Low DC charging speed is less harmful?

[Kaan34]

Hi guys,
I have DC charging stations around me with different speeds of charging from 30kw/h to 180 kw/h. Most of the time even 50 kw/h is fine for me when I don’t need superfast charging. So I know that DC charging is not good for battery health. But how about the speed? Is 50 kw/h is less harmful then 180 kw/h or they’re almost the same since both are DC?

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[Donlam]

The heat to the battery received when dc charging is harmful to it. Just an example in direct current (time x charging speed = heat in the cells). Not only kw charging speed!

 

[Kaan34]

The heat to the battery received when dc charging is harmful to it. Just an example in direct current (time x charging speed = heat in the cells). Not only kw charging speed!

Thank you, I see the point. But which one is better than? Just an example; 50kwh*2 hour charging or 100 kwh*1 hour; will still 50kw charger produce less heat and better or they are just the same? What do you think?

 

[SergeyIndy]

I follow the manual (Mobility and Minor Repairs -> Charging) and deep experience of the forum on the subject:

1. AC Charging is preferred using Timer function. I use that and the car manages the balance of best possible strategy to charge overnight to get to the target (mine is 85% by 6am from 9pm plug-in time with charger set to 48Amp output and car showing expected 10.x kW showing small loss from 11kW spec expectation). This means it does not try to charge as fast as possible given plenty of time to get to the target so it does that in short sprints as I can tell from the charger logs, assuming to be as gentle as possible on the battery.

2. DC Charging is to be used when you want to charge as fast as possible (per manual). I have a local EA station that I can charge for free with all stalls rated at 150kW, but I would not use it since AC charging is preferred for local motoring. However, if I am on a long trip, then if I have time (i.e., dining near the charge point), then I would use the lower possible kW such as 50kW with Battery Friendly option checked, and use Charging Planner to pre-heat the Battery to optimal temp on arrival.

However, overall consensus from the forum in my understanding, is that the battery and the "code" that manages charging and cooling is very robust so there is nothing you can do to harm the battery.

 

[Teufel Hund]

Thank you, I see the point. But which one is better than? Just an example; 50kwh*2 hour charging or 100 kwh*1 hour; will still 50kw charger produce less heat and better or they are just the same? What do you think?

No expert on the matter but the car is designed for both. I suspect that AC charging is the preferred method for the health of the battery. There is a forum member on here (sorry forgot their name) that has ONLY done DC charging for like 2 years or something. That members battery health if I remember correctly wasn’t that far off from others that have used both types of charging. At the end of the day I wouldn’t stress it too much. Try to use AC when you can and don’t worry about DC charging when you want or need to. The battery is under warranty for 8 years.

 

[Donlam]

Thank you, I see the point. But which one is better than? Just an example; 50kwh*2 hour charging or 100 kwh*1 hour; will still 50kw charger produce less heat and better or they are just the same? What do you think?

In theory they are the same but many variable like how the battery management react and work to cool down the battery. Always ac charging if you can, I would use 11-22kw charging speed all the time. I think every person has their own way and preference.

 

[daveo4EV]

it makes no difference to the warranty - charge when you want and how you want - porsche controls the battery you do not - nothing you do is going to affect the battery - there is too much software between the plug and a raw cell for your actions to make much of a difference

 

[daveo4EV]

this question keeps coming up in various forms - here is a similar but not identical thread - the discussion in this thread is pretty spot on…

https://www.taycanforum.com/forum/t...-have-less-charging-cycles.16183/#post-249092

 

[daveo4EV]

but to answer the question posed in the subject directly…

Q: "Low DC charging speed is less harmful?"
A: Yes - slower charging is "less hard" on the battery than "faster" charging

but what is left unsaid is - is there enough difference in impact in such a way that you will ever "notice" - I believe the answer to that is much much more muddy…there is no doubt slower charging is better for LiON cells - but the actual impact and how it would manifest itself in terms of your use of the battery is much much harder to quantify.

 

[Kaan34]

but to answer the question posed in the subject directly…

Q: "Low DC charging speed is less harmful?"
A: Yes - slower charging is "less hard" on the battery than "faster" charging

but what is left unsaid is - is there enough difference in impact in such a way that you will ever "notice" - I believe the answer to that is much much more muddy…there is no doubt slower charging is better for LiON cells - but the actual impact and how it would manifest itself in terms of your use of the battery is much much harder to quantify.

