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Discussion Starter #1 (Edited)
I ran ED BMS Diag and while all the other numbers seem good, the very first bit says "Battery Status: DEGRADED". There's only one comment in the headers that says "Flag showing if degraded cells are found, or battery failiure present." It looks like my battery capacity is down about 10% which seems quick for 24,000km -- although I guess it's close to four years old now...

194 days ago:
CAP mean: 18503 As/10, 51.4 Ah
CAP min : 18672 As/10, 51.9 Ah
CAP max : 18894 As/10, 52.5 Ah

This test:
CAP mean: 17068 As/10, 47.4 Ah
CAP min : 16855 As/10, 46.8 Ah, # 57
CAP max : 17318 As/10, 48.1 Ah, # 7

I suppose I should take it in before the official 48 months? Is there anything they'll do under warranty.

Code:
-----------------------------------------
--- ED Battery Management Diagnostics ---
--- v1.0.1                            ---
-----------------------------------------
Connect to OBD port - Waiting for CAN-Bus 


CMD >>all
Reading data....................OK
-----------------------------------------
Time [hh:mm]: 11:02,   ODO : 24377 km
-----------------------------------------
Battery Status   : DEGRADED

Battery Production [Y/M/D]: 2014/1/15
Battery-FAT date   [Y/M/D]: 2014/1/16
Rev.[Y/WK/PL] HW:2013/29/0, SW:2014/18/0
-----------------------------------------
SOC : 100.0 %, realSOC: 98.5 %
HV  : 388.1 V, -0.41 A, -0.16 kW
LV  : 14.4 V
-----------------------------------------
CV mean : 4169 mV, dV = 26 mV
CV min  : 4145 mV
CV max  : 4171 mV
OCVtimer: 4155 s
-----------------------------------------
Last measurement      : 194 day(s)
Measurement estimation: 0.706
Actual estimation     : 0.094
CAP mean: 18503 As/10, 51.4 Ah
CAP min : 18672 As/10, 51.9 Ah
CAP max : 18894 As/10, 52.5 Ah
-----------------------------------------
HV contactor state ON, low current: 34 s
Cycles left   : 289843
of max. cycles: 300000
DC isolation  : 11405 kOhm, OK
-----------------------------------------
Temperatures Battery-Unit /degC: 
module 1: 16.0, 17.2, 16.7
module 2: 16.7, 17.8, 16.8
module 3: 16.2, 17.5, 16.2
   mean : 16.8, min : 16.0, max : 17.8
coolant : 15.6
-----------------------------------------
# ;mV  ;As/10
01;4169;17045
02;4169;17200
03;4169;17200
04;4169;17200
05;4169;17160
06;4169;17083
07;4170;17318
08;4170;17278
09;4170;17045
10;4170;17122
11;4170;17318
12;4170;17045
13;4169;16968
14;4169;17006
15;4169;17083
16;4168;17006
17;4169;17045
18;4170;17045
19;4170;17045
20;4169;17083
21;4169;17045
22;4170;17083
23;4170;17122
24;4170;17083
25;4168;17083
26;4168;17006
27;4169;17160
28;4170;17122
29;4169;17083
30;4169;17122
31;4169;17160
32;4170;17006
33;4170;17006
34;4170;17006
35;4169;17045
36;4170;17045
37;4168;17083
38;4171;17045
39;4170;16968
40;4171;16930
41;4170;16968
42;4170;16930
43;4171;17083
44;4170;17083
45;4170;17006
46;4169;17045
47;4168;17045
48;4171;17045
49;4168;17045
50;4170;17006
51;4169;17045
52;4171;17045
53;4169;17083
54;4170;17083
55;4169;17160
56;4169;17045
57;4145;16855
58;4170;17045
59;4170;17006
60;4169;16968
61;4170;17083
62;4170;17045
63;4170;17083
64;4169;17083
65;4168;17083
66;4170;17083
67;4168;17083
68;4170;17083
69;4168;17006
70;4169;17083
71;4169;17045
72;4170;17083
73;4170;17083
74;4170;17083
75;4169;17083
76;4170;17122
77;4170;17045
78;4170;17122
79;4170;17122
80;4169;17083
81;4168;17160
82;4170;17122
83;4169;17083
84;4168;17045
85;4170;17006
86;4169;17045
87;4168;17006
88;4168;16968
89;4170;17122
90;4169;17083
91;4168;17006
92;4168;16968
93;4169;17006
-----------------------------------------
Individual Cell Statistics:
-----------------------------------------
CV mean : 4169 mV, dV= 26 mV, s= 2.64 mV
CV min  : 4145 mV, # 57
CV max  : 4171 mV, # 38
-----------------------------------------
CAP mean: 17068 As/10, 47.4 Ah
CAP min : 16855 As/10, 46.8 Ah, # 57
CAP max : 17318 As/10, 48.1 Ah, # 7
-----------------------------------------
Voltage Distribution (dV= 26 mV):
*---------------------------------->[=]-*
4145   00 > [4169; 4169; 4170] < 00  4171
min         [p25; median; p75]        max
-----------------------------------------
Reading data....OK
-----------------------------------------
Status OBL Charger-Unit: 
User selected : 16 A
Cable maximum : 204 A
AC L1: 124.0 V, 0.6 A
DC HV: 388.2 V, 0.0 A
DC LV: 14.5 V
-----------------------------------------
Temperatures Charger-Unit /degC: 
Reported       : 15
Cooling plate  : 15
Inlet socket   : NA
-----------------------------------------
Reading data.OK
-----------------------------------------
Status Cooling- and Subsystems: 
Temperature   : 13.6 degC
Cooling fan   : 0.0 %
Cooling pump  : 38.0 %, 14 degC
              : 14.2 V, 0.2 A
OTR:
Cooling fan   : 4 h
Cooling pump  : 6063 h
Battery heater: 0 h, OFF
Vaccum pump   : 32.192 h
Pressure 1, 2 : -595 mbar, -600 mbar
-----------------------------------------
 

