
#15 d-3499mah, c-3453mah
#16 d-3497mah, c-3451mah
#17 d-3494mah, c-3448mah
#18 d-3492mah, c-3445mah
#19 d-3488mah, c-3444mah
#20 d-3487mag, c-3441mah- changed wait time to 15min
#21 d-3485mah, c-3439mah
#22 d-3483mah, c-3439mah
#23 d-3482mah, c-3438mah
#24 d-3482mah, c-3437mah
#25 d-3480mah, c-3435mah
#26 d-3478mah, c-3434mah
#27 d-3477mah, c-3432mah
#28 d-3475mah, c-3430mah
#29 d-3473mah, c-3428mah
#30 d-3471mah, c-3427mah- changed wait time to 20min
#31 d-3469mah, c-3424mah
#32 d-3468mah, c-3422mah
#33 d-3466mah, c-3423mah
#34 d-3467mah, c-3422mah
#35 d-3466mah, c-3423mah
#36 d-3465mah, c-3424mah
#37 d-3467mah, c-3422mah
#38 d-3465mah, c-3419mah
#39 d-3463mah, c-3417mah
#40 d-3461mah, c-3415mah- changed wait to 30 minutes
#41 d-3459mah, c-3414mah
#42 d-3457mah, c-3412mah
#43 d-3457mah, c-3413mah
#44 d-3457mah, c-3413mah
#45 d-3456mah, c-3412mah
#46 d-3456mah, c-3411mah
#47 d-3455mah, c-3409mah
#48 d-3455mah, c-3407mah
#49 d-3451mah, c-3406mah
#50 d-3450mah, c-3403mah
#51 d-3448mah, c-3403mah
#52 d-3447mah, c-3401mah
#53 d-3445mah, c-3401mah
#54 d-3446mah, c-3394mah- 24hr wait between discharge/charge for #54
#55 d-3455mah, c-3410mah
#56 d-3452mah, c-3406mah
#57 d-3450mah, c-3404mah
#58 d-3448mah, c-3401mah
#59 d-3446mah, c-3400mah
#60 d-3444mah, c-3399mah
#61 d-3445mah, c-3397mah
#62 d-3444mah, c-3397mah
#63 d-3443mah, c-3397mah
#64 d-3443mah, c-3397mah- peak battery temp 99f
#65 d-3442mah, c-3395mah
#66 d-3441mah, c-3394mah
#67 d-3437mah, c-3392mah
#68 d-3438mah, c-3390mah
#69 d-3436mah, c-3389mah- changed to 45min wait
#70 d-3434mah, c-3387mah
#71 d-3433mah, c-3387mah
#72 d-3433mah, c-3387mah
#73 d-3432mah, c-3388mah
#74 d-3434mah, c-3387mah
#75 d-3432mah, c-3386mah
#76 d-3430mah, c-3383mah
#77 d-3429mah, c-3382mah- peak temp 97f
#78 d-3428mah, c-3381mah- raising temp
#79 d-3428mah, c-3382mah- peak temp 98f, raising temp more
#80 d-3428mah, c-3383mah- peak temp is still 98f, im using 1731mah at 10amps, ill insulate box to raise peak temp
#81 d-3429mah, c-3383mah- peak 100f
#82 d-3428mah, c-3382mah
#85 d-3425mah, c-3378mah
#90 d-3419mah, c-3375mah
#95 d-3407mah, c-3359mah
#99 d-3402mah, c-3356mah
switching back to 30 minute wait

battery lost 149mah over 100 cycles

got rid of the 10amp discharge and changed wait time to 15min.

the battery had a day to sit idle before starting cycle 100 with new settings

discharge mah increased by 80mah????

#100 d-3482, c-3414mah

i dont have time to try and figure out why or how for a few days, going to let it cycle and see what happens. i wonder if continually cycling without a break affects it, maybe every 25 cycles it needs a day off?

