Stop at 80%

[Alun26]

Now that I’ve had the ZS for a whole day I’ve done a few miles going into town a few times, so the batt is now at about 70%, is there a way to schedule to stop charging when the batt get’s to 80% using the iSMART app, as the ZS doesn’t “talk” to my Ohme home pro charger?
Thanks
G

 

[Nutnut]

Maybe reading this thread will be of help (search function top right of the page), from another Ohme user:

Scheduled Charging

Hi all, Following on from my satnav issue which has been solved after following advice here (:)), I am having trouble setting up the scheduled charging. There is nothing in the pdf manual about scheduled charging. I have an Ohme Pro wall charger (which was installed months before I got the...

www.mgevs.com

And maybe also the thread these are posted in:

If you have a SR (standard range) ZS then you cannot set a charging limit. This is down to the battery chemistry difference to the LR battery meaning that it does not harm your battery to charge to 100% regularly on the SR.

LR yes you should be able to set the 80% but not on the SR as it has LFP battery chemistry which is supposed to be regularly charged to100% to preserve maximum capacity, unlike the LR's Li-ion which should only be charged to 80% it is just MG hasn't updated the display software although charge limit is disabled.

ZS 2022 handbook is only PDF online, after all, most people don't read them anyway

 

[N2STY]

If it's a long range the car will stop charge
If is a short range then it needs the 100%anyway

 

[MichaelJHunt]

Now that I’ve had the ZS for a whole day I’ve done a few miles going into town a few times, so the batt is now at about 70%, is there a way to schedule to stop charging when the batt get’s to 80% using the iSMART app, as the ZS doesn’t “talk” to my Ohme home pro charger?
Thanks
G

For the LR - Go to the Charger Management Screen and adjust the slider to the charge level you require.

Note that as said above, the SR will always charge to 100%

 

[Alun26]

Thanks for this, I have the SR version, so will just have to guesstimate ?‍ Until Ohme implement the API for MG cars.

 

[MichaelJHunt]

Thanks for this, I have the SR version, so will just have to guesstimate ?‍ Until Ohme implement the API for MG cars.

There is no requirement for the SR to stop at 80%. In fact, it is recommended to charge to 100% with the SR version due to the type of battery.

 

[Coulomb]

My understanding is that there is still value in limiting the SR's LFP battery to 80% most of the time. So I disagree with MG's decision to take away that functionality in the SR.

Going to 100% on LFP will cost less degradation than with. NMC, but not zero. Most of the harm will come while charging to 100%, not from holding it there, as you have to boost the cell voltage to around 3.5 VPC to charge to 100%, but LFP will relax to about 3.35 VPC (from memory) when you stop charging. The lower the voltage, the lower the degradation.

I believe it's also true that stopping at 80% isn't much better than stopping at 60% for LFP, but you have to draw the line somewhere, and 80% is a convenient figure. But if you're at 70% and know that you won't need more for some time, then there is no need to charge to 80%, as long as you spend a day per month near 100% for equalising. Of course, few of us can predict when we might have an unplanned need for more range.

The notion that LFP "needs" or even "likes" to be at 100% all the time is in my view wrong and slightly harmful.

Some, possibly many SR drivers may consider the small degradation caused by always charging to 100% to be worth it for the undeniable convenience of doing so. But that doesn't make it wrong to limit most charges to 80% or lower if that suits your lifestyle.

 

[MichaelJHunt]

My understanding is that there is still value in limiting the SR's LFP battery to 80% most of the time. So I disagree with MG's decision to take away that functionality in the SR.

Going to 100% on LFP will cost less degradation than with. NMC, but not zero. Most of the harm will come while charging to 100%, not from holding it there, as you have to boost the cell voltage to around 3.5 VPC to charge to 100%, but LFP will relax to about 3.35 VPC (from memory) when you stop charging. The lower the voltage, the lower the degradation.

I believe it's also true that stopping at 80% isn't much better than stopping at 60% for LFP, but you have to draw the line somewhere, and 80% is a convenient figure. But if you're at 70% and know that you won't need more for some time, then there is no need to charge to 80%, as long as you spend a day per month near 100% for equalising. Of course, few of us can predict when we might have an unplanned need for more range.

The notion that LFP "needs" or even "likes" to be at 100% all the time is in my view wrong and slightly harmful.

