[Wilf69]

Good morning all, I am on the journey to my first EV and still fact finding. I have been following various You Tube channels and magazines etc for over a year so am reasonably well informed and I’ve done all the soul searching and come up with a 200m real range requirement. What’s this based on? Nothing more than what is likely to be my ’regular’ longer trip, i.e trips to Cornwall to see friends which we hope to resume soon and 200m would get us there with some local driving before needing to charge. Unconscious bias is a difficult thing to spot so I’m probably over egging a bit but car size is also important here and it seems many of the cars I shortlist come with this capacity anyway. So, the question....I understand good management is to routinely charge between say 10 and 80% with periodic full charges. If I end up with car with a bigger battery is there a longevity problem with routinely doing 30 to 70% for example, purely because of the longer charge time? I would be a home charging user for over 95% of the time as well. For added context I am a solar user with storage. My current cars are a 1977 MGB and a 2018 BMW 118i and we handed the Mini back early in lockdown so the next car will replace the BMW.

First of several questions over the coming months I expect so all insights welcomed and appreciated. Thanks in advance.

 

[electricdriver]

So, the question....I understand good management is to routinely charge between say 10 and 80% with periodic full charges. If I end up with car with a bigger battery is there a longevity problem with routinely doing 30 to 70% for example, purely because of the longer charge time?

Welcome...in short, the answer is no. Received wisdom is that the less the cycle range, and the closer it is centred to 50% capacity, the less battery degradation there is. So 30-70 is better than 20-80. But don't obsess about it, most modern EVs have systems that minimise the damage and manage heat etc well. As long as you don't routinely leave the car sitting at very low or very high states of charge for a long time all will be well.

Warning...this topic is possibly the most contentious there is in the EV world. Someone will be along in a minute to tell you that it's absolutely critical to manage charging to the nth degree...personally, I don't worry about it too much!

 

[farmergiles]

The only thing against a large battery that you rarely use is the cost. There is plenty of evidence that charging a battery between 30-70% will increase it's life BUT you should charge at home to 100% about once a month so the BMS can balance the cells (don't leave it at 100% for long periods).

Of course, a larger battery reduces the charging frequency - I only need charge my 62w Leaf once a week and to 100% about every 4 weeks. I will charge to 100% if going on a long journey (>200miles) and then to 90% on a public rapid charger en route.

This Carwow video is quite informative and they also have one with smaller EVs - Zoe, Honda, Corsa etc.

Teslas and some Kias seem to give the best range.

 

[Edd Beesley]

Good morning all, I am on the journey to my first EV and still fact finding. I have been following various You Tube channels and magazines etc for over a year so am reasonably well informed and I’ve done all the soul searching and come up with a 200m real range requirement. What’s this based on? Nothing more than what is likely to be my ’regular’ longer trip, i.e trips to Cornwall to see friends which we hope to resume soon and 200m would get us there with some local driving before needing to charge. Unconscious bias is a difficult thing to spot so I’m probably over egging a bit but car size is also important here and it seems many of the cars I shortlist come with this capacity anyway. So, the question....I understand good management is to routinely charge between say 10 and 80% with periodic full charges. If I end up with car with a bigger battery is there a longevity problem with routinely doing 30 to 70% for example, purely because of the longer charge time? I would be a home charging user for over 95% of the time as well. For added context I am a solar user with storage. My current cars are a 1977 MGB and a 2018 BMW 118i and we handed the Mini back early in lockdown so the next car will replace the BMW.

First of several questions over the coming months I expect so all insights welcomed and appreciated. Thanks in advance.

If you daily use is low then stick the limiter on 70% and plug it in every night. Job done.

 

[dk6780]

As above. You also sound like someone who will not own the car for its whole lifetime so it's unlikely to be your problem. People obsess about the battery life but it really is not the problem people make it out to be unless you have a car with a small battery and require all of the range.

 

[Swagman]

As above. You also sound like someone who will not own the car for its whole lifetime so it's unlikely to be your problem. People obsess about the battery life but it really is not the problem people make it out to be unless you have a car with a small battery and require all of the range.

Exactly.
Unless you intend to own the EV for 10 years or so, there's very little to worry about.
I've never considered battery management of my personal transport whatsoever, but then again I lease, so it becomes someone elses problem further down the line.