#101 d-3457, c-3409mah
#102 d-3450, c-3399
#103 d-3441, c-3390
#104 d-3443, c-3384
#105 d-3427, c-3379
#106 d-3423, c-3373
#107 d-3420. c-3370
#108 d-3415, c-3368
#109 d-3411, c-3364
#110 d-3413, c-3363
#111 d-3410, c-3361
#112 d-3408, c-3358
#113 d-3407, c-3357
#114 d-3400, c-3353
august.15 quit testing

its been 2 weeks with the battery sitting and voltage dropped from 4.191v to 4.140v. topped off the battery so the testing would start at 4.191v.



heres the chart with 10 amps removed



#115 d-3375, c-3299
#116 d-3355, c-3304
#117 d-3357, c-3307
#118 d-3360, c-3309
#119 d-3360, c-3310
#120 d-3361, c-3311
#121 d-3359, c-3310
#122 d-3360, c-3309
#123 d-3360, c-3309
#124 d-3359, c-3310
#125 d-3360, c-3311
#126 d-3361, c-3313
#127 d-3362, c-3312
#128 d-3361, c-3312
#129 d-3363, c-3312
#130 d-3361, c-3312
#131 d-3361, c-3311
#132 d-3361, c-3310
#133 d-3360, c-3309
#134 d-3359, c-3310
#135 d-3350, c-3297
#134 d-3348, c-3299
#135 d-3350, c-3299
#136 d-3349, c-3299
#137 d-3348, c- after discharge, frign windows shut down computer next batch of numbers will be high than level off again but at
#135 the battery did behave odd, might need another break?

i charged battery with 2amps, 0.10c/o. 3294mah
let sit 5hrs and voltage dropped to 4.16v,
charged to 4.2v with 0.7amps, 0.10 c/o. 27mah



#138 d-3369, c-3292
#139 d-3345, c-3294
#140 d-3346, c-3295 going to let it cycle til it acts up again
#141 d-3347, c-3299
#142 d-3349, c-3297
#143 d-3348, c-3297
#144 d-3347, c-3297
#145 d-3347, c-3295
#146 d-3344, c-3294
#147 d-3344, c-3293
#148 d-3343, c-3294
#149 d-3342, c-3291
#150 d-3343, c-3292
#151 d-3344, c-3293
#152 d-3343, c-3293
the software does 15 cycles at a time and stops. testing had stopped and battery voltage dropped to 4.17v so i topped up the charge, im going to change charge c/o amps to 0.05amps from 0.10 amps to see what happens on cycle #154
#153 d-3358, c-3293
software wouldnt let me go lower than 0.10 amps so dropped charge to 3amps from 3.75
#154 d-3353, c-3293
#155 d-3342, c-3292
#156 d-3342, c-3290
#157 d-3339, c-3288
#158 d-3338, c-3288
#159 d-3338, c-3288
#160 d-3338, c-3287
#161 d-3336, c-3287
#162 d-3337, c-3289
#163 d-3339, c-3289
#164 d-3338, c-3288
#165 d-3338, c-3286
#166 d-3336, c-3285
#167 d-3324 the battery just acted up with big mah drop. going to bring 10 amp discharge back

#120 was 3361mah and #166 was 3336mah for a 25mah loss over 45 cycles

heres the 10amp curve, peak battery temp 99f/37c



#168 d-3341, c-3280
#169 d-3328, c-3280
#170 d-3328, c-3279
#171 d-3327, c-3278
#172 d-3327, c-3278
#173 d-3327, c-3277
#174 d-3325, c-3276
#175 d-3323, c-3274
#176 d-3322, c-3272
#177 d-3319, charged to 3.57v and put it on the shelf

i think im done testing this battery, if it cant handle 10 amps without losing less than 0.5mah/cycle, its not very good. 7.5amp seems ok

im going to retest this battery for a few cycles. i saw the mnke 26650 battery didnt like to run constantly without suffering a big mah loss after about 24 hrs? plus the mnke and p42a didnt like to be cycled without an extended break between charge/discharge cycles. in the numbers above you can see where the battery "acts up"

