Charging battery to full on regular basis or allow it to go down to 5 percent before topping up

[dido]

Hi,
I am new to the EV driving and charging.
Will be collecting my MG4 Long Range next week. I got a home charger fitted and waiting for the car.
I have a rather long commute to work about 120 mile both ways, on average 3m per kWh I expect about 40 kWh consumption each day.
Should I plug in the car on arrival to top up or should I regularly allow it to drain before topping up.
What's recommend for battery life etc.

 

[Ian Key]

I'd be tempted to charge to 80% at each end of your journey which will give you enough range for diversions etc. and then to do a balance charge once a month.

 

[tsedge]

No need to drain modern batteries to keep them healthy, those days are done.

Recommendations for the LR car are a monthly 100% charge to balance and when range is needed, otherwise charge to 80% as often as you like.

Ian beat me to it! ?

I'd be tempted to charge to 80% at each end of your journey which will give you enough range for diversions etc. and then to do a balance charge once a month.

 

[stevegus]

Charge the car up to 100% on delivery as this will do a battery balancing charge.

The battery in the LR and Trophy does not like charging to 100% regularly. Most charges should be to 80% and only to 100% every couple weeks to make it do a balance charge.

The infotainment battery screen actually calls the top 20% “long journey” mode.

Personally im going to infrequently charge mine without putting 5-10% in wherever possible. Id suggested keeping charge cycles down will be better for battery life

 

[tsedge]

Personally im going to infrequently charge mine without putting 5-10% in wherever possible. Id suggested keeping charge cycles down will be better for battery life

Does that make a difference? I thought modern BMSes made that unnecessary, but I will bow to your expertise, I am not a battery engineer.

 

[stevegus]

Does that make a difference? I thought modern BMSes made that unnecessary, but I will bow to your expertise, I am not a battery engineer.

This isn’t exactly in my area of expertise- but its info I’ve obtained from the net from various sources re NMC cells.

Charge cycles are quoted as 500-1000 cycles. How this affects PARTIAL charge cycles is unclear but i dont want to be a guinea pig.

And its pretty much stated on here and elsewhere that the general consensus is keep between 20-80% and dont store at 100%. And going regularly to single digit numbers doesnt seem a great idea.

The driving range screen on the LR also has a line at 80% with the top 20% as long journey mode or similar.

None of the above it seems applies to the SR battery pack which seems able to take more abuse.

It just seems that plugging in the LR battery every day to put 8% or so back in to get 100% -as an example- might not be a great idea.

 

[RichDragon]

I don't go on many long journeys and some weeks only use 15% of the batteries charge, if there's sunshine I plug charger into my Trophy and charge it till the tick appears on the MyEnergi app screen. Occasionally it will balance the batteries for about half an hour using very little power. I only charge once a week but always to 100%, some people don't advise charging over 80% but imho if the car is likely to go poof! Then software should limit the last few percent.

BTW: obviously everything's working on my Trophy......apart from sound from the satnav, not being able to bind my phone to the iSmart app., Headlights ALWAYS come on, and shall I just say the usual idiosyncratic behaviour we have come to expect from technology knowing better than the Driver....

 

[Barrie]

Whats the point in having an EV that you should only charge to 80% ? Should we just pay for 80% of the car then ? Okay, for those of you that only do short journeys thats fine but I need my car for work and it has to be ready to cover 250km in a day at short notice. I charge mine via a granny only to 100% every time and allow it to balance everytime. After 30k of driving in 18 months my battery SOH is still 100%. The BMS will look after your battery.

 

[Ian Key]

Not everyone with the LR battery is going to use their car soon after charging to 100% so the advice is to only charge to 80% unless you are going to use it soon afterwards.

Some of us have purchased the car outright and intend keeping it for a good number of years and want to look after the car as we won't be handing it back after the end of the PCP.

 

[Tig170]

If your doing 240 miles round trip, eachday ?? - if so wow thats 40,000-50,000 miles a year on just commuting! - Your battery warranty will be up longbefore anything else, so wouldn't worry too much.

I have the LFP version, 7000miles & 2.8% degredation

 

[Barrie]

No, thats 250km and I dont do that every day !! I just need the car available at 100% charge as if one of my customers has an issue and I need to visit them it can be a 250km round trip at very short notice.

 

[jpk]

How long is too long to leave the battery at 100%. I commute around 85 miles per day, 70-75 on the motorway, and was hoping to only charge every 2 days. I'm still waiting on my trophy to be delivered so don't know what my miles/Kw is gonna be but I tend to sit around 65mph on the motorway.

 

[bear1]

I have the LFP version, 7000miles & 2.8% degredation

Apologies for going slightly off topic: how do you know your better degradation?

