Need to determine if logs look healthy. CAC good but has SOC dips to 0% w little mileage

[baselsalam]

I'm currently looking at purchasing a roadster, and got the logs and analyzed through VMSParser.

Even though the CAC looks pretty good (154+),
the SOC shows some odd statistics while the car was at the dealership.

It looks like this (hypothetical dates and mileage)

Date                Mileage  SOC%
1/1/2019 15:00      20000     66
<gap of a day>
1/3/2019 11:00      20000.5   0
1/4/2019 11:00      20000.5   62
1/5/2019 11:00      20000.5   61
1/6/2019 11:00      20000.5   61

So basically, there's a gap in the middle, followed by SOC of 0%, then back to an SOC slightly higher than before.
In addition, the time the daily logs are getting collected got reset.

Is this common?

Other than that, the 2 most significant recent drives are showing an extrapolated range of almost 200 miles
(58miles driven with 28% SOC drop).

 

[im4uttx]

If you have the logs, you should be able to see charging in addition to SOC% to see if there is something wrong with the 0% (does it show charged back up?) or something else. I would not worry too much about a "0%" reading in the middle of the dates without any charging getting it back to the same range as before/after.

Experts: I wonder if the ECC disconnect (?) was tripped? Would that have done this?

If the time was "corrected" due to changing from one time zone to another, that might change the collection time. More critical is the state of the battery, which 154+ seems good enough.

If you have the VIN, there are folks here that might be able to give more information on the history if it.

 

[baselsalam]

The SOC % indicates no charging activity around these times.

Here's another case, with no change in mileage at all:
SOC%
75
75
75
74
74
73
<gap>
0
72
72
71

 

[baselsalam]

Btw, before I was able to get a diagnostic dump on this roadster, I had to do a VMS reset (under passenger footwell, unplug blue/black plugs).

Before that it was giving me the "memory stick failure" error.

 

[im4uttx]

My understanding is the "memory stick failure" could be just the size of the memory stick, or something related to that. I have a 16G stick that is working fine, but first time, I got an error even though it apparently captured all the data. Since then I have not had trouble, but recommendation is 4Gb stick.

I see the 0% on first reading after VMS restart on my log, and another time after an error code 65535 (?) and record type XX05. Seems like could be some type of error causing these occasionally. I see 2-3 in 3 years.

 

[baselsalam]

Oh it def wasn't a memory stick issue, since I had it preformatted to match the tesla supplied stick, and the stick worked after the VMS reset.

History of these "drop to 0" incidents, with gradually declining SOC before/after indicating it wasn't charging:
2019/06
2019/05
2017/06
2016/06
2015/03
2013/05
(and so on, once every year or two).

So it seems to have roughly happened once a year, with 2 incidents this year.

 

[X.l.r.8]

It may have been run to less than 10 in range mode. I have not looked to see what mine shows when I do that. I’m just thankful it charges back up. Lol.

 

[im4uttx]

It may have been run to less than 10 in range mode. I have not looked to see what mine shows when I do that. I’m just thankful it charges back up. Lol.

No, I think these are just "blips" in recording of data. I have a few in the 3 years on my logs, one since I purchased, and definitely did not run it low.

 

[X.l.r.8]

Ah, I should look at my logs as I regularly run it down to sphincter tightening levels.

 

[petergrub]

No, I think these are just "blips" in recording of data.

I was going to say it was a programming glitch in the VMSparser tool. However, I took a look at the raw log data for the daily records on one of my log files and I see it too. Weird..

If you want to get an idea of the health, you should look for the delta between the minimum and maximum brick voltages too. That will play a role in how your range is calculated. A normal healthy pack will have a brick voltage delta of <.05V.

I see the 0% on first reading after VMS restart on my log, and another time after an error code 65535 (?) and record type XX05.

That's an excellent observation! Those 65535 errors usually indicate that a module has rebooted. The data will decode to ASCII revision of the module.

 

[im4uttx]

So basically, there's a gap in the middle, followed by SOC of 0%, then back to an SOC slightly higher than before.
In addition, the time the daily logs are getting collected got reset.

Is this common?

Based on observations from others, it seems like the "0%" is common, if only occasional. If it happens a LOT, then it could be something to raise concern.

@petergrub has the correct info for battery health, in addition to just the CAC. Just for information, checking mine, looks like Vmin-Vmax > 4.04-4.07, so less than the .05, and CAC of ~155.