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Curious - did you run the test the same way as the first one? Did you follow the procedure that seems to be the European standard. IIRC discharge the battery to under 40% for at least two hours, recharge it to 100% and then run the test.

As I own two of these, I'm very interested in what you find out.

Len
2014 EV Coupe 12,500 miles
2014 EV Cabriolet 1,700 miles
 

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Curious - did you run the test the same way as the first one? Did you follow the procedure that seems to be the European standard. IIRC discharge the battery to under 40% for at least two hours, recharge it to 100% and then run the test.
And the question was still open whether the the 40% SOC was in absolute terms rather than the indicator, so it should be run down to a bit below 20 percent just to be sure.

That much degradation in only a half year sure seems like an awful lot after almost no degradation for 3 years.
 

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Discussion Starter #4
And the question was still open whether the the 40% SOC was in absolute terms rather than the indicator, so it should be run down to a bit below 20 percent just to be sure.

That much degradation in only a half year sure seems like an awful lot after almost no degradation for 3 years.
FWIW, 196 days aligns with nothing. The last time I had it into Mercedes was March 2016 -- that's a lot longer than 196 days. I'm not sure where that comes from. Since running the last test, two days have passed, so it's counting from something.

Took it down to 33% for about half an hour and reran the test. I'll wait until it's 100% and run it again. Tomorrow, I'll see if I can get it down to under 20% and do the two-hours wait.

