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[pacificcricket]

Folks, I have this 10 year old bike with a firmware that's probably ~4 years old and SoC has been going crazy last couple of years. The bike would charge to 100% but while plugged in would go down to 97% or so within an hour or so. Then when riding SoC drops very fast, which arguably is expected for an old battery, but then I could arrive at my destination at as little as a 0% SoC left, and within an hour of being switched off SoC can go up anywhere from 20 to 30%. Likewise sometimes when getting down to 0% at highway speed, getting to the surface and slowing down to 25-35MPH SoC will start climbing back up to 10-15%.

Any idea what's going on with the BMS ?

[MVetter]

Sounds like one or more weak cells are showing their age. Start watching the cell balance field in your Zero app. You can quickly blip your kill switch at stop lights to see the value shown on your app if you've got your phone easily viewable on the bike during rides. I wouldn't be surprised if it's high double or even triple digits at times.

If you want to be more thorough you can download the bike's logs on your phone and then upload them using Greg's parsing tools: https://home.hasslers.net/zerologparser/log_parser.php

Post the link for the BMS logs here and I can look them over and try and make sense of it.

[pacificcricket]

Great suggestion, will try to pull the logs and analyze them next time I'm seeing that. Thank you.

[MVetter]

The logs have a TON of archived data in them. It may even go back years. There's no reason to wait. Pull them now.

[pacificcricket]

Seeing this on the last ride :

