Do I charge to 80% or 100%?

[Kevin Smith]

Battery is Lithium Ferro Phosphate so you can charge to 100% as often as you like. they recommend at least once a week. When you do there is no room in the battery to put energy back when going down hill or slowing up so it's not quite as efficient for the first few miles. What makes most sense is to think ahead and let it run down gradually but not so low you need to go and charge at higher prices. in this way since we don't do many miles we tend to go down gradually over a week or so perhaps with an occasional partial top up and then work our way back up for a weekly peak or for a peak if we have a long trip planned sooner. We have only used a granny lead at home (we've rock solid electrics) and so it takes 3-4 nights of 7 hours cheap electricity to get back from a low point . They say it's the number of cycles up and down that is limited on a battery so in this way 1000 cycles (inexact order of magnitude guess) would last 20 years. I'm happy with that. An Aussie Tesla taxi driver got 666,000km from his LFP without noticing degradation but then it told him it was suboptimal so he swapped it out under warranty! He didn't sweat the limits just charged as fast as he wanted as often as he wanted.

 

[Bam Bam]

Battery is Lithium Ferro Phosphate so you can charge to 100% as often as you like. they recommend at least once a week. When you do there is no room in the battery to put energy back when going down hill or slowing up so it's not quite as efficient for the first few miles. What makes most sense is to think ahead and let it run down gradually but not so low you need to go and charge at higher prices. in this way since we don't do many miles we tend to go down gradually over a week or so perhaps with an occasional partial top up and then work our way back up for a weekly peak or for a peak if we have a long trip planned sooner. We have only used a granny lead at home (we've rock solid electrics) and so it takes 3-4 nights of 7 hours cheap electricity to get back from a low point . They say it's the number of cycles up and down that is limited on a battery so in this way 1000 cycles (inexact order of magnitude guess) would last 20 years. I'm happy with that. An Aussie Tesla taxi driver got 666,000km from his LFP without noticing degradation but then it told him it was suboptimal so he swapped it out under warranty! He didn't sweat the limits just charged as fast as he wanted as often as he wanted.

I think it is 1,000 cycles for NMC. 3,000 cycles for LFP.

Which is 600,000 miles expected battery life in the MG4 SE SR. Doubt our car do will do that much!

 

[Rolfe]

I suppose it depends on how much range loss you think is too much. They base the calculations on 70%. That might still leave plenty range for someone who doesn't do long journeys, but be an unaccceptable degradation for someone who does.

 

[KingA]

As others have said the SE model has an LFP battery which is more robust in handling 100% charges. There's lots of conflicting advice on this. It's true you won't damage the battery by charging to 100% but there is evidence that you will maximise the life of an LFP battery if you avoid doing this all the time. When you don't need the range it's best to charge to between 60 and 75% (if you are planning to do only local journeys) and top up regularly. See the Battery University web site that has a lot of technical data that points to this being the case. But don't stress about it. Charge to meet your needs.
As others have mentioned you're supposed to do a balance change every few months to charge to 100%.

 

[Nobbyplopps]

Hi everyone,I'm excited to share that I'll be receiving my first EV, the MG4, this week. However, I have some questions about the charging process.Can I safely charge my car to 100% all the time? I've noticed that many people recommend charging only up to 80% and avoiding 100%, but I'm not sure which battery is in my car. I have the 51 kWh standard range version, and I am from the UK, if that helps.

May I also ask, Is it safe to always charge my car? For example, if the battery is at 65%, can I charge it to full, or should I wait until the battery percentage drops to around 10%? I will be driving approximately 40 miles each day, so the battery percentage will drop daily. Should I wait until it gets low to charge, or can I charge it every day regardless of the current battery percentage?

I really appreciate everyone's help ?

Depends if you are leasing the car. If you are going to hand it back after the contract ends then it doesn’t really matter as any battery deterioration isn’t your problem.

