[Jim H]

Now that I have a Bolt, replacing my '13 Volt, i get to decide whether to charge every day, even when only driving 50 or so miles per day, or wait until the charge level is low, e.g. below half, before recharging.
In other words, are there any disadvantages to multiple shallow charging cycles vs. fewer deeper charging cycles? If not, then I'd plug in every night to use AC power for battery maintenance like heating etc., but this means a lot more charging cycles over the lifetime of the car/battery. Does the advice change based on ambient temperatures, i.e. northern winters vs rest of the year?
I realize many will have an opinion on this, but what is the hard data, if any?

 

[rhodomel]

multiple shallow charging is much better than deeper charging cycles. theoretically, the Bolt's battery pack is protected from deep charging cycles because you don't access all of its charging capacity. You might set it to have a downhill setting so that it will have a lower state of charge no matter how long you plug it in.

 

[saghost]

GM and LG came up with a brand new chemistry for the Bolt, and no one has any real experience with it yet.

Lithium Ion batteries generally don't have memory effects, and are usually happiest close to fifty percent charge - spending time at very low and very high states of charge is bad for longevity, and spending time at high states of charge at high temperatures tends to degrade cell capacity.

If you don't need the range regularly, using hilltop reserve daily is an easy way to bring the SoC down so you aren't always charging to "100%" (one hundred percent of the user available SoC isn't the same as one hundred percent of nominal rated capacity, but it's still really high.)

 

[Henry_FL]

From the Bolt forum ( not this one ) there was some good discussions about this, the consensus was the battery would get the most years by keeping the charge in the 60-70% of capacity range. Frequent top of, even with hilltop reserve on is pushing the battery to ~90% plus, which will have an effect in degradation due to dendrite growth in the lithium.

When I had the Volt I always topped off, plugged in 24/7. Now with the Bolt, I only charge once a week unless I have a trip that needs the actual maximum range.

Here is the thread, a really good read!

http://www.mychevybolt.com/forum/viewtopic.php?f=11&t=7231

 

[Jmaj]

The owners manual is mute on the subject, and to my knowledge no GM engineer has chimed in on a forum on this subject. So I plug in whenever I have the opportunity and it gets a full top off every night.

 

[Jim H]

It is my plan to use the hilltop reserve once we get to more normal temps so that "full charge" would be less than the 90%. My range during this sub-zero spell in Minnesota dropped to about 145 miles for a full charge so I didn't want to routinely knock it even lower although I probably could when I know I won't need the extra miles.
Thanks for the information.

 

[llninja]

I always use Apple’s advice when it comes to LiIon batteries. Plug it in anytime you can, but once in awhile drain a full battery nearly all the way down to let the electrons flow. Once per month is what they recommend. I recently had a laptop start complaining for me to service the battery because it sat mostly unused, always plugged in, topped off, and never drained. after resetting the SMC and filling it, then draining it, so far that has done the trick.

 

[linkim]

Here is an excerpt from an article entitled “Proper Care Extends Li-Ion Battery Life” http://www.powerelectronics.com/mobile/proper-care-extends-li-ion-battery-life

Use partial-discharge cycles. Using only 20% or 30% of the battery capacity before recharging will extend cycle life considerably. As a general rule, 5 to 10 shallow discharge cycles are equal to one full discharge cycle. Although par- tial-discharge cycles can number in the thousands, keeping the battery in a fully charged state also shortens battery life. Full discharge cycles (down to 2.5 V or 3 V, depending on chemistry) should be avoided if possible.

This article is from 2008, so a bit dated. However, the general comments are still valid.
The bottom line is that shallow charge/discharge cycling is better for battery cycle life.

 

[scottf200]

Here is an excerpt from an article entitled “Proper Care Extends Li-Ion Battery Life” http://www.powerelectronics.com/mobile/proper-care-extends-li-ion-battery-life

Use partial-discharge cycles. Using only 20% or 30% of the battery capacity before recharging will extend cycle life considerably. As a general rule, 5 to 10 shallow discharge cycles are equal to one full discharge cycle. Although par- tial-discharge cycles can number in the thousands, keeping the battery in a fully charged state also shortens battery life. Full discharge cycles (down to 2.5 V or 3 V, depending on chemistry) should be avoided if possible.

This article is from 2008, so a bit dated. However, the general comments are still valid.
The bottom line is that shallow charge/discharge cycling is better for battery cycle life.

The following article on batteries "similar" to what Tesla is using but I suspect there are parallels in concepts.

