Charging battery to full on regular basis or allow it to go down to 5 percent before topping up

[Frank]

Guys,

Unless you are keeping your car for a long time (i.e. past the warranty time or mileage) stop worrying about a so called charging regime. Let the BMS and the warranty do all the worrying for you.

I have had four EVS and plug them in EVERY night, I don't worry about flat 12v batteries or does my car need balancing because plugging it in EVERY night and unplugging it when I am just about to use it deals with these issues. And if the battery degrades (as it will, no matter what you do) so what, do you think an ICE car doesn't, it does, it's called wear and tear, do you think a 3/4 year old ICE gets the same range (MPG) as a new one, of course not.

So enjoy your car, plug it in EVERY night and you have the convenience of starting with a full charge every day and you won't be caught out with a sudden unexpected long journey.

Finally, unlike an ICE car that is losing its range( i.e. wearing out) it can be accompanied with more noise, vibration, unpleasant and possibly slower to drive whereas an EV with battery degradation will (in most cases) be just the same to drive as when you bought it except the range is reduced.

Regards

Frank

PS the first person in this post should definitely plug it in EVERY night.

Whats the point in having an EV that you should only charge to 80% ? Should we just pay for 80% of the car then ? Okay, for those of you that only do short journeys thats fine but I need my car for work and it has to be ready to cover 250km in a day at short notice. I charge mine via a granny only to 100% every time and allow it to balance everytime. After 30k of driving in 18 months my battery SOH is still 100%. The BMS will look after your battery.

View attachment 16968

Well done , Barrie. I always charge mine EVERY night regardless of SOC and my current car , an EV6 is still at 100% SOH after nearly 18000 miles.

Regards

Frank

PS I have had a MG ZS, two Konas and EV6 and every one of them was charged every night.

 

[tsedge]

It is the same amount of charging of the batteries whether you do it in big chunks or piecemeal.

Strongly agree with @Frank that this is not something people need to worry about with modern batteries.

It reminds me of conversations about revving before switching off ICE engines and waiting for an ICE engine to warm up before driving off - makes no difference to the average user.

 

[Rolfe]

I have a fair bit of sympathy with what Frank says, particularly since I have an SR battery and that's more or less how we're told to treat the SR anyway. However, I am planning to keep this car until it falls to bits, so I'm prepared to take sensible measures to prolong its life. I think the advice about treating 80% as "full" in the LR battery unless you are planning on a long trip the next day is being offered for a reason and given the way the app can be set, surely not at all onerous. If I had an LR, that's what I would be doing.

I think it's a myth that ICE cars lose range over time. I have kept three cars until they'd done over 100K miles (and one to about 60K miles) and maintained a complete petrol consumption record for all of them. They all were turning in the same MPG at the end as they did when new.

With one exception. The engine on my Golf was replaced under warranty after failing catastrophically at about 35K miles. The new engine had significantly better petrol consumption than the original one, and maintained that until the day Copart collected it earlier this month, 100K miles later.

 

[maskull]

I have a fair bit of sympathy with what Frank says, particularly since I have an SR battery and that's more or less how we're told to treat the SR anyway. However, I am planning to keep this car until it falls to bits, so I'm prepared to take sensible measures to prolong its life. I think the advice about treating 80% as "full" in the LR battery unless you are planning on a long trip the next day is being offered for a reason and given the way the app can be set, surely not at all onerous. If I had an LR, that's what I would be doing.

I think it's a myth that ICE cars lose range over time. I have kept three cars until they'd done over 100K miles (and one to about 60K miles) and maintained a complete petrol consumption record for all of them. They all were turning in the same MPG at the end as they did when new.

With one exception. The engine on my Golf was replaced under warranty after failing catastrophically at about 35K miles. The new engine had significantly better petrol consumption than the original one, and maintained that until the day Copart collected it earlier this month, 100K miles later.

I think you are correct about the myth of ICE cars losing range . I have had two hybrids for about 3and a half years and 50000 + miles in each case .
Both had better fuel efficiency when exchanged than when new ...by a long way

 

[Rolfe]

I never noticed an improvement other than when the engine was replaced, but I have concrete evidence of no deterioration whatsoever over many years and 100,000+ miles.