 

[Rolfe]

As others have said the SE model has an LFP battery which is more robust in handling 100% charges. There's lots of conflicting advice on this. It's true you won't damage the battery by charging to 100% but there is evidence that you will maximise the life of an LFP battery if you avoid doing this all the time. When you don't need the range it's best to charge to between 60 and 75% (if you are planning to do only local journeys) and top up regularly. See the Battery University web site that has a lot of technical data that points to this being the case. But don't stress about it. Charge to meet your needs.
As others have mentioned you're supposed to do a balance change every few months to charge to 100%.

Every week. It's the long charge that only has to be done every few months.

 

[KingA]

Every week. It's the long charge that only has to be done every few months.

Where does it say a balancing charge is required every week?

 

[Rolfe]

Somewhere in the manual.

 

[Bam Bam]

Somewhere in the manual.

You mean you don't know it off by heart? For each and every MG model? ?

 

[Rolfe]

That's @siteguru. Ask him.

 

[KingA]

Somewhere in the manual.

I was talking about the balancing charge which is what the MG4 EV manual calls an equalisation charge (using a low power charger). The manual says at regular intervals but I don't think this is every week. It does say if you drive the car every day to charge to 100% every week and to do a low power charge every 3 to 6 months, under the high voltage battery pack section.

 

[fnegroni]

I was talking about the balancing charge which is what the MG4 EV manual calls an equalisation charge (using a low power charger). The manual says at regular intervals but I don't think this is every week. It does say if you drive the car every day to charge to 100% every week and to do a low power charge every 3 to 6 months, under the high voltage battery pack section.

You are technically correct: they only ask that you fully charge / charge to 100% (neither of which technically include a balancing charge) once a week if the vehicle is used daily.

However, a balancing charge on an LFP (Type 2) pack only takes 20 minutes so when performed once every week or two. To me it makes little sense to charge all the way to 100% and then interrupt the charge.

 

[Rolfe]

The manual isn't written as clearly as it might be. They obviously intend that the car should balanced. No particular reason to take the car to 100% otherwise.

 

[Deleted member 11291]

Attached below one example of battery care guidance, a lot more online available.

https://www.smarthomecharge.co.uk/features/how-do-you-take-care-of-your-electric-car-battery/?utm_source=Smart+Home+Charge&utm_campaign=9b1180c138-EMAIL_CAMPAIGN_2024_07_05_01_39&utm_medium=email&utm_term=0_bf032075b3-09b1c71744-%5BLIST_EMAIL_ID%5D&mc_cid=9b1180c138

 

[Rolfe]

Just a point about the balance charge which may not be important.

When charging on the granny lead, my car (SE SR) invariably balances for 30-35 minutes. I have also observed it do exactly the same thing when charging on public AC chargers. I have just got a Zappi, and I have not observed it charging from the mains on that so I don't know, but I assume that (just like the public AC chargers) it will again do the same thing.

However, when charging directly from solar excess, it doesn't do that. Sometimes it doesn't balance at all, and although occasionally it does, the most I've ever seen it do is 15 minutes. Often it's just a minute or two.

Today I came in from a short trip on 98%, so I plugged in the granny cable and watched. Balanced for 32 minutes.

It doesn't seem to be the Zappi that's cutting the power, because what I'm seeing is "EV is preventing charging" and then it flips to "EV full". Most of the time there has been plenty solar excess available. Looks like the car is doing something slightly odd, maybe in response to fluctuating incoming power.

Just worth noting.

 

[KingA]

Information for other manufacturers like Tesla suggests that charging to 100% is more about calibrating the system (so range estimates are good), than about maximising the battery life.
For maximal battery life, keeping the charge between 60 and 75% seems to be best when doing shorter journeys with LFP batteries. When planning a longer journey, it makes sense to charge to 100% on low power and keep the charger connected for a while after it reaches 100% for the equalisation charge.
When you come to sell the vehicle, it's possible the resale value will be affected by the battery health. It's a personal choice as to whether you bother about this.

 

[wattmatters]

Note that anything up to 11 kW AC charging is considered low power.