Stop Start has been around a while now - how are the batteries and starter motor's?

[Zak33]

We've had Stop Start cars now for a long time. In essence, the engine cuts out in stationary traffic/at junctions, and restarts when you put your foot on the clutch to pull away. It lowers CO2 emmissions in the urban cycle test.

In heavy traffic, with a lot of cars, it will lower the fumes without a doubt.

As anyone who has it knows, there are other drains on the car's electrical sub system and that often stops it working every time. Air Con, Heated Rear Window etc. If the car's battery is anything other than really well charged up it won't Stop/Start until the car's management system thinks it's safe to do so. Little cars often don't have it fully effective in towns as the stop start effect with a small alternator leaves the battery too low for it to work a lot.

But many years have passed now.... and my motor trade sources are reporting a far higher sales rate of car batteries and starter motors now. And for starter motors that's often a labour rate to go with that too.

So..... what's your experience? To be fair, we cant look at this for cars under Warranty, because if it fails in that time it's likely to be a manufacturing issue of the item. Most batteries and starter motors should be fine and dandy for 3 years.

But in the 5th and 6th years?

[Gerrard]

I have never trusted them and has become second nature to turn it off whenever I start the car (annoying you can't default it to off because of the emission test set-up requires it). Since my commute is relatively short (15-20min), I would rather have the alternator running as long as possible. So I am afraid I can't contribute to this survey.

[CAT-THE-FIFTH]

They stop more and start less as they get older??!!

[wazzickle]

I love it. It's not without issues, I'd say there are some design flaws and unless you know it well it can very occasionally present as a danger - there's no reason that I can discern to lock the steering when you engage it - but when it's running smoothly it makes me very happy to know I'm doing my bit to minimize emissions.

[DanceswithUnix]

annoying you can't default it to off because of the emission test set-up requires it

You can in my car, an Alfa Giulietta face-lift model, though apparently in the earlier models it did re-enable when you turn the car on. However, at 3 years old the battery is iffy so all it does is light up a stop/start disabled light above the switch but I can confirm that the light remembers its state from one day's use to the next

Not a fan of stop/start generally so I haven't bothered doing anything about it not working. I gather it is almost always the battery, specially on a second hand car if it has been standing on a garage forecourt for some weeks waiting to be sold which can degrade the battery. It is also more difficult than normal batteries to find a good replacement and the batteries are damned expensive or I would have just popped to Halfords and bought one. I have read that a dodgy battery can also make the engine feel more lumpy when cold (which I assumed was just normal small engine behaviour) so I might make the effort just for that. Owners who had their Alfa from new and use it a lot report still being on the first battery without issue, so it does sound like the batteries just don't like occasional use.

Generally, I think start/stop needs nearly all the hardware for a mild hybrid but without the benefit of being a mild hybrid, so I think it is pretty dumb.

[Zak33]

Y I have read that a dodgy battery can also make the engine feel more lumpy when cold

A low power battery on the edge of dead, might concievably mean it starts badly and with low voltage to the ignition pack/spark plugs for petrol cars causing a bad tickover from cold start but that implies it NEEDS a battery, or a new ignition pack or plugs. But simply using jump leads from another car once will tell you if that's it. If it's still lumpy, the ingition pack or plugs are at the end of their life.

Quality batteries have to cost more - lead costs money and lead weighs a lot and you need it in the battery. Light batteries, phyicially weighing less, are lower quality in almost every case.

I hate cheap car batteries... hate them.

[Zak33]

i cant remember who said it... a large US powertrain company...

but the average non stop start car in it's life time uses the starter motor 50,000 times.
but the average stop start car will use it's starter 500,000 times.

what was important wasn't just the starter motor though...

when an engine is running, the oil pump keeps the crankshaft bearings full of oil and the metal doesn't actually touch any other metal...(which is why a god oil change regularly is so good for an engine)

BUT.. when it stops the oil pressure drops and the crank shaft rests on the bearings... so you wear out the crank was faster.

[Zak33]

found it....
http://www.federalmogul.com/en-US/Pages/Home.aspx

Autocar spoke to them ages ago
https://www.autocar.co.uk/car-news/n...r-car-s-engine

A normal car without automatic stop-start can be expected to go through up to 50,000 stop-start events during its lifetime,” says Gerhard Arnold, who is responsible for bearing design at Federal Mogul.

“But with automatic stop-start being activated every time the car comes to a standstill, the figure rises dramatically, perhaps to as many as 500,000 stop-start cycles over the engine’s life.”

