Stop start batteries... is it a sign?

It's likely to be one of the first things the car switches off if the battery is low.

Get a multimeter and see if the voltage has dropped a bit.

Mine does that, it apparently shows that the battery is getting older, and not holding a full charge. During colder weather the battery will get a hammering anyway.

Mine started working yesterday after a few miles drive, but normally I’m not driving more than about 15 miles with it being dark at each end.

I have got a little digital battery check jobby, that goes into the aux socket, needed one for checking the battery state on stored cars at work, I must remember to put it in the car and run a check on the static charge status, the car will need a service in another 6000 miles by which time the battery will be four years old, and may well need replacing.

Yes.

New battery may want programming in. Had similar with our Focus before the battery went. It worked again for a while and then didn't. I didn't have it reprogrammed as I didn't realise for several months that might be what the problem was and given that car's use as a short journey / runabout it's probably better for it and the battery that it doesn't work.

Yeah, I'm being lazy, i'll do the multimeter (battery under the boot panel is annoying for this). Car is coming up to 5 years old so it's probably about time.

Minimum temperature we've had in the last few weeks is about 19, so definitely not cold weather.

Like the idea of a battery check jobby.

Could also be a module needing reset, my Focus was all flaky until we got that done and it's been fine since.

Dunno what software and dongle an Alfa uses but it might be relatively cheap to pick up a suitable dongle and software to check what error messages are stored and what the battery health is like.

Do check if you have more than one battery.

My V70 had a beautifully hidden stop start mini sized AGM battery under the scuttle.

Dunno what software and dongle an Alfa uses but it might be relatively cheap to pick up a suitable dongle and software to check what error messages are stored and what the battery health is like.

I looked into that recently. IIRC it wasn't as cheap as you'd hope. Luckily I have a mate that runs a European car tuning business. I recently had to get a windscreen replacement and the firm didn't have ability to clear an erroneous fault code on the screen camera and therefore weren't able to replace the screen until I got it done. Massive PITA to go to an Alfa dealer for me, but my mate was able to do it.

Definitely only one battery.

I looked into that recently. IIRC it wasn’t as cheap as you’d hope.

Ah well, it usually sits on either end of two extremes. Was worth checking though.

I'd speak to your mate and see what diagnostics come back with, at least you might be able to reset the battery control module and let it relearn if there aren't any troubling fault codes.

Depends upon your car usage like others have said above. My mum's Nissan Note is used once a week if it's lucky and it can take a solid 30 minutes of running before the stop/start begins to work again at times despite the battery being less than a year old and coded correctly. The original battery lasted 6 years before it just packed up without any obvious warning.

Does it get taken out for long drives? It might just be needing a few good runs to get the battery charged up and ready to go.
Happens with my car as it does short journeys but a decent run seems to fix it for a few days.

It rarely gets used for less than 30 mins on the open road 50-70mph - should be enough i'd have thought.

Is this a typical sign that the batteries on its way out?

Our car battery is 11 years old and the stop start hasn't worked for at least 5 years. No issue with normal battery function.  Van is 6 and that's the same despite a 30 mile commute to charge it every day.

I definitely won't be changing them just for the stop start to work again.

Just bought a car and stop start doesnt work. Fully charged the battery and still doesn't work.

Either it's broken, not holding enough charge or the battery isn't correct somehow.

Its not a problem until you hit traffic snd watch your mpg drop and your the only one with fumes coming out the exhaust.

This happened to me on a fairly new car I bought 2nd hand. The car had been sat for sometime without the battery being trickle charged.

New battery and stop / start worked fine again

Standard car batteries cannot be recovered once the charge has got too low

As Matt mentioned, they often have a separate smaller battery, I know my Discovery has (currently not working)

Is this a typical sign that the batteries on its way out? Incidentally, I find it odd that there’s endless tech on modern cars, but nothing telling me what my battery health is.

If I flick through the display options on my (aftermarket) stereo - ie whether it shows the station, the track curently playing or whatever, one of the surprise  options is it displays the battery voltage.

Batteries take a long time to charge. The big stop-start battery in my Volvo would take 4+ hours of motorway driving to refill after standing for a long time.

Sharing my own experience. 2021 E Class Mercedes. Just had its 46v battery replaced after 18,000 miles. Would have cost me over £3,000 but covered under warranty.

I would drive to work (60 miles) and would get a message saying that the 12v battery needed charging. Then we drive to the Alps (11 hours non-stop) and even that wasn’t enough!

Turns out it was the 46v battery not feeding the 12v battery. Apparently they don’t like to be left alone and don’t actually charge well unless you drive for hours and hours.

Sounds like a design flaw to me, but let’s see what happens next. The dealer said that Mercedes have refused these warranty claims on slightly older cars because during Covid when cars sat idle for long periods they had lots of failures. Sounds lame to me, but might be indicative of lots of cars now having battery issues. The damage caused by battery drain and inactivity over the last 3 years has stored up lots of battery issues. ‘There’s a lot of it about!’

