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Discussion Starter · #1 ·
If I understand correctly, too frequent and too many DCFC sessions may affect the health of the HV battery.

I know that Bolt has a good thermal management but would still be cautious in too much DCFC charging.


So what would be a safe number/frequency to DCFC.

Would 70% charge once a week be ok, without affecting the battery health?

I ask because we have a free DCFC station nearby and planning to use it once a week

Thanks
 

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It is like cigarettes. One a week is better than ten a day. Why are you planning to use the DC charger once a week. If it is because it is free, I'd say no. If it is because you are going to be driving farther than you can get comfortably on a charge that day, then sure. It beats taking a stinker. :)
 

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For me, the local DCFC is used when the SOC is ~33% and I feel I need a boost to ~80% and I can shop/eat/read for the hour long charge. Otherwise L2 is ok, for my needs.


Someone else can answer the degradation issue.
 

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I would suggest that if this were an issue, it would say so in the manual.

The max 42 kW rate (on a '50 kW' charger) is about 0.7C, hardly a big strain.

My 2013 LEAF would take the same charge rate into a 22 kWh battery... about 2C, with zero active cooling, and the battery temp would jump >20°F. And Nissan said to not do it 'too much'.

If you can't tell, I'm mad that GM doesn't let us charge the Bolty's a little faster than they do. Grrr.
 

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Some manufacturers warn against frequent Fast Charging. Chevy does not.

I have not heard any reports or seen any threads about degradation in the Bolt so do what is convenient. Models that are prone to degradation have very vocal owners reporting issues in less than a year and the Bolt has been on the road longer than that. Just my opinion (and I'm likely in the minority). YMMV
 

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I would suggest that if this were an issue, it would say so in the manual.

The max 42 kW rate (on a '50 kW' charger) is about 0.7C, hardly a big strain.

My 2013 LEAF would take the same charge rate into a 22 kWh battery... about 2C, with zero active cooling, and the battery temp would jump >20°F. And Nissan said to not do it 'too much'.

If you can't tell, I'm mad that GM doesn't let us charge the Bolty's a little faster than they do. Grrr.
I agree with these comments. The Bolt doesn't charge that fast and from what I've read, when it gets above 75% it's essentially level 2 charging. I wouldn't sweat the weekly DCFC at all. Depending upon your electricity rate, the free charge may minimize the cost of whatever degradation there will be in the future.
 

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Discussion Starter · #8 ·
Thanks for the input. My typical weekly use is aprox 700km and I’ve been charging 3 times a week at home.

As weather gets warmer and range improves, I’ll probably be charging two times a week. Thinking once at home and once at DCFC.

Cheers
Darsh
 

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Frankly, I'd be DCFC charging when the battery drops below my "comfort zone" and I want more charge for THAT DAY. (That is, IF you can charge at 240V overnight - you should be able to get up to "full" on an overnight, 240V charge.)

If it's because the electricity is "free", then I would probably be charging at the DCFC as well, and fairly often - but I'd stop the charge before 80%. How much is your time worth? You will be sitting there starting at ... something while it charges. I'd probably stop at a free DCFC on the way home any day it was convenient when the battery is under 50%, and charge up to 65-70% or so (15-25 minutes), then 'add a bit' to get the battery level up to my comfort level at home (for whatever my next day's driving would be). This is providing the DCFC isn't out of the way (I wouldn't drive 10 miles for free electrons). Now, if you can't overnight charge at 240V at home ...

Anyhow, charging up to ~70% shouldn't cause much of a problem on the Bolt's battery - because of the thermal management. Heat is the enemy of the battery, and charging a hot battery. The battery heats up while fast charging, so a DCFC starting at 5% means that the battery will be a LOT warmer upon reaching 75% in that case than if the battery had been at 60% when starting. Unless traveling, I try to avoid charging more than 50% of capacity at any one go at a DCFC - less when it is hot out (over 85F). But then, I'm a trifle paranoid.
 
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Frankly, I'd be DCFC charging when the battery drops below my "comfort zone" and I want more charge for THAT DAY. (That is, IF you can charge at 240V overnight - you should be able to get up to "full" on an overnight, 240V charge.)
I charge at home with the stock EVSE on a 240V circuit - that means it takes me almost 24 hours to get a full charge from empty. But here's the thing: I've never really had to charge from empty. The battery is usually at least 1/4 to 1/2 full when I park for the evening, and the one time I deliberately ran the battery down (to see how it behaved) I didn't need full charge the next day anyway so I was just fine.

I've often thought that if I really needed to do long trips on consecutive days that I could plug into a DCFC for 30 to 60 minutes to "top up" before driving home and charging in the garage overnight - but so far I've never had the need to do that. However, I have gone on a few longer day trips where I've needed a DCFC to complete the journey, so for me it's an option very well worth having.

The importance of DC Fast Charging is a very individual thing. But for me, at least, my expectations of how much charging I'd need to supplement my overnight fills and how much power I'd need for my home charger were higher than what I've found my actual use to be.
 

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I looked up my EVgo fast charging history, and I've fast charged 29 times since I got my Bolt. I've fast charged several more times on non-EVgo networks, so total lifetime fast charge count is probably close to 40.
I have been charging my Bolt to 100% the last few days and logging the TorquePro raw SOC readings. First 2 times I charged full, the raw SOC% number registered 96.1%. The last time I fully charged, the raw SOC% was 96.5. When my Bolt was brand new, I observed that same max 96.5% raw SOC number. So at least from my TorquePro readings, after almost 17k miles and ~40 fast charges, there seems to be no battery degradation observable. FWIW I usually have HTR active and charge every 4-5 days.