 

[siteguru]

ABRP app (with a premium subscription) and an OBD11 dongle.

 

[aalberola]

Seems that doing daily small charges (5%-10%) to top to 80% is not recommended but brakes regen is doing exactly that a lot of small charges continuosly. So, must we expect battery degradation due to brakes regen? Or it is also safe to top battery to 80% daily with small charges?

I would like to top to 80% my Trophy/Luxury battery with small charges using FV energy everyday if that does not degrades my batteries.

What do yoy think?

Thank you.

 

[tsedge]

Seems that doing daily small charges (5%-10%) to top to 80% is not recommended but brakes regen is doing exactly that a lot of small charges continuosly. So, must we expect battery degradation due to brakes regen? Or it is also safe to top battery to 80% daily with small charges?

I would like to top to 80% my Trophy/Luxury battery with small charges using FV energy everyday if that does not degrades my batteries.

What do yoy think?

Thank you.

I don't think it makes any difference whether you do lots of small charges or a few big ones. Modern battery management systems are very clever in how they manage the cells internally.

 

[Rolfe]

The title of this thread scared the wits out of me. Allow the battery to go down to 5%? What was the OP smoking? Quite apart from the real risk of running out if you're regularly going down that far before you look for a charging opportunity, what about contingencies? If your car is sitting in your driveway at 10% and you're thinking no, I'll leave it until I've done another short run and got it down to 5%, then some unforeseen emergency crops up, you do not have a car. Or at least, you do not have one with a useable range on it.

My MG4 with a full battery has about half the range on it compared to my Golf with a full tank of petrol, so that's an issue for a start. I could (and did) leave the Golf in the drive with only enough petrol for maybe 50 miles, but I knew that getting it filled up would only delay me by about five minutes if something unforeseen cropped up. If I did that with the MG4 it's going to be an hour's delay - and I have a rapid charger that can get me from 20% to 85% in 55 minutes 400 yards away. Not everyone has that.

I'm getting used to this new way of working. With the SR battery I just plug in and let it fill up and balance if I get home under 80% - maybe even under 90%, depending on how I'm feeling. If I had the LR I'd do the same, but rather bring it back to 80% if I got home under 60% or maybe under 70%, depending. There's a real feeling of security knowing that the car is fuelled and ready to go at any time, and from everything I've read, these modern batteries are fine with this.

 

[RichDragon]

I've got the Trophy and everyone seems to be an expert, but my philosophy is if I get home after doing a few short runs and there's 85% showing, I always stick it on charge via my Zappi2 and get it back up to 100%. I've been doing this for six months and the BMS seems to do its balancing act about once every six charges so no problems (well apart from the usual MG ones of course). I rarely do 120 mile journeys but as I have a Tesla BATTERY too, sunshine has filled my tank every time. Driving electric nearly gives me the same buzz as riding my ICE motorbike and once the sodium batteries are here the prices of everything electric is going to drop like a stone. Happy ☺ motoring all.

 

[Rolfe]

You'll have to show me the working there. I know about the Brave New World we're expecting with the sodium batteries, but I didn't realise they were going to lower the price of electricity as well.

Do you leave your Trophy sitting unused at 100% for more than a day or so? I thought that was the main thing with the LR battery, that it didn't like to be held at 100% because of the space occupied by the lithium ions or some technobabble along these lines.

I have never yet caught my SR battery not doing its balancing act after reaching 100%. It usually takes about half an hour, but it always seems to do it.

 

[profdraper]

All of which depends entirely on the battery chemistry & am surprised that this is not mentioned anywhere here. Just like the difference between (say) the long range and the short range Teslas, the MG short range models use LFP battery chemistry whereas the long range (or Mk1 MG ZS EV) use NMC chemistry. Both have different charrging recommendations, charging cycle lifspans and SOC indiosynracies. In general, LFPs can be regulary charged to 100% without too much concern whereas the NMCs require the usual 80% then 100% balancing matra.

Some external battery chemistry experts still recommend the 20-80% regime on the LFP tho', but with the current iSmart or Internal charge scheduling, the LFP MG models do not allow for charging to anything but 100%. The only way around this is to set the scheduling time accordingly & via a little math for your home charger.

The odd MG manual refers to 'type 1' and type 2' batteries, never identifies what they are, but from the charge figures it is clear about longer vs. shorter charging times for. Is the equalisation recommedations that seem odd & given that the LFP is usually fully charged.

Easiest therefore for LFP maybe simply to set & forget, always charge to 100% as many owners do. The LFP has rated 10k cycles vs the NMC at 3k cycles, plus there's the lengthy warranty already.