Battery charging... make 80% the new 100%

[ruggedscotty]

If they started making the 80% point the new 100% start to get decent range at 80% rather than this mythical 100% as trying to charge to 100% is what blocks the chargers....

The tipping point is almost upon us, ICE is going to be consigned to history.

[paradigital]

Or just make the DEFAULT charge capacity for rapid charging only, 80%. Make it hard to change accidentally, and a large warning regarding increased charge times and diminishing returns on your journey time that you have to accept before changing the limit.

There will be fringe cases whereby charging to 100% is required (last stop before a charge black hole for example), and there’s no reason at all to make charging to 100% difficult at home (and in some instances it would be a bad thing, such as LFP batteries).

[5s Alive]

I already only charge to 80% ish because much higher to takes too long. Most of the rapids that I've used are time limited to 45/60 mins with overstay penalties and this usually keeps them clear - of EVs at least.

[HoHoHo]

The bigger problem is 90% of EV owners don’t understand you don’t charge to 100% at the service station or garage, you go to 80% max and then move on.

I arrived at a fast charger the other day to find the family next to me were there already when I arrived with about 85% showing on their charger. We stayed longer than I needed simply because there were 50 cars covered in lights and my son was interested in having a look. By the time I left some 20 minutes later I was up to 80% from 10% and they were still watching the LED display desperately trying to reach 100%.

I left thinking…..why?

The reason is they didn’t understand 80-100% takes an age and simply isn’t worthwhile.

[samoht]

Are you drunk? (No judgement, it's NYE).

I'm not convinced that cars charging beyond 80% is truly a major cause of charger unavailability, vs chargers being broken, slow, or refusing to work with certain cars.

It's also worth noting that in many cases a fully utilised charging facility is throttled by the total available power, so if one car out of four is trickling in the last 5%, the other three cars are probably getting a faster charge than they otherwise could. In this state the total charging throughput of the site is determined by the overall power not the power drawn by any one EV, so the actual capacity isn't being 'wasted' by one car charging beyond 80%. If all four bays are occupied by nearly-full EVs, this would however represent wasted capacity.

If I'm making a trip that requires a single stop, I'd rather stay at that one stop for an extra 5 minutes to charge up to 85-90% than stop a second time, even if the total charging time would be less, the time and hassle of a second stop wouldn't be worth it.

There's nothing magic about 80%, different EVs have quite different charging curves. For instance a BMW i4 would still be pulling almost 50kW well beyond 90% full, a perfectly respectable rate that's as high as the peak rate for many popular EVs such as the i3, Leaf or Ioniq 38.



I haven't seen 45 or 60 minute time limits where I've charged, I think time limits make sense in principle but if you're getting a charge much slower than your car can take (eg due to the whole site being busy) it would add insult to injury to pay more for a worse service. Ideally the time limit would only count the period where the car itself is the limiting factor rather than the charger.

[off_again]

Good point. In the Mach-e forums there are a lot of threads around what to charge to and so on. As you might imagine, there is also a LOT of misinformation that gets peddled around.

But, if you read the manual (RTFM) you will have it clearly documented. NCM batteries are fitted to the Premium and above models and LFP to the Select models. For NCM batteries, Ford recommends to charge to 90% and to allow the battery to cool before you start a charging session. For LFP, Ford recommends to charge to 100% and ensure that you charge to 100% at least once per month (to keep the guess-o-meter reading somewhat accurately).

But this is where it gets a little complicated. A Select AWD (LFP) has 230 miles range and the Premium AWD (NCM) is 270 (at 90% recommended charge). Is 50 miles worth the $5k price difference? How do you explain this to a customer who isnt technical? You can charge one to 100% all the time as its recommended, but the other one to 90% and to minimize fast charging.... blah blah. Most people will have fallen asleep by then!

I agree in principle though - lets agree a max recommended charge and have some sort of better range calculation than WLTP. That way consumers might have some way to actually compare models!

[HoHoHo]

Not drunk (yet!), I might be later……

I thought the vast majority of batteries deliberately slowed charging down after 80% to help with battery life - I’m happy to be corrected.