Screenshot attached is the reading I took this morning after a 100% charge.
 

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These times when you charge to 100%, the TorquePro shows 96+%, which would seem to indicate the TorquePro is showing percentage of actual capacity. I would be curious to know what percentage the MyChevy app shows at those times. Wondering if it is showing percentage of actual, or of accessible.
 

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Unless you are charging EVERY DAY and planning on keeping the car for 10+ years, I doubt that monthly or weekly DCFC will affect battery life, but the truth is NO ONE KNOWS.




Charging faster than necessary is what you should really ask yourself about. If you want free energy from DCFC (if you have access to such a thing), then you are exchanging free energy for potential battery wear in the future.


However, charging via L2 also heats up the OnBoard Charger (OBC). That stresses the OBC and will reduce its life. Are you going to worry about that, now?


I think you are overthinking it and being concerned about nothing. GM builds protections into its cars. USING it reduces its life.


Enjoy the car, please.
 

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These times when you charge to 100%, the TorquePro shows 96+%, which would seem to indicate the TorquePro is showing percentage of actual capacity. I would be curious to know what percentage the MyChevy app shows at those times. Wondering if it is showing percentage of actual, or of accessible.
The MYchevy app will say "full". The TorquePro # is the raw SOC%.
 

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Anyone have temp stats for charging on a 25KW DCFC? Figure I recharge when the battery nears 25% and charge up to 70%.
 

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Anyone have temp stats for charging on a 25KW DCFC? Figure I recharge when the battery nears 25% and charge up to 70%.
The battery temperature, while charging, will depend on the ambient temperature, how hard you were just driving, and how fast you are charging. The battery conditioning system won't let the battery get above 90 F.
 

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Unless you are charging EVERY DAY and planning on keeping the car for 10+ years, I doubt that monthly or weekly DCFC will affect battery life, but the truth is NO ONE KNOWS.




Charging faster than necessary is what you should really ask yourself about. If you want free energy from DCFC (if you have access to such a thing), then you are exchanging free energy for potential battery wear in the future.


However, charging via L2 also heats up the OnBoard Charger (OBC). That stresses the OBC and will reduce its life. Are you going to worry about that, now?


I think you are overthinking it and being concerned about nothing. GM builds protections into its cars. USING it reduces its life.


Enjoy the car, please.
Humans have an amazing capacity to take a learned experience and try to project that experience on a completely different situation. 2011 Leafs had terrible batteries, no thermal management, and relatively high DCFC charging rates. These caused charging failures. But it also firmly implanted the idea in the EV communities collective mindset that fast charging is universally dangerous and damaging to batteries. Notwithstanding that the Bolt has nearly 3 times the battery capacity, active thermal management, a completely different battery chemistry, and a much slower charging rate with very early and hard tapers, which Bolt owner routinely complain about. It's a completely different situation, yet folks still ask if DCFC hurts the battery.

There's no hard evidence from the wild that indicates that frequent DCFC charging of Bolts does any damage. I'd bet money that GM likely has charging to destruction data on the battery that it's likely that the parameters set makes it virtually impossible to do any significant damage to the battery by charging it with DCFC all the time.

DCFC is going to be important as EV adoption increases. There will be more and more people who will not have regular overnight charging opportunities. There will be others that will need to depend on the flexibility that DCFC offers. Putting the fear of DCFC into potential adopters will simply slow adoption.

So I agree. The car is designed to be charged using its charging interfaces. GM would be foolish to design it in such a way that using those interfaces damages the car. Nissan was foolish.

ga2500ev
 

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Old thread, but it's worth mentioning that SOC and battery capacity are different things. SOC is determined by cell voltage. A battery that has degraded capacity can still charge to 100% SOC. It will just have less energy to release before the cell voltage goes down to what we call 0% SOC. The voltage threshold for both 100% and 0% SOC are not hard physical limits of the cell chemistry, but are engineered target voltages that are chosen to allow the cell to have an acceptable lifetime. The physical zero energy voltage would be zero volts (!), but that would destroy the cell. Cell voltage also varies a little bit with temperature, so take the SOC percentages as a rough approximation as they will move around a bit. Same with battery capacity. Drive slowly on a moderately warm day and you'll be able to get more energy out of the pack than driving quickly on a cold day. I suspect that the battery capacity reported via the ODBC PID does a live guesstimation of capacity based on voltage drop over energy used. That's why it goes up and down seasonally. It's very useful for guesstimating range, but not really any good for guesstimating battery degradation.
 

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There's no hard evidence from the wild that indicates that frequent DCFC charging of Bolts does any damage.
Indeed, there is evidence to the contrary. NewsCoulomb recently posted his 100,000 mile update, and he says that he's seen no real battery degradation since his 70,000 mile report where he stated that his battery had degraded by around 9%. And I believe that he almost exclusively charges his Bolt at DC fast chargers.
 

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Indeed, there is evidence to the contrary. NewsCoulomb recently posted his 100,000 mile update, and he says that he's seen no real battery degradation since his 70,000 mile report where he stated that his battery had degraded by around 9%. And I believe that he almost exclusively charges his Bolt at DC fast chargers.
Most of his charging is at his work place on L2, but much of his driving is on his long trips where he does crap loads of DCFC charging.

Keith

PS: There is still speculation over weather or not the batter software recall made any changes to available capacity... some say it did others say it didn't, and we will never get an answer from Chevy... Eric mentioned in his 70K mile update that he had the recall done and didn't know if they played a part in his 9% degradation.
 
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