I've just had a thought @reeksy as it's an Alfa, do you get a warning light on the dashboard after a short, (5 mins?) time.

My daughter has a Fiat 500 which also doesn't do stop start, (that's 3 of 3 in our house!) but this one is because an actuator arm that depresses the clutch position switch has broken off. It's held on by a couple of pigeon shit spot welds and is a common problem apparently. Some Alfa's may be similar from the same company stable.

FunkyDunc
Free Member

This happened to me on a fairly new car I bought 2nd hand. The car had been sat for sometime without the battery being trickle charged.

New battery and stop / start worked fine again

Standard car batteries cannot be recovered once the charge has got too low

Sometimes you can get them going with a smart charger. With the price of stop/start batteries, it's worth getting a cheap one like the Maypole MP7428 I have. It was able to recover my car's battery which died after being laid up for covid. I seem to recall it detected the fault and went through some kind of recovery cycle.

Turns out it was the 46v battery not feeding the 12v battery. Apparently they don’t like to be left alone and don’t actually charge well unless you drive for hours and hours.

There are a few manufacturers who've had this issue with the 12v charging side of the 48v electrics. Some have rolled out software updates to fix. Others haven't (or their hardware doesn't have the capability to take a better software).

My V70 had a beautifully hidden stop start mini sized AGM battery under the scuttle.

I had the original version of that in my C30 DrivE a decade or so ago. The list of "special considerations" to protect the battery was HUGE. And they were about £600 to replace and recode to the car. By the time i got my second and third version of the system, they could (almost) be hot swapped. For about 100 quid.

@damascus

Either it’s broken, not holding enough charge or the battery isn’t correct somehow.

Or you need a software update, a module reset or something else that's seemingly unrelated. I thought my alternator was on the blink as all signs pointed to that, nope, was a software issue and an update sorted it.

In my case it was the first signs of battery failure. Stop start unavailable initially, followed by slower to turn over, followed by not catching on the first turn in very cold weather then it's time for jump leads. Can't complain really, it was the original battery and the van will be ten years old this year.

I always turn it off. Stopping and starting an engine constantly must be a sure way to premature wear.

I always turn it off. Stopping and starting an engine constantly must be a sure way to premature wear.

I also don't bother clipping my seatbelt in, as I don't want to wear it the mechanism.

I also don’t bother clipping my seatbelt in

Don't be silly.

No sillier than thinking that they don't actually design in margin for more stops and starts... and protections to make sure it doesn't stop when it would cause wear.

Same has just happened to a mate. Got new car, older car not used for a couple of months till he got round to selling it, stop start light now on. We've told him to drive it for a bit, if no change, new battery.

Stopping and starting an engine constantly must be a sure way to premature wear.

You should write into a car manufacturer - they need to know!

There are loads of safeguards that won't do it unless the conditions are such that it won't prematurely wear the engine so I don't think its that big of a deal. There will always be some stories you hear but of course, no-one posts on the internet that their car's fine.

Start stop stopped working on my car last winter unless it'd been driving for ages then it would do one or two starts and turn off again (it shows you if the system's active on the dash). So I had the battery tested and it was giving 400A instead of 800. That was enough to start the car normally but the system didn't like it so shut the start/stop off. New battery, all fine. If I don't drive it for a couple of weeks in cold weather it takes some time to refill the battery.

On the other hand our hired Kia rarely did start/stop, and that was almost new.

No sillier than thinking that they don’t actually design in margin for more stops and starts

Maybe they do, maybe they don't. So long as it lasts 3 years/100k or whatever their responsibility is, maybe that's 'their' target. I do know that generally lots of very expensive parts now need changing as routine service items eg DPF's, DMF's etc and engines are susceptible to a lot of wear and produce more horrible stuff at start up.

It's another way of frigging the data to pretend the emmisions are lower and fuel economy is higher whilst introducing more wear (additional batteries required and therefore replaced etc) and unreliability.

Conflating a safety system that has saved countless lives with a costly workaround that actually reduces reliabilty is a bit daft IME. Your cars, do what you like but I'm not joining in on this one.

 I do know that generally lots of very expensive parts now need changing as routine service items eg DPF’s, DMF’s etc

Do they? My 11 year old diesel hasn't had anything replaced yet.

engines are susceptible to a lot of wear and produce more horrible stuff at start up.

I think that's only when they're cold.  Are you saying that leaving your car running produces less horrible stuff?

additional batteries required and therefore replaced etc

Our three cars only have the one battery each

Conflating a safety system that has saved countless lives with a costly workaround that actually reduces reliabilty is a bit daft IME

Are you sure you meant to use 'conflating'? Because that doesn't make sense.

Maybe they do, maybe they don’t. So long as it lasts 3 years/100k or whatever their responsibility is, maybe that’s ‘their’ target.

Targets haven't changed in the 25 years i've been doing this. Cost of maintenance has changed (more emissions controls etc), but the time to massive and terminal failure is (broadly) the same, some may "fail" earlier due to being uneconomic to repair though.