It still doesn’t seem logical to stay for 20 minutes or for less than 15% when you can get that in minutes if you stop again later rather than a few minutes if you stop later - I don’t know if they needed 100% to get home or were simply determined to get to the magical ‘full’ battery charge.

I still also think that currently technology used in some EVs simply isn’t charging quickly enough. I had a look at a new Mercedes the other day next to my car and that charges at snail speed compared to my car and that makes a huge difference if we are all hoping to simply drive into a charging station and be off in 15 minutes or so much like we fill up with petrol.

The only way EVs will work is if you can splash and dash giving you a reasonable distance to hand, you can’t have a queue of cars all waiting for hours to charge.

[samoht]

The majority of EVs have a charging rate which declines as the battery fills, peaking somewhere around 20-30% SoC and going down from there. Some are gradual and others have larger 'steps' in rate. 80% is a fairly common place to have a step, but it's by no means universal. Almost all EVs are well below their peak charge rate well before 80% charged, so it's somewhat arbitrary and varies by model.


In general I agree that EV drivers would benefit from understanding the charging curve of their own vehicle and how to make it work for them, and not simply assume that they should wait until the battery is fully charged before leaving a fast charger but make intelligent trade-offs for their own journey.

However, that can't be reduced to a simplistic 'you should always fast-charge to 80%' - the optimum depends on the car, the journey and the passengers preferences for fewer vs shorter stops.


Incidentally I've tried a couple of times to draft a "all you need to know about owning an EV" type document, but it always ends up getting so long and technical that I find it hard to believe many people would want to read it all!

[Johnson897210]

I had a great phone, it used to charge to 100% and lasted a day. Then it became half a day, and then I had to buy a new one as the battery life was utterly hopeless…

[Johnson897210]

James6112 said:

Johnson897210 said:

I had a great phone, it used to charge to 100% and lasted a day. Then it became half a day, and then I had to buy a new one as the battery life was utterly hopeless…

Which has zero relationship to EV batteries, which invariably come with an 8 year warranty.
Buy a better phone next time?

Good lord the usual misinformation delivered in record time.

8 years…

[HoHoHo]

Johnson897210 said:

James6112 said:

Johnson897210 said:

I had a great phone, it used to charge to 100% and lasted a day. Then it became half a day, and then I had to buy a new one as the battery life was utterly hopeless…

Which has zero relationship to EV batteries, which invariably come with an 8 year warranty.
Buy a better phone next time?

Good lord the usual misinformation delivered in record time.

8 years…

Are you suggesting they don’t come with 8 years…

[off_again]

HoHoHo said:

The only way EVs will work is if you can splash and dash giving you a reasonable distance to hand, you can’t have a queue of cars all waiting for hours to charge.

^ This

It takes a shift in the way you think about their use. The idea that you have to fill to 100% every time does not make sense, especially if you are away from home and using public chargers. You charge to what you need + a little contingency. Thats it.

And we shouldn't forget that the lower the SoC, the faster it will charge, though mileage will vary across different manufacturers. The Mach-e is pretty good and flat (though slow compared to more recent EV's) but absolutely plummets at 80%. Consider the charging curve!

If you are stupid enough to sit and wait for your car to charge to 100% each and every time, you will be spending a lot of time waiting. Switching from an ICE to an EV this is one of the big things to adjust to.

[off_again]

Johnson897210 said:

I had a great phone, it used to charge to 100% and lasted a day. Then it became half a day, and then I had to buy a new one as the battery life was utterly hopeless…

You do realize that while the underlying chemistry might be similar, their operation is completely different?

Phone batteries are constrained by space and weight and typically have fairly limited capabilities around their charging mechanisms. They have got better in recent years, but are still fairly limited in what they can do.

Its well known that a phone battery typically will degrade over time. This is usually due to the number of charge cycles that you put through it. In a lot of cases, we are charging our phones daily, so they are getting hit hard with the impact of the charging process. An EV on the other hand isnt charging to 100% each time every day. In a lot of cases its going to be once every 3-4 days for the average user (its once per week for me!) and hence this part of the chemistry equation is very different.