 

[Rolfe]

Seriously, if you have an LR battery, why not do what Frank says, but rather than charging to 100% every night, simply charge to 80% every night - except for days you know you will need to call on the full range of the car?

One or two members have mentioned that their jobs require them to be ready to drive 250 miles in a day, even though they won't be called on to do that very often. But that's relatively unusual. Most of us can surely get by keeping say 200+ miles range on the car on a routine basis and only putting in the full range when it's going to be needed.

 

[JDMB]

It’s also important (maybe ) to understand about what a battery cycle is, in particular what a full cycle is, and the depth of discharge in the equation around charging, a quick summary here .

Although I think, in my non expert opinion here, in many cases, it’s probably not worth worrying about. IIRC, the MG4 was built on a new battery platform that is modular too, and if there are issues with the battery, the whole thing doesn’t need to be replaced, theoretically making this work, should it need it, cheaper.

Some interesting info here too, New Tests Prove: LFP Lithium Batteries Live Longer than NMC - OneCharge

 

[profdraper]

Best charging behavior for LFP batteries

I have been writing about the importance of LFP (LiFePO4) batteries for a while now, but I haven’t written about the best charging behavior for this battery chemistry yet. It’s time to write a small, but important article about the subject, especially because I have seen some confusion on online...

pushevs.com

How to Take Care of Your Electric Vehicle Battery

We asked a battery expert to answer all your questions about maximizing every charge.

www.wired.com

LIFEPO4 SOC And Everything Else You Need To Know! » LiFePo4 Australia

LiFePo4 SOC and everything else you need to know about LFP chemistry and their use as batteries

lifepo4.com.au

 

[JDMB]

Best charging behavior for LFP batteries

I have been writing about the importance of LFP (LiFePO4) batteries for a while now, but I haven’t written about the best charging behavior for this battery chemistry yet. It’s time to write a small, but important article about the subject, especially because I have seen some confusion on online...

pushevs.com

How to Take Care of Your Electric Vehicle Battery

We asked a battery expert to answer all your questions about maximizing every charge.

www.wired.com

LIFEPO4 SOC And Everything Else You Need To Know! » LiFePo4 Australia

LiFePo4 SOC and everything else you need to know about LFP chemistry and their use as batteries

lifepo4.com.au

Thanks for these. The Wired article backs up my views too.

I’ve got a Trophy, and I’m not really going to worry about how I charge it. In fact, the only thing I’ve been worried about so far was my first charge at a Gridserve point on the motorway and it wouldn’t accept my card!! Luckily, a quick call to the number on the side of the point sorted it out - the operator rebooted the point and the card reader sprung into life again.

I’ve also got a Tesla Powerwall 2 and dedicate 20% of that to backup power. Admittedly it’s operated by Tesla and Octopus automatically on the (soon to be gone) Tesla Energy Plan and then I’ll have to flip it myself, but again, I’m not overly worried on the charging side.

 

[Rolfe]

Ow! That's getting on for TMI, I think.

My feeling is this. We have been repeatedly told that these batteries do not suffer from a memory effect and there is no need to discharge them fully, either every time or on a regular basis, so we should be fine about plugging them every night and having a full charge every morning. That's part of the attraction of these cars after all - that they can be charged at home and most of us will never need to spend a moment refuelling our cars outside of relatively infrequent long-trip situations.

We're told that the SR doesn't care a button about being left sitting on 100% charge, and indeed it rather likes it, so why not simply bring it to 100% overnight, every night? (Well, see below on that.)

We're told, however, that the LR doesn't like this, and prefers not to sit at 100% charge. We're given a handy app whereby we can, in effect, treat 80% charge as if it was the maximum, and simply bring the battery to that level every night - and apparently it will balance itself when you do that. Unless you think you might be called on to drive more than 80% of the car's range at a moment's notice, why not handle it that way? I don't think this advice is being given simply for the hell of it.

My one caveat with bringing the SR car up to 100% every single night is that every single morning you are going to start out with no regenerative braking. If you're only doing short journeys most days then that adds up to a fair proportion of your driving time spent without useful regeneration. This is, on average, going to damage the car's efficiency. I'm still trying to square this circle, maybe charge it to 100% once or twice a week or whenever I know I'll be doing a longer trip.

