Car battery MK8

[Eric Bloodaxe]

17 hours ago, Eric Bloodaxe said:

I'll report what happens in the morning.

Sitrep this morning after car left locked overnight:

No change:  interior/boot light still not operating, S/S still showing unavailable, and same after driving 10 miles or so doing various errands.

(Interior light does come on after switching off ignition, and slowly fades (which I think was normal from memory), but nothing on opening door to exit).

After standing for about 30 minutes after driving, battery voltage showing 12.4 which is still not brilliant, about 80%, so I'll give it a longer dose of the charger for the rest of the day.

Seems odd that I've only seen this particular issue reported in respect of the ST - plenty of other stuff for Mk 8 Fiestas (usually S/S) as we know. Trying to think of any current draw unique to the ST?

[Eric Bloodaxe]

On 1/27/2024 at 10:44 AM, Eric Bloodaxe said:

I'll give it a longer dose of the charger for the rest of the day.

Which I did. This morning the multimeter was reading 13v but still no interior lights. However, after a drive of 10 miles or so to the start point of my Sunday stroll, all lights came on after parking up - the BMS must have finally caught up.

S/S still showing unavailable, but as we know there are lots of reasons for that and it was still cold this morning - just above freezing. Not that I'm much bothered about that and usually disable it anyway.

Only thing I came up with on the theme of what's different about the ST compared with my previous Mk 8 is that it has footwell lights. I don't drive much at night now, but a lot of my recent limited mileage has been in the dark for various reasons so that plus headlights could have added to the issue I suppose.

I'll have to make my regular battery top ups even more regular, it seems!

 

[Eric Bloodaxe]

Just updating my own battery saga, which seems a pretty similar story to the Focus ST thread running at present.

Start/stop has remained AWOL since the last post in January. I normally disable it with the switch in Normal mode (it's disabled in Sport mode in any case) but I've stopped bothering as it seems it ain't gonna work anyway. Interior lighting comes and goes.

Measuring the resting battery voltage shows around 12.4v (or about 80% SOC). A full cycle on the charger takes it up to 13.2v but after a few days, even if driven frequently, it settles back around 12.4v. Charging seems ok, 14.8v or so when engine is running.

I had similar experience with my previous Mk8 ST-L, but with some differences.

- Similar story on battery voltage

- Got the "systems off to save battery" message occasionally on the ST-L, only seen it once (iirc) on the ST.

- Interior lights always worked on the ST-L, irrespective of battery voltage

On both cars though, never had a starting problem - first touch of the button

Car's in for its first service in about 2 weeks, and I mentioned the issue when booking it in with the usual dealer who supplied the car. I've gone there for years, and they're usually pretty good, so I'll see if they come up with any brilliant suggestions. However, the immediate reaction of the service adviser when I mentioned it was "have you got a decent battery charger?" so I'm not counting on anything!😀

 

[unofix]

2 hours ago, Eric Bloodaxe said:

Measuring the resting battery voltage shows around 12.4v (or about 80% SOC). A full cycle on the charger takes it up to 13.2v but after a few days, even if driven frequently, it settles back around 12.4v. Charging seems ok, 14.8v or so when engine is running.

I'd say what you describe as perfect, and completely normal.

2 hours ago, Eric Bloodaxe said:

Start/stop has remained AWOL since the last post in January. I normally disable it with the switch

Yes we all tend to jump to the conclusion that it is low SOC when S/S fails to work, but in reality there are about 114 things that need to be 'just right' before it will work.

 

[Eric Bloodaxe]

31 minutes ago, unofix said:

in reality there are about 114 things that need to be 'just right' before it will work.

Only 114?😀

[Tizer]

3 hours ago, Eric Bloodaxe said:

Measuring the resting battery voltage shows around 12.4v (or about 80% SOC)

When my resting Voltage dropped to 12.4, which was when I decided to change my battery, my SOC was in the 50 or low 60's according to FORScan.

The trigger point for Stop Start to be disabled because of battery State of Charge is 68%.

[Eric Bloodaxe]

I often lurk on Toyota hybrid forums out of interest. This morning I was catching up with the very similar "12V battery issues" thread on a Yaris forum. It has now reached 95 pages (!) so far from just being a Ford issue.

[alexp999]

2 minutes ago, Eric Bloodaxe said:

I often lurk on Toyota hybrid forums out of interest. This morning I was catching up with the very similar "12V battery issues" thread on a Yaris forum. It has now reached 95 pages (!) so far from just being a Ford issue.

It's just an issue of all car makers having to meet emission targets. Even EVs have problems with the 12V where manufacturers are trying to prioritise driving range.

[Eric Bloodaxe]

Just now, alexp999 said:

It's just an issue of all car makers having to meet emission targets. Even EVs have problems with the 12V where manufacturers are trying to prioritise driving range.

Absolutely, Alex. I was just mentioning the point for the benefit of those who are not serial forum lurkers and might get the impression this is a Ford problem.

EVs certainly have the same issue - the AA reported that 16.8% of EV call-outs in the 12 months to October 2023 were related to 12V battery problems, while only 2.3% were due to the traction battery being out of charge.

[alexp999]

15 minutes ago, Eric Bloodaxe said:

Absolutely, Alex. I was just mentioning the point for the benefit of those who are not serial forum lurkers and might get the impression this is a Ford problem.

EVs certainly have the same issue - the AA reported that 16.8% of EV call-outs in the 12 months to October 2023 were related to 12V battery problems, while only 2.3% were due to the traction battery being out of charge.

You mean those of us who develop a twitch when we see the words stop/start in thread titles for the millionth time? 😅

[unofix]

2 hours ago, alexp999 said:

the words stop/start

I'm away for a lie down in a dark room 🤣

[Eric Bloodaxe]

On 3/22/2024 at 5:52 PM, unofix said:

I'm away for a lie down in a dark room 🤣

Lie down now, I'm about to mention s/s!😀

As earlier post, had the car in today for its first service, and as mentioned, asked them to give the battery/charging system a once over. I was pretty confident it's the "system", but there do seem to have been the odd cases of "dud" batteries and as it's still under warranty, worth a check.

Just been to collect and was shown a very impressive set of figures and a graph which basically showed the battery was fine, alternator output as it should be, and all operating as per the set parameters of the system.

There followed a quite lengthy rant from the service guy on how useless these modern systems are, which would do credit to many on this forum! I've been going there for years and they are well aware of my views on some forms of "progress" - I doubt they'd be so candid with a newer customer!

They'd had the car on charge while I'd left it for the day, so everything worked on collection even "you know what" - it'll be interesting to see how long that lasts.

 

[Eric Bloodaxe]

On 4/2/2024 at 5:37 PM, Eric Bloodaxe said:

They'd had the car on charge while I'd left it for the day, so everything worked on collection even "you know what" - it'll be interesting to see how long that lasts.

 

Well, about 3 days is the answer to that one. S/s has gone awol again, interior lights back to sometimes they work, sometimes not.😀 

Meanwhile I see the similar thread on the Toyota Yaris forum is now up to 97 pages, over 2,400 posts and more than 267,000 views, so we're not alone. 

[unofix]

27 minutes ago, Eric Bloodaxe said:

S/s has gone awol again

It was last seen in Halfords shopping for a new battery 🤣