Chevy Bolt EV Forum banner

1321 - 1340 of 1350 Posts

·
Registered
Joined
·
17 Posts
.... aluminum casing on the cells conducts heat decently well. Pouch cells don't have a casing to conduct the heat. Also 1/3rd of the cylinder surface in contact with the cooling plates is significantly more than the Bolt.

A 2170 cell has ~4600mm^2 of surface area along the sides. ~7.15 square inches.3000 cells - 21,450 sqin of surface area. One third - let's call it 7,000sqin.
It's all about the minimum "thermally addressable" unit of capacity! Smaller cell size helps with homogeneity a lot.

I have some Model 3 cells with me now and it's pretty clear the casings are nickel/steel, not aluminum, given that they're ferromagnetic.
 

·
Registered
Joined
·
544 Posts
Discussion Starter · #1,323 ·
It's all about the minimum "thermally addressable" unit of capacity! Smaller cell size helps with homogeneity a lot.

I have some Model 3 cells with me now and it's pretty clear the casings are nickel/steel, not aluminum, given that they're ferromagnetic.
You make an excellent point. I assumed it was aluminum, and it's steel. How odd. Although I'm sure it's very complicated and beyond our simple understanding lol.
 

·
Registered
Joined
·
544 Posts
Discussion Starter · #1,325 ·
It's looking like line #122 HPCM HV is pack voltage.
Oddly there's no high resolution pack voltage directly in the BECM ... There is one that looks high definition. Taken from my notes:

"Hybrid/EV Battery Back Voltage" flickers between 373.88 and 373.36
But you can see there the minimum increment is 0.52V. Despite it being a 16-bit number, it's like they only have 8-bit resolution there to a 500V maximum.

Most of the voltages presented in GDS2 respond this way as well. I guess they have little need in most places to have any more accuracy at the pack level than 8-bit or 0.52V.

Note that the Hybrid Power Control Module is the one in the front of the car above the motor that distributes power. So that one does have 0.01V increments but will be slightly different than pack voltage due to voltage losses in the line between the battery and the HPCM, especially under load.

There do appear to be at least 2 different average cell voltages which have ?12 bit? resolution. So even if you multiply that by 96 to get a pack voltage it will still be high definition. At least to 0.03V accuracy.
 

·
Registered
Joined
·
18 Posts
I've been racing EV's since 2014 and like to keep an eye on lowest and highest cell voltages and overall pack voltage. Absolutel accuracy isn't that important as the pack goes up and down under load anyway. Now that I've figured out how to communicate reliably with the adapter I'll explore some of the other parameters. It's all part of the fun. :)
 

·
Registered
2019 LT Slate Grey Metallic
Joined
·
53 Posts
Hmm, 4.164V maximum is about right. Can you grab the voltages at full charge and after left for a while? I mean best would be to log all night long after the full charge has completed if possible. I want to see if they're balancing the cells more aggressively now.
Alright, 3rd charge to 100%. This time I let it go until the EVSE shut off.
(I uploaded the snapshots to my Dropbox page).
The numbers seem a bit better (within the error margin?):
Battery Capacity Estimated: 58.5728
Battery levels: min 4.139, avg 4.148, max 4.157 (18mv)
State of Charge HD Raw 96.0357%
State of Charge Raw 96.0784%
Once the car finished charging, the EVSE stayed on supplying 0.5A for 3.5H before shutting down.

Question: I used to schedule charging to 100%, to end just before leaving to keep it at 100% for only short periods of time. With this new diagnosis software in place, is it better to end the charge to 100% earlier to let this diagnosis take place?

P.S. The charge ended at midnight so I didn't have the possibility of monitoring it throughout the night... :)
 

·
Registered
Joined
·
8,685 Posts
The final fix keeps the computers on and monitoring the battery for up to 12 hours after the charge has completed. During this time, the 12V system's power is supplied by the APM which is powered by the HV system, which gets its power through the OBCM powered by your plugged in L2.

So this is perfectly expected. 120W or so makes sense. It's likely 50W or so for the computers based on what I've calculated in the past, and float charging the 12V will take some power too. The OBCM and APM are both very inefficient at low power, so I would expect significant losses there.
I sort of slid over this description when you first posted it. I thought I remembered you saying an hour or so. But dang! I have been monitoring our Bolt today, after a "hilltop" charge. It is still at it, over two hours after the charge finished. So this whole time the onboard charger, accessory battery charger, and high power electronics coolant pump have been humming away. There is enough wasted energy, just at the charge port, to keep the port 8 F warmer than ambient.

