Do I charge to 80% or 100%?

[Bam Bam]

AHH what is this regen? how does it work? So you get 20% of battery back?

Electric cars (including hybrids) can use the electric motor to slow the car.

It effectively reverses the action of the motor so it is charging the battery from the wheels rather than using the charge to make them spin.

There are different settings which determine how strong this effect is - I have it on full all the time but some don't like having it on so high on the dual carriageway. But then I use adaptive cruise control a lot, particularly on dual carriageways (another favourite feature of mine on the car).

If you are in traffic then it is very useful because you are creeping forward a bit and then putting a bit of the power back into the battery. Plus you go up a big hill and then use the electric system to slow you down the other side and get some of the gravitational energy back into your battery.

However, if the battery is full this does not work - you can't regen power into the battery if it is already full up.

Regen has the benefit of slowing the wearing of the brakes but the main thing is that it gives you some of your power back - I've seen figures up to 20%, but that might be only under ideal conditions.

 

[Sophiameow]

Electric cars (including hybrids) can use the electric motor to slow the car.

It effectively reverses the action of the motor so it is charging the battery from the wheels rather than using the charge to make them spin.

There are different settings which determine how strong this effect is - I have it on full all the time but some don't like having it on so high on the dual carriageway. But then I use adaptive cruise control a lot, particularly on dual carriageways (another favourite feature of mine on the car).

If you are in traffic then it is very useful because you are creeping forward a bit and then putting a bit of the power back into the battery. Plus you go up a big hill and then use the electric system to slow you down the other side and get some of the gravitational energy back into your battery.

However, if the battery is full this does not work - you can't regen power into the battery if it is already full up.

Regen has the benefit of slowing the wearing of the brakes but the main thing is that it gives you some of your power back - I've seen figures up to 20%, but that might be only under ideal conditions.

Hi thank you but I'm still kinda confused how exactly does it work? I assume it works automatically? So just drive normally? But you said it won't work if the vehicle is at 100%? What about when it drops to 90%? Will it start regen once it hit 90%? Can you see this on the dashboard? Thanks again ?

 

[Bam Bam]

Hi thank you but I'm still kinda confused how exactly does it work? I assume it works automatically? So just drive normally? But you said it won't work if the vehicle is at 100%? What about when it drops to 90%? Will it start regen once it hit 90%? Can you see this on the dashboard? Thanks again ?

I can't think of anything on the dashboard but the percentage of the battery is on there so you can see that easily enough.

The first time I filled the car to 100% I nearly crashed into someone at the roundabout near our house because the car didn't slow itself as I had got used to. Lesson learned!

From what I have been able to tell it gradually gets more available as you free up more battery, but others might know more. You get the full effect at some point between, say, 85% and 95% but I've not noted down exactly what point it is.

 

[decrep]

AHH what is this regen?how does it work? So you get 20% of battery back?

This is the main advantage of electric cars. ease your foot off the accelerator, and instead of the battery powering the wheels, the wheels charge the battery.
It's called "regenerative braking", because battery charging is "generated" by converting the vehicle kinetic energy to electricity.

In one pedal driving mode, you hardly need to use the brakes at all. It sounds very unfamiliar at first, but doesn't take long for it to become the preferred method of driving. For my wife and me anyway.

 

[Coulomb]

"Regen" is short for "regeneration", where the EV seamlessly reverses the usual power flow, turning the motor into a generator, putting energy back into the battery (charging it) instead of using friction brakes to slow the vehicle down. You still have friction brakes of course, in case you need a sudden stop.

The net effect is that EVs with regeneration (all of them apart from a few very unusual cases) end up with about 10-20% more range than if there was no regeneration. As a useful side effect, the brake pads last much longer, sometimes for half of the life of the vehicle.

There is sometimes a need to force friction brake use so the brake rotors don't rust from lack of use, but there is no need to worry about that for a long time.

