Vantage MY2025 - 12V Battery Warnings - what's normal?
Discussion
Hello,
I have a (new to me) 2 year old MY2025 Vantage. Been with me 2 weeks, has had a number of 12V warnings on the dash - been back to the dealer and had the 'big' May 2026 update which supposedly should fix any issues with modules not sleeping properly and causing drain. Battery was checked and health reported good apparently.
Drove it home (45 miles) so should be totally charged and topped up, it's only sat overnight. This morning it's been fine driving around (5 miles out, stop, 5 miles back) but at the point of ignition, it flashes a 12V warning. I can see on the telemetry screen the battery dropping to about 11.8V as it starts the car.
My query is - is this just a 'normal' drop under ignition load and the car is being a bit hasty to throw a 12V warning so I can ignore it, or is this still a sign of the battery being a bit weak/drained by something?
I'm worried if this is a bit weak, how it would cope if it was actually left for 2 weeks or so not driven at an airport or something. Also concerned if this is an issue about it progressing. Obviously it's only been with me a short time and not keen to start a merry go round of problems relating to it. I understand a battery conditioner is good practice for leaving it anything over 10-14d or so but I feel 'overnight' after a long drive would be really beyond acceptable in terms of the battery coping with daily life.
When left to sit for a few hours or overnight, the battery monitor shows about 12.1 or 12.2V and this drops to 11.8V while starting. Fine while driving - the usual 14.5V you'd expect.
Thanks!
I have a (new to me) 2 year old MY2025 Vantage. Been with me 2 weeks, has had a number of 12V warnings on the dash - been back to the dealer and had the 'big' May 2026 update which supposedly should fix any issues with modules not sleeping properly and causing drain. Battery was checked and health reported good apparently.
Drove it home (45 miles) so should be totally charged and topped up, it's only sat overnight. This morning it's been fine driving around (5 miles out, stop, 5 miles back) but at the point of ignition, it flashes a 12V warning. I can see on the telemetry screen the battery dropping to about 11.8V as it starts the car.
My query is - is this just a 'normal' drop under ignition load and the car is being a bit hasty to throw a 12V warning so I can ignore it, or is this still a sign of the battery being a bit weak/drained by something?
I'm worried if this is a bit weak, how it would cope if it was actually left for 2 weeks or so not driven at an airport or something. Also concerned if this is an issue about it progressing. Obviously it's only been with me a short time and not keen to start a merry go round of problems relating to it. I understand a battery conditioner is good practice for leaving it anything over 10-14d or so but I feel 'overnight' after a long drive would be really beyond acceptable in terms of the battery coping with daily life.
When left to sit for a few hours or overnight, the battery monitor shows about 12.1 or 12.2V and this drops to 11.8V while starting. Fine while driving - the usual 14.5V you'd expect.
Thanks!
12.1V to 12.2V sounds a bit low to me. I'd be expecting more like 12.6V if it's fully charged - unless there's a significant current drain which would drop the voltage; but I doubt that.
As the car is new to you, but only 2025 it's safe to assume it's the original battery, but you don't know how many times the previous owner (and/or dealer) allowed it to go flat - and lead-acid batteries do not like being completely discharged.
The 2C Astons had much better quiescent current drain than the VH models like mine, so assuming there isn't a problem I'd expect 2 weeks sitting to be no problem at all - mine will do that.
To your comment about battery conditioners. The best ones are not just "chargers" but designed to keep the battery in the best possible condition (as the name suggests) and after topping the battery up they will use subtle voltage cycles to minimise sulphation and other lead-acid ills. So they are best used all of the time if you can, not after 14 days to top the battery up. My V8V lives on an Optimate if it's not being driven. It's not a case of "acceptable" - of course it will sit overnight - it's just optimisation
As the car is new to you, but only 2025 it's safe to assume it's the original battery, but you don't know how many times the previous owner (and/or dealer) allowed it to go flat - and lead-acid batteries do not like being completely discharged.
The 2C Astons had much better quiescent current drain than the VH models like mine, so assuming there isn't a problem I'd expect 2 weeks sitting to be no problem at all - mine will do that.
To your comment about battery conditioners. The best ones are not just "chargers" but designed to keep the battery in the best possible condition (as the name suggests) and after topping the battery up they will use subtle voltage cycles to minimise sulphation and other lead-acid ills. So they are best used all of the time if you can, not after 14 days to top the battery up. My V8V lives on an Optimate if it's not being driven. It's not a case of "acceptable" - of course it will sit overnight - it's just optimisation
Thanks,
That's at 12.1V overnight from a long drive of 45 miles, it goes down to circa 11.9V when sat for maybe two days. I suppose at only two weeks in, i'm concerned this might represent ongoing issues and considering whether it may be better to hand it back. Not really keen to be back and forth with issues straight away. Dealer has had the car back already to 'sort' the problem and apparently battery health is fine.
Just wondering whether it's normal for the current pull on ignition to drop the voltage that much, to the point the car gets upset about it. If not then I think it's an indication of an ongoing issue.
My suspicion certainly was that it's covered only 3800 miles in two years, previous owner letting the battery die a few times would be top of my list, but the dealer says it tested fine so....
That's at 12.1V overnight from a long drive of 45 miles, it goes down to circa 11.9V when sat for maybe two days. I suppose at only two weeks in, i'm concerned this might represent ongoing issues and considering whether it may be better to hand it back. Not really keen to be back and forth with issues straight away. Dealer has had the car back already to 'sort' the problem and apparently battery health is fine.
