Degradation - 50 kw DC Fast vs. AC Level 2

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FloridaSun

FloridaSun

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I wonder what difference in battery degradation DC charging makes?? Have there been any scientific studies on that? Does DC charging degrade the battery faster than for example charging to 100%? The reason why I'm asking is because a new FREE 50kw charger just became available in a nearby town and I have been using it a lot lately.. I barely charge at home anymore.. Any time, I run the battery below 40%, I drive to that charger to get to about 82 - 83% charge. I wonder if it's wise not to charge on a 50kw charger too frequently?? I would like to know facts on the contribution of DC charging to battery degradation. Any information would be appreciated.
 
That other thread about charging a kona to 100% had a YouTube video with a lecture about what causes batteries to go bad.

#1 thing is temperature. DCFC causes more of a temp rise, so there is some concern there. But cars with good thermal management wont have as much trouble here.

#2 is just how high you charge. If you only charge to 80%, then you avoid a lot of the issues.

#3 is how long us the battery at a high SOC, esp when the temps are higher. Sort of a combination of time plus the other two items.

I personally have switched to doing DCFC in the morning when it is cooler. I hit 76kW this morning.
 
ericy said:
That other thread about charging a kona to 100% had a YouTube video with a lecture about what causes batteries to go bad.

#1 thing is temperature. DCFC causes more of a temp rise, so there is some concern there. But cars with good thermal management wont have as much trouble here.

#2 is just how high you charge. If you only charge to 80%, then you avoid a lot of the issues.

#3 is how long us the battery at a high SOC, esp when the temps are higher. Sort of a combination of time plus the other two items.

I personally have switched to doing DCFC in the morning when it is cooler. I hit 76kW this morning.
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So, you think that it's just the temperature that makes it worse for the battery?? Here in Florida, the temperature between charging Level 2 and DC fast in summer is within 3 - 5 degrees Fahrenheit (2 - 3 Celsius). Battery temperature with Level 2 charging is about 94 - 96 degrees and battery cooling does not come on in most cases even though sometimes it does.. Battery temperature with DC Fast charging gets up to about 100.4 degrees and battery cooling keeps it at that level.. So, the temperature difference is minimal.. If temperature is the only concern, I don't think that there is too much harm frequently charging DC fast as long as I don't charge much over 80%.. I usually charge to 82 - 83% to be at 80% when I get back home from the charger..
 
I don't think it's just temperature. I would think it's also how much you "push" the electrons into the battery (kW). That's why there is limitations on that.

The Kona only charges at ~77kW max but the Regen gets up to 150kW. So why can't you charge it at an Electrify America Charger at 150kW? Because that would be a prolonged stress on the battery, vs. a short Regen burst of 150kW.

However if your free DC charger is only 50kW and you charge to only 80% I wouldn't worry too much about it.
 
Esprit1st said:
I don't think it's just temperature. I would think it's also how much you "push" the electrons into the battery (kW). That's why there is limitations on that.

The Kona only charges at ~77kW max but the Regen gets up to 150kW. So why can't you charge it at an Electrify America Charger at 150kW? Because that would be a prolonged stress on the battery, vs. a short Regen burst of 150kW.

However if your free DC charger is only 50kW and you charge to only 80% I wouldn't worry too much about it.
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I was thinking the same but it would be nice to see an actual study like we have studies on how charging from/to different SoC levels can affect battery degradation.. I wonder if there are similar studies for DC vs. AC charging..
 
DC or AC doesn't matter. AC will be covered into DC in the cars charger. So it all is DC because it's the only way the battery works. So basically it comes down to kW anyways.
 
I don't think degradation is going to be a prevalent factor with this pack, AC or DC charging.
Even at 2% per year in worse conditions, it will probably be 15 years before your lifetime warranty kicks in.
The best thing to hope for is even degradation of all the cell groups.
The one thing that I would be more wary of, is cell imbalance particularly in the 38 cell groups that are in the stacked part of the modules.
Depending on the location of the temperature sensors, this might not be something easily monitored, and will probably show up as an "early turtle".
Of course Torque Pro should give some indication of that if one or more of the cell groups remains millivolts behind the rest, but trying to convince Hyundai of that using third party software would be a challenge upon itself.
 
electriceddy said:
I don't think degradation is going to be a prevalent factor with this pack, AC or DC charging.
Even at 2% per year in worse conditions, it will probably be 15 years before your lifetime warranty kicks in.
The best thing to hope for is even degradation of all the cell groups.
The one thing that I would be more wary of, is cell imbalance particularly in the 38 cell groups that are in the stacked part of the modules.
Depending on the location of the temperature sensors, this might not be something easily monitored, and will probably show up as an "early turtle".
Of course Torque Pro should give some indication of that if one or more of the cell groups remains millivolts behind the rest, but trying to convince Hyundai of that using third party software would be a challenge upon itself.
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I hope that you are right.. At my driving, 15 years means over 500k miles..
My cell balances look beautiful as of right now.. Cell 39 is 0.02 off.. other than that, everything looks beautiful..

Screenshot_20200706-153042_Torque.webp
Screenshot_20200706-153050_Torque.webp
 
So, aside from the question about DC vs AC charging and battery life, is there any info on whether how often/how long you charge makes a difference? For example, is it better to let it get down to 20-25% then charge to 80% or so, or to top it off when I'm at 50-60%? Or does it make no difference at all. And apologies if there's a thread already covering this that I missed.
 
Bruce M. said:
So, aside from the question about DC vs AC charging and battery life, is there any info on whether how often/how long you charge makes a difference? For example, is it better to let it get down to 20-25% then charge to 80% or so, or to top it off when I'm at 50-60%? Or does it make no difference at all. And apologies if there's a thread already covering this that I missed.
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Based on studies by Battery University, they got the longest life charging between 65 and 75%, followed by 45% to 75%. I would not recommend running down the battery below 40% on a regular basis.
 
FWIW my leaf had 2000 DC fast charges when I purchased it used. By my calcs that's one change every week day for 4-5 years, 45 km per charge or approx 7 kWh per charge.

Battery degradation is no worse than leafs that have been AC charged their whole life.

What probably help is the DC charge rate is tapers for the last few KWh so the pack probably never got hot.

Because it was driven daily, it never sat at 100% for a long period of time. And likewise was never drained down low.
 
gooki said:
FWIW my leaf had 2000 DC fast charges when I purchased it used. By my calcs that's one change every week day for 4-5 years, 45 km per charge or approx 7 kWh per charge.

Battery degradation is no worse than leafs that have been AC charged their whole life.

What probably help is the DC charge rate is tapers for the last few KWh so the pack probably never got hot.

Because it was driven daily, it never sat at 100% for a long period of time. And likewise was never drained down low.
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Thanks for posting this.. Good to see real life experience.. That's exactly the kind of information that I want to see.. Real life experience.. So, charging to 100% or running down the battery to a low SoC are worse than Fast charging.. Thanks..
 
BlueKonaEV said:
Based on studies by Battery University, they got the longest life charging between 65 and 75%, followed by 45% to 75%. I would not recommend running down the battery below 40% on a regular basis.
Click to expand...

Thanks! If you have a link to that study, I'd be very interested in reading it.
 
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