The samsung 40T doesnt seem to care, gives consistent mah/cycle with short break and doesnt "act up".

what does that mean if a battery is in a solar system and what about regen on ebikes?

im going to play a little bit with this battery by giving it a break every 24hrs just to see what happens.
7.5/5/2.5 amp discharge, 2amp charge will cycle 10x then 24hr break



#178 d-3334, c-3281
#179 d-3334, c-3283
#180 d-3335, c-3283
#181 d-3336, c-3283
#182 d-3335, c-3282
#183 d-3336, c-3281
#184 d-3332, c-3281
#185 d-3333, c-3279
#186 d-3331, c-3276
#187 d-3330, c-3278 sept.25/3:30 stopped test for 24hrs
sept.26/3pm discharge started
#188 d-3349, c-3261
#189 d-3318, c-3265
#190 d-3319, c-3270
#191 d-3324, c-3275
#192 d-3327, c-3276
#193 d-3328, c-3277
#194 d-3329, c-3279
#195 d-3329, c-3278
#196 d-3330, c-3278
#197 d-3331, c-3283, going to keep cycling til big mah drop
#198 d-3333, c-3285
#199 d-3335, c-3283
#200 d-3334, c-3284
#201 d-3332, c-3279
#202 d-3329, c-3276
#203 d-3326, c-3275
#204 d-3326, c-3273
#205 d-3325, c-3270

goatman said:

im going to retest this battery for a few cycles. i saw the mnke 26650 battery didnt like to run constantly without suffering a big mah loss after about 24 hrs? plus the mnke and p42a didnt like to be cycled without an extended break between charge/discharge cycles. in the numbers above you can see where the battery "acts up"

The samsung 40T doesnt seem to care, gives consistent mah/cycle with short break and doesnt "act up".

what does that mean if a battery is in a solar system and what about regen on ebikes?

im going to play a little bit with this battery by giving it a break every 24hrs just to see what happens.
7.5/5/2.5 amp discharge, 2amp charge will cycle 10x then 24hr break

#178 d-3334, c-3281
#179 d-3334, c-3283
#180 d-3335, c-3283
#181 d-3336, c-3283
#182 d-3335, c-3282
#183 d-3336, c-3281
#184 d-3332, c-3281
#185 d-3333, c-3279
#186 d-3331, c-3276
#187 d-3330, c-3278 sept.25/3:30 stopped test

Click to expand...

From 3550 to 3330 in 185 cycles, 6.2% drop. If you drain the battery two times every week (one big ride during weekend and one big ride during the week, or several small ones). You are looking at 6.2% loss from using it for 2 years!! After that you only have to take care to store it at 50% or so. I think this battery can easily serve 5 years if used in the above way.

i agree, im testing for myself and sharing. if you follow mooch i think he thinks? the p42a is better than a 40t for vaping. for my area i can get a 40t for $10 or a p42a for $11.50

im looking for a 10amp cell with a good life cycle and the 40T did alot better

also i can drain down a 40T, like riding to work and plug it in right away for charging but the p42a needed to sit for about an hour before charging
the p42a might do alot better if you let it sit like you mention

sept.26/3pm test resumed, the battery was cold, 70f when test started,

#188 d-3348, c-3261

cycle #206, wanted to see available capacity at 0.8amp discharge from 4.2v to 3.2v. 3472mah

Hello, I have seen your temperature cut-off test. To my understanding, if the temperature of this P42A reaches the limit, the battery will discharge no more. Following the datasheet, it claimed the battery could work at maximum 60 degree C. The tests that you conducted, the temperature range for cut-off is from 87f to 101f (equivalent to 30.5 degree C to 38 degree C). Is it correct?