 

[freddym]

Good morning all, I am on the journey to my first EV and still fact finding. I have been following various You Tube channels and magazines etc for over a year so am reasonably well informed and I’ve done all the soul searching and come up with a 200m real range requirement. What’s this based on? Nothing more than what is likely to be my ’regular’ longer trip, i.e trips to Cornwall to see friends which we hope to resume soon and 200m would get us there with some local driving before needing to charge. Unconscious bias is a difficult thing to spot so I’m probably over egging a bit but car size is also important here and it seems many of the cars I shortlist come with this capacity anyway. So, the question....I understand good management is to routinely charge between say 10 and 80% with periodic full charges. If I end up with car with a bigger battery is there a longevity problem with routinely doing 30 to 70% for example, purely because of the longer charge time? I would be a home charging user for over 95% of the time as well. For added context I am a solar user with storage. My current cars are a 1977 MGB and a 2018 BMW 118i and we handed the Mini back early in lockdown so the next car will replace the BMW.

First of several questions over the coming months I expect so all insights welcomed and appreciated. Thanks in advance.

Entirely over thinking this. Just avoid anything German and you will be fine 😜

 

[DSLRed]

Entirely over thinking this. Just avoid anything German and you will be fine 😜

I am gonna have a bet now that the OP is on his way to pick up his new ID.3

As per above Wilf69, I wouldn't stress about it. Just don't make the mistake of charging to full routinely and you'll be fine. I am charging at home all the time due to lockdown and just set the max to 80%. I tend to plug in before it drops below 45% as I know that the car will get back to my max within my 4 hour cheap Octopus window. I am only charging once a week at present.

Above all, enjoy your new car!!

 

[Big277wave]

I look at the extra price for a large battery as in terms of how many hours you've had to work to pay for the depreciation you're expecting over your ownership vs how many hours it saves you spending at rapid chargers. Bottom line is it worth spending £5K to avoid a rew rapid half hour charging sessions a year.

Provided the car's battery has a proper thermal management system, used sensibly you should expect minimal degradation.

 

[Phlashman]

Charge to 100% all the time. You paid for it, use it.

I've done that for years first with my leaf then e-Golf and not had any noticeable degradation, I'm doing the same with my ID.3.

No idea why people stress about range and at the same time cut their battery size down 40% voluntarily.

 

[DSLRed]

Charge to 100% all the time. You paid for it, use it.

I've done that for years first with my leaf then e-Golf and not had any noticeable degradation, I'm doing the same with my ID.3.

No idea why people stress about range and at the same time cut their battery size down 40% voluntarily.

When I am back on the road every day doing long miles after this lockdown lark then I'll be happy to charge to 100% every night because I will need the range and will be on the road within an hour or two of the car hitting 100.

Right now, I simply don't need the range. So am happy to follow received wisdom about not leaving it at high states of charge for long periods.

 

[farmergiles]

I

When I am back on the road every day doing long miles after this lockdown lark then I'll be happy to charge to 100% every night because I will need the range and will be on the road within an hour or two of the car hitting 100.

Right now, I simply don't need the range. So am happy to follow received wisdom about not leaving it at high states of charge for long periods.

Yes, I am not averse to charging to 100% regularly, however, I will probably buy the Leaf at the end of the PCP and keep until I pop my clogs or banned from driving on health grounds, so I do want to monitor how the SOH declines as it ages from time to time.

 

[Hitstirrer]

A lot of such concerns come from months of research prior to jumping into the EV world. You have identified the consensus view after that period but that isn't a set in stone regime that must be observed or the world will end. A better way to regard the ideal battery charging strategy is to take note of it but not let it become a daily treadmill.

Six years ago when much of this data was not yet settled I simply plugged my Leaf 24 in every night on a dumb charger and started next day with 100%. The result? No degradation after three years. However, if I had been influenced by the 30/70 or 20/80 mantra that is now regurgitated in the EV world then I would have probably had more range anxiety by trying to operate on 40 to 60% of the battery's capacity.

Please relax on this subject. It is much overhyped. By all means, take note of the perceived wisdom and be aware of the advice but don't let it become a constant concern over EV ownership because it really isn't a major issue.

 

[cdlb]

If I end up with car with a bigger battery is there a longevity problem with routinely doing 30 to 70% for example, purely because of the longer charge time?

Nope. Remember that "70%" depends a lot on what car you buy, some have a large buffer at the top already, some don't, so your perceived 70% is unlikely to be an actual 70% SOC. Same goes for 100%, so when people say "don't charge to 100%", you need to consider that in the context of what you're actually going to buy, because not all 100%s are created equally. A genuine 100% charge onto a battery isn't great, but a well designed system should never let you do that in the first place.