 

[decrep]

From what I have been able to tell it gradually gets more available as you free up more battery, but others might know more. You get the full effect at some point between, say, 85% and 95% but I've not noted down exactly what point it is.

I've done the test on our MG4 SE SR, And it will drop into one pedal drive at 92%
By the sound of it, other cars may be different.

A bit higher than that about 95% a lower level of regen starts happening.
It's very simple really, there has to be room in the battery to take the extra charge. The car won't let you overcharge the battery.

 

[fnegroni]

My round trip commute to work is 50 miles daily, which is roughly 25% charge in my Standard Range.
My weekly routine is:
make sure the battery is at 100% by Monday morning.
Monday evening I arrive back home with 75% charge left.
I charge for 5 hours at night on the granny charger at 8.5p per kWh, which brings the battery back up to 93%, ensuring I use the cheapest electricity and I still have a good amount of regen on my commute.
Repeat the process Monday evening: arrive home at 68% charge, charge about 18% overnight, leave for work on Tuesday with 86%
The process continues all week: Wednesday morning battery is at 80%, Thursday morning at 65, Friday morning at 56%.
I charge again on Friday night, Saturday night and Sunday night and the battery is at 100% and fully balanced on cheap electricity once weekly, and never goes below 50% and I have the most regen.

 

[unbornidentity]

Oops, didn’t see page two so when I posted so ignore the below ?

Regen is where the car uses the motor as an electric generator to act as a brake. So instead of wasting energy heating up the brake discs it dumps the energy back into the battery which also slows the car down when you lift off the throttle.

It can’t do that if the battery is too full so the car is less efficient and the brakes don’t feel as strong.

One pedal driving takes that a bit further and the car will come to a complete stop and apply auto hold without you touching the brake pedal. But it dumps more energy into the battery so needs the battery to be a bit less charged to work than normal regen.

Hi thank you but I'm still kinda confused how exactly does it work? I assume it works automatically? So just drive normally? But you said it won't work if the vehicle is at 100%? What about when it drops to 90%? Will it start regen once it hit 90%? Can you see this on the dashboard? Thanks again ?

You can see when regen is working as there is a power indicator on bottom right of the screen that’s show power being used. It displays a negative figure when it’s using regenerative braking. In the lowest setting it normally displays -5% and on the highest up to -25%.

 

[DixieTGS]

In addition to all the above:
Whichever regen mode you've selected, when you brake lightly the car will add some extra regen before using the actual brakes which saves a little more energy. This happens automatically and you will be unaware of when it occurs.

For example on an SE LR with regen set to 3, taking your foot off the accelerator can give up to 18% regen. If you need to use the brake as well the regen can go up to 25%, the same as if using OPD.

But forget about the numbers, as long as you drive reasonably calmly the car will do an excellent job of getting the best out of the battery.

 

[siteguru]

Juts one more thing to bear in mind ... the power figure shown in the driver display is an instantaneous indication of power use (or regen when shown in green); I've seen regen figures as high as 25% on mine, but that doesn't mean I'm getting 0.25 * 50.8 = 12.7 kWh of power back - that would only apply if the 25% regen was happening continuously for one hour.

i.e. you don't get as much energy back into the battery as the screen numbers might make you think.

[ Edit moderator: "as much power" → "as much energy" ]

 

[Bam Bam]

Juts one more thing to bear in mind ... the power figure shown in the driver display is an instantaneous indication of power use (or regen when shown in green); I've seen regen figures as high as 25% on mine, but that doesn't mean I'm getting 0.25 * 50.8 = 12.7 kWh of power back - that would only apply if the 25% regen was happening continuously for one hour.

i.e. you don't get as much power back into the battery as the screen numbers might make you think.

Indeed.

If you are driving on dual carriageway consistently at 65 mph you will get virtually no regen - only when going down a steep hill if there are any.

But for a journey with a lot of stops and starts an electric car really comes into its own.