Code:
-----------------------------------------
--- ED Battery Management Diagnostics ---
--- v1.0.1                            ---
-----------------------------------------
Connect to OBD port - Waiting for CAN-Bus 
........CONNECTED
-----------------------------------------
Reading data........
-----------------------------------------
Time [hh:mm]: 18:31,   ODO : 24419 km
-----------------------------------------
SOC : 33.0 %, realSOC: 41.2 %
HV  : 336.8 V, -1.10 A, -0.37 kW
LV  : 12.9 V
-----------------------------------------
ENTER command... (? for help)
CMD >>all
Reading data....................OK
-----------------------------------------
Time [hh:mm]: 18:31,   ODO : 24419 km
-----------------------------------------
Battery Status   : DEGRADED

Battery Production [Y/M/D]: 2014/1/15
Battery-FAT date   [Y/M/D]: 2014/1/16
Rev.[Y/WK/PL] HW:2013/29/0, SW:2014/18/0
-----------------------------------------
SOC : 33.0 %, realSOC: 41.2 %
HV  : 332.6 V, -15.69 A, -5.22 kW
LV  : 14.8 V
-----------------------------------------
CV mean : 3580 mV, dV = 28 mV
CV min  : 3561 mV
CV max  : 3589 mV
OCVtimer: 4521 s
-----------------------------------------
Last measurement      : 196 day(s)
Measurement estimation: 0.706
Actual estimation     : 0.093
CAP mean: 18503 As/10, 51.4 Ah
CAP min : 18672 As/10, 51.9 Ah
CAP max : 18894 As/10, 52.5 Ah
-----------------------------------------
HV contactor state ON, low current: 0 s
Cycles left   : 289838
of max. cycles: 300000
DC isolation  : 18016 kOhm, OK
-----------------------------------------
Temperatures Battery-Unit /degC: 
module 1: 13.5, 19.0, 14.6
module 2: 14.1, 19.2, 15.5
module 3: 13.1, 19.3, 16.1
   mean : 16.0, min : 13.1, max : 19.3
coolant : 6.3
-----------------------------------------
# ;mV  ;As/10
01;3561;17045
02;3578;17200
03;3584;17200
04;3583;17200
05;3585;17160
06;3586;17083
07;3588;17318
08;3587;17278
09;3582;17045
10;3583;17122
11;3590;17318
12;3583;17045
13;3583;16968
14;3583;17006
15;3583;17083
16;3582;17006
17;3582;17045
18;3583;17045
19;3584;17045
20;3582;17083
21;3582;17045
22;3583;17083
23;3584;17122
24;3582;17083
25;3582;17083
26;3582;17006
27;3581;17160
28;3582;17122
29;3578;17083
30;3576;17122
31;3566;17160
32;3562;17006
33;3573;17006
34;3577;17006
35;3580;17045
36;3583;17045
37;3583;17083
38;3583;17045
39;3582;16968
40;3582;16930
41;3583;16968
42;3583;16930
43;3584;17083
44;3583;17083
45;3583;17006
46;3584;17045
47;3583;17045
48;3585;17045
49;3583;17045
50;3582;17006
51;3583;17045
52;3584;17045
53;3584;17083
54;3584;17083
55;3582;17160
56;3583;17045
57;3571;16855
58;3583;17045
59;3582;17006
60;3578;16968
61;3578;17083
62;3566;17045
63;3562;17083
64;3572;17083
65;3578;17083
66;3579;17083
67;3580;17083
68;3582;17083
69;3582;17006
70;3582;17083
71;3580;17045
72;3584;17083
73;3584;17083
74;3583;17083
75;3583;17083
76;3583;17122
77;3583;17045
78;3583;17122
79;3586;17122
80;3583;17083
81;3584;17160
82;3584;17122
83;3582;17083
84;3582;17045
85;3583;17006
86;3585;17045
87;3582;17006
88;3582;16968
89;3585;17122
90;3580;17083
91;3579;17006
92;3575;16968
93;3567;17006
-----------------------------------------
Individual Cell Statistics:
-----------------------------------------
CV mean : 3581 mV, dV= 29 mV, s= 5.35 mV
CV min  : 3561 mV, # 1
CV max  : 3590 mV, # 11
-----------------------------------------
CAP mean: 17068 As/10, 47.4 Ah
CAP min : 16855 As/10, 46.8 Ah, # 57
CAP max : 17318 As/10, 48.1 Ah, # 7
-----------------------------------------
Voltage Distribution (dV= 29 mV):
*---------------------->---[==|---<-----*
3561   11 > [3581; 3583; 3583] < 02  3590
min         [p25; median; p75]        max
-----------------------------------------
Reading data....OK
-----------------------------------------
Status OBL Charger-Unit: 
User selected : 16 A
Cable maximum : 204 A
AC L1: 0.0 V, 0.0 A
DC HV: 0.0 V, 0.0 A
DC LV: 14.9 V
-----------------------------------------
Temperatures Charger-Unit /degC: 
Reported       : NA
Cooling plate  : NA
Inlet socket   : NA
-----------------------------------------
Reading data.OK
-----------------------------------------
Status Cooling- and Subsystems: 
Temperature   : 7.1 degC
Cooling fan   : 0.0 %
Cooling pump  : 75.3 %, 9 degC
              : 14.3 V, 2.2 A
OTR:
Cooling fan   : 4 h
Cooling pump  : 6065 h
Battery heater: 0 h, OFF
Vaccum pump   : 32.225 h
Pressure 1, 2 : -533 mbar, -538 mbar
-----------------------------------------
 

