How long should the 12 volt, battery last ?

[Laurence Brown]

We have had ther MG ZS for 40,000 miles and I am worried the 12 volt, battery will suddenly let us down - where and when we least expect it to.

When driving the meter still shows a healthy charge, but really, a nearly four year old battery still functioning as if it were new?! The longetivity pleasantly surprises me.

Do you put yours on charge?
I think we did once overnight.

Has anyone experienced a dying battery please?

 

[Gadget Geek]

C

Thread 'Twelve Volt Battery Dead after 2 Week Holiday'

Oct 9, 2024

I purchased my ex-demo MG4 Trophy back in May, 5 months of stress free motoring. On returning from a 2 week holiday last weekend, car parked on my drive plugged in, only to discover the car was completely dead! Luckily, I've RAC cover, they tested the twelve volt battery, it was completely drained on any power. The RAC jumped started the car, I drove it to my local MG4 garage.

The garage workshop tested the twelve volt battery, all ok - and told me (I'm struggling to believe) apparently it isn't unusual for the twelve volt battery to be drained of power if left unattended for 2 weeks...

• cottii2306
• battery drain electric holiday jumpstart mg4
• Replies: 43
• Forum: MG4 EV Forum

• 
• 

A

Thread 'Car won’t open and it seems 12v battery is dead'

Nov 28, 2023

Hello,
I’ve had my mg4 SR for 3 months nearly. I was quite poorly the last two days so never went outside to my car.

Today I tried to open my car with the fob to no response. I tried the manual key entry but that didn’t work either.

I assume the 12v battery died - my question is how do I now charge it? Is there a way to open the bonnet?

• aquib99
• 12 volt battery 12v battery mg4
• Replies: 9
• Forum: MG4 EV Forum

B

Thread '12V battery (theres many of these!)'

Oct 25, 2023

Hi guys,

Seen a few posts about 12V batteries... I've had issues since delivery. 12V died so was rescued AA, however jumping it didn't work. As a result they recovered to a garage, they replaced the 12V and sent me on my way.

Called AA again last week as was dead on drive... they jumped and all good. I did a long journey yesterday (approx 200mi round trip) so thought that's plenty to fully charge the 12V. I keep having issues though with the warning 12V low.

When I observed, I noticed a reading of 14.3V when in ready. Drops to 12.8V when not in ready mode and drops exactly 0.1V per...

• buln
• 12 volt battery 12v battery mg zs ev
• Replies: 13
• Forum: MG ZS EV Forum

Thread 'Dead 12V battery - any help and advice please?'

Aug 6, 2023

MG5 SR late 2020. Just got back from 5 days away having left car standing on drive as usual. Car was turned off and locked.

Keys (both) wouldn't unlock the car. Appeared completely dead. Unlocked manually and car would not turn on. Opened bonnet and removed cover. Disconnected 12 volt battery - it measures 2.5 volts open circuit...?

Ok so something has caused the battery to go flat. I have it on charge now which may or may not recover it.

The question is how will it be safe to reconnect it and how much current should be drawn from the 12V with the car off?

What can have caused the...

• rogerco
• 12 volt battery battery mg5
• Replies: 41
• Forum: MG5 EV Forum

S

Thread '12V battery'

Jun 21, 2023

Owner of MGZS EV Long range. A month or so after taking delivery the car wouldn’t start. AA called, charged battery got me to dealer. This is visit 1 , charged battery , caused by not being fully charged on delivery . I already had the car booked in as it was showing a “ do not park for more than 3 days “ message. All good.
Still same error coming up .. visit 2 . Battery health good, showing no drainage of battery. A day or so same message plus airbag warning. Visit 3 new sensor fitted, battery heath good , no drainage BUT did I always lock the car with key/ button whenever I switched...

• sandra54
• 12 volt battery battery mg zs ev
• Replies: 32
• Forum: MG ZS EV Forum

• 

And many more.

 

[mattdav]

We have an MG ZS EV '70' plate so over 4 years old now and 22k miles. I've never had any problems with the 12V battery.

I have fitted a Bluetooth battery monitor to keep an eye on things and alert me to any problems. They're £30 on Amazon.

Watch Mr EV's video to see what it's all about - Battery Monitor. and the one I bought is here.

Here's my data for the last 15 days (well, I haven't sync'd it for a few days but you get the gist).

 

[Tim Green]

I think that is too much information! Dropping to 12V regulary is not what I would like to see!

 

[pollenface]

I really like the 12V monitoring capability of a Victron 75/15 mppt, shows 30 days history with daily highest & lowest voltages.

I think it's good practice to change the 12V battery at the first sign of weakness, as others have stated, carry a lithium jump starter to get you out of trouble.

If you're using the car regularly, the regular charging of the 12V battery provided by the car will help keep it healthy and lower the rate of sulfation/capacity loss.

 

[securespark]

Our last car was a Honda Diesel. We bought it new and it was registered in November 2009.