Divide those number of cycles by 365 or 300 or whatever number of days per year you want. Pretty long.

"500 cycles? But that’s (relatively) low! Yes. But what is not shown on the spec sheet is that when you partially charge and discharge, degradation of the battery capacity is reduced. Thus, you can do over
40 000 charge/discharge cycles when going from 30% to 70% only. Or over
35 000 charge/discharge cycles from 20% to 80%;
28 000 cycles from 10% to 90%;
15 000 cycles from 8% to 92%,
07 500 cylces from 6% to 94%, and the capacity reduction goes faster and faster, finally reaching
00 500 cycles when recharging from 0% to 100%."

http://blog.evandmore.com/lets-talk-about-the-panasonic-ncr18650b/

 

[theflew]

Per the Bolt manual :

"It is recommended that the vehicle be plugged in when temperatures are below 0°C (32°F) and above 32°C (90°F) to maximize high voltage battery life."

 

[Norton]

Per the Bolt manual :

"It is recommended that the vehicle be plugged in when temperatures are below 0°C (32°F) and above 32°C (90°F) to maximize high voltage battery life."

+1 for this reason alone.

The saddest part of the Jim's post is the 'location' - Minnesota.....

If it was me, I'd use 'Hilltop Reserve' daily but definitely keep it plugged in all the time for the TMS to keep the battery temp happy.
(Not topping to 100% SOC has theoretical battery life advantages.)
Hopefully you have a 7.2 kW L2 at home.

And always do a 'Preheat' using house power before driving.
I'd preheat before every single drive regardless if it's plugged in or not because,,, "Baby, it's cold outside."

When the weather becomes bearable then you can let it sit around for days at partial SOC. The battery would like that!
That's how I operate. Mine is at 100% SOC for only a few hours per day,, except for this time of year... Nobody likes winter.

 

[JoeMap]

It is my plan to use the hilltop reserve once we get to more normal temps so that "full charge" would be less than the 90%. My range during this sub-zero spell in Minnesota dropped to about 145 miles for a full charge so I didn't want to routinely knock it even lower although I probably could when I know I won't need the extra miles.
Thanks for the information.

Jim H, thanks for providing these details. I'm getting about the same range on the GOM (not Max or Min) and I've been pretty concerned. I just bought my Bolt last Saturday, just in time for the coldest prolonged weather we've seen in southeast Missouri in years. Twice this week, I had to drive a 120 mile round trip - half interstate - for medical purposes and didn't feel comfortable taking the Bolt. Btw, this has not gone over well with my better half because she wanted the Volt, with the range extender.

My experience is that my Min range most accurately reflects miles driven (< 350 so far) and the Min range has only shown about 120 miles when fully charged. The GOM just teases me.

And the cold weather is killing efficiency with about 2.2 mi/kWh.

Any thoughts on the above are appreciated...and sorry for hijacking the thread.

Joe

 

[Jmaj]

And the cold weather is killing efficiency with about 2.2 mi/kWh.

Joe

I took my Bolt for a spin today at 7 F. 2.2mi/kwh is exactly what i got. I didn't precondition it but it was garaged at a temp below freezing. Cabin 68F, auto heated seats.
The wife is right (darn it), you should have got a Volt if you have to make long roadtrips under any weather conditions. Or convince the medical center to put in a Level 2 EVSE.

 

[llninja]

I took my Bolt for a spin today at 7 F. 2.2mi/kwh is exactly what i got. I didn't precondition it but it was garaged at a temp below freezing. Cabin 68F, auto heated seats.
The wife is right (darn it), you should have got a Volt if you have to make long roadtrips under any weather conditions. Or convince the medical center to put in a Level 2 EVSE.

L2 isn't fast enough, they need to put in an L3.

 

[Steverino]

are there any disadvantages to multiple shallow charging cycles vs. fewer deeper charging cycles?

I know the Volt's kWh Used display can be thrown off by many small top-offs vs "full" (the Volt never does a full discharge) discharge/recharge. Perhaps the Bolt kWh used can get out of whack as well, I don't know. But I don't expect to fully discharge the Bolt's battery during our normal use, so I'll be "topping off" daily, especially given the winter weather range. The battery is more than adequate for our long commute, even in winter, but we want to be prepared for a freak 3-4 hour snow storm traffic jam.

 

[Jmaj]

L2 isn't fast enough, they need to put in an L3.

I thought about that. The joke answer is considering how long we wait to see a doctor an L2 is good enough, the serious answer is cost.

Edit - a Chargepoint Single 25kw CCS station is $12,500.