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Discussion Starter #7 (Edited)
Getting the chance to get it down under 20% SoC. Here's the dump: It seems the battery status has returned to OK, which is great news. Now I'll charge it back up to 100% and see what I hit. Seems like every now and then a really deep cycle is good for the system? I always thought keeping the battery around 60 to 70% was ideal and that deep cycles were bad...?

Code:
CMD >>all
Reading data....................OK
-----------------------------------------
Time [hh:mm]: 18:43,   ODO : 24854 km
-----------------------------------------
Battery Status   : OK

Battery Production [Y/M/D]: 2014/1/15
Battery-FAT date   [Y/M/D]: 2014/1/16
Rev.[Y/WK/PL] HW:2013/29/0, SW:2014/18/0
-----------------------------------------
SOC : 16.5 %, realSOC: 22.6 %
HV  : 330.3 V, -0.78 A, -0.26 kW
LV  : 14.3 V
-----------------------------------------
CV mean : 3541 mV, dV = 12 mV
CV min  : 3532 mV
CV max  : 3544 mV
OCVtimer: 1338 s
-----------------------------------------
Last measurement      : 211 day(s)
Measurement estimation: 0.706
Actual estimation     : 0.088
CAP mean: 18503 As/10, 51.4 Ah
CAP min : 18672 As/10, 51.9 Ah
CAP max : 18894 As/10, 52.5 Ah
-----------------------------------------
HV contactor state ON, low current: 28 s
Cycles left   : 289788
of max. cycles: 300000
DC isolation  : 47493 kOhm, OK
-----------------------------------------
Temperatures Battery-Unit /degC: 
module 1: 22.3, 28.0, 23.3
module 2: 22.9, 28.3, 23.8
module 3: 21.8, 28.1, 24.4
   mean : 24.8, min : 21.8, max : 28.4
coolant : 14.8
-----------------------------------------
# ;mV  ;As/10
01;3534;17045
02;3538;17200
03;3541;17200
04;3540;17200
05;3540;17160
06;3545;17083
07;3542;17318
08;3541;17278
09;3542;17045
10;3542;17122
11;3542;17318
12;3543;17045
13;3543;16968
14;3543;17006
15;3544;17083
16;3541;17006
17;3542;17045
18;3542;17045
19;3542;17045
20;3541;17083
21;3542;17045
22;3543;17083
23;3545;17122
24;3543;17083
25;3544;17083
26;3543;17006
27;3541;17160
28;3543;17122
29;3541;17083
30;3541;17122
31;3538;17160
32;3535;17006
33;3539;17006
34;3541;17006
35;3541;17045
36;3543;17045
37;3542;17083
38;3542;17045
39;3541;16968
40;3541;16930
41;3542;16968
42;3541;16930
43;3543;17083
44;3542;17083
45;3541;17006
46;3542;17045
47;3542;17045
48;3543;17045
49;3543;17045
50;3542;17006
51;3543;17045
52;3543;17045
53;3542;17083
54;3544;17083
55;3543;17160
56;3543;17045
57;3532;16855
58;3543;17045
59;3543;17006
60;3541;16968
61;3541;17083
62;3538;17045
63;3536;17083
64;3539;17083
65;3541;17083
66;3542;17083
67;3541;17083
68;3543;17083
69;3541;17006
70;3542;17083
71;3541;17045
72;3543;17083
73;3542;17083
74;3543;17083
75;3544;17083
76;3543;17122
77;3543;17045
78;3544;17122
79;3545;17122
80;3543;17083
81;3544;17160
82;3543;17122
83;3543;17083
84;3542;17045
85;3543;17006
86;3543;17045
87;3542;17006
88;3541;16968
89;3544;17122
90;3542;17083
91;3541;17006
92;3539;16968
93;3537;17006
-----------------------------------------
Individual Cell Statistics:
-----------------------------------------
CV mean : 3542 mV, dV= 13 mV, s= 2.20 mV
CV min  : 3532 mV, # 57
CV max  : 3545 mV, # 6
