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Discussion Starter #41
When you plug in, you are activating the Bolt EV's 240 V onboard charger, which requires cooling.
Of course I am activating the onboard charger when I plug in. But why should the onboard charger require cooling if it has not been used? Seems terribly wasteful to me. It's been consuming about 1/2 kwh per cycle. Are you saying that the charger is on the same coolant circuit as other electronics that got hot from driving 10 miles, so it gets cooled along with them?
 

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You do know that there are 3 coolant tanks in the Bolt, right? Read...

Yes, I know that there are three coolant circuits, but there is only one AC compressor that does the cabin and the batteries. My point is I think turning on the cabin HVAC does nothing for the batteries unless they are calling. I may be misinterpeting people here but it seems to me they think by turning on the cabin to cool they also cool the batteries. I could be wrong but I think this is not true.
 

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Of course I am activating the onboard charger when I plug in. But why should the onboard charger require cooling if it has not been used? Seems terribly wasteful to me. It's been consuming about 1/2 kwh per cycle. Are you saying that the charger is on the same coolant circuit as other electronics that got hot from driving 10 miles, so it gets cooled along with them?
When you say the L2 charger is being plugged in but "not been used," what do you mean? My point with cooling electronics is that they heat up almost immediately upon activation (no warm up period).
 

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Discussion Starter #44
When you say the L2 charger is being plugged in but "not been used," what do you mean? My point with cooling electronics is that they heat up almost immediately upon activation (no warm up period).
We need to distinguish between the onboard charger and the EVSE. You said the onboard charger, so that's what I mean. And I mean I don't understand why the onboard charger would need cooling almost immediately. If that's true, then every time I plug in the car, the cooling cycle should start. But it doesn't. The cooling cycle only runs after I have driven a significant distance.
 

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We need to distinguish between the onboard charger and the EVSE. You said the onboard charger, so that's what I mean. And I mean I don't understand why the onboard charger would need cooling almost immediately. If that's true, then every time I plug in the car, the cooling cycle should start. But it doesn't. The cooling cycle only runs after I have driven a significant distance.
Yes, the difference is probably based on the temperature of the electronics' cooling system at the time you plugged in.
 

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Also, this is going back to your earlier post. It is possible that your battery was hot (a 10-mile drive wouldn't normally warm it up that much). But say the battery is hot, or at least over 85 F. The parameters might be different for each of the following:
  • Car off - unplugged
  • Car off - plugged into L2 AC
  • Car off- plugged into DCFC
  • Car on - unplugged
  • Car on - plugged into L2 AC
  • Car on- plugged into DCFC
And each of those could have different temperature parameters, and each of those sets of parameters could be different for different model years.

Basically, what I'm saying is that there are a lot of unknowns, and my comments (and presumably Sean's) were about the battery coolant system specifically when the car is on/off and plugged into DCFC.
 

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Discussion Starter #47
Very good sir. My takeaway is that when DC charging, leave the car on, but when AC charging, turn the car off.

So we know that high temperature is bad for the battery. How bad is it for the electronics? And what can we say along these lines about best practices in cold weather?
 

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Very good sir. My takeaway is that when DC charging, leave the car on, but when AC charging, turn the car off.

So we know that high temperature is bad for the battery. How bad is it for the electronics? And what can we say along these lines about best practices in cold weather?
Actually, no. If it's DC fast charging before the step down (typically ~50%), leave the car off (turning it on will activate more aggressive battery conditioning, resulting in a slower effective charging speed). If it's past the step down on 125 A or faster DCFC, feel free to turn the car on as any additional power for the battery and cabin conditioning will be drawn from the charger without affecting the effective charging speed. If it's charging on a 100 A DC fast charger, leave the car off until the second step down (typically 65% to 70%) because, again, turning it on will activate more aggressive battery conditioning, resulting in a slower effective charging speed. For slower than 100 A DC chargers (really just the 24 kW units), you should probably leave the car off the entire time because the Bolt EV will max out the charger's power until it reaches about 85% battery.

In the case of AC charging, there's simply no reason to turn it on when charging. The battery and climate conditioning can max out the fastest AC charging rate for the Bolt EV, and even if the battery is warm, it's unlikely to continue to heat up while AC charging (unlike what would happen when DCFC).
 

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Of course I am activating the onboard charger when I plug in. But why should the onboard charger require cooling if it has not been used? Seems terribly wasteful to me. It's been consuming about 1/2 kwh per cycle. Are you saying that the charger is on the same coolant circuit as other electronics that got hot from driving 10 miles, so it gets cooled along with them?
The on board AC charger as well as the other power electronics and the transmission share a common cooling loop. This cooling loop consists of a cooling pump and radiator. The cooling pump runs most of the time the car is turned on. This helps ensure that the temperature of all of the components is consistent as well as not too hot. When the car is turned off, the cooling pump would normally shut off. Any residual heat just decays.