I have everything in our house on power strips, to avoid phantom loads. So much for saving the planet. :rolleyes:
 

·
Registered
Joined
·
257 Posts
I sort of slid over this description when you first posted it. I thought I remembered you saying an hour or so. But dang! I have been monitoring our Bolt today, after a "hilltop" charge. It is still at it, over two hours after the charge finished. So this whole time the onboard charger, accessory battery charger, and high power electronics coolant pump have been humming away. There is enough wasted energy, just at the charge port, to keep the port 8 F warmer than ambient.

I have everything in our house on power strips, to avoid phantom loads. So much for saving the planet. :rolleyes:
I sort of slid over this description when you first posted it. I thought I remembered you saying an hour or so. But dang! I have been monitoring our Bolt today, after a "hilltop" charge. It is still at it, over two hours after the charge finished. So this whole time the onboard charger, accessory battery charger, and high power electronics coolant pump have been humming away. There is enough wasted energy, just at the charge port, to keep the port 8 F warmer than ambient.

I have everything in our house on power strips, to avoid phantom loads. So much for saving the planet. :rolleyes:
I guess I missed that bit of info. I don't think my charger is reporting any draw after charging completes (unless the car goes into cooling mode). Should I be worried?
 

·
Registered
Joined
·
8,685 Posts
I guess I missed that bit of info. I don't think my charger is reporting any draw after charging completes (unless the car goes into cooling mode). Should I be worried?
Do you have Torque Pro? If you do, look at the high power coolant loop pump. Or just stick your ear on the hood at the driver's side front. You can hear the pump humming away.
 

·
Registered
Joined
·
1,678 Posts
I have everything in our house on power strips, to avoid phantom loads. So much for saving the planet. :rolleyes:
LOL. Having to stop at one extra light or, God forbid, making even one short extra trip will negate months, if not years, worth of your phantom loads. I think of chasing phantom loads as equivalent to the plastic identifiers on items that aren't recyclable. It can make people FEEL like they are making a difference, but that's it.
 

·
Registered
Joined
·
8,685 Posts
LOL. Having to stop at one extra light or, God forbid, making even one short extra trip will negate months, if not years, worth of your phantom loads. I think of chasing phantom loads as equivalent to the plastic identifiers on items that aren't recyclable. It can make people FEEL like they are making a difference, but that's it.
Totally agree. It is about reducing my sense of guilt. Comes from being brainwashed Catholic, as a child. Logically, I know we are just hanging around while they roll the credits.
 

·
Registered
Joined
·
58 Posts
P.S. The 4680 "tabless" design will only be superior to ordinary cylindrical cells if it's cooled from the top and bottom. Otherwise, it'll be worse - more diameter (coke can vs. Sharpie) means more spiral layers of jelly roll and higher thermal resistance.
I'm sure Tesla's new design will have ways to pull the heat from the ends of the cylinder to however the cooling plates are designed. The cells have thicker walls too, which will increase the thermal transmission.
It is precisely the tabless 4680's unique design that allows the increased diameter over the 1865's and 2170's. If it were structured (tabbed) as the 1865's or 2170's, it would probably combust before it reached the end of the drag strip. As birchy states, the electrons are traveling significantly further using the tabbed design.
Rather than running the current the entire length of the jelly roll, (a couple of feet), it reduces the distance to a maximum of the 80mm height. This reduces the amount of resistance heat significantly.
If you watch the battery day presentation last September, they went into great detail about the cooling plate being at the top (and or bottom) rather than using the sides for thermal management. That would be the preferred method to regulate the 1865 and 2170 cells over the current cooling fin too but I assume the tab/electronics made that design a no go.
They don't seem to have hit the wall though in controlling the temperature as the new Plaid Model S is still using the 1865's and will run a 1.99 second 0-60 and 200 mph with a single speed transmission. We'll have to see if it can do a full lap of the Nurburgring though to fully test the thermal management.

That cooling plate concept is what allows the 4680's to become a structural component using the steel shells of the cylindrical cell as the transfer vector to the battery pack perimeter as well as the top and bottom plates to resist torque if I'm understanding it correctly. By replacing the radiator fins between the cells with a structural epoxy, it can now act as a monolithic shear panel adding horizontal rigidity to the chassis.
At the end of the day, pulling the heat from the sides of a cylindrical cell is not as effective as from the bottom.
 

·
Registered
Joined
·
257 Posts
After much manual testing, I think it's official that my 2019 thinks it now has a 55 kWh battery. I'm still fuzzy on the validity of the run down test because if the percent remaining is based on what the computer thinks is the capacity, then of course the manual test is going to closely match the capacity PID...and mine does.