-----------------------------------------
CAP mean: 17068 As/10, 47.4 Ah
CAP min : 16855 As/10, 46.8 Ah, # 57
CAP max : 17318 As/10, 48.1 Ah, # 7
-----------------------------------------
Voltage Distribution (dV= 13 mV):
*----------------->--------[==|==]------*
3532   04 > [3541; 3542; 3543] < 00  3545
min         [p25; median; p75]        max
-----------------------------------------
Reading data....OK
-----------------------------------------
Status OBL Charger-Unit: 
User selected : 16 A
Cable maximum : 204 A
AC L1: 0.0 V, 0.0 A
DC HV: 0.0 V, 0.0 A
DC LV: 14.4 V
-----------------------------------------
Temperatures Charger-Unit /degC: 
Reported       : NA
Cooling plate  : NA
Inlet socket   : NA
-----------------------------------------
Reading data.OK
-----------------------------------------
Status Cooling- and Subsystems: 
Temperature   : 14.5 degC
Cooling fan   : 0.0 %
Cooling pump  : 67.1 %, 16 degC
              : 13.9 V, 1.8 A
OTR:
Cooling fan   : 4 h
Cooling pump  : 6130 h
Battery heater: 0 h, OFF
Vaccum pump   : 32.684 h
Pressure 1, 2 : -687 mbar, -692 mbar
-----------------------------------------
 

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g
Seems like every now and then a really deep cycle is good for the system? I always thought keeping the battery around 60 to 70% was ideal and that deep cycles were bad...?
Deep cycling is definitely _not_ good for pack health - it is just that the battery management syatem will only make a accurate cell capacity measurement if they are cycled deeply. I'm sure the actual cell capacities never were degraded - although, I'm curious if the measurement changes when charging back full. It would seem to me that measurements taken during charging or discharging would work equally well at measuring capacity. Both ways shouldn't be needed, but your next test will tell.

It is important that the pack gets charged completely full semi-regularly because the syatem goes into a "balance mode" at the end of charging - basically throttling back the charging current and allowing each cell to be "topped off" to exactly the same voltages by shunting the current past the full cells to the not-quite full ones until they all have the very close to the same voltage. It's mechanically analogous to filling an ice tray where you reduce the faucet flow and allow the full ice-cube-cells to spill over to the ones that aren't full yet, until they are all even.

But otherwise, the ideal way to charge the car would be to not even fill the pack completely but instead manually shut off charging at the 90 percent point or so. This is inconvenient so I doubt anyone does it. I do use a timer on my EVSE (charging station) so that most of the time, the pack sits on full for no more than a couple hours before use. The "charge and depart" feature in the Smart ED is also supposed to do this, but I've never gotten it to work - it charges at the full rate until done no matter how I set it. The preheat/precool before departure does work though. It's very useful in winter - allowing you to pre-warm the inside of the car and melt the ice/snow using "shore power" instead of the battery.
 