Then we are onto the charging systems - an EV has a sophisticated mechanism to manage, control and keep consistency through the charging process. Its going to be at much higher volt range, even up to 800v in some of the very modern stuff. a phone? Maybe 5v? And this charging can be spread efficiently across the battery pack itself. Its balanced, very efficient and ensures that it is fully optimized.

Then there is the depth of charge, which will impact the life of a battery. An EV almost always builds in a big chunk of its capacity as contingency for loss over time, but also to ensure that you dont drain the battery to 0. Its typically around 3% - 5%. which means that the EV battery is running at peak efficiency. A phone? Not so much. Charge from low to 100% on a daily basis? Yeah, thats going to kill it pretty quickly in comparison. And you are charging a phone MUCH more frequently remember.

And then there is thermal management. Phone manufacturers have got pretty clever these days around this and can spread the heat generated in charging well. But this is just as a by product of the changing process. An EV can get its batteries up to the most efficient temperature for charging AND keep it there as the batteries are being charged. So again, maintaining efficiency, minimizing any loss as well as ensuring longevity of the batteries as a whole.

There are a lot more points but you get the picture. Tesla probably did more harm than good when they talked about the original Roadster and that it used hundreds of laptop batteries. It was true then, but with the advent of the Model S, everything changed. You cannot compare a phone battery life to an EV (though I would exclude the original Leaf because that had a crap battery).

So yeah, constantly charging your phone each day and not considering its use is why you killed the battery!

[raspy]

off_again said:

^ This

It takes a shift in the way you think about their use. The idea that you have to fill to 100% every time does not make sense, especially if you are away from home and using public chargers. You charge to what you need + a little contingency. Thats it.

And we shouldn't forget that the lower the SoC, the faster it will charge, though mileage will vary across different manufacturers. The Mach-e is pretty good and flat (though slow compared to more recent EV's) but absolutely plummets at 80%. Consider the charging curve!

If you are stupid enough to sit and wait for your car to charge to 100% each and every time, you will be spending a lot of time waiting. Switching from an ICE to an EV this is one of the big things to adjust to.

I now charge 5-10% to 60% when using rapid chargers on road trips.

[essayer]

Owners shouldn’t be expected to learn about chemistry and battery cell complexities.

Manufacturers should design cars to be charged to 100% the majority of the time, and chargepoint operators should publicise that there’s no point going over 80% on a rapid charger (maybe even force disconnect if the points are all in use, etc)

People will learn the fundamentals .. it won’t go as far when it’s cold, it won’t charge as fast unless the battery is warm .. but expecting normal people to understand different operating parameters within versions of the same model is just ridiculous..

[otolith]

[CrgT16]

I only tend to charge what I need to get home with 10-15% charge. Why waste time and money on a DC charger. My stop is never longer than 10 min.

EV works well for me, no issues with range anxiety or wasting hours waiting for car to charge. The car sorts its charge for you…

[CoolHands]

I would be 99% sure the information’s fake anyway - so they can keep modifying it (ie giving gradual access to the reserved capacity) with the over the air updates to make the battery degradation less apparent over the years.

[survivalist]

essayer said:

Owners shouldn’t be expected to learn about chemistry and battery cell complexities.

Manufacturers should design cars to be charged to 100% the majority of the time, and chargepoint operators should publicise that there’s no point going over 80% on a rapid charger (maybe even force disconnect if the points are all in use, etc)

People will learn the fundamentals .. it won’t go as far when it’s cold, it won’t charge as fast unless the battery is warm .. but expecting normal people to understand different operating parameters within versions of the same model is just ridiculous..

I’ve only ever charged ours to 100%. Don’t know if there’s a setting that limits it, but if there is it isn’t obvious.

Always been slow charged though, so assume it doesn’t make a huge amount of difference.

Public charging looks annoying, so just take a different car if the return trip is longer than the EV range.

Drove to London today. Seems all the incentives to use an EV are gone, so took the petrol car as it has better entertainment to keep the children happy on the journey.

[anonymous-user]

Just make the cost rate on public chargers increase after 20-30 minutes charging time.