Chevy Bolt EV Forum banner
1 - 20 of 29 Posts

·
Registered
Joined
·
7,900 Posts
The charger will always deliver more energy than the battery actually stores due to inefficiencies and the power needed to run other systems such as the car's computers, battery conditioning, etc.

The best way to judge battery capacity is to use either the MyChevy app or Torquepro to determine the starting and ending battery state of charge % when you go on a trip, and compare that to the starting and ending kWh used figures in the Energy information display.

For example, if your trip started with 10 kWh used / 80% state of charge and ended with 40 kWh used and 30% state of charge then it means you used 40 - 10 = 30 kWh which represents 80 - 30 = 50% of your battery capacity. 30 kWh / 50% (which is really 30 kWh / 0.5) indicates that the battery holds 60 kWh.

The wider the state of charge percentage range, the more accurate - although even this is an estimate by the battery management system and can vary based on factors like temperature.
 

·
Registered
Joined
·
1,280 Posts
Yes, it is possible to get some clue from that. A bit of loss and use math and there you go. Will still be a guess.
 

·
Registered
12/16 build, 2017, white LT
Joined
·
11,057 Posts
The best way to judge battery capacity is to use either the MyChevy app or Torquepro to determine the starting and ending battery state of charge % when you go on a trip, and compare that to the starting and ending kWh used figures in the Energy information display.
And this method could be much more accurate, if GM would show us kWh into, as well as out of, the battery, like my electric assist bicycle computer does. This would have required an extra line of code, no doubt. :mad:
 

·
Registered
Joined
·
7,900 Posts
And this method could be much more accurate, if GM would show us kWh into, as well as out of, the battery, like my electric assist bicycle computer does. This would have required an extra line of code, no doubt. :mad:
Well, they sorta do. The "kWh used" since last full charge on the Energy Information screen is a "net" figure - it goes up when you're pulling energy out of the battery and it goes down then you're putting energy into the battery.
 

·
Registered
12/16 build, 2017, white LT
Joined
·
11,057 Posts
Well, they sorta do. The "kWh used" since last full charge on the Energy Information screen is a "net" figure - it goes up when you're pulling energy out of the battery and it goes down then you're putting energy into the battery.
That is like saying we keep track of our current population, but ignore births and deaths, so we sorta know what is going on.
 

·
Registered
Joined
·
7,900 Posts
That is like saying we keep track of our current population, but ignore births and deaths, so we sorta know what is going on.
Yeah , we sorta do... ;)

I guess my question is: how would knowing the inflows and outflows for the battery help you? You can see the instantaneous power transfer on the Driver Information Console, and in terms of optimizing driving behaviour that seems like better feedback that an end-of-trip sum.

I'm not trying to be combative, but it seems angry-emoji-level important to you and so I'm wondering if I'm missing something...
 

·
Registered
12/16 build, 2017, white LT
Joined
·
11,057 Posts
I guess my question is: how would knowing the inflows and outflows for the battery help you?
Because if you keep track of the Wh or Ah in, and out, by simple subtraction you can show the actual capacity of the battery. This is what my electric assist bicycles do. Every time I ride, I know the percent SoC used, and the actual usable battery capacity available on that ride. This is not rocket science.
 

·
Registered
Joined
·
7,900 Posts
Because if you keep track of the Wh or Ah in, and out, by simple subtraction you can show the actual capacity of the battery.
But isn't that exactly what you get with the "kWh Used", which has already done that subtraction for you?
 

·
Registered
12/16 build, 2017, white LT
Joined
·
11,057 Posts
But isn't that exactly what you get with the "kWh Used", which has already done that subtraction for you?
No, it is not. If I drive from 100 % DIC SoC to 0% DIC SoC, and the center screen shows 58 kWh used, but in reality it was 55 kWh out + 3 kWh regenerated = 58 kWh, 58 kWh is not the capacity of you battery. With the current stupid system, the only way you could know your actual battery capacity would be to never use regen. You could do this on a banked oval track, I suppose.
 

·
Registered
Joined
·
7,900 Posts
No, it has not. If I drive from 100 % DIC SoC to 0% DIC SoC, and the center screen shows 58 kWh used, but in reality it was 55 kWh out + 3 kWh regenerated = 58 kWh is not the capacity of you battery.
But that's not how it works. If you use 55 kWh and regen 3 kWh then the display will show 52 kWh used. I have watched that display count backwards while going down lengthy descents from mountain pass to valley here in British Columbia.
 

·
Registered
12/16 build, 2017, white LT
Joined
·
11,057 Posts
But that's not how it works. If you use 55 kWh and regen 3 kWh then the display will show 52 kWh used. I have watched that display count backwards while going down lengthy descents from mountain pass to valley here in British Columbia.
Gad! You are right! I feel like a complete idiot....not for the first time :ROFLMAO:
 

·
Registered
2020 Chevy Bolt and all Tesla models owned by me and my family
Joined
·
685 Posts
EA advertised energy delivered is energy to the battery plus all losses on the charger box ....cooling the cable....coolant pump and losses involved from AC to HV DC ....so this numbers are not true representation of charge delivered.
 

·
Registered
2022 Chevy Bolt EV
Joined
·
108 Posts
Charging losses are higher with higher charging speeds. I read somewhere (please don't quote me on this as not sure I remember the numbers right) that average losses are:
  • 3-4% for 50 kWh speed
  • 5-6% for 150 kWh speed
  • 8-10% for 350 kWh speed
 

·
Registered
2020 Chevy Bolt and all Tesla models owned by me and my family
Joined
·
685 Posts
Charging losses are higher with higher charging speeds. I read somewhere (please don't quote me on this as not sure I remember the numbers right) that average losses are:
  • 3-4% for 50 kWh speed
  • 5-6% for 150 kWh speed
  • 8-10% for 350 kWh speed
That is correct and it will be user that pays for losses....Kw delivered are with all losses to the CCS handle.
 

·
Registered
Joined
·
1,033 Posts
That is correct and it will be user that pays for losses....Kw delivered are with all losses to the CCS handle.
And then you have to add resistive losses in the battery before you can calculate net kWH into battery

So the losses are about:
AC/DC: 10%
Removing heat: 3-4%
Battery resistance: 3 - 5%

Going back to @Twitchy, 12 kWh metered is about 12*0.83 = 9.96 kWh net into battery suggesting a capacity of 9.96/0.19 = 52.4 kWh
 
1 - 20 of 29 Posts
Top