We found out it was a 2007 build and had been hanging around in the dealership network. Consequently, the battery was goosed, although, this wasn't mentioned when we bought it. But I negotiated some "cash back" to replace it, as it kept letting us down.

I bought a Bosch S6 Stop/ Start battery from Tayna which was absolutely amazing and did the car proud from around 2 months old until after we got the MG4 in mid 2023. In fact we sold the car with it still going strong. By this point, the car had done 175,000 miles, nearly all of them with the Bosch battery.

 

[Tim Green]

There is no doubt there are good batteries and bad batteries, often down to how they were treated before use in a car. If there is any doubt about any particular battery, best to just change it for a new one. I also recommend Tayna who do next day delivery.

 

[mj224]

I had to change my 12V battery after 4 years or so. ZS EV CV70.

I suspect the EO Charger might have something to do with it, by leaving the car switched for a long period, The Charger went *its up at the same time. MG dealer charged me £200+ for a replacement...

 

[JohnV6]

I generally seem to manage 7 to 9 years. I use a battery conditioner if the car is idle for long periods.

However when I changed my Morgan last July the car had sat at the dealers for 9 months. The dealer told me they kept their cars on conditioners . Six months later at just under 2 years old it failed.

I didn't think it could be the battery so called out the AA. Their guy told me AGM batteries, which this was, often fail at 2 years. I too went to Tanya for a replacement.

 

[BrianG]

I would recommend a Ctek battery keeper... the .8 amp will work just fine and put it onto the battery and leave it on for as long as you can every few months. I kept a battery on an Astra going for 16 years, it had been my work car for about 10 years and done 80k miles after that it was little used but the battery keeper would bring the green telltale back on the battery even if left unused for 3 months. I would leave it on for a week or more to work its magic!

 

[apzs]

My 12V battery lasted 2.5 years and had only done about 21k miles.

 

[Tinnycan]

Mine lasted 3 yrs with 120,000 Km

 

[Ann Barraclough]

We have had ther MG ZS for 40,000 miles and I am worried the 12 volt, battery will suddenly let us down - where and when we least expect it to.

When driving the meter still shows a healthy charge, but really, a nearly four year old battery still functioning as if it were new?! The longetivity pleasantly surprises me.

Do you put yours on charge?
I think we did once overnight.

Has anyone experienced a dying battery please?

Yes my battery died on me last weekend.
I could not start the car at all and had to ask for a lift. I have had this car MG ZS from April this year. I don’t drive much and when getting in touch with the MG garage they are saying that I don’t drive the car enough. How can I charge the battery without driving it or is there something else that is using the battery? Help please.

 

[Scotsman]

You could buy a trickle charger with automatic shut off , that will save your battery if not using the car enough especially if only doing short journeys. Some batteries will last about five years depends how much the individual is using the car ?

Smart trickle charger will only charge when your 12 volt battery drops below a certain voltage that would be the best for you . When a car is running the alternator will charge the battery between 13.5 and 14.5 obviously if doing short journeys it might not get charged as high as that especially if you have lights heated seat etc on .

 

[Gadget Geek]

You could get something like this;

Portable 600W Solar Panel Kit With 100A Charger Controller For Car RV Caravan Efficient Charging Monocrystalline : Amazon.co.uk: Business, Industry & Science

Portable 600W Solar Panel Kit With 100A Charger Controller For Car RV Caravan Efficient Charging Monocrystalline : Amazon.co.uk: Business, Industry & Science

www.amazon.co.uk

 

[mattdav]

Yes my battery died on me last weekend.
I could not start the car at all and had to ask for a lift. I have had this car MG ZS from April this year. I don’t drive much and when getting in touch with the MG garage they are saying that
I don’t drive the car enough how can
I charge the battery without driving it or is there something else that is using the battery. Help please.

I bought a CTEK battery charger during Covid when I wasn't driving my car at all. It may have been overkill but I just connected it to the battery and plugged it in for a few hours (or a couple of days) once a month or so. There are other brands (I think Noco are pretty good too) that offer smart chargers that will charge, trickle charge, maintain your 12v battery. All you have to do is connect it to the battery and plug it in. This way you can maintain your 12v even if you don't drive the car.

 

[securespark]

I have a CTEK that charges my camping battery and used to keep the battery topped up when I wasn't driving regularly.

When the battery in my Diesel Octavia got goosed, it did a fantastic job on the de sulphation cycle and brought it back to life. It was winter and snowing and the battery was showing 1.2V.

The CTEK won't charge unless it's above 2V, so I got the hairdryer on an extension lead and after about 20 minutes, it rose to 2.1V and then started charging.

But by the end of the charge, it was almost as good as new.

 

[BOB353]

I was under the impression that the 12V battery was charged along with the traction battery?

If the battery only lasted about 6 month I would be hitting MG up for warranty replacement.

My ZS EV has only done 4,500km in the 9 months since buying it new in November 2024 and have had no problems even only using it once a week.