This means between December and late March, I lost 6 or 7 kWh. How does that happen? Driving in a super cold snap? I did do that a few times (once I had to floor it to get up a hill in -20 degree weather). Secret signal from GM after they realized the 2019s might have an issue? I've been told that's sheer lunacy. Interestingly, all the capacity numbers numbers I've been able to find from 2019 owners aren't far off from my "new" capacity and as far as I can tell, these owners arrived at those numbers only recently. That's strange since there's a GM doc that shows the 2019s are supposed to have a capacity somewhere between the 60 kWh of the 2017-2018 and the 66 kWh of the 2020. I can attest through past testing and the 2019 capacity PID added late last year that my car reported and behaved as if it had a 62 kWh battery. Not anymore. What happened? Did my battery legitimately degrade that much in a few months? I'm dubious.
 

·
Registered
Joined
·
8,685 Posts
After much manual testing, I think it's official that my 2019 thinks it now has a 55 kWh battery.
Our 2017 has a ~52 kWh usable capacity. Welcome to the wonderful world of batteries. Don't worry. I can almost guarantee you will not get below 36 kWh usable for 8 years, or 100K miles.
 

·
Registered
Joined
·
1 Posts
Impressive.

If you ever want to join the Gretio team send me a message.
But I can understand if you want to do your own thing (and please by all means).
 

·
Registered
Slate Gray 2019 Premium all packages
Joined
·
129 Posts
Ok I finally had the time to get the images and charging power before and after the update...
! * Before Update ***
Battery % DIC: 11.0%
SoC Raw HD: 15%
Charge to 70%: 37.808 kWh
Charge t0 100%: 18.236 kWh
After charge to 100%
DIC: 100%
SoC: 97.0

!* First charge after update *
First Charge after update
Start SoC Raw: 79.1%
Start DIC: 80.4%
End Soc Raw:96.0
End Soc Dic: 100%
Cap Raw: 174.0 Ah
Batt Cap Est: 55.7

!**** Second charge after update
Star SoC Raw 15.9
Start DIC % 12.2
Cap Raw: 174.5 Ah
Batt Cap Est: 55.8
End Soc Raw:96.0
End Soc Dic: 100%
Cap Raw: 174.5 Ah
Batt Cap Est: 55.8

So it would seem now the 100% DIC of charge is now 96% SoC vs 97% before the update
I have also was logging all battery voltages and the should be part of part of the database.

Freddy
 

·
Registered
Joined
·
257 Posts
Our 2017 has a ~52 kWh usable capacity. Welcome to the wonderful world of batteries. Don't worry. I can almost guarantee you will not get below 36 kWh usable for 8 years, or 100K miles.
Not worried. I was able to make my longest routine trip without issues. I just don't think 12% degradation in three months is remotely normal. Luckily, it magically stopped.
 

·
Registered
2020 Chevy Bolt and all Tesla models owned by me and my family
Joined
·
461 Posts
After much manual testing, I think it's official that my 2019 thinks it now has a 55 kWh battery. I'm still fuzzy on the validity of the run down test because if the percent remaining is based on what the computer thinks is the capacity, then of course the manual test is going to closely match the capacity PID...and mine does.

This means between December and late March, I lost 6 or 7 kWh. How does that happen? Driving in a super cold snap? I did do that a few times (once I had to floor it to get up a hill in -20 degree weather). Secret signal from GM after they realized the 2019s might have an issue? I've been told that's sheer lunacy. Interestingly, all the capacity numbers numbers I've been able to find from 2019 owners aren't far off from my "new" capacity and as far as I can tell, these owners arrived at those numbers only recently. That's strange since there's a GM doc that shows the 2019s are supposed to have a capacity somewhere between the 60 kWh of the 2017-2018 and the 66 kWh of the 2020. I can attest through past testing and the 2019 capacity PID added late last year that my car reported and behaved as if it had a 62 kWh battery. Not anymore. What happened? Did my battery legitimately degrade that much in a few months? I'm dubious.
Here is 2020 with 6600 miles after being in the freezer commercial type it went from 197.33 Ah to this.
This are @Telek formulas that I didn't adjust for true findings...
I have used 63.4 Kwh before Bolt said screw you Call Towing.
I do a lot of experiments so like @Telek does...
Don't be so hard broken by values you read via obd2. Test it and if found incorrect let as know so @Telek can do adjustments to formulas.
 
1321 - 1340 of 1350 Posts
Top