I do know that lots of very expensive parts now need changing as service items eg DPF’s, DMF’s etc and engines are susceptible to a lot of wear and produce more horrible stuff at start up.

Soooo, you really don't know then, it's *cold* start that does the majority of the nasties, a minimal load, hot start barely even registers. Stop/start systems inhibit stops with a cold engine, they've been doing that since it was first introduced. DPF/DMF aren't service items either. Never have been, neither are catalytic convertors or NOx traps.

It’s another way of frigging the data to pretend the emmisions are lower and fuel economy is higher whilst introducing more wear (additional batteries required and therefore replaced etc) and unreliability.

FWIW, stop start is one of the best systems in a conventional driveline for reductions in emissions and increases in fuel economy for such a small added cost. Not sure if that many conventional stop start systems still uses an auxiliary battery anymore, i know most of the big players dropped them years ago. They weren't needed.

My car has a big battery for the start-stop and a small auxiliary battery which powers the alarm and remote locking etc. This is a good way to do it, IMO, because if your battery goes flat you only need to boost it enough to switch on the electronics, and the main starter battery (the expensive one) is protected. I don't think this is related to it being start/stop though.

The biggest downside IMO is that when the battery eventually needs replacing it's £250 not £120. That said, mine lasted 9 years so it's not a big cost in the grand scheme of things. And I'm happy that it's not chugging out pollutants when I'm stopped.

I would rather have one of the mild hybrids though so it spends more time stopped and can creep forward in traffic. Wait, no, actually I'd rather have an EV and get rid of all that ICE related bollocks.

This is a good way to do it, IMO, because if your battery goes flat you only need to boost it enough to switch on the electronics, and the main starter battery (the expensive one) is protected.

Interesting, is this the Merc?

I don't really understand though.... why/how is your main battery protected?

And "you only need to boost it enough to switch on the electronics" ..... for what?

(obvs you've got two batteries to go wrong instead of one!)

Edit: Wait.... do you mean if there's a power drain from the alarm/central locking system?  If so, gotcha - although there's also a number of systems connected to the main battery that could just as easily drain it.

Interesting, is this the Merc?

Yes.

The small one in the boot is to power the alarm and central locking and whatever else is needed when the car's off. The main battery is disconnected, at least I think so.

Car starter batteries are designed for maximum current delivery not maximum capacity. So the aux battery, whilst smaller, has good capacity. I've never run it flat, but if I did I assume I'd still be able to open the car manually and start it with the key which would (you'd hope) use the main battery which has been protected from being flattened by the alarm.

It's 9.5 years old and the aux battery still tested ok. It's in the boot under the floor, so it's an AGM battery because you cannot have liquid acid sloshing around in the interior of the car.

The Prius had a similar aux battery that you could flatten by leaving interior lights on, but since the main traction battery was 300V you couldn't boot up the electronics with that alone. You had to boost the aux battery using jump leads but as soon as you got everything booted up it would run from the 12V supply from the inverter/transformer off the traction battery.

My battery failed about 2 years after stop start stopped working, so mark it in diary.

They always fail when critical, day before airport run.

Nice to get a warning.

I’ve just replaced the AGM battery in my CLS. The stop start was intermittent at the best of times but it’s been difficult to start at all recently and a smart charger indicated the battery was at 60%. By using said smart charger on maintenance mode I haven’t needed to get the new battery coded and the start stop is fully operational.
I got the battery from ECP’s eBay shop for under £140 delivered.

I just swapped the battery as normal on the assumption that the aux battery would keep everything running whilst the main one was disconnected.

I thought that too but was assured I needed to use the charger. 🤷‍♂️

Seemed to work ok. I had heard that you on some cars you need to tell the car what battery it is so it can change charging or whatever accordingly, but I didn't do that. I seem to remember paying slightly more for a battery that was identical in spec so it wouldn't matter.

It’s in the boot under the floor, so it’s an AGM battery because you cannot have liquid acid sloshing around in the interior of the car.

So it seems that you can..... the battery for my car is under the passenger seat and is lead acid!

It’s in the boot under the floor, so it’s an AGM battery because you cannot have liquid acid sloshing around in the interior of the car.

So it seems that you can….. the battery for my car is under the passenger seat and is lead acid!

Indeed - see a transit with a lead acid directly under the drivers seat and the contacts for battery less than 2cm from the steel mechanism....

Seemed to work ok. I had heard that you on some cars you need to tell the car what battery it is so it can change charging or whatever accordingly, but I didn’t do that. I seem to remember paying slightly more for a battery that was identical in spec so it wouldn’t matter.

It's not the spec of the battery that matters, it's the aging factors. As they get older they need more energy to charge and the discharge curve changes. So all your electronics (and alternator/generator outputs may need to be tweaked).
Depends how shagged the battery was when you took it out.

Cars with 48 volt (and higher) system don't care, because the battery systems are doing all sorts of internal measuring and reporting out anyway. And they can monitor the 12v battery status much easier, as there's no alternator wanging random current spikes all over the place.

Didnt read all the replies. Ignore