MGS5 12V battery dead

[Lovemyev]

I have seen the state of charge go from 70% to 80% while plugged in over night for example.

Yeah - This is very true, the 12 volt battery does receive a charge, when the traction battery is being charged from an A/C supply.
Previous MG models are configured in the same way.
I think it would be helpful if the 12 volt battery just had a bit more spare capacity though tbh.
I can’t help but feel that at its present factory size, there is very little margin for any extra drain / usage in standby mode.
Therefore it is easy to get caught out with a flat battery.
A larger 12 volt battery, would mean it being less reliant on the car having to be in ready mode almost constantly, in order to maintain its fully charged state.
Manufactures have been reducing and reducing the size / capacity of 12 volt batteries for a long time now.
This action reduces production costs and also the total weight of the car.
Reducing weight has a big saving when it comes to improving the efficiency / economy of any car.
Recharging the 12 volt battery on ICE vehicles, is different as charging is provided by a high output alternator when the engine is running.
An alternator has the ability to very quickly replace any consumed energy, straight back into the battery.
Allowing manufacturers to install more economical, smaller / lighter batteries.
The smaller battery is only required to turn the car over, then the alternator instantly replaces any energy consumed.
I just don’t feel that an EV’s charging system is as urgent in its approach to replenishing battery energy somehow .
I think if I was to replace our 12 volt battery, I would strongly consider installing a battery with just a bit more storage capacity myself.
The factory battery is only under warranty for 12 months, so it only needs to last that long anyway.

 

[Ian Key]

I replaced the battery on my MG4 after 2 years with a Yuasa YBX5012. Same physical size but larger capacity.

 

[Chris H]

When you were in the car fitting the screen protector did you press the brake pedal to turn the car on?

Is this a thing? My S5 turns on when I sit in the seat, not when I press anything.

 

[emmrecs]

Is this a thing? My S5 turns on when I sit in the seat, not when I press anything.

To be absolutely correct, the S5 begins its boot sequence when you sit on the driver's seat; it only goes to full "Ready" mode, i.e. is driveable, when you press the brake pedal.

 

[dx4100]

What @emmrecs said.... I found out the hard way

READY will display.

In theory you shouldn't need it in READY mode. But READY mode 100% guarantees the 12v is then being looked after by the main battery.

 

[Tibor]

Thanks to you all for this thread, the same happened to me today and knew what to expect and do - MG assistance / AA came out, jump started, and then I drove 1h to get the batter back to 13.9V - maybe staying on the driveway in Ready more would have done the same, but it was more enjoyable this way except for the list of error signs / messages on the dashboard.

It was interesting driving with most things disabled, hardly any steering return force, true coast mode (0 regen). I actually would prefer if there was a "no regen" mode, and only use the brakes for regen. But that's another topic...

Question - after the jump start the AA guy said the error codes/messages will disappear in 20 mins - they did not. What is your experience?

 

[bilbo]

Thanks to you all for this thread, the same happened to me today and knew what to expect and do - MG assistance / AA came out, jump started, and then I drove 1h to get the batter back to 13.9V - maybe staying on the driveway in Ready more would have done the same, but it was more enjoyable this way except for the list of error signs / messages on the dashboard.

It was interesting driving with most things disabled, hardly any steering return force, true coast mode (0 regen). I actually would prefer if there was a "no regen" mode, and only use the brakes for regen. But that's another topic...

Question - after the jump start the AA guy said the error codes/messages will disappear in 20 mins - they did not. What is your experience?

You need to turn the steering wheel lock to lock to clear the errors.

 

[Ian Key]

Question - after the jump start the AA guy said the error codes/messages will disappear in 20 mins - they did not. What is your experience?

As @bilbo said turn the steering wheel lock to lock and take it for a quick drive. If they haven't cleared by then get out and lock the car before unlocking and starting the car.

 

[Shwd mae]

An update on my 12V battery.
Car returned today, problem fixed (I hope). To be fair to the dealership, they have been great. They had to contact MG in China, who logged into the car from there after the T block was replaced. Everything now seems fine.
An observation, and I may be completely wrong. I decided to create a new MG account and connect to the car in case this was part of the original problem. No problem, car remained connected to the MG app without logging me out. I then connected to my 'EV energy app' for my Rolec charger, and then the message 'this app is logged in from another device' reappeared with me having to continuously log back onto the app when I wanted to use it!
I have now removed the car from the 'EV energy'app just in case this was causing the battery drain problem! Hoping I can charge the car using just the MG app!
Hope this makes sense, and is of help to others.