Here is an attempt to depict where the energy goes in an EV:
Electric Vehicle with Energy Recuperation – Sankey Diagrams

In a fossil car the majority of the energy is lost to heat and only about 20% gets used.

Plus that energy could in theory (and hopefully with in the future in practice) come from renewable sources.

Hi thank you but I'm still kinda confused how exactly does it work? I assume it works automatically? So just drive normally? But you said it won't work if the vehicle is at 100%? What about when it drops to 90%? Will it start regen once it hit 90%? Can you see this on the dashboard? Thanks again ?

Also to say, all of this is priced in to the car's efficiency and range estimation.

As others have said, the car does the regen when you lift your foot off the accelerator or press the brake.

Though the way you drive will impact on how much you get. Drive smoothly and you hardly need to use the friction brake. Your motor and battery replace the old-fashion brake most of the time.

The regen will be a part of the reason why you get better range on some journeys than you do on others.

 

[Coulomb]

I've seen regen figures as high as 25% on mine, but that doesn't mean I'm getting 0.25 * 50.8 = 12.7 kWh of power back - that would only apply if the 25% regen was happening continuously for one hour.

The 25% doesn't mean 25% of the battery capacity, it means 25% of the maximum power the car can deliver. So it's unitless.

You could convert it to power by looking up the rated power for your model and multiplying by that number. For example, if the maximum power was 125 kW (per ev-database.org for the 51 kWh MG4), then 25% regen would imply 125 x 25 / 100 = 31.25 kW. If you could maintain that for an hour (as a thought experiment, not in reality of course), that would add 31.25 kWh of energy to the battery.

 

[Buster72]

The 25% doesn't mean 25% of the battery capacity, it means 25% of the maximum power the car can deliver. So it's unitless.

You could convert it to power by looking up the rated power for your model and multiplying by that number. For example, if the maximum power was 125 kW (per ev-database.org for the 51 kWh MG4), then 25% regen would imply 125 x 25 / 100 = 31.25 kW. If you could maintain that for an hour (as a thought experiment, not in reality of course), that would add 31.25 kWh of energy to the battery.

Good post.

 

[Tuareg]

Plus that energy could in theory (and hopefully with in the future in practice) come from renewable sources.

Nearly 50% of the energy supplied by the European grid is already sourced from renewables and that percentage rises every year.

 

[DerekH]

Y

Thank you. Does that mean I can pretty much charge my car everyday regardless of what the current battery percentage is? And charge it to 100%

Yes

 

[BingBong]

100% for sr.

Once in 3-6 months ho helow 10 and then charge to 100 for battery calibration

 

[Matt x power]

I charge mine to 90 percent because I like to be different ?

 

[DavecUK]

.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.

With your battery chemistry yes and even with LMH. batteries, it's not so bad, if you are going to drive/commute the next day and bring it down to 80%. The latter battery really dislikes being at a full state of charge for any length or time. I expect even at 100%, there must be some small buffer and it's not really 100%

 

[KiwiMG4]

There are many idiots posting videos on YouTube...

Also lots of idiots posting on the internet.

Jerry Pan is a well respected EV SME in the New Zealand MG community, who is a MG salesman and produces quality MG reviews and instructional guides.

 

[Rolfe]

Honestly, if you have the SR LFP battery, just don't worry about it. Charge it up to 100% any time you like, and indeed make a point of doing that and letting it balance its cells at 100% for 30-35 minutes every so often. The manual says once a week, but that's going to depend on your mileage.

Also do that <10% to 100% charge (and balance) in a single go on an AC charger at least every six months. Hysteresis curve, coulomb counting, yadda yadda. The car needs to see the full range of the battery every so often to keep the GOM calibrated.

Any advantage to getting obsessive with only charging between 20% and 80% and the rest of the waffle you hear people come out with is so marginal it's not worth getting your panties in a bundle about. The battery is going to last longer than the car.