Just wondering whether it's normal for the current pull on ignition to drop the voltage that much, to the point the car gets upset about it. If not then I think it's an indication of an ongoing issue.
My suspicion certainly was that it's covered only 3800 miles in two years, previous owner letting the battery die a few times would be top of my list, but the dealer says it tested fine so....
No problem.
I wouldn't expect a car to show a voltage warning on cranking. So my non-expert opinion is either the car has some issues where it's pulling a lot of current when it shouldn't (and a decent auto-electrician would be able to test for that) or the battery is toast, irrespective what the dealer says. And 11.9V after two days? That's not right.
Whether to hand it back is your call, of course, but I get you don't want to accept a lemon. One gambit you could try is to tell the dealer you want him to try a new battery to see if that fixes the issues - if not he can have the car back. That might incentivise him to at least try a battery and, if he says "no", hand him the keys. It'll be much more trouble for him if he has to take it back than fitting a battery.
I don't know where you are and how your consumer protection laws go in terms of giving the dealer an opportunity to fix (which it sounds like they have). I can say with pretty well absolute confidence that you should not get a "low voltage" warning at any time with these cars unless you've been sitting with something like the radio on for a while without the engine running - I've had one warning in my car in seven years, and that was me running the radio and nav system without the engine running while I was doing some map diagnostics.
Usual caveats about me not knowing the car, your circumstances or the dealer, your mileage may vary, yada yada
I wouldn't expect a car to show a voltage warning on cranking. So my non-expert opinion is either the car has some issues where it's pulling a lot of current when it shouldn't (and a decent auto-electrician would be able to test for that) or the battery is toast, irrespective what the dealer says. And 11.9V after two days? That's not right.
Whether to hand it back is your call, of course, but I get you don't want to accept a lemon. One gambit you could try is to tell the dealer you want him to try a new battery to see if that fixes the issues - if not he can have the car back. That might incentivise him to at least try a battery and, if he says "no", hand him the keys. It'll be much more trouble for him if he has to take it back than fitting a battery.
I don't know where you are and how your consumer protection laws go in terms of giving the dealer an opportunity to fix (which it sounds like they have). I can say with pretty well absolute confidence that you should not get a "low voltage" warning at any time with these cars unless you've been sitting with something like the radio on for a while without the engine running - I've had one warning in my car in seven years, and that was me running the radio and nav system without the engine running while I was doing some map diagnostics.
Usual caveats about me not knowing the car, your circumstances or the dealer, your mileage may vary, yada yada
File under dealer won’t replace clearly dud battery most likely caused in their showroom in order to penny pinch.
I leave my 21 model on the conditioner whenever not driving it. I bought it at two years old and it would be shaky on start after not driving for a few days. It had about 2500 miles on it when I bought it.
My 18 model was the same as this too but I switched out the 500 ton boat anchor standard battery for a Deadweight Industries Lithium-Iron Phosphate battery, 20kg lighter and starts first time every time even if I leave it for weeks.
I leave my 21 model on the conditioner whenever not driving it. I bought it at two years old and it would be shaky on start after not driving for a few days. It had about 2500 miles on it when I bought it.
My 18 model was the same as this too but I switched out the 500 ton boat anchor standard battery for a Deadweight Industries Lithium-Iron Phosphate battery, 20kg lighter and starts first time every time even if I leave it for weeks.
LTP said:
To your comment about battery conditioners. The best ones are not just "chargers" but designed to keep the battery in the best possible condition (as the name suggests) and after topping the battery up they will use subtle voltage cycles to minimise sulphation and other lead-acid ills. So they are best used all of the time if you can, not after 14 days to top the battery up. My V8V lives on an Optimate if it's not being driven. It's not a case of "acceptable" - of course it will sit overnight - it's just optimisation
Totally agree.I'd be disappointed if a 2 year old battery is failing but not impossible.
At the very least I'd be putting yours on a suitable conditioner ( I use both Optimate for my lithium battery GT8 and CTEK for all the others including the lawn tractor and quad ) and seeing what happens after that has gone through its thing and the light or lights turn green.
Mine all live on the conditioners other than the daily and then just get plugged straight back in.
For the cost of say the CTEK MXS5 (Amazon usually your best bet ) at least then you could get some comfort assuming too that the dealer doesn't do much in the meantime.
Better to have and not need rather than the other way round.
Davil said:
File under dealer won t replace clearly dud battery most likely caused in their showroom in order to penny pinch.
I leave my 21 model on the conditioner whenever not driving it. I bought it at two years old and it would be shaky on start after not driving for a few days. It had about 2500 miles on it when I bought it.
My 18 model was the same as this too but I switched out the 500 ton boat anchor standard battery for a Deadweight Industries Lithium-Iron Phosphate battery, 20kg lighter and starts first time every time even if I leave it for weeks.
What size of the Deadweight Industries battery did you go for? Searches indicate the 2025MY Vantage has an 850 CCA capacity battery, which seems fairly large.I leave my 21 model on the conditioner whenever not driving it. I bought it at two years old and it would be shaky on start after not driving for a few days. It had about 2500 miles on it when I bought it.
My 18 model was the same as this too but I switched out the 500 ton boat anchor standard battery for a Deadweight Industries Lithium-Iron Phosphate battery, 20kg lighter and starts first time every time even if I leave it for weeks.
Edited by flyingalbatross on Tuesday 23 June 17:27
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