Thank you…

 

[rs38]

the Taycan's manual states roughly "try to minimize charges with >50kW"..
this is ~ 0,5C and therefore like charging you hybrid PHEV with AC in 2h.

from time to time you'll find 20kW DC chargers like at IKEA, I consider them do be less harmfull as 22kW AC as they "stress" less components and do not need OBC cooling. The battery does not care
whether DC or AC

 

[Kaan34]

the Taycan's manual states roughly "try to minimize charges with >50kW"..
this is ~ 0,5C and therefore like charging you hybrid PHEV with AC in 2h.

from time to time you'll find 20kW DC chargers like at IKEA, I consider them do be less harmfull as 22kW AC as they "stress" less components and do not need OBC cooling. The battery does not care
whether DC or AC

That was what I was trying to figure out, thanks..

 

[rim23]

the Taycan's manual states roughly "try to minimize charges with >50kW"..
this is ~ 0,5C and therefore like charging you hybrid PHEV with AC in 2h.

from time to time you'll find 20kW DC chargers like at IKEA, I consider them do be less harmfull as 22kW AC as they "stress" less components and do not need OBC cooling. The battery does not care
whether DC or AC

Maybe 20kw dc is even better as the cars components do not convert ac->dc (just a wild guess).

 

[daveo4EV]

Maybe 20kw dc is even better as the cars components do not convert ac->dc (just a wild guess).

if it's 20 kW it's probably a 400V FastDc charger - which means the 800V DC booster would be employed…

my attitude is it's best not to overthink this stuff - there is a BMS (battery management system) collection of software/hardware that managed the "raw" DC flow to the battery - it very very likely makes no difference what the input source is (AC/DC power) - because the BMS hardware is a gatekeeper to the "raw" DC inputs to the battery and the modules/cells to "charge" the battery…

only Porsche engineers know what actually happens when charging their battery - trying to "improve" your battery's longevity by changing what type of charger you plug into - is like trying to push a rope uphill…you're just too far removed from the actual software/hardware doing the actual voltage/amp adjustments to have _ANY_ affect…

and by the time 8 years/100,000 miles goes by - what ever state your battery is in - it's impossible to detertmine what if any affect any of your actions had on the battery…

and what outcome are you trying to manage to make it "better"?

honestly parking the car in the middle of a open parking lot for 2 weeks in Phoenix, AZ in the middle of august at 100F+ temps will have way way way more impact on battery health than any "charging" shenanigans...

the honest truth is we have no idea what we're doing - what outcome you're trying to manage, and how to gauge if you've been successful. The batteries going do what it's going to do - and there is very very very little you can do about it. It's not under your control.

• don't fast charge "too often"
• don't charge to 100% and let it sit there
  • don't always charge to 100% - charge to 85% or less
• don't let the battery get "too hot"
• don't let the battery get "too cold"
• don't run it down to low single digit % "too often"

that's about all you can do...everything else is based on the sum total of everything done to the battery over the life of vehicle - no one action will have any deterministic outcome.

 

[rim23]

if it's 20 kW it's probably a 400V FastDc charger - which means the 800V DC booster would be employed…

my attitude is it's best not to overthink this stuff - there is a BMS (battery management system) collection of software/hardware that managed the "raw" DC flow to the battery - it very very likely makes no difference what the input source is (AC/DC power) - because the BMS hardware is a gatekeeper to the "raw" DC inputs to the battery and the modules/cells to "charge" the battery…

only Porsche engineers know what actually happens when charging their battery - trying to "improve" your battery's longevity by changing what type of charger you plug into - is like trying to push a rope uphill…you're just too far removed from the actual software/hardware doing the actual voltage/amp adjustments to have _ANY_ affect…

and by the time 8 years/100,000 miles goes by - what ever state your battery is in - it's impossible to detertmine what if any affect any of your actions had on the battery…

and what outcome are you trying to manage to make it "better"?

honestly parking the car in the middle of a open parking lot for 2 weeks in Phoenix, AZ in the middle of august at 100F+ temps will have way way way more impact on battery health than any "charging" shenanigans...

the honest truth is we have no idea what we're doing - what outcome you're trying to manage, and how to gauge if you've been successful. The batteries going do what it's going to do - and there is very very very little you can do about it. It's not under your control.

• don't fast charge "too often"
• don't charge to 100% and let it sit there
  • don't always charge to 100% - charge to 85% or less
• don't let the battery get "too hot"
• don't let the battery get "too cold"
• don't run it down to low single digit % "too often"

that's about all you can do...everything else is based on the sum total of everything done to the battery over the life of vehicle - no one action will have any deterministic outcome.

I’m just speculating with my engineering gut. But you’re right.. I forgot the 400-800v conversion. Nevertheless, Porsche engineers have made everything so that we can just enjoy the Taycan.

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