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Discussion Starter #1 (Edited)
There’s a new-ish 100kW DCFC charging station at my city’s old downtown and I think it’s not charging me to use it at the moment. So I decided to take the liberty of using it to check out the changes that the recent (March-April 2020) DCFC update my 2018 Bolt EV got.

1. Agressive use of heater

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Before the update, the battery heater was only seen working on a cold day, and usually shut down as the temperature reached around 20C (68F).

But after the update, it seems to use the heater liberally to maintain the battery as warm as possible. On one session where the battery was at 15C (59F), the heater started out at full power (2kW) and gradually tapered off, shutting down at 23C (73F). On another session, the heater was on full even though the battery started out at 20C (68F). The heater was turned off at 25C (77F).

I’m guessing that the BMS is now trying to raise the battery temperature to the sweet spot (apparently around 23-25C) as quickly as possible even on a relatively cool-to-warm day, so that the charging speed can be maxed out whenever possible.


2. Reduced “time to 80% charge” precision

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Before the update, the car’s dashboard displayed the “time to 80% charge” in 1-minute precision. But now it shows this information in 5-minute precision.

I think this was changed because this number isn’t as accurate in real life as the initial precision implied. The underlying algorithm probably hasn’t changed, though - I remember seeing the “5 minutes left” for about 7 to 8 minutes before it reached the 80% mark.


3. No shutoff at 100%?

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I need to check whether this is a charger-specific thing or the result of the DCFC update, but I was now able to consistently keep charging my Bolt EV beyond reaching 100% displayed SoC (95% raw SoC). It charges to around 97% raw SoC and resets the used kWh counter just like when I use an L2 charger.

Almost all DCFC chargers I’ve used in the past two years shut off after reaching a specific displayed SoC. Most were either at 94% or 100%. When the shutoff happens at 100%, the car didn’t reset the kWh counter because it wasn’t “full” full.

I need to use the DCFC that did the 100% shutoff before the update to confirm or dismiss that this behaviour is update related - will report back when this is done.
 

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I just phoned one of my local Chevy dealers. I was told that they would do the update free of charge....but only until the end of the month. After that it would require a cost for the technician's time. I was kinda cheesed as I did not receive any notice from GM about this. So if you're desire is to do this "on the house" set up your appointment today.

Dayle
 

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Thanks. I will call the dealer. I wouldn't mind doing it if it is free.

-TL

Sent from my SM-N960U using Tapatalk
 

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Discussion Starter #6
I just phoned one of my local Chevy dealers. I was told that they would do the update free of charge....but only until the end of the month. After that it would require a cost for the technician's time. I was kinda cheesed as I did not receive any notice from GM about this. So if you're desire is to do this "on the house" set up your appointment today.

Dayle
That's kind of disappointing. GM Korea is providing the update for free on its nationwide servicing network until April 2022, but apparently the dealerships in the States decide for themselves?

 

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To follow up for just a moment.....the update was done by one of the Chevy dealers here in Lansing (Feldman) and I picked up the car yesterday (4/29). I drove it enough over the last few days that I was down to ~25% SOC so I decided to see what kind of power she would accept with the new update. I connected to a 150kW EA charger (100298-04) across town. It was 53F and overcast today. I carefully monitored time, power, SOC. I took readings every two minutes. It started at 34kW and rose slowly to 46kW over 20 minutes. At 48% SOC (20 minutes in), it throttled back to 37kW. It held steady at 37kW for another 14 minutes. At 60% SOC (34 minutes in), it again throttled down to 24kW. It held there for several minutes and I assumed it would stay there for the duration to 80% SOC. I disconnected at 66% SOC and went home to process the data. 25.2kWhr collected in just under 41 minutes.

Unfortunately, I do not have data with this kind of detail from before the update. I also don't have one of those cute ODB2 tools to collect this kind of data.

Does this look like data others have seen?

Since I can get 20 - 25kW free from several Chevy dealerships in the area (Lansing, Okemos, Detroit, Jackson, Grand Rapids, Charlotte), it certainly looks like I need to be cognoscente of what the SOC is when I make my DCFC choices for charging away from home. Above 60% SOC, I don't gain anything by connecting to a high powered system (EVGo, EA)....and the price is right.

Dayle
 

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Discussion Starter #8
To follow up for just a moment.....the update was done by one of the Chevy dealers here in Lansing (Feldman) and I picked up the car yesterday (4/29). I drove it enough over the last few days that I was down to ~25% SOC so I decided to see what kind of power she would accept with the new update. I connected to a 150kW EA charger (100298-04) across town. It was 53F and overcast today. I carefully monitored time, power, SOC. I took readings every two minutes. It started at 34kW and rose slowly to 46kW over 20 minutes. At 48% SOC (20 minutes in), it throttled back to 37kW. It held steady at 37kW for another 14 minutes. At 60% SOC (34 minutes in), it again throttled down to 24kW. It held there for several minutes and I assumed it would stay there for the duration to 80% SOC. I disconnected at 66% SOC and went home to process the data. 25.2kWhr collected in just under 41 minutes.

Unfortunately, I do not have data with this kind of detail from before the update. I also don't have one of those cute ODB2 tools to collect this kind of data.

Does this look like data others have seen?

Since I can get 20 - 25kW free from several Chevy dealerships in the area (Lansing, Okemos, Detroit, Jackson, Grand Rapids, Charlotte), it certainly looks like I need to be cognoscente of what the SOC is when I make my DCFC choices for charging away from home. Above 60% SOC, I don't gain anything by connecting to a high powered system (EVGo, EA)....and the price is right.

Dayle
The drops you saw at those percentages are typical of the pre-2020 Bolts. As far as I can see they were not really affected by the update. As for the charging speed, the post-48% ones are normal. The ones before that are affected by the battery temperature, but seems somewhat faster than what I would expect compared to the ones pre-update given the ambient temperature you mentioned.
 

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Discussion Starter #9
More on the #3 - I used another DCFC and this time, it got shut off immediately after reaching 100% displayed SoC. This is the same behaviour I observed before the update, so nothing has changed on this front. It just seems to be the peculiarity of the DCFC I used for writing the initial post.
 
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