04040     06/14/2024 19:37:19   INFO:  Enabling Charger 3
 04041     06/14/2024 19:37:19   CIB timeout: 5001 ms
 04042     06/14/2024 19:37:24   Disarmed                   PackTemp: h 25C, l 25C, PackSOC: 73%, Vpack:107.588V, MotAmps:   0, BattAmps:   1, Mods: 01, MotTemp:  24C, CtrlTemp:  19C, AmbTemp:  21C, MotRPM:   0, Odo:52141km
 04043     06/14/2024 19:38:24   Disarmed                   PackTemp: h 25C, l 25C, PackSOC: 73%, Vpack:107.575V, MotAmps:   0, BattAmps:   0, Mods: 01, MotTemp:  23C, CtrlTemp:  19C, AmbTemp:  21C, MotRPM:   0, Odo:52141km
 04044     06/14/2024 19:38:53   DEBUG: Module scheme changed from Stopped mode to Running mode
 04045     06/14/2024 19:38:53   DEBUG: Module mode Change Does Not Require Disconnect
 04046     06/14/2024 19:39:24   Riding                     PackTemp: h 25C, l 24C, PackSOC: 72%, Vpack:107.502V, MotAmps:   0, BattAmps:   1, Mods: 10, MotTemp:  25C, CtrlTemp:  20C, AmbTemp:  20C, MotRPM: 255, Odo:52141km
 04047     06/14/2024 19:40:24   Riding                     PackTemp: h 25C, l 24C, PackSOC: 72%, Vpack:108.188V, MotAmps: -68, BattAmps: -36, Mods: 10, MotTemp:  29C, CtrlTemp:  23C, AmbTemp:  20C, MotRPM:2134, Odo:52141km
 04048     06/14/2024 19:41:24   Riding                     PackTemp: h 25C, l 24C, PackSOC: 71%, Vpack:104.037V, MotAmps:  77, BattAmps:  53, Mods: 10, MotTemp:  33C, CtrlTemp:  24C, AmbTemp:  20C, MotRPM:2886, Odo:52142km
 04049     06/14/2024 19:42:24   Riding                     PackTemp: h 25C, l 25C, PackSOC: 68%, Vpack: 99.342V, MotAmps: 111, BattAmps: 107, Mods: 10, MotTemp:  37C, CtrlTemp:  27C, AmbTemp:  19C, MotRPM:3756, Odo:52143km
 04050     06/14/2024 19:42:24   Batt Dischg Cur Limited    667 A (97.80%), MinCell: 3526mV, MaxPackTemp: 25C
 04051     06/14/2024 19:43:24   Riding                     PackTemp: h 26C, l 25C, PackSOC: 64%, Vpack: 96.691V, MotAmps: 115, BattAmps: 107, Mods: 10, MotTemp:  41C, CtrlTemp:  28C, AmbTemp:  18C, MotRPM:3758, Odo:52145km
 04052     06/14/2024 19:43:24   Batt Dischg Cur Limited    551 A (80.79%), MinCell: 3423mV, MaxPackTemp: 26C
 04053     06/14/2024 19:44:24   Riding                     PackTemp: h 26C, l 26C, PackSOC: 59%, Vpack: 96.708V, MotAmps: 114, BattAmps: 109, Mods: 10, MotTemp:  44C, CtrlTemp:  29C, AmbTemp:  19C, MotRPM:3756, Odo:52146km
 04054     06/14/2024 19:44:24   Batt Dischg Cur Limited    497 A (72.87%), MinCell: 3408mV, MaxPackTemp: 26C
 04055     06/14/2024 19:45:24   Riding                     PackTemp: h 27C, l 26C, PackSOC: 51%, Vpack: 94.580V, MotAmps: 113, BattAmps: 113, Mods: 10, MotTemp:  47C, CtrlTemp:  30C, AmbTemp:  19C, MotRPM:3754, Odo:52148km
 04056     06/14/2024 19:45:24   Batt Dischg Cur Limited    403 A (59.09%), MinCell: 3317mV, MaxPackTemp: 27C
 04057     06/14/2024 19:46:25   Riding                     PackTemp: h 28C, l 27C, PackSOC: 40%, Vpack: 93.760V, MotAmps: 102, BattAmps: 113, Mods: 10, MotTemp:  50C, CtrlTemp:  31C, AmbTemp:  19C, MotRPM:3753, Odo:52150km
 04058     06/14/2024 19:46:25   Batt Dischg Cur Limited    322 A (47.21%), MinCell: 3285mV, MaxPackTemp: 28C
 04059     06/14/2024 19:47:24   Riding                     PackTemp: h 29C, l 28C, PackSOC: 30%, Vpack: 94.631V, MotAmps: 109, BattAmps: 104, Mods: 10, MotTemp:  52C, CtrlTemp:  31C, AmbTemp:  18C, MotRPM:3759, Odo:52151km
 04060     06/14/2024 19:47:24   Batt Dischg Cur Limited    333 A (48.83%), MinCell: 3301mV, MaxPackTemp: 29C
 04061     06/14/2024 19:48:24   Riding                     PackTemp: h 30C, l 29C, PackSOC: 22%, Vpack: 94.335V, MotAmps:  94, BattAmps: 103, Mods: 10, MotTemp:  54C, CtrlTemp:  31C, AmbTemp:  18C, MotRPM:3755, Odo:52153km
 04062     06/14/2024 19:48:24   Batt Dischg Cur Limited    330 A (48.39%), MinCell: 3278mV, MaxPackTemp: 30C
 04063     06/14/2024 19:49:25   Riding                     PackTemp: h 31C, l 29C, PackSOC: 14%, Vpack: 93.334V, MotAmps: 106, BattAmps: 116, Mods: 10, MotTemp:  56C, CtrlTemp:  32C, AmbTemp:  18C, MotRPM:3757, Odo:52154km
 04064     06/14/2024 19:49:25   Batt Dischg Cur Limited    237 A (34.75%), MinCell: 3243mV, MaxPackTemp: 31C
 04065     06/14/2024 19:50:25   Riding                     PackTemp: h 32C, l 30C, PackSOC:  9%, Vpack: 92.906V, MotAmps: 117, BattAmps: 123, Mods: 10, MotTemp:  57C, CtrlTemp:  32C, AmbTemp:  18C, MotRPM:3753, Odo:52156km
 04066     06/14/2024 19:50:25   Batt Dischg Cur Limited    242 A (35.48%), MinCell: 3233mV, MaxPackTemp: 32C
 04067     06/14/2024 19:51:25   Riding                     PackTemp: h 33C, l 31C, PackSOC:  6%, Vpack: 93.582V, MotAmps: 103, BattAmps:  98, Mods: 10, MotTemp:  59C, CtrlTemp:  32C, AmbTemp:  18C, MotRPM:3755, Odo:52158km
 04068     06/14/2024 19:51:25   Batt Dischg Cur Limited    167 A (24.49%), MinCell: 3230mV, MaxPackTemp: 33C
 04069     06/14/2024 19:52:25   Riding                     PackTemp: h 34C, l 32C, PackSOC:  4%, Vpack: 92.327V, MotAmps:   0, BattAmps:1860, Mods: 00, MotTemp:16973C, CtrlTemp:  66C, AmbTemp:-14336C, MotRPM:20140, Odo:476295km
 04070                       0   0x00 