Don't think this has been mentioned in this thread yet, but a slow charge is less "stressful" on the batteries than a rapid charge, so if you're worried about longevity, your plan to home charge 95% is right on point. Having said that, don't be afraid to rapid charge when you need to - flooring the accelerator is more stressful on a combusion engine and drivetrain than taking it gently, but it doesn't mean that you should never do it.

 

[farmergiles]

Nope. Remember that "70%" depends a lot on what car you buy, some have a large buffer at the top already, some don't, so your perceived 70% is unlikely to be an actual 70% SOC. Same goes for 100%, so when people say "don't charge to 100%", you need to consider that in the context of what you're actually going to buy, because not all 100%s are created equally. A genuine 100% charge onto a battery isn't great, but a well designed system should never let you do that in the first place.

Don't think this has been mentioned in this thread yet, but a slow charge is less "stressful" on the batteries than a rapid charge, so if you're worried about longevity, your plan to home charge 95% is right on point. Having said that, don't be afraid to rapid charge when you need to - flooring the accelerator is more stressful on a combusion engine and drivetrain than taking it gently, but it doesn't mean that you should never do it.

It was quite easy to deduce on the Carwow videos, which EVs had buffers in the way some of them just stopped very soon after there was zero range left, whereas others did a good few miles with the display showing zero.

 

[NGee]

I would look at it from the point of view of bigger battery being less stressed by this charging approach.

As said, a charge to 100% once a month or so will ensure the BMW keeps track of what's going on.

Perhaps the more important consideration is how often you will need the full battery capacity, and would you do "better" to have smaller battery which usually makes for a cheaper and lighter car, and accept that you'll be doing a little bit more fast charger on your longer route. This is, of course, entirely down to your likely usage profile and personal preferences! I only say this as you refer to driving "to Cornwall ... and 200m would get us there with some local driving before needing to charge". An approach that meant stopping for 30 minutes to charge at the 3/4 point might not impact much on your life, have no impact on your daily use, but open up other vehicles?

 

[Mr_ess_jay]

Just manage the battery as per the user manual. Don't obsess, life's too short and there are for more interesting things out there to think about.

The only thing I would consider with the battery is not to buy one so big that you never use full range before recharging, you'll just waste energy carrying the extra heavy weight around and dampen the performance.

Don't buy the 300 mile battery for the twice a year range requirement. It's just a waste of cash if nothing else.

 

[Petriix]

Charge to 100% all the time. You paid for it, use it.

I've done that for years first with my leaf then e-Golf and not had any noticeable degradation, I'm doing the same with my ID.3.

No idea why people stress about range and at the same time cut their battery size down 40% voluntarily.

Regardless of battery health, it's objectively less efficient to charge to 100% every day: charging losses are higher as the battery voltage increases; cell balancing uses a fair amount of energy (typically 2kWh in my MG5) for zero tangible gain in range; and regenerative braking is limited when the battery is full so energy is lost to friction.

I estimate that the total lost energy for every 100% balance charge is around 3kWh in comparison to just charging to 80% most days and only balance once per month. If you do that every day then you could be wasting 1000kWh per year.

 

[freddym]

I would look at it from the point of view of bigger battery being less stressed by this charging approach.

As said, a charge to 100% once a month or so will ensure the BMW keeps track of what's going on.

Perhaps the more important consideration is how often you will need the full battery capacity, and would you do "better" to have smaller battery which usually makes for a cheaper and lighter car, and accept that you'll be doing a little bit more fast charger on your longer route. This is, of course, entirely down to your likely usage profile and personal preferences! I only say this as you refer to driving "to Cornwall ... and 200m would get us there with some local driving before needing to charge". An approach that meant stopping for 30 minutes to charge at the 3/4 point might not impact much on your life, have no impact on your daily use, but open up other vehicles?

BMW?

 

[cdlb]

It was quite easy to deduce on the Carwow videos, which EVs had buffers in the way some of them just stopped very soon after there was zero range left, whereas others did a good few miles with the display showing zero.

There's more than one buffer, and a driving test doesn't tell you everything.

• There is a buffer above 100% reported to actual 100%. Actual 100% can damage the battery. This is a buffer provided by the BMS.
• There is a buffer below 0% reported to actual 0%. Actual 0% can damage the battery. This is a buffer provided by the BMS.
• There is a buffer below 0% reported to where the car shuts down. The battery is not at actual 0% at this point, to prevent damage. This is a buffer programmed into the GOM.

Driving the car only tells you the last one. You need to query the BMS for cell status for the other two.