Effect of frequent rapid charging on battery

[LukeTim]

I have had my mg4 for only a few weeks and currently don’t have a wall charger at home, but I work from home so I also dont have an opportunity to plug into an AC charger at my place of work either. As such, when I get the opportunity to charge I have found myself tending towards using rapid chargers because that way I can get a substantial charge within an hour and then be on my way.

I do intend to get a wall charger installed fairly soon, but I’m wondering what, if any, effect this frequent rapid charging might be having on the battery longevity. Should I stop and find another way to charge until I can get the home charger?

I do know that I need to do a 100% slow charge for balancing once a month but in that case I believe I can rapid charge to 80/90% and granny charge the rest over night.

 

[Rolfe]

You have the SE SR which has the LFP battery, and these can take pretty much anything you want to throw at them. I wouldn't worry about what you're doing at the moment. However.

The LFP battery likes to be balanced quite often - if you are AC charging then you let it go to 100% and balance every time you charge. They recommend once a week but it does depend on how often you're charging. As you say though, for now you can DC charge to 80-90% and then put the car on the granny charger overnight. I did that quite often when I first got my car, because the local DC charger was particularly cheap at the time.

Another point which will not trouble you yet is that there is a recommendation to run the car down below 10% then charge it all the way to 100% in a single run on an AC charger, every few months. (They say every 3-6 months.) This can be done on a granny charger but it takes about 26 hours, and you have to be confident your electrical socket can take it. It will not harm the battery if you don't do this, but the car needs it as a calibration charge. LFP batteries in particular have a flat discharge curve and over the weeks and months the car loses track of where the bottom of the well is. If you don't let it see the bottom every so often, then calibrate as it climbs to the top in one go, you can find that you have a nasty surprise one day when the car runs low and suddenly sees the bottom - 20 miles before its original estimate.

But don't worry about your rapid charging, the LFP can take it and there's nothing wrong about what you're doing.

 

[webhiker]

I always feel sad when I read questions like this ?
Remember, your car is an object to be used, it even comes with 7 years of warranty.
Yes, if you for 7 years solely DC charge it will have an impact. Theoretically DC charging will impact also for shorter periods, but in my mind, this will be insignificant. Any type of car will degrade by usage, but remember that the intent of any car is to be used.
Use your car with pleasure, do slow charges when you can, do 100% AC charges once in a while, but most importantly enjoy ?

 

[Rolfe]

I think that's the point. I remember having an argument with my PhD supervisor about the two meanings of the word "significant". He was talking about statistically significant. I said OK, but so what, if you can show that a certain intervention raises heart rate by 2 bpm that's a statistically interesting finding, but a completely insignificant clinical effect.

Think about the old question about whether not putting the milk in your tea until you're ready to drink it will make it cool down more quickly. If you measured it very precisely the answer would be yes, there would be a statistically significant effect. But it might be only a second, or a fraction of a second!

A lot of these hand-wringing exhortations that you shouldn't do this or that or you'll damage your battery are in the "insignificant clinical effect" category. Some boffin in a lab might be able to measure a difference in degradation speed, but your battery is probably good for half a million miles and counting. Does it matter if you vary that by a few hundred or even a few thousand miles either way? Once an LFP battery has settled down, maybe lost 10 miles of range early on, it's likely to stay the same until the actual car is close to falling apart.

Do the balance charging every week or so if it's convenient. Try to make time to do a <10% to 100% and balance charge on AC at least every six months. Otherwise, do what works best for you and don't worry about it.

 

[bedsev]

Do you have zap map? I don't have a home charger either but there are a couple of 7k AC chargers that are cheaper than local DC chargers that I put my car on and then leave it all day whilst I am working and then pick it up. I have to walk about 6 mins each way.

 

[DixieTGS]

Another thing which will help your bank balance a lot and your battery a bit is to bung your granny charger on every time you get home even if it is at 90%. As you work from home I'm surprised the bulk of your charging isn't done with granny charger anyway (unless it's awkward to have it plugged in during the day for some reason).

 

[Rolfe]

Yes, it's still going to be cheaper than DC chargers even at daytime rates.

 

[Tuareg]

I always feel sad when I read questions like this ?
Remember, your car is an object to be used, it even comes with 7 years of warranty.
Yes, if you for 7 years solely DC charge it will have an impact. Theoretically DC charging will impact also for shorter periods, but in my mind, this will be insignificant. Any type of car will degrade by usage, but remember that the intent of any car is to be used.
Use your car with pleasure, do slow charges when you can, do 100% AC charges once in a while, but most importantly enjoy ?

Correct, far to much over analysis over this and many other aspects of EVs. There seems to be a large contingency of EVs owning their buyers rather than the other way around. Enjoy the 7 year warranty, it's a car, an appliance, it's there to be charged up and used.

 

[Ian Key]

Lets keep this simple. You are getting a home charger fairly soon so you won't do any damage to the battery meanwhile.

You don't say how often you are charging but as you have the LR battery keeping the battery between 40% and 80% unless you need the range is optimal. And as you suggested once a month charge it up to 90% ish then top it up and do a balance charge with the granny charger.

Apart from that don't over think it and enjoy the car.

