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Discussion Starter · #1 ·

27777


I assume 287 means miles. So 238 / 287 = 82.9%. This would mean the BMS makes the top and bottom 8% are off-limits for charging... What do you think?
 

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The EPA mileage rating for any auto is based on very strict, reproducible, comparable conditions. Its only use is to compare two different autos prior to purchase. What mileage you as a driver achieve may bear NO resemblance to this number. The four "T"s determine range: temperature (outside), terrain (net uphill or downhill, not "hilly"), technique (speed, "jackrabbit" starts, coasting), and temperature (inside setting {heat or air conditioning}). I have gotten 320 miles on a single charge. I have also gotten 170 miles. Usable battery capacity certainly has some fudge factors contained within. But I do not think it is a strict percentage (like 8%) where electrons cannot be added in or teased out.
 

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But I do not think it is a strict percentage (like 8%) where electrons cannot be added in or teased out.
On the one hand, there is an internal (raw) SoC and a displayed (user) SoC where 0% on the uSoc corresponds to 4% rawSoc and 100% uSoc corresponds to 96% rawSoC. But that doesn't mean that we could ever get to 0% or 100% rawSoC. That would only be possible if the batteries were perfectly balanced, which they won't be.
 

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Discussion Starter · #5 · (Edited)
On the one hand, there is an internal (raw) SoC and a displayed (user) SoC where 0% on the uSoc corresponds to 4% rawSoc and 100% uSoc corresponds to 96% rawSoC. But that doesn't mean that we could ever get to 0% or 100% rawSoC. That would only be possible if the batteries were perfectly balanced, which they won't be.
Actually, more like usable capacity of the battery is from 8% to 92% SOC.

And get this... just decoded of why Hill Top Reserve Mode is 87%.
87% X 92% = 80% !!! This matches the general advice to NOT charge over 80% SOC.
And, I guess this mean to NOT go below 10%, which is about 20% SOC.
 

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Actually, more like usable capacity of the battery is from 8% to 92% SOC.
My data is based on what I personally see via ODB-II (e.g., when I charge to full, it's 96% raw SoC) and by GM's own data, as found in the JSON file in the myChevrolet app dumped on Reddit here (but also grabbable from the iOS .ipa file). As I mentioned in this post, according to GM itself (from comments scattered through the JSON file):
  • -3.2% uSoC = 1% hvSoC (and car won't go below 1% hvSoC)
  • 0% uSoC = 4% hvSoC
  • 6.52% uSoC = 10% hvSoC
  • 10.87% uSoC = 14% hvSoC
  • 100% uSoC = 96% hvSoC
(hvSOC is what I call raw SoC @Telek's ODB-II PID file calls 鈥淪tate of Charge HD Raw鈥).

So, that's what my data is based on. @wesley has similar data from empirical readings via ODB-II.

What, if anything, are your claims based on, @p7wang?
 

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Discussion Starter · #7 · (Edited)
Mine's my guess based on the chart, which seems to have been provided by GM鈥檚 Tim Grewe. See article. Does your numbers resemble the chart? Of course, it could also be that the chart was from the initial release and as the battery was improved, GM adjusted the usable capacity for 2019 Bolts like Tesla. If that were the case, then the 'EPA range' should be 248 miles for the 2019 Bolt. It's known that the info reported to the agencies is not always the most up to date, example is the headlight that was poor in 2017, acceptable in 2019, but GM failed to send the updated into to IIHS.
 

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Mine's my guess based on the chart, which seems to have been provided by GM鈥檚 Tim Grewe. See article.
I also read the article. The graph you seem to be using is dated 2019-01-11 (January 11, 2019), and it is mentioned in the text:

Bradley Berman (insideevs.com) said:
Dec. 2018 鈥 Jan. 2019: I continue to pull data from my Bolt鈥檚 computer system, revealing that the threshold of low to high voltage is beyond the accepted threshold. (See screenshots below.)
It might have confused you that Berman described his graph as a 鈥渟creenshot鈥, but it's pretty clear that the graph comes from him, not Grewe.
 

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Discussion Starter · #11 ·
I also read the article. The graph you seem to be using is dated 2019-01-11 (January 11, 2019), and it is mentioned in the text:

It might have confused you that Berman described his graph as a 鈥渟creenshot鈥, but it's pretty clear that the graph comes from him, not Grewe.
I am not so sure, I doubt he made that chart himself. I still think the chart came from GM.
 

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I am not so sure, I doubt he made that chart himself. I still think the chart came from GM.
Obviously you thank that, since the whole thread is based on this misunderstanding.

We know from the text that Berman was pulling data from the car. What makes you think he'd be incapable of plotting it? What do you think he's referring to with 鈥淪ee screenshots below鈥?

It would sure be unusual for GM folks to bring a strange hard-to-read graph to an interview (and then never explicitly mention it). But if you want to believe that the guy from GM came along with a USB stick containing the file 鈥渂olt-battery-cells-2-charging-event.jpg鈥 and handed it to Berman, well, fine, believe it. But don't expect many other folks here to think your reasoning makes sense.
 

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Discussion Starter · #14 ·
X axis appears to be time in minutes of a level 2 charge
OK, I see that now but it just adds more confusion. The gray line starts at 25% and goes up to 100%, so that is 75% SOC/45KWh. Charging that in 287 min/4.78 hours would mean a charge rate of 9.4KW. That would mean 294V @ 32A charging!

Maybe someone drew that chart with a crayon. ;)
 
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