• I charged to 100% on Wednesday night as I knew I was setting off on a long trip on Thursday.
• I brought the car up to 100% again on Thursday evening at a destination charger in a car park while I was at the theatre, to ensure I had enough charge to do the whole day on Friday, as I was heading for a hotel with no charging facilities.
• I got home on Friday on 26% and obviously charged to 100% on Friday night.
• The car didn't turn a wheel on Saturday, but on Sunday I came home on 57%. Again I charged to 100%

This all makes pretty good sense to me, because I did a lot of driving and very little of it was between 95% and 100% where regeneration is minimal. However yesterday I did two trips, and came home from the second about 10.30 in the evening still with 88% charge. What's the point of bringing it to 100% and losing regeneration if I'm only going to drive it a few miles? Was there even any actual point in charging it on Sunday night and so starting Monday with no regeneration, when I'm not planning another long trip until Thursday?

I didn't charge last night, it's still sitting on the drive at 88%. That's enough to cover any sudden need to go somewhere that I hadn't anticipated. I can putter around for a couple of days without charging again, then charge on Wednesday night ready for the Thursday trip.

I'm sure I'll get the hang of this with practice, but at the moment I'm still feeling my way. The satisfaction of having a car sitting there at 100% charge ready to go is attractive, but if I'm only making short trips most days this is at the expense of efficiency by losing regenerative braking.

 

[bowfer]

I have a fair bit of sympathy with what Frank says, particularly since I have an SR battery and that's more or less how we're told to treat the SR anyway. However, I am planning to keep this car until it falls to bits, so I'm prepared to take sensible measures to prolong its life. I think the advice about treating 80% as "full" in the LR battery unless you are planning on a long trip the next day is being offered for a reason and given the way the app can be set, surely not at all onerous. If I had an LR, that's what I would be doing.

I think it's a myth that ICE cars lose range over time. I have kept three cars until they'd done over 100K miles (and one to about 60K miles) and maintained a complete petrol consumption record for all of them. They all were turning in the same MPG at the end as they did when new.

With one exception. The engine on my Golf was replaced under warranty after failing catastrophically at about 35K miles. The new engine had significantly better petrol consumption than the original one, and maintained that until the day Copart collected it earlier this month, 100K miles later.

It’s absolutely no myth that ICE cars lose efficiency with time.
It’s an unavoidable mechanical fact.
Valves can’t bounce around billions of times without wearing, piston rings can’t scrape up and down a bore millions of times without wearing.
And that’s just the internals, you have all the peripherals wearing out too (turbos / EGRs / injectors etc)
You simply didn’t have one long enough to see the deterioration, 100k miles isn’t a lot these days.

 

[Rolfe]

Best charging behavior for LFP batteries

I have been writing about the importance of LFP (LiFePO4) batteries for a while now, but I haven’t written about the best charging behavior for this battery chemistry yet. It’s time to write a small, but important article about the subject, especially because I have seen some confusion on online...

pushevs.com

OK, I read that after typing the above. Time for yet another rethink I suppose.

 

[Rolfe]

It’s absolutely no myth that ICE cars lose efficiency with time.
It’s an unavoidable mechanical fact.
Valves can’t bounce around billions of times without wearing, piston rings can’t scrape up and down a bore millions of times without wearing.
And that’s just the internals, you have all the peripherals wearing out too (turbos / EGRs / injectors etc)
You simply didn’t have one long enough to see the deterioration, 100k miles isn’t a lot these days.

Maybe it happens after 100K miles. The longest I ever kept one engine going for was 120K miles and there was no sign of it. But Frank was talking about appreciable loss of range after only a three to four years.

 

[Kithmo]

I was under the impression that charging to 100% is no problem as long as it's not left sitting for days at 100%. Charge to 100% and go is ok.

 

[Rolfe]

I am seeing so many conflicting pieces of advice I don't know whether I'm coming or going.

 

[JDMB]

I am seeing so many conflicting pieces of advice I don't know whether I'm coming or going.

You’ll struggle to do anything wrong with an LFP battery, so keep on doing what you’re doing. It’s got a 7 year warranty anyway.

I’ve the NMC battery. Again, I’m not overly bothered about degradation.

 

[Frank]

I am seeing so many conflicting pieces of advice I don't know whether I'm coming or going.

