Battery Depletion before Recharging

[Anonymous]

I have experience with battery fade. It happens!

Michael: It's been 100+ all week here in the San Fernando Valley and probably hotter in my garage!

If I am not always plugged in, as you suggest, then what triggers my Bolt EV's coolant system, to protect my battery pack?

Software.

Even if it is not plugged in?

 

[SeanNelson]

If I am not always plugged in, as you suggest, then what triggers my Bolt EV's coolant system, to protect my battery pack?

There are systems in the Bolt that are always "on" even when the car is nominally powered down. They run off the 12V battery and do things like watch for the appearance of the key fob, maintain cell communications for remote status checking, watch for scheduled charge events, etc. etc. They also monitor the battery temperature and turn on the heaters or A/C unit (which run off the main traction battery) to maintain its temperature within a certain range if necessary. It's my understanding that this temperature control (also known as "battery conditioning") is done as long as there is at least a 30% charge available in the main traction battery.

 

[devbolt]

Michael: It's been 100+ all week here in the San Fernando Valley and probably hotter in my garage!

If I am not always plugged in, as you suggest, then what triggers my Bolt EV's coolant system, to protect my battery pack?

Software.

Even if it is not plugged in?

The Bolt's battery thermal management system runs automatically as long as there is more than 30% SOC. That's why there's a "Battery Conditioning" section for the Energy Detail screen.

 

[cyaopec]

My Volt has about 60k on the battery and I see no degradation.

Doesn't mean that there wasn't any degradation. Just that the larger battery allows the car to hide it.

With a software change, the Bolt could do the same. Reduce the available battery to 42kWh, and there will be zero degradation visible to the driver.

Not true. There all Volts that are down to 10.3 and lower. So the Volt does not hide anything. But mine is fine with 60k miles on the battery. The question is can you get to 100k with a TRIVIAL 3-6% loss with LG batteries. As I can easily beat EPA numbers by 10% having a degradation of 10% would put me right back to EPA estimates, which is fine by me.

 

[michael]

Software.

Even if it is not plugged in?

The Bolt's battery thermal management system runs automatically as long as there is more than 30% SOC. That's why there's a "Battery Conditioning" section for the Energy Detail screen.

And once the battery is down to 30%, (or even 60%) it is very tolerant of increased temperature so this is not a problem. Furthermore, my experience with the Focus Electric showed that battery temperature remains moderate even if the TMS does not function, due to large thermal mass and good insulation. Hot daytime temperatures were balanced by cooler night temps and there was not a great deal of diurnal variation. I would expect the same of the Bolt.

In the case of the Focus, the battery temperature never got to the point where it triggered the TMS unless actually driving or charging. In the morning (if not charging overnight) it would typically be 60-70 ish, and even on very hot days and in direct sunlight would never go up much.

Several years ago someone studied the thermal performance of a Volt parked in Arizona

http://gm-volt.com/2013/05/03/volt-battery-thermal-management-system-in-the-hot-arizona-sun/

He found that with no activity of the TMS the battery temp increased by less than 10 degrees ( 82 to 90 prox) over 7 afternoon hours despite near 100 F ambient and direct Arizona sun. This is consistent with my observations with the Focus Electric.

 

[Anonymous]

That is good information to know, especially as we continue to suffer through this heat wave.

Thank you!

 

[michael]

My Volt has about 60k on the battery and I see no degradation.

Doesn't mean that there wasn't any degradation. Just that the larger battery allows the car to hide it.

With a software change, the Bolt could do the same. Reduce the available battery to 42kWh, and there will be zero degradation visible to the driver.

Not true. There all Volts that are down to 10.3 and lower. So the Volt does not hide anything. But mine is fine with 60k miles on the battery. The question is can you get to 100k with a TRIVIAL 3-6% loss with LG batteries. As I can easily beat EPA numbers by 10% having a degradation of 10% would put me right back to EPA estimates, which is fine by me.

One can't draw that conclusion. It is equally possible that the DOD window was opened but not by the exact amount to maintain the usable completely unchanged.

That said, almost everyone will agree that the Gen1 Volt batteries have held up remarkably well. It remains to be see if the Gen2 batteries do as well, since they may be pushing them a little harder to achieve the increased range.

 

[Posatronic]

Always
Be
Charging

This is the easiest solution for the user. For many, it was necessary for 80-mile EVs. It wasn't necessary for the OP with his 80-mile EV, and will be less necessary with a 240-mile EV.

Plenty of sources indicate that Lithium batteries prefer lower states of charge. I have read/heard that the ideal is somewhere between 20-40%. From that, it would be ideal to charge to about 40%, and not charge again until it's down to 20%. But what's the difference in life between doing that and always charging to full? Nobody knows.

My MO for a Bolt would be to use the Hilltop Reserve, and plug in whenever it's convenient. I would only go to full right before a long trip (>150 miles). That seems like a good balance of being gentle on the battery and convenience to me personally.

I believe it's closer to 55% and lower. Not much difference any lower for storage for long periods of time. If you are using most of the 238milea then don't worry.