Thanks.

bigboy061293 said:

Hello, I have seen your temperature cut-off test. To my understanding, if the temperature of this P42A reaches the limit, the battery will discharge no more. Following the datasheet, it claimed the battery could work at maximum 60 degree C. The tests that you conducted, the temperature range for cut-off is from 87f to 101f (equivalent to 30.5 degree C to 38 degree C). Is it correct?

Thanks.

Click to expand...

if i go hotter it suffers more capacity loss per cycle

So "cut-off" here is made by you, not the battery itself, am I right?

I also discharge high current (12S6P), 110A in total, about 18A for 1 cell. The cell seems to get hot (about 77 degree C) and I have the power lost. For while, nearly 30s to 1 minute, it came back as normal. Is that the symptom of cut-off by high temperature?

im doing lifecycle for 10amp max. 10/7.5 discharge cell temp rises, 5amp it stays the same temp.
ES hasnt let me answer????? in long sentences

bigboy061293 said:

So "cut-off" here is made by you, not the battery itself, am I right?

I also discharge high current (12S6P), 110A in total, about 18A for 1 cell. The cell seems to get hot (about 77 degree C) and I have the power lost. For while, nearly 30s to 1 minute, it came back as normal. Is that the symptom of cut-off by high temperature?

Click to expand...

how long do you discharge high current for, are you sure volt sag isnt hitting the lvc of the controller

goatman said:

bigboy061293 said:

So "cut-off" here is made by you, not the battery itself, am I right?

I also discharge high current (12S6P), 110A in total, about 18A for 1 cell. The cell seems to get hot (about 77 degree C) and I have the power lost. For while, nearly 30s to 1 minute, it came back as normal. Is that the symptom of cut-off by high temperature?

Click to expand...

how long do you discharge high current for, are you sure volt sag isnt hitting the lvc of the controller

Click to expand...

Hi, have packed 12S6P. I discharge it around 10 - 12min from full 50.4V down to 36V at 4000W-4400W. I do not have connected to any controller at all. I made myself the current/voltage/power measuring tool for monitoring (I make drones so the power measuring tool works fine and precisely). Temperature is measured by attaching temp sensor to surface of cells. I am facing 2 problems:

1. Temp goes high, as I stated, at 77 degreeC (at the 8-9 mins)
2. Whenever I adjust load for >4400W, the battery seem discharge no more, i.e. voltage of cells go high and current go low so that it does not keep the 4400W load as I expect.

once you hit 3.2v battery temperature will start to rise quickly, try stopping discharge at 3.2v/cell see what happens

Thanks. I am trying in next few days. However the heat problem is different from the stop discharging problem. As I stated, when I try to go over 4400W (about 16A-20A for each cell), the entire battery will stop discharging for a short moment (1s - 2s) and after that, it recover back. Do you have any ideas, thanks!

Are you sure it's not some malfunction in your test rig? I can't see why a battery would stop discharging on it's own.

Frank said:

Are you sure it's not some malfunction in your test rig? I can't see why a battery would stop discharging on it's own.

Click to expand...

Thanks Frank, I also expect that my system went wrong. To figure it out, I need advices from the you guys. I am willing to share my configuration and your helps are valuable. Moreover, if you have experienced this situation before, it is good to know that the cell itself has problems (at high power discharge and rising temperature).

Can you test cell capacity at lower temps? At and below -0 C? These are reported to perform well at low temps but I haven’t seen testing confirmation.

wiredsim said:

Can you test cell capacity at lower temps? At and below -0 C? These are reported to perform well at low temps but I haven’t seen testing confirmation.

Click to expand...

You might mean the ambient temperature < 0C? If so, I am sorry that it is impossible for me to do. We just can conduct tests in 25 - 35 degree C. Packing the cells in close spaced keep the temperature rising quickly.

Yes- I suppose for my purposes I’d be interested in seeing the cells start at somewhere between -40 and -20 and then how quickly they raise to higher operating temps and what that impact is to total capacity.