Some, possibly many SR drivers may consider the small degradation caused by always charging to 100% to be worth it for the undeniable convenience of doing so. But that doesn't make it wrong to limit most charges to 80% or lower if that suits your lifestyle.

“ My understanding is that there is still value in limiting the SR's LFP battery to 80% most of the time.”

What is your information source that LFP batteries are better if charged to 80% most of the time?

Tests carried out on the LFP battery demonstrate that repeated cycling from 0% to 100% to 0% has very little detrimental effect on the battery.

The LFP battery is good for around 4000 charge cycles maintaining 80% of its charge capacity.

Even if you assume an average of 150 miles per charge cycle that will give you 600,000 miles of driving and still the battery will have 80% of its range capacity. Lots of other things on your car are going to wear out before the battery does.

However, if you think that not charging your battery to its full capacity is in some way going to help, then that is it your decision, though this is against accepted advice.

IMHO, just charge the car and drive it, don’t worry about the battery.

Note that Tesla also recommends charging their cars fitted with LFP batteries to 100% as often as possible.

Tesla Model 3 RWD Owner Talks Charging, LFP Battery Degradation

He fully charges the battery to 100% 3–5 times a week and doesn't let it stay at a very low state of charge for long periods of time.

insideevs.com

Tesla Recommends Charging Model 3 RWD's LFP Battery To 100%

Tesla has issued revised charging guidance for the entry-level Model 3 RWD equipped with equipped with lithium iron phosphate (LFP) battery cells.

insideevs.com

 

[TheArcher]

Euan McTurk on YouTube 'Plug Life TV' is a real battery expert and well worth watching.

 

[Coulomb]

What is your information source that LFP batteries are better if charged to 80% most of the time?

Merely that it's well known that voltage, along with temperature, is one of the known killers of any battery chemistry. Voltage gives particles potential energy to overcome energy barriers, temperature gives them kinetic energy to do the same. The energy barriers are to well-known irreversible chemical reactions that reduce battery capacity.

Tesla also recommends charging their cars fitted with LFP batteries to 100% as often as possible.

Yes, but I read somewhere that Tesla LFP batteries (which are some of the earliest LFP EV batteries) have shown way more degradation than expected.

I can't quickly find that post, but see for example

https://www.autoevolution.com/news/the-puzzling-reason-why-tesla-misleadingly-recommends-charging-the-lfp-batteries-to-100-187075.html

that more or less supports my position.

I don't disagree that the difference in degradation (charging to 100% always versus to 80% mostly) is small. Just that since it's non-zero, if you have the lifestyle to support it, it may be worth doing.

 

[Coulomb]

Euan McTurk on YouTube 'Plug Life TV' is a real battery expert and well worth watching.

And what does he say on this matter? (Pardon my laziness.)

 

[Whiskery]

so the batt is now at about 70%, is there a way to schedule to stop charging when the batt get’s to 80% using the iSMART app, as the ZS doesn’t “talk” to my Ohme home pro charger?

Alun

I started the thread on the "Scheduled Charging" and I got a lot of help from this forum with setting the Ohme up.

My SR charges, via the Ohme app, from 0030-0430. So far in the last couple of weeks this hasn't failed. The key is to have no schedules set up on the iSmart app or the cars onboard charging screen. This is vital as there might be a conflict if there is a schedule set up.

Next, I set up a schedule in the Ohme app to start at 0030 and finish at 0430 (the times of my off- peak tariff with Octopus Go).

In the tariff screen I made sure (and this is where I originally got fouled-up) that where I had to input the maximum per-kwh amount, I was inputting 7.50p. This is in fact the correct figure but the app didn't like it, so I tried putting in 8.50p as the maximum price.

My comment from the above thread "So I tried setting the off-peak charge at 8.5p (mine is actually 7.5p) in the Ohme app and lo and behold the charge started and finished during my off-peak hours." It worked and thank you to @N2STY for this tip.

Now, I just plug in late afternoon/early evening (depending on if I need to use the car) and it charges as per my schedule.

The advantage of using the Ohme app over the cars iSmart app/on board screen is that if I have to charge away from the house, I don't need to disable the cars charging schedule to start a charge, if that makes sense.

Don't forget we don't have to worry unduly about stopping at 80% with the SR.

Hope this helps you.

 

[N2STY]

Yes, but I read somewhere that Tesla LFP batteries (which are some of the earliest LFP EV batteries) have shown way more degradation than expected.