 

[emmrecs]

An observation, and I may be completely wrong. I decided to create a new MG account and connect to the car in case this was part of the original problem. No problem, car remained connected to the MG app without logging me out. I then connected to my 'EV energy app' for my Rolec charger, and then the message 'this app is logged in from another device' reappeared with me having to continuously log back onto the app when I wanted to use it!
I have now removed the car from the 'EV energy'app just in case this was causing the battery drain problem! Hoping I can charge the car using jut the MG app!

Interesting!

As someone who has needed to use my Battery Booster pack four times in the last two weeks to get the car to "start" (and who also has a Rolec charger, the ev.energy app and received the same "logged in from another device" message on the MG app) I was beginning to wonder whether the cause of my (far too) frequently exhausted 12V battery might be linked to the fact that, unlike for my previous MG5 PFL, I had linked my MG account and so did see data for the S5 in the charger app. And the app seems to request data from the car very regularly.

Having removed the car from the ev.energy app I no longer see the "logged in from another device" message and can go straight into the MG app. In fact, I don't even have to log in any more!

The ev.energy app keeps asking me to "Reconnect my car" but I'm ignoring its warnings about "losing the facility to smart charge" because, based on my past experience, it isn't true..

So, don't consider charging the car using just the MG app. Based on my previous experience the ev.energy app does not need your car's data; I had my MG5 PFL (no iSmart app available) with the Rolec charger for nearly four years and was always able to use the ev.energy app to control the charging. The app needs only to connect to your charger, that is the critical part. If your charger drops the connection for any reason, that is when problems can occur!

I have set an 80% charge limit in the MG app, although tomorrow I will need to change this to 100% (in preparation for Christmas Day and Boxing Day travels to family) so will be interested to see what happens!

I'll be very interested to also hear of your experience going forward and I'll be sure to try and remember to post back with what I see with reference to the 12V battery repeatedly "failing"!

 

[Shwd mae]

Thanks for the reply. I see what you mean in the EV app. I have now 'added' the MG, but I have not 'linked' the MG account. Fingers crossed.

 

[dx4100]

I also use the ev energy app.

To make all this work properly you need to create a "Secondary Account" in the MG app settings. You then use this for ev energy. You will no longer get the message about being logged out.

You use the main account and ev energy uses the second account.

If you don't connect the ev energy app in this way you do lose the ability to properly smart charge.

Smart charging will still be scheduled but without knowing the current battery level the system presumes you need a full 100% charge every time. If it knows you only need x percentage then it can schedule it more smartly. This is the advantage of connecting the car to the app.

This is important if your on a day night tariff as it may start the smart charge too early to take full advantage of your night rate.

When I had my 12V issue I got paranoid the ev energy app had something to do with it. Now I think it's a red herring. Not had any issues since reconnecting my vehicle.

Hope this helps

This should demonstrate what I mean...

I was doing a top up last night and only needed something like 10-15 % or so. Can't exactly remember.

Because the ev energy knew i only needed a small amount it could schedule the smart charging to make full use of the smart charging algorithms.

Without this it would have started to charge much earlier with no gap like you see in the screen shots.

 

[Shwd mae]

Thanks for the info.
I can still set the 'smart settings' in the EV energy app to 'only charge off-peak', I have also set this in the MG app, as well as the 'percentage charge'. Vehicle charged no problem last night.
I entered the details for my vehicle in the EV app, I just didn't give permission/details for my MG account.

 

[dx4100]

Not sure if you do get it (sorry if you have and I am labouring the point). You will see smart charging and it will still charge but....

The current setup will do what I call a "dumb" smart charge. Takes around 11 hours to charge the MG from 0% to 100% (give or take). So if you ask ev energy to get your car ready for 7am its going to presume it needs a 100% charge as it as no other information so it will schedule a "smart charge" to start around 8pm. Keep in mind the charger and car don't communicate the battery percentage. Thats why they have the API integration.

The actual reality may vary slightly but without knowing the current state of charge for the car then it can't intelligently when to judge charging.

