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[Froginhoo]

Hi,
hope someone can help me out solve this riddle. Recently I installed the Otten charger after my OBC got "kaputt" 😊

Now, when charging, I experienced a jump in SOC from 86% to 100% on the dashboard. I opened the app, it showed 100% as well but the bike was still charging und cell Voltage was at 115V. When I checked my BMS log today I found "SOC adjusted for voltage" and now I'm concerned. Is everything alright? Why, out of a sudden, did the BMS found such a huge gap in cell voltage? And what does "Voltage Across Contactor: -849mV (Possibly welded)" mean?

Code: [Select]

09751     07/11/2020 09:31:09   Discharge level            049 AH, SOC: 53%, I:-19A, L:3782, l:3770, H:3785, B:003, PT:021C, BT:035C, PV:105944, M:Charge
 09752     07/11/2020 09:41:09   Discharge level            046 AH, SOC: 55%, I:-19A, L:3808, l:3796, H:3811, B:003, PT:021C, BT:036C, PV:106663, M:Charge
 09753     07/11/2020 09:51:09   Discharge level            044 AH, SOC: 58%, I:-18A, L:3836, l:3825, H:3841, B:005, PT:022C, BT:037C, PV:107489, M:Charge
 09754     07/11/2020 10:01:09   Discharge level            041 AH, SOC: 60%, I:-19A, L:3867, l:3855, H:3872, B:005, PT:023C, BT:038C, PV:108358, M:Charge
 09755     07/11/2020 10:11:09   Discharge level            039 AH, SOC: 63%, I:-18A, L:3899, l:3888, H:3901, B:002, PT:023C, BT:039C, PV:109203, M:Charge
 09756     07/11/2020 10:21:09   Discharge level            036 AH, SOC: 65%, I:-18A, L:3927, l:3916, H:3930, B:003, PT:024C, BT:038C, PV:109999, M:Charge
 09757     07/11/2020 10:31:09   Discharge level            034 AH, SOC: 68%, I:-17A, L:3955, l:3945, H:3957, B:002, PT:024C, BT:039C, PV:110775, M:Charge
 09758     07/11/2020 10:41:09   Discharge level            031 AH, SOC: 70%, I:-18A, L:3983, l:3972, H:3985, B:002, PT:024C, BT:039C, PV:111555, M:Charge
 09759     07/11/2020 10:51:09   Discharge level            029 AH, SOC: 73%, I:-18A, L:4011, l:4000, H:4013, B:002, PT:025C, BT:039C, PV:112333, M:Charge
 09760     07/11/2020 10:56:20   Charged To Full            027 AH, SOC: 74%,         L:4026,         H:4028, B:002, PT:025C, BT:040C, PV:112759
 09761     07/11/2020 11:01:09   Discharge level            026 AH, SOC: 75%, I:-17A, L:4040, l:4030, H:4043, B:003, PT:025C, BT:040C, PV:113156, M:Charge
 09762     07/11/2020 11:49:39   DEBUG: CAN Link Is Down   
 09763     07/11/2020 11:49:43   DEBUG: CAN Link Is Up   
 09764     07/11/2020 11:49:43   Contactor was Opened       Pack V: 116974mV, Switched V: 118035mV, Prechg Pct: 101%, Dischg Cur: 4294950796mA
 09765     07/11/2020 11:49:44   DEBUG: CAN NOT Receiving Syncs   
 09766     07/11/2020 11:49:49   DEBUG: CAN Link Is Down   
 09767     07/11/2020 11:50:13   Voltage Across Contactor: -849mV (Possibly welded)   
 09768     07/11/2020 11:50:13   [color=yellow][b]SOC adjusted for voltage[/b][/color]   old:   15032065uAH (soc:86%), new:   0uAH (soc:100%), low cell: 4168 mV
 09769     07/11/2020 11:52:50   System Turned Off   
 09770     07/11/2020 11:52:50   DEBUG: Switching to voltage SOC mode. SOC: 100%, VSOC: 100%, Ihall: -750mA, Iext: 0mA   
 09771     07/11/2020 11:52:51   DEBUG: Entered Idle State   
 09772     07/11/2020 11:52:57   Current Sensor Zeroed      old: 2518mV, new: 2520mV, corrfact: 236
 09773     07/11/2020 11:52:58   Discharge level            000 AH, SOC:100%, I:000A, L:4161, l:4161, H:4163, B:002, PT:026C, BT:041C, PV:116535, M:Idle


[TheRan]

It kind of looks like part of the log is missing. The final charge status is 75% at 113.2v and then a few lines after it says 116.9v, and then the last line shows it sitting at 116.5v. The high and low cell values at 4.161v and 4.163v look normal and the balance of 2mV is also good.

[Froginhoo]

Thanks for your quick reply @TheRan
It‘s what came out of the log parser...
I don‘t know to to get better results though

[TheRan]

Didn't mean to imply you'd left anything out, I can tell by the line numbering that it's all there. What I meant is it almost seems like it stopped logging at some point. There's even a gap of 48 minutes, do you know it it was still charging from 11:00 to around 11:49? I would assume so as it would have only been at 75% at 11:00 and you said you saw it jump from 86% up to 100%.

As for the "SOC adjusted for voltage" thing, looking at it again I have a theory for what caused the jump. I don't think the bike bases the SOC solely on the battery voltage (makes sense, otherwise it would be constantly changing as the voltage drops under load and then recovers when resting) but rather also takes the capacity into account. Notice that it notes the capacity of 150Ah in the same line so it must think that would correspond to 86% SOC, but that's actually the 100% capacity (perhaps you've lost some over time, how many miles are on your bike?) so it re-calibrated itself (although I don't know why it says 0Ah is the new 100%).

[Froginhoo]

The bike now has a little more than 10.000km and is a 2016 SR.

As for the 49 Minutes I can‘t remember what happened during this time. But I will monitor my next charges and corresponding logs a little closer...

[BrianTRice@gmail.com]

The BMS changes modes of SoC indication in some conditions. Historically, it used to be that there'd be "coulomb counting" (integrating current over time to estimate discharge total) and "voltage-based estimation" (where the at-rest or operating voltage would be measured very well but then indirectly used to infer SoC).

On older firmware, when the battery comes to a resting state at the end of a charge, or when the bike is turned off and left to sit for a couple minutes, voltage estimation mode would kick in.

On newer firmware, there's a kind of multivariate model compiled from a lot of training, which had a lot of jumpy issues accommodating real world conditions it wasn't trained on, BUT it seems to be less jumpy now. Nevertheless, if there is a jump, it is likely because of this general concept of mode-switching in the SoC calculation method. I just can't speak to it very accurately without attempting to reverse engineer Zero's firmware, which I don't have time for.

One article about this for the Zero: https://zeromanual.com/wiki/State_of_Charge

Now, as to voltage itself, it is worth noting that battery terminal voltage is dynamic depending on charging and discharging (riding) operations. Voltage sags under the load of current going out, and voltage rises or lifts when current comes in, because of the internal resistance of the pack forming a circuit resistive element.

All of this to say that the rate of charge or discharge changes voltage by a more or less proportional amount, and so when charging tapers and stops, voltage levels off in a way that is reacting to the taper.

In short, it's complicated. Focus on whether the SoC indication is hard to work with (I think Zero doesn't do a good job helping the rider understand battery state, and the focus on SoC with no other indications is a weird product-design-engineering myopia that got us here).

[Froginhoo]

Thanks for your explanation BrianTRice. I‘m a lot less worried after all these postings here