This is true then they told there customers to charge to 100% and the problem went away I think this is why the advice now on LFP is to change to 100% whenever ever you can and I believe its more for the bms as well so the gom is more accurate this could explain when people park there car at 60% and come back a few hours it shows less then drive the car and gom drops much slower bms struggling to see soc as it did not start with a good reference point of 100%

 

[Coulomb]

this could explain when people park there car at 60% and come back a few hours it shows less then drive the car and gom drops much slower bms struggling to see soc as it did not start with a good reference point of 100%

Good point. It may be that in the real world having a better remaining range estimate is more important for longevity than the small advantage of charging to 80% most of the time.

I think I found the post I was thinking of, in the My Nissan Leaf forum. On re-reading, it was one claim, and more or less refuted in the next few posts (over the page).

Even after all that, I would still be stopping at 80% most of the time if I owned an LFP EV.

Official Tesla Model Y Thread - Page 21 - My Nissan Leaf Forum

mynissanleaf.com

 

[Striker]

“ My understanding is that there is still value in limiting the SR's LFP battery to 80% most of the time.”

What is your information source that LFP batteries are better if charged to 80% most of the time?

Tests carried out on the LFP battery demonstrate that repeated cycling from 0% to 100% to 0% has very little detrimental effect on the battery.

The LFP battery is good for around 4000 charge cycles maintaining 80% of its charge capacity.

Even if you assume an average of 150 miles per charge cycle that will give you 600,000 miles of driving and still the battery will have 80% of its range capacity. Lots of other things on your car are going to wear out before the battery does.

However, if you think that not charging your battery to its full capacity is in some way going to help, then that is it your decision, though this is against accepted advice.

IMHO, just charge the car and drive it, don’t worry about the battery.

Note that Tesla also recommends charging their cars fitted with LFP batteries to 100% as often as possible.

Tesla Model 3 RWD Owner Talks Charging, LFP Battery Degradation

He fully charges the battery to 100% 3–5 times a week and doesn't let it stay at a very low state of charge for long periods of time.

insideevs.com

Tesla Recommends Charging Model 3 RWD's LFP Battery To 100%

Tesla has issued revised charging guidance for the entry-level Model 3 RWD equipped with equipped with lithium iron phosphate (LFP) battery cells.

insideevs.com

Michael, interesting info thank you, do you have similar stats for the batteries in the LR
eg, how many charge cycles = 80% SOH ?

 

[MichaelJHunt]

Michael, interesting info thank you, do you have similar stats for the batteries in the LR
eg, how many charge cycles = 80% SOH ?

For the LR, 80% SOH would be 2000 cycles.

If you assume 200 miles range per charge you would get 400,000 miles.

With the LR you can improve the life of the battery by staying between 20% to 80%.

I think with a modern BMS and thermally controlled batteries we don’t need to worry about charging the battery.

Info source is here:

New Tests Prove: LFP Lithium Batteries Live Longer than NMC - OneCharge

Recent independent degradation tests of commercial lithium batteries prove - LFP chemistry is safer and has a longer life-span than NMC.

www.onecharge.biz

 

[Striker]

For the LR, 80% SOH would be 2000 cycles.

If you assume 200 miles range per charge you would get 400,000 miles.

With the LR you can improve the life of the battery by staying between 20% to 80%.

I think with a modern BMS and thermally controlled batteries we don’t need to worry about charging the battery.

Info source is here:

New Tests Prove: LFP Lithium Batteries Live Longer than NMC - OneCharge

Recent independent degradation tests of commercial lithium batteries prove - LFP chemistry is safer and has a longer life-span than NMC.

www.onecharge.biz

Thanks very much, that puts it in to perspective, I have free charging at work, most of my journey's are local, so I tend to keep it below 80% during the week, on Friday's I often top it up to 100% if I know that I'll be needing it

I'm not overly precious about it, but I think it makes sense to keep it between 50-80% if it doesn't impact my plans

 

[Alun26]

Just done my first charge at Tesco pod point rapid 50kW, i'm guessing the £30 is a holding charge and they will not actually charge me/credit card company this?

 

[N2STY]

How much did it come to?

 

[Alun26]

£2.62 I was only there for about 10min but it put in about 15%. Interestingly the 4 off free 7k chargers where all used and 2 motors had the owners having a kip! ?