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Discussion Starter #10
Deep cycling is definitely _not_ needed for pack health - it is just that the battery management syatem will only make a accurate cell capacity measurement if they are cycled deeply.
Gotcha.
It is important that the pack gets charged completely full semi-regularly because the syatem goes into a "balance mode" at the end of charging - basically throttling back the charging current and allowing each cell to be "topped off" to exactly the same voltages by shunting the current past the full cells to the not-quite full ones until they all have the same voltage. It's mechanically analogous to filling an ice tray where you reduce the faucet flow and allow the full ice-cube-cells to spill over to the ones that aren't full yet, until they are all even.

But otherwise, the ideal way to charge the car would be to not even fill the pack completely but instead manually shut off charging at the 90 percent point or so. This is inconvenient so I doubt anyone does it. I do use a timer on my EVSE (charging station) so that most of the time, the pack sits on full for no more than a couple hours before use. The "charge and depart" feature in the Smart ED is also supposed to do this, but I've never gotten it to work - it charges at the full rate until done no matter how I set it. The preheat/precool before departure does work though. It's very useful in winter - allowing you to pre-warm the inside of the car and melt the ice/snow using "shore power" instead of the battery.
I've heard that this doesn't work for ANYONE. But from the SoC vs Real SoC measurements, it's not really going to 100% anyway.
 

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Okay, I'm confused. Which Ah numbers are you supposed to use? I always thought it was the second set, i.e. these:

-----------------------------------------
CAP mean: 17068 As/10, 47.4 Ah
CAP min : 16855 As/10, 46.8 Ah, # 57
CAP max : 17318 As/10, 48.1 Ah, # 7

and they aren't so good and aren't that different from your first test that you were concerned about?

Len
2014 EV Coupe 12,600 miles
2014 EV Cabriolet 1,900 miles
 

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Discussion Starter #12
Okay, I'm confused. Which Ah numbers are you supposed to use? I always thought it was the second set, i.e. these:

-----------------------------------------
CAP mean: 17068 As/10, 47.4 Ah
CAP min : 16855 As/10, 46.8 Ah, # 57
CAP max : 17318 As/10, 48.1 Ah, # 7

and they aren't so good and aren't that different from your first test that you were concerned about?

Len
2014 EV Coupe 12,600 miles
2014 EV Cabriolet 1,900 miles
You're right, but this was at 16.5% SoC, so until I'm back to full and then it SHOULD remeasure CAP.
 

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Discussion Starter #13
So ... the "all" report isn't as useful as the Battery Report, which is a separate test. I've been unable to get that reading to change one iota or the days. But the "warm" estimate is near the original SoC. I guess testing in the cold makes a difference.

Code:
CMD >>rpt
Reading data....................OK
-----------------------------------------
---       Battery Status Report       ---
-----------------------------------------
Time [hh:mm]: 11:26,   ODO : 24872 km

Battery Status   : OK

Battery Production [Y/M/D]: 2014/1/15
Battery verified   [Y/M/D]: 2014/1/16

realSOC          : 80.2 %, SOC: 82.0 %
Charged capacity : 46.8 Ah, min. Cell# 57
BMS estimate     : 51.9 Ah, value @25degC 
Measurement done : 212 day(s) ago
* Watch timer for OCV state, redo test! *
Estimation factor: 0.706, poor!
*** Don't trust and redo measurement! ***

OCV timer        : 5414 s, @14.0degC
OCV state        : OK

DC isolation     : 9119 kOhm, OK

Voltage Distribution (dV= 29 mV):
*----------------------------->---[|=]--*
3929   08 > [3954; 3955; 3956] < 00  3958
min         [p25; median; p75]        max
-----------------------------------------
 
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