[pacificcricket]

And BMS was reporting this around the same time :

02983     06/14/2024 19:39:15   ERROR: PL536 had 1 invalid cell events
 02984     06/14/2024 19:39:15          Worst event: 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 23438, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000
 02985     06/14/2024 19:39:15          ADC Data   : 2755, 274F, 2735, 273E, 274B, 2748, 2755, 2747, 274E, 275D, 2754, 2751, 2759, 2756, 275F, F000, 0000, 0000, 2751, 2754, 2752, 2752, 2752, 2756, 275C, 2759, 275D, 274D
 02986     06/14/2024 19:39:16   ERROR: 4/6000   PL536 Read Attempts Failed. Breakdown: conv- 0, (crc,timeout)- 1=(1,0) 2=(2,0) 3=(38,0) 4=(16,0) 5=(10,0)
 02987     06/14/2024 19:39:17   Discharge level            025 AH, SOC: 72%, I:  0A, L:3830, l:3832, H:3845, B:015, PT:025C, BT:028C, PV:107530, M:Bike On
 02988     06/14/2024 19:39:17   SOC:25510,91076,25520,91080,72,72,72,2
 02989     06/14/2024 19:40:15   ERROR: PL536 had 1 invalid cell events
 02990     06/14/2024 19:40:15          Worst event: 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000, 0000
 02991     06/14/2024 19:40:15          ADC Data   : 2733, 272E, 2718, 271C, 2729, 272C, 2735, 2727, 272F, 2740, 2735, 2731, 2738, 2737, 27FE, 0000, 0000, 0000, 2731, 2736, 2731, 2732, 2732, 2735, 273C, 2738, 273E, 272E
 02992     06/14/2024 19:40:17   Discharge level            025 AH, SOC: 72%, I: 21A, L:3776, l:3816, H:3793, B:017, PT:025C, BT:029C, PV:106023, M:Bike On
 02993     06/14/2024 19:40:17   SOC:25729,90615,25804,91080,72,71,72,39
 02994     06/14/2024 19:41:17   Discharge level            026 AH, SOC: 72%, I: 68A, L:3687, l:3765, H:3706, B:019, PT:025C, BT:029C, PV:103568, M:Bike On
 02995     06/14/2024 19:41:17   SOC:25967,89964,26124,91080,72,65,72,77
 02996     06/14/2024 19:41:17   ERROR: 1/6000   PL536 Read Attempts Failed. Breakdown: conv- 0, (crc,timeout)- 1=(3,0) 2=(3,0) 3=(29,0) 4=(6,0) 5=(1,0)
 02997     06/14/2024 19:42:17   Discharge level            027 AH, SOC: 69%, I:102A, L:3557, l:3705, H:3584, B:027, PT:025C, BT:029C, PV:100029, M:Bike On
 02998     06/14/2024 19:42:17   SOC:27503,87079,27662,91080,70,58,69,149
 02999     06/14/2024 19:43:17   Discharge level            029 AH, SOC: 65%, I:110A, L:3438, l:3611, H:3485, B:047, PT:026C, BT:030C, PV: 96958, M:Bike On
 03000     06/14/2024 19:43:17   SOC:29381,82047,29542,91080,68,43,65,185
 03001     06/14/2024 19:43:17   Discharge cutback          82%
 03002     06/14/2024 19:43:17   559A
 03003     06/14/2024 19:44:17   Discharge level            031 AH, SOC: 59%, I: 91A, L:3405, l:3558, H:3476, B:071, PT:026C, BT:029C, PV: 96560, M:Bike On
 03004     06/14/2024 19:44:17   SOC:31103,75732,31266,91080,66,31,59,173
 03005     06/14/2024 19:44:17   Discharge cutback          73%
 03006     06/14/2024 19:44:17   500A
 03007     06/14/2024 19:45:17   Discharge level            033 AH, SOC: 52%, I:120A, L:3346, l:3518, H:3442, B:096, PT:027C, BT:030C, PV: 95390, M:Bike On
 03008     06/14/2024 19:45:17   SOC:32884,67822,33048,91080,64,19,52,200
 03009     06/14/2024 19:45:17   Discharge cutback          60%
 03010     06/14/2024 19:45:17   409A
 03011     06/14/2024 19:46:17   Discharge level            034 AH, SOC: 42%, I:115A, L:3269, l:3441, H:3397, B:128, PT:028C, BT:030C, PV: 93825, M:Bike On
 03012     06/14/2024 19:46:17   SOC:34832,59355,34997,91080,62,5,42,208
 03013     06/14/2024 19:46:17   Discharge cutback          46%
 03014     06/14/2024 19:46:17   315A
 03015     06/14/2024 19:47:17   Discharge level            036 AH, SOC: 32%, I:110A, L:3268, l:3433, H:3394, B:126, PT:029C, BT:030C, PV: 93805, M:Bike On
 03016     06/14/2024 19:47:17   SOC:36654,53199,36821,91080,60,4,32,202
 03017     06/14/2024 19:47:17   Discharge cutback          49%
 03018     06/14/2024 19:47:17   331A
 03019     06/14/2024 19:48:17   Discharge level            038 AH, SOC: 23%, I:117A, L:3285, l:3450, H:3411, B:126, PT:030C, BT:030C, PV: 94247, M:Bike On
 03020     06/14/2024 19:48:17   SOC:38411,49485,38580,91080,58,6,23,200
 03021     06/14/2024 19:48:17   Discharge cutback          48%
 03022     06/14/2024 19:48:17   329A