If the charger is subsequently used, the coolant temperature may already be somewhat elevated so the coolant pump may start so that the AC charger receives cooling. It may already be somewhat warm since it would have been heated up by the other power subsystems.

The cooling pump does not take much energy but it is not necessary unless one of the power units is operating.

Exactly what you heard is really unknown unless you could confirm what was running when you heard the sound. You can see coolant circulating through the right hand reservoir when the power system cooling pump is running.
 

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Discussion Starter #50
If it's DC fast charging before the step down (typically ~50%), leave the car off (turning it on will activate more aggressive battery conditioning, resulting in a slower effective charging speed). If it's past the step down on 125 A or faster DCFC, feel free to turn the car on as any additional power for the battery and cabin conditioning will be drawn from the charger without affecting the effective charging speed.
Per your advice in one of your YouTube videos, I never DCFC beyond the step down. But I am willing to sacrifice some speed to protect the battery. That's my takeaway.
 

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So we know that high temperature is bad for the battery. How bad is it for the electronics? And what can we say along these lines about best practices in cold weather?
[/QUOTE]

High temp is not good for the electronics either. However it likely does not suffer as much as the battery. Low temp does not matter so much.

I try to follow the recommendations in the manual. I leave the car plugged in whenever possible. I also park the car in a protected area. This allows as much flexibility as possible for the software to do it's thing.

I also care about my comfort so If I am in the car while DCFC, I run the HVAC.
 

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Per your advice in one of your YouTube videos, I never DCFC beyond the step down. But I am willing to sacrifice some speed to protect the battery. That's my takeaway.
Hmm. Traditionally, I've tried to recommend not charging past the second step down, which is 65% to 70% battery. The reason being is, it gives the car a chance to cool the battery and you a chance to precondition the cabin. Because the Bolt EV can draw 7 to 10 kW of additional power, you're actually consuming about 45 kW from the charger from 50% to 70% and not really losing much as a result. Some of that represents energy that would be pulled from the battery when driving, which reduces your range. Finally, being able to travel 120 to 140 miles at freeway speeds (or as much as 170 to 180 miles if you're behaving yourself) between DC fast charging stops makes for a much better travel experience than having to stop every 100 to 110 miles.
 

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Discussion Starter #53
Finally, being able to travel 120 to 140 miles at freeway speeds (or as much as 170 to 180 miles if you're behaving yourself) between DC fast charging stops makes for a much better travel experience than having to stop every 100 to 110 miles.
I've been using Electrify America exclusively in trips between Georgia and Kentucky, and find that they are spaced about every 100 miles.
 

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Haha NewsCoulomb, you do have that pretty well fine tuned. That's a good idea to use the "excess" charger power after the step down to condition the cabin. Hey, you are paying for it, may as well use it. I forgot that recommendation.

That especially makes sense if you leave the car right after starting the session.

On the flip side I guess if the car is already cool/warm, it does not take all that much to just keep it at that temp if you do stay in the car. I guess it would depend on how I felt that day or what I had planned . LOL
 

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I've been using Electrify America exclusively in trips between Georgia and Kentucky, and find that they are spaced about every 100 miles.
Yes, it depends on where you are. Out West, a lot of the EA chargers are spaced about 70 miles apart, which enables Bolt EV owners to skip a number of chargers. When I was testing the 2020 Chevy Bolt EV driving from Baker, CA to Beaver, UT and back, I was able to skip over one to two EA charging sites for all but the last leg of the trip. Also, though, we tend to have more options that aren't EA, though EA is usually the only faster than 50 kW option.
 

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Haha NewsCoulomb, you do have that pretty well fine tuned. That's a good idea to use the "excess" charger power after the step down to condition the cabin. Hey, you are paying for it, may as well use it. I forgot that recommendation.

That especially makes sense if you leave the car right after starting the session.

On the flip side I guess if the car is already cool/warm, it does not take all that much to just keep it at that temp if you do stay in the car. I guess it would depend on how I felt that day or what I had planned . LOL
Yes, it's all about flexibility. For the most part, the only times I stick with my car on trips is if I'm shooting a video. Otherwise, I plug in and do whatever I have to do. Things are a bit different right now, but traditionally, I'll just plug in, go have a meal, shop, or whatever, and when I come back, it's near the step down. If I know I'm not going to return in time for the step down, I'll sometimes activate preconditioning through the MyChevy app in the meantime.
 
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