That’s a big jump and one that poses major challenges to the durability and life of the engine’s bearings.

A fundamental component of the engine and also one of the heaviest is the crankshaft. It’s supported as it spins by a number of precision ground journals along its length running in ‘plain’ main bearings (no ball bearings or rollers, just smooth metal). These are the main bearings and the effect is greater on the bearing at the back of the engine immediately adjacent to the starter motor.

When the engine is running, the crankshaft and main bearing surfaces don’t actually touch, but are separated by a super-thin film of oil, fed under pressure and pumped around the bearing surfaces by the action of the spinning crankshaft. This process is called ‘hydrodynamic lubrication’ but when the engine stops, the crank settles onto the bearing, the two metal surfaces coming into contact.

[Xlucine]

I've heard that applies to the cylinder liner/piston contact as well.

Installing an electric pump to keep the oil pressure up wouldn't solve the problem - hydrodynamic bearings don't work unless one of the parts is spinning.

[Zak33]

I've heard that applies to the cylinder liner/piston contact as well.

Installing an electric pump to keep the oil pressure up wouldn't solve the problem - hydrodynamic bearings don't work unless one of the parts is spinning.

that's exactly right.

The oil companies have for YEARS been making oils that try to stick... going right back to Castorl Magnatec.

but the thing is.. a spinning crankshaft holds itself up. But it weighs a lot. And when it rests back down, it's back to metal on metal.

If the amount of engine starts in it's life time goes up from 50,000 to half a million... that's a lot more wear.

[DanceswithUnix]

A low power battery on the edge of dead, might concievably mean it starts badly and with low voltage to the ignition pack/spark plugs for petrol cars causing a bad tickover from cold start but that implies it NEEDS a battery, or a new ignition pack or plugs. But simply using jump leads from another car once will tell you if that's it. If it's still lumpy, the ingition pack or plugs are at the end of their life.

Quality batteries have to cost more - lead costs money and lead weighs a lot and you need it in the battery. Light batteries, phyicially weighing less, are lower quality in almost every case.

I hate cheap car batteries... hate them.

I normally buy decent batteries, seems a false economy not to as not only will you buy twice for buying cheap but could well be stranded somewhere as a result of that.

These aren't just "good" batteries though, the AGM requirement for stop/start means you have to try and source a good AGM battery. For my car I don't even have the option of going to Halfords to just go buy one.

OFC a knackered AGM will still supply cold crank amps like a conventional battery, but the terminal voltage will be down from the usual 14.4V and I guess that is what will make the car a bit lumpy. It isn't that it is misfiring or anything, more that the engine management is hunting a bit trying to optimise the turbo pressure, valve lift etc so the power sort of pulses slightly up the rev range rather than being properly smooth. If you drive with a heavy right foot you probably wouldn't notice

Edit: Reading this, AGM apparently has a lower lead content than normal batteries so the cost isn't that: http://batteryuniversity.com/learn/a..._glass_mat_agm

[Butcher]

All this makes me glad I don't have start stop (despite having a 2013 car).

[DanceswithUnix]

Just went and peeked under the bonnet of my car, apparently I don't even have an AGM battery, I have an EFB battery. Sounds like it will happily take an 027 AGM battery though.

Googling for car batteries isn't usually this hard

[Zak33]

car batteries are complex now....

Some cars (BMW) need the battey/charge ECU coding to the type of battery fitted. The alternator's charge to a specific output according to battery installed.

not coding it can allegedly shorted the life of many electrical components!

[Tumble]

my mondeo is frankly rubbish at battery stuff. According to the Ford tech I spoke to, the alternator doesn't turn on until the battery reaches 75% charge. The start/stop won't work unless the battery's at 85% So it pretty much never works. Interestingly, I had to jump start Mrs Tumble's little Jazz not so long ago, and the start/stop began working again. The car is about 2.5 years old, but has 76k on the clock.

[peterb]

car batteries are complex now....

Some cars (BMW) need the battey/charge ECU coding to the type of battery fitted. The alternator's charge to a specific output according to battery installed.

not coding it can allegedly shorted the life of many electrical components!

Its more complex than that, for optimal life of an AGM battery, the charge rate needs to change as the battery ages (allegedly). That said, my BMW had an AGM battery fitted (from new) and it lasted 8 years - and that didn't have any ECU battery registration (even the BMW dealers were surprised it had an AGM battery fitted to that model - it doesn't have stop/start).