You have the SE SR which has the LFP battery, and these can take pretty much anything you want to throw at them. I wouldn't worry about what you're doing at the moment. However.

@Rolfe his profile says he has a SE LR which is the NMC battery

 

[Rolfe]

Sorry, thanks for pointing that out, I must have misread his profile at the beginning.

Please disregard my irrelevant witterings, @LukeTim.

 

[DixieTGS]

... And my comments should say charge to 80% unless doing a longer trip the next day when 100% will be fine.

 

[fnegroni]

I do know that I need to do a 100% slow charge for balancing once a month but in that case I believe I can rapid charge to 80/90% and granny charge the rest over night.

The more you charge on ac/granny the better, but that works too

 

[Rolfe]

It'll be fine. Lots of high mileage cars that have been used as taxis and DC charged a lot, and their batteries are in a pretty decent state of health. (It would still be cheaper to use the granny as much as possible though.)

 

[FrankMG4]

LFP battery: good video at
NMC battery (long range):

 

[Kevin Smith]

Granny all the way - done 15,000 miles on our granny so far. Waiting for a Zappi which the DNO just approved as we have a looped supply. paying less the 10p/kWh at night until last week now 11p on ECO7 with octopus - 7 hours x1.8kWx4mi/kWh = 50 miles per night on cheap - should go well if you work from home a lot. If you need more just add daytime charging at home which is still cheaper than public...

 

[Kevin Smith]

LFP battery: good video at
NMC battery (long range):

The LFP video affirms my strategy of letting the battery gradually reduce its state of charge over several days' use and then gradually recharging in 3-4 nights of 7 hours on the granny lead giving a limited time in the 75-100% range but still reaching 100% about weekly to keep calibration right. I also like his comments about the fact battery use is not our only consideration as we want to use our car so a pragmatic dose of salt all round and charge it as you have to when you need to!

 

[Jto]

I have had my mg4 for only a few weeks and currently don’t have a wall charger at home, but I work from home so I also dont have an opportunity to plug into an AC charger at my place of work either. As such, when I get the opportunity to charge I have found myself tending towards using rapid chargers because that way I can get a substantial charge within an hour and then be on my way.

I do intend to get a wall charger installed fairly soon, but I’m wondering what, if any, effect this frequent rapid charging might be having on the battery longevity. Should I stop and find another way to charge until I can get the home charger?

I do know that I need to do a 100% slow charge for balancing once a month but in that case I believe I can rapid charge to 80/90% and granny charge the rest over night.

Hi
Recommend to watch YouTube channel Petrol Ped and look up

The Truth about EV Battery Life and Charging Best Practice ! Will explain.​

 

[Rolfe]

I honestly don't much like that American guy's videos. He reads papers written by other people (people who have even pointed out that other researchers found different results) then pontificates. He takes statistically significant findings of very small differences, then preaches that owners should follow the routines he has devised, when the fact is that the amount of difference any of that will make to a battery that's expected to do half a million miles anyway is pretty negligible.

He preaches one thing based only on longevity (maybe how to add 5,000 miles to a battery that's going to do 500,000 miles) without considering day to day use or convenience. Then he brings these points in and contradicts himself, and ends up with a fudge. I think his approach is only going to encourage people to become paranoid worry-worts about their cars, when they should simply be driving them.

See the first few posts in this thread. For the LFP battery, try to balance at 100% on an AC charger reasonably often (once a week might be excessive, depending on mileage) and do a <10% to 100% and balance AC charge every few months. Maybe every six months or so. This all keeps the calibration accurate, which might be important to you some day. But even if you fail to do this and the calibration slips (let's just hope you got home OK), you can fix it by actually doing these things. You won't have done any permanent damage worth mentioning.

Just enjoy your car and don't worry too much about it.

 

[Jto]

I have to say my HS PHEV is charged every night to 100% and I have been doing the for over 3 years. I have done a run yesterday which I do each a year and this year I done 26 miles and the distance left in the battery was 9 miles. I am getting more then the 32 miles a round 35 to 36 miles. Not too sure what type of lithium battery is in this car but doing OK.

 

[fnegroni]

I honestly don't much like that American guy's videos. He reads papers written by other people (people who have even pointed out that other researchers found different results) then pontificates. He takes statistically significant findings of very small differences, then preaches that owners should follow the routines he has devised, when the fact is that the amount of difference any of that will make to a battery that's expected to do half a million miles anyway is pretty negligible.

He preaches one thing based only on longevity (maybe how to add 5,000 miles to a battery that's going to do 500,000 miles) without considering day to day use or convenience. Then he brings these points in and contradicts himself, and ends up with a fudge. I think his approach is only going to encourage people to become paranoid worry-worts about their cars, when they should simply be driving them.

See the first few posts in this thread. For the LFP battery, try to balance at 100% on an AC charger reasonably often (once a week might be excessive, depending on mileage) and do a <10% to 100% and balance AC charge every few months. Maybe every six months or so. This all keeps the calibration accurate, which might be important to you some day. But even if you fail to do this and the calibration slips (let's just hope you got home OK), you can fix it by actually doing these things. You won't have done any permanent damage worth mentioning.

Just enjoy your car and don't worry too much about it.

I thought his LFP video was really good.