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post #21 of 27 (permalink) Old 09-04-2016, 09:52 PM
 
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Quote:
Originally Posted by SuperSmartie View Post
Battery capacity is always measured in Ah. The kWh energy capacity is very dependent on discharge conditions, so it's always just a "nominal" value, assuming some "nominal" voltage, typically 3.7V for LiIon. Don't pay too much attention to the kWh figures, focus on the Ah ones.



Only in so far that the two diverge at the low end: When the dashboard guessgauge shows zero, the BMS typically still shows >10% left, which is really there and can be used (I tested that). So you can still get home if the dashboard gauge hits zero and you have a few miles left to go.
Problem is, without the odyssey box you can't depend on it. The difference is not always 10%, it can be anywhere between zero and 20%.



Excellent! The more heads, the more ideas!
How about building a local display that shows realSOC, so you really can use the hidden potential?
The problem here is whether tapping this "hidden" capacity involves drawing some of the battery cells down below their safe minimum discharge voltage -- this can do irreparable damage to the traction battery.

I'd assume the stock battery controller allows for a broad safety (and battery longevity) margin. How much of either or both are you willing to give up for more range?
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post #22 of 27 (permalink) Old 09-06-2016, 08:49 AM
 
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The BMS prevents deep-discharge. It disconnects the battery when the first cell drops to 3.0V. This is after the car first stopped and had to be turned off and on again to drive a bit further.

Now it may still not be great for the battery to go there regularly. But in a pinch, I'd rather know when it'll run out before it does.
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post #23 of 27 (permalink) Old 10-10-2016, 08:32 AM
 
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Since I play around a bit with arduinos, I may put one of these together as well.

Slightly off topic but on the battery issue, does anybody know what the purpose of the recent factory software update for our batteries, was for? I had it done before I picked up my new 2014 Electric model. Just curious what it was about, if anybody knows.
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post #24 of 27 (permalink) Old 11-11-2016, 07:54 AM
 
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Originally Posted by cornwallav8r View Post
Since I play around a bit with arduinos, I may put one of these together as well.

Slightly off topic but on the battery issue, does anybody know what the purpose of the recent factory software update for our batteries, was for? I had it done before I picked up my new 2014 Electric model. Just curious what it was about, if anybody knows.
Ok, just to update my progress. I assembled and tested one of these, it works quite well! Had an unrelated problem with the CANBUS adapter, and then with an old Arduino board since replaced, but the software and utility of the thing is quite stellar.

Thanks again to the author @odyssey for this project.
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post #25 of 27 (permalink) Old 11-13-2016, 06:57 AM
 
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My battery stats, just for fun.
MS >>all
Reading data....................OK
-----------------------------------------
Time [hh:mm]: 09:34, ODO : 867 km
-----------------------------------------
Battery-Production [Y/M/D]: 2014/2/25
Rev.[Y/WK/PL] HW:2014/7/0, SW:2014/18/0
-----------------------------------------
SOC : 100.0 %, realSOC: 97.6 %
HV : 387.1 V, -0.53 A, -0.21 kW
LV : 14.5 V
-----------------------------------------
CV mean : 4156 mV, dV = 26 mV
CV min : 4133 mV
CV max : 4159 mV
OCVtimer: 5208 s
-----------------------------------------
Last measurement : 38 day(s)
Measurement estimation: 0.547
Actual estimation : 0.241
CAP mean: 18972 As/10, 52.7 Ah
CAP min : 18332 As/10, 50.9 Ah
CAP max : 18653 As/10, 51.8 Ah
-----------------------------------------
HV contactor state ON, low current: 152 s
cycles left : 299055
of max. cycles: 300000
DC isolation : 65534 kOhm, NO FAULT
-----------------------------------------
Temperatures Battery-Unit /degC:
module 1: 14.3, 15.4, 14.0
module 2: 14.5, 15.7, 14.1
module 3: 13.9, 15.3, 13.1
mean : 14.5, min : 13.1, max : 15.7
coolant : 12.2
-----------------------------------------
# ;mV ;As/10
01;4157;18910
02;4156;18788
03;4157;18547
04;4158;18941
05;4158;18757
06;4158;18697
07;4158;18879
08;4158;18818
09;4158;18818
10;4158;18879
11;4157;18849
12;4156;18941
13;4157;18667
14;4157;18757
15;4159;18757
16;4158;18697
17;4157;18879
18;4158;18849
19;4157;18667
20;4157;18697
21;4156;18667
22;4158;18757
23;4158;18757
24;4157;18788
25;4158;18879
26;4158;18667
27;4157;18727
28;4157;18727
29;4157;18697
30;4157;18757
31;4156;18577
32;4156;18818
33;4157;18788
34;4157;18879
35;4157;18849
36;4158;18941
37;4157;18879
38;4157;18788
39;4158;18697
40;4153;18637
41;4158;18697
42;4156;18727
43;4156;18941
44;4158;18577
45;4158;18818
46;4154;18849
47;4158;18849
48;4155;18941
49;4157;18849
50;4155;18757
51;4158;18697
52;4157;18727
53;4156;18788
54;4157;18788
55;4157;18697
56;4156;18757
57;4157;18788
58;4157;18757
59;4155;18757
60;4156;18910
61;4157;18879
62;4156;18757
63;4157;18788
64;4157;18788
65;4156;18727
66;4157;18788
67;4156;18727
68;4156;18818
69;4157;18818
70;4133;19351
71;4157;18667
72;4156;18757
73;4158;18818
74;4158;18757
75;4157;18637
76;4156;18818
77;4158;18757
78;4157;18577
79;4158;18788
80;4158;18818
81;4158;18757
82;4156;18788
83;4157;18788
84;4158;18818
85;4158;18788
86;4157;18941
87;4158;18910
88;4157;18910
89;4158;18849
90;4158;18818
91;4158;18637
92;4158;18667
93;4157;18727
-----------------------------------------
Individual Cell Statistics:
-----------------------------------------
CV mean : 4157 mV, dV= 26 mV, s= 2.67 mV
CV min : 4133 mV, # 70
CV max : 4159 mV, # 15
-----------------------------------------
CAP mean: 18785 As/10, 52.2 Ah
CAP min : 18547 As/10, 51.5 Ah, # 3
CAP max : 19351 As/10, 53.8 Ah, # 70
-----------------------------------------
*** Experimental Data - NOT VERIFIED ***
Maximum Capacity @45C: 56.3 Ah
Aging-Loss: 0.004 %
Unknown Counter: 0x2E00D
-----------------------------------------
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post #26 of 27 (permalink) Old 01-10-2017, 12:34 PM
 
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Thanks to OP. I built one of this and it is super useful. Thanks again.
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post #27 of 27 (permalink) Old 02-25-2017, 05:21 PM
 
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Garage
As a life-long software developer with little-to-no electronics skills (last time I tried to solder anything I burnt the IC out), I decided to try grabbing a Freematics OBD-II dongle (Arduino-compatible) and port Odyssey's code to it. I'll keep posting updates here as I go along.
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