12v Battery ?

JKW

JKW

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Current car a Kia e Niro (next almost certainly an MG4 !) - a common problem with the Kia relates to the 12v battery which goes flat often without reason for some drivers. Does the MG4 have a separate 12v battery ? I've not seen any comments relating to one, and "search" didn't throw up any answers.
 
Yes, it does. I have seen several threads where people were discussing the possible danger of a flat 12v battery, and various theories being propounded, but I don't recall anyone saying it had actually happened to them.
 
JKW said:
Thanks for that Rolfe, at least I now know and am pleased it doesn't seem a problem with the MG4.
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Unfortunately there are quite a number of people who have come back to their car to find the 12v battery dead and can not drive it until the 12v has been charged. I'm sure if you just put 12v in the advanced search you will find the posts.
 
memo said:
Unfortunately there are quite a number of people who have come back to their car to find the 12v battery dead and can not drive it until the 12v has been charged. I'm sure if you just put 12v in the advanced search you will find the posts.
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There are several possible causes:
  • Cheap 12V SAIC batteries that don't hold their charge well.
  • Parasitic drain a few people seem to have (not many as far as I can tell).
  • Bugs in the system that prevent the 12V battery being charged.

There has been a bunch of reports as mentioned but I wouldn't say it is common or a normal experience to have a problem. As MG4s age, however, 12V battery replacement will become more common - the eNiro has been around a lot longer so it may turn out to be common for the MG4 too in time.

Some people are carrying around a 10mm spanner and a Li-Ion backup charger so they can rescue themselves if the problem strikes.

Some people are proactively replacing the 12V battery with a more expensive type - eg a leisure battery, that should last much better.

Either way, modern EVs ask a lot of the 12V battery and modern 12V batteries seem to be low quality and need regular replacement, so this problem is unlikely to go away.
 
JKW said:
Current car a Kia e Niro (next almost certainly an MG4 !) - a common problem with the Kia relates to the 12v battery which goes flat often without reason for some drivers. Does the MG4 have a separate 12v battery ? I've not seen any comments relating to one, and "search" didn't throw up any answers.
Click to expand...
Yes it has a 12v battery, but haven’t had any issues
 
Another possible cause of flat battery is turning off auto lights and then switching them on manually and then parking up without turning them off. Some versions of the car do not have an alarm to warn you lights have been left on. Already discussed on another thread.
 
I wonder if someone can tell me this. I've seen links to lithium battery chargers that are marketed to start ICE cars with flat batteries and are reported also to work with EVs in this situation.

Like this - Amazon product ASIN B0BNPMVMZH)

They look attractive, especially the weight.

However, I have a lead/acid jump-starter battery pack I bought in 2018 which is still in good nick. Would this also work on an MG4? I can't see any reason it wouldn't. Its only drawback is that it's bigger and heavier than the lithium ones. I'm reluctant to shell out for a lithium one when the lead/acid one is still working.
 
No reason it shouldn't. The car just needs enough power to wake up then the main battery will take over charging the 12v one.
 
Any 12v battery or emergency charger will work, it is an ICE 12V battery, exactly the same.

The one thing you must never do is jump start an ICE car from your EV. Apart from that, everything is the same.
 
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Yes, I knew never to use an EV to jump-start an ICE. I just can't decide whether it's worth carrying the lead/acid battery pack on a just-in-case basis, especially given the weight. I only carried it with me in my Golf if I was intending to leave the car unused for some time. (It was bought because I went off on a 10-week cruise in the middle of winter, leaving the car parked at the docks in Bristol.) Otherwise it was in my garage and available to start the car if I woke up to a flat battery some morning.

I have literally no idea what the likelihood is that my MG4's 12v battery might go flat while I'm out and about.
 
Alternatively, just use MG Assist if the battery fails.
Didn’t I read that the smart charging functions without having to wake up the car? In which case, a 12v battery failure should be low risk.
 
Kia have had specific issues with flat 12v as a result of over the air wake up calls to the car. This was also highlighted by Octopus who suspended Intelligent Octopus for a while for this reason. Polling the car and connecting too frequently can flatten the 12v apparently. There are of course other causes.
 
IanMK said:
Alternatively, just use MG Assist if the battery fails.
Didn’t I read that the smart charging functions without having to wake up the car? In which case, a 12v battery failure should be low risk.
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The smart charging seems to work well on my car. I've had no trouble. It seems to kick in when battery voltage drops to12.3v, but I believe only activates if main battery is above a certain charge.
 
12v disconnect works on lamborghinis as well:ROFLMAO:

And at 10m 23s theres a blue MG5 in the background(y)😍🤫
 
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