[MVetter]

I was hoping you'd just post a link to the entire log because I'm only able to see tiny bits of it now. I'm more interested in the BMS logs than MBB ones.

Regardless, what I will say is that over the course of 5 minutes your pack balance plummeted from 19mV to 128mV. The cell in question dropped like a stone from 3.765vdc, which is like 55%ish, down to 3.269vdc which is like -10%. Shows all the signs of an old, worn out pack. A pack is only as good as its weakest cell and you've got at least one fairly weak cell in there.

[pacificcricket]

Here is the entire log: https://home.hasslers.net/zerologparser/logs/538SD5Z29ECB03576_BMS0_2024-06-18.txt

Indeed, weak cell could be doing it. So the thing I don't understand, and it goes back to my original question - does the BMS balance it while the bike is switched off ? How is it draining it to zero and then recovering on its own over time ?

[MVetter]

You've definitely got one or more weak cells in there.

00869     05/19/2024 18:20:33   Discharge level            024 AH, SOC: 56%, I:136A, L:3206, l:3411, H:3397, B:191, PT:026C, BT:027C, PV: 93315, M:Bike On

That's 191mV out of balance. To answer your question, balancing is something the BMS does when the bike is in charge mode, plugged in, and is somewhere above 110 volts if I'm not mistaken. So like 80% and above. At least that's what I was told.

[pacificcricket]

Yeah, balancing during charging is what I'd expect too, but somehow the SoC keeps climbing while in storage.

[MVetter]

That's due to voltage recovery. Like we've established, you've got one or more weak cells that is *plummeting* before the others. Often times when the pack is turned off, these cells will recover a lot of that voltage so the pack adjusts accordingly.

[pacificcricket]

I've never seen cells doing voltage recovery in this fashion (I have several DIY packs in projects). Without load voltage will recover some, but it's not going to grow the longer the load is removed.

[MVetter]

02572     06/11/2024 13:43:26   Discharge level            061 AH, SOC:  5%, I:  0A, L:3418, l:3456, H:3500, B:082, PT:039C, BT:038C, PV: 97245, M:Idle

PV = Pack Voltage = 97.245. Bike is keyed off around 1:43pm that day.

02590     06/11/2024 15:29:45   Discharge level            069 AH, SOC: 24%, I:  0A, L:3534, l:3534, H:3546, B:012, PT:034C, BT:030C, PV: 99184, M:Bike On

Bike turned off for a bit. At 3:29pm the bike is turned back on and PV = 99.184vdc. Lowest cell went from 3.418vdc to 3.534vdc. Highest cell went from 3.500vdc to 3.546vdc. Sitting idle for an hour the pack voltage went up 1.939 volts and the SoC went from 5% to 24%. I'm just trying to make sense of the bike's data shown here.

[pacificcricket]

Yeah, I appreciate you trying to help out. The data is a bit weird with this one.