Rolfe,

This is the trouble, so I just don't worry about it , I plug it in EVERY night because in reality it's convenient and I have NEVER had any problems with the 12v battery, but more importantly for main battery health it never goes out of balance as plugging it in EVERY night to an AC source (don't forget the battery can't balance with rapid DC Charging) let's the BMS do this, as and when it needs to be done. Of all my EVs I can't even tell when they balanced as I was never around when it happened, all I can say is I never got a message from my BMS to say it was required.

All the best

Frank

 

[Rolfe]

You’ll struggle to do anything wrong with an LFP battery, so keep on doing what you’re doing. It’s got a 7 year warranty anyway.

I’ve the NMC battery. Again, I’m not overly bothered about degradation.

This was my thought. I have no doubt that all these articles by the learned electronics gurus are correct, but it's unclear how much difference their advice makes. Sweating over how to charge the SR to 70% when the app won't allow that to be done automatically? Is it worth it if the gain from doing it is minimal? Even if you plan to keep the car till it falls apart?

How about setting off with only 70% charge, so reducing your range by more than 30% (since nobody in their right mind is going to go down to zero)? How about holding off charging unitl the car is down close to 20%, and then discovering that you need to go somewhere, urgently, right now? All these are considerations that influence real world behaviour.

I'm inclined not to plug it in every night if I've only done short journeys, for the regeneration more than anything, but I'm not inclined to let it go below say 40-50% because I'd be screwed if something unexpected came up. I mean, a huge chunk of the advantage of an electric car is that you can begin every day with a full charge if you want to, and never have to worry about refuelling away from home unless you need to travel further than the range of the car. All these shenanigans significantly reduce the practical range that you're left with.

Certainly unless I have to race off right now, the car can always have half an hour or more on the rapid charger at the end of the road. But this really negates the advantage of being able to have it sitting ready to go, which is such a selling point.

 

[Rolfe]

This is the trouble, so I just don't worry about it , I plug it in EVERY night because in reality it's convenient and I have NEVER had any problems with the 12v battery, but more importantly for main battery health it never goes out of balance as plugging it in EVERY night to an AC source (don't forget the battery can't balance with rapid DC Charging) let's the BMS do this, as and when it needs to be done. Of all my EVs I can't even tell when they balanced as I was never around when it happened, all I can say is I never got a message from my BMS to say it was required.

Thanks very much for the advice, appreciated. If I had the LR I'd probably do that, but take it to 80% rather than 100%, and just do the 100% thing however often it's recommended, or before a long journey, but it comes to the same thing.

I don't have a wall box, because right now I'm not seeing the need for one. My routine is that if the car has only gone a short distance in the day I'll leave it, to preserve the regeneration as much as anything. Last night I came home quite late on 88% and just abandoned it in the drive rather than reverse into the garage to hook up the granny charger. I haven't used it today. Now, unexpectedly, I have to drive say 30 miles tomorrow. Do I go out and put it on the granny charger now? I could, but I don't see the point really. I'll get back about 50% charge and then the car can sit on the granny charger so it's full by mid-day on Thursday when I have a round trip of over 100 miles planned. (I'll be staying away several nights. The hotel I'm staying at has a charger but it's an expensive commercial operation, not a guest courtesy affair. And I want to have a contingency agailable.)

If I get back any time with a pretty low SoC, certainly if it's below 30%, I just shove it on the rapid charger at the end of the road for the 55 minutes time allowed or until it makes maybe 80-85% SoC, then I move it into the garage and finish the charge on the granny charger so it can balance. It always balances after it has reached 100%, I've never seen that not happen.

This routine is working, it's just such a novel way of working that I'm still at the stage of thinking, should I charge tonight if I've only done ten miles today?

I really think I read somewhere that if the SR battery has to be left undriven for a period of time, to leave it at 100% if possible, but in any case with as much in it as possible. That contradicts some of what is being said.

 

[MartinSEsr]

If your doing 240 miles round trip, eachday ?? - if so wow thats 40,000-50,000 miles a year on just commuting! - Your battery warranty will be up longbefore anything else, so wouldn't worry too much.

I have the LFP version, 7000miles & 2.8% degredation

How do people check the battery degradation? I know how to on my iphone, but not on the MG4.

Thanks!