How long can I leave my Trophy charged at 100%?

[Lee Morris]

I'm due to travel from Yorkshire to Forres, near Inverness, tomorrow but I don't have the ability to charge the car overnight.

Would I be okay charging the car today and leaving it at 100% overnight or could that damage the battery?

Thank you

 

[PristDean]

Overnight is absolutely fine

 

[Rolfe]

Yes!

Watch this video about this issue, it's really quite reassuring. These batteries are more robust than a lot of doom-and-gloom mongers admit, and overnight is, like, NOTHING.

 

[meicd]

I am doing it and leaving overnight. No issues.

 

[Lee Morris]

Thank you for all your advice. Will charge it up now and not have to worry ?

 

[Captain]

The "damage" is minimal and only if you do it on a regular basis....

As long as you usually only charge between 20 and 80 percent the battery will last the lifetime of the car ?

 

[Rolfe]

As I understand it, if you need the full range on a more-or-less daily basis you can charge it to 100% often, because you're not letting it sit and fester at that charge, but rather driving it back down under 80% not long after charging it. (Disclaimer, LFP battery owner here.)

 

[RichDragon]

Hi, I drove a Trophy MG4 and regularly charge it to 100% and leave for a couple up to five days and have had no problems. Have done this for over seven months.

 

[Rolfe]

Hmmm. I wouldn't have expected you'd have encountered any trouble as a result of doing that in only seven months. It's a question of battery degradation over years. It's not going to kill it stone dead, but after a number of years the battery isn't going to be in as good a condition as it would have been in if you'd avoided doing that.

But having said that, the battery guru guy in this video seems fairly relaxed about "a couple to five days" so perhaps it's a relatively small effect.

 

[tsedge]

Once again... battery fears are overblown, just use your car as you would like to and follow these golden rules:

If a SR (LFP) charge to 100% once a week and let it balance.

If a LR (NMC) charge to 100% at least once a month and let it balance and don't leave at over 80% for days and days at a time, especially if you are going to be away.

If (and only if) you are keeping the car for 10 years or more OR are a taxi driver (or similar very high mileage driver), then read up about battery tech and baby your battery.

 

[Rolfe]

My feeling about the LFP, and the way I use it, is that I run the car until I want more charge in it, either because I know I'll need it the next day, or simply as a contingency in case I want to go somewhere unexpectedly. Then I charge it to 100% and let it balance. So that might be twice in a week, or it might not be as often as once a week. What I don't do, unless I'm on a long journey of course, is charge to less than 100% then carry on driving again.

My reasoning is that the main reason for doing the 100% and balance thing is to make sure the % charge and the GOM are displaying as accurately as possible. If the car is always balanced when it's charged, it shouldn't really matter if it's longer than a week. The algorithms will be working from the correct information of the 100% start, so should remain accurate. There's no particular reason to charge it up again a week after you last charged it, if you've only driven about 50 miles since then. But any time the car is on an AC charger, I'll let it go to 100% and balance.

 

[wandle MG4 trophy]

I have complained twice to my dealer about the target charge on my Trophy changing upwards or downwards autonomously. They raised a technical case with MG HQ and they forwarded to me their response

......."They have also said that although the percentage shows 100% on the vehicle and App display the HV battery will only be charged to 80% the other 20% is reserved in case of overcharge and a Customer will never be able to access this percentage

This is the same when the battery gets to depletion. There will still be 18% charge but unusable so you can charge the car to 100% as shown on your vehicle display or app". ...........

Their response makes sense but why then the mantra to keep the Trophy battery between 20% and 80%? Maybe they are just being overcautious?

 

[Rolfe]

That squares with what that video I posted says - there is always a buffer factored in to preserve battery health and longevity. However I didn't think it was close to 38% of the total battery capacity, which is what these figures imply.

The entirety of the response you quote is odd though. If they have shut off the top 20% then why are you not supposed to use the top 20% of the accessible charge on a routine basis? I have a slight suspicion that someone might be confusing two things.

 

[MoDolph]

......."They have also said that although the percentage shows 100% on the vehicle and App display the HV battery will only be charged to 80% the other 20% is reserved in case of overcharge and a Customer will never be able to access this percentage

This is the same when the battery gets to depletion. There will still be 18% charge but unusable

They are talking rubbish. The total capacity of the battery is 64kWh and they let you use 61.7kWh. This means that there is a buffer of ~3.6%. How much of this is at the top vs the bottom I don't know but it's still nothing like what they are saying.

 

[Rolfe]

They are talking rubbish. The total capacity of the battery is 64kWh and they let you use 61.7kWh. This means that there is a buffer of ~3.6%. How much of this is at the top vs the bottom I don't know but it's still nothing like what they are saying.

Now THAT is much more like what I had been led to believe. Just a few KWh locked off to protect the battery. Quite worrying that someone at MG HQ said that a total of 38% was locked off.

 

[Ian Key]

......."They have also said that although the percentage shows 100% on the vehicle and App display the HV battery will only be charged to 80% the other 20% is reserved in case of overcharge and a Customer will never be able to access this percentage

This is the same when the battery gets to depletion. There will still be 18% charge but unusable so you can charge the car to 100% as shown on your vehicle display or app". ...........

What a load of Smartish.
If that was true then 38% of the battery isn't available. Can you really see MG restricting the theoretical range to 281miles when if those percentages were available it would give a nearly world beating range of 388 miles.

 

[Rolfe]

If a dealer had said that, I'd be slightly concerned. That MG HQ is supposed to have said it is more than slightly scary. Please tell me they left the work experience student on the phones.