So if you only need 20% charge for example its likely to start early and miss out on things like your 12am to 5am night rate.

Have a look next time you charge and see if what I am saying is true. Do a 20% top up and see when it starts the charge. If I am right it will start much earlier than it needs to.

 

[emmrecs]

So if you ask ev energy to get your car ready for 7am its going to presume it needs a 100% charge as it as no other information

But the percentage to which the car should be charged is/can be set in the iSmart app or the car itself! The ev.energy app doesn't need to know this figure, the car "controls" how much it takes. The ev.energy app controls when it gives.

In my previous MG5 PFL (so iSmart app not available) the ev.energy app, set to its Smart Charging option, would only charge when, in my case, there was excess Solar Power available OR in the off-peak period. Is that different with the S5?

However, since my car is now plugged in, with minimal solar power available, I do see it is charging, though I have set it to 100% (in the MG app) because of "Christmas Travel", but this does seem to be different to what happened with my previous car. And that 100% setting seems to NOT stick!

 

[dx4100]

But the percentage to which the car should be charged is/can be set in the iSmart app or the car itself! The ev.energy app doesn't need to know this figure, the car "controls" how much it takes. The ev.energy app controls when it gives.

In my previous MG5 PFL (so iSmart app not available) the ev.energy app, set to its Smart Charging option, would only charge when, in my case, there was excess Solar Power available OR in the off-peak period. Is that different with the S5?

However, since my car is now plugged in, with minimal solar power available, I do see it is charging, though I have set it to 100% (in the MG app) because of "Christmas Travel", but this does seem to be different to what happened with my previous car. And that 100% setting seems to NOT stick!

I think you are missing something.

To effectively smart charge ev energy needs to know five data points.

1, Current charge = 40%
2, Target charge = 80%
3, Ready time = 7am
4, Battery Capacity = 64kw (also via API)
5, Charger Charger rate = 7kw

1 & 2 are only available via the API. 3 to 5 are inputed in the Ev Energy App.

With all five data points EV Energy now knows it needs to give the car 25.6kw of energy before 7am and it works out the best way to do that based on their algorithm and type of charger being used.. 25.6kw / 7kw = around 3 1/2 hours charge time (fag packet as there is a little more to it all). So it will work out how best to do this depending on your tariff and grid demands before 7am. It will stop and start charging during this time. Nothing to do with the car. All driven by EV Energy. See my screenshots. At some point towards the end the car will say I am at 80% and will stop taking charge but that is the very final stage.

Without these five data points the smart charging only gets less smart. And if its not smart enough it could cost you money. It will still "work" but its not working to the best of its capability.

How else would it know when to effectively start charging ? It has to fall back on what info is only in the app which isn't much help. e.g. Battery Capacity = 64kw instead of 25.6kw it actually needs.

If I am missing something then please say so.

 

[dicky ticker Dave]

Just out of interest are most of the S5 the trophy spec Carson the forum. As a poor pensioner I could only afford the lower spec SE long range but having less toys I (touch wood) I don’t seem to have any problems as of yet apart from the crap auto main beam/ dip function and speed recognition.

 

[dx4100]

Just out of interest are most of the S5 the trophy spec Carson the forum. As a poor pensioner I could only afford the lower spec SE long range but having less toys I (touch wood) I don’t seem to have any problems as of yet apart from the crap auto main beam/ dip function and speed recognition.

I think most people went for the Trophy yes. I think its a matter of opinion how good or bad the auto beam and speed recognition is. Compared to my Skoda they are rubbish but compared to the Mazda 3 this car replaced that didn't have them at all they are 100% better

 

[TimothyN]

The amazing deal I was offered only applied to the Trophy LR. I think that the lower spec shorter range would actually have been more expensive, ironically.

 

[Lovemyev]

The amazing deal I was offered only applied to the Trophy LR. I think that the lower spec shorter range would actually have been more expensive, ironically.

When we bought our S5 Trophy, the dealer told me that they had not ordered a single SE model since its launch, as the introduction deals offered in the Trophy was so good at that time.
Plus, if it remains the same, he said that he could not see them ordering any for stock.
Only ordering SE by request.
It was a similar situation with the ZS EV models really, the difference in price vs equipment gained and bigger range almost made it a one horse race TBF.