Mini Cooper Forum banner

Does Start / Stop increase engine wear with negligible fuel savings?

1 - 20 of 42 Posts

·
Registered
Joined
·
270 Posts
Discussion Starter · #1 ·
I thought start stop was cool but in winter I thought it was very likely going to cause extra wear as the car barely warms up fully on a short commute.

I read that unless you stop for a minute or more you barely save any fuel anyway.

Also once the car does warm up fully the cooling circulation systems and oil pump shut down when the car stops - which may not be good as parts of the engine overheat and more wear occurs on start before oil pressure and circulation kicks in to lubricate everything.

Finally the starter motor must work much harder over the vehicle life which obviously will reduce its life span assuming that each cycle will cause wear.

So what is the consensus - I am no mechanic - what do experts think?
 

·
Super Moderator
Joined
·
8,822 Posts
Supposedly the starter motor and battery are uprated. 45k miles in my Cooper s and it was still perfect but.........I do think the savings are marginal unless you're stopping for over 30s. I too heard 1 minutes but that was years ago.. I wonder if anyone has researched this?
 

·
Registered
Joined
·
179 Posts
I always switch the feature off as soon as I start the car.
Unless you are in heavy town traffic, I think it's just a waste of time and a gimmick.

It only stops the car for a couple of minutes anyway and it will then restart the engine, so no use at all if you are stuck at a level crossing (railway crossing), and thats the time when you really need it....

I also find if you are in a long traffic queue the people will tend to keep creeping forward bit by bit so you have to keep starting the engine to move forward all the time, and if you only move forward a few feet the engine won't switch off again.

All rather pointless IMO on my daily commute!
 

·
Registered
Joined
·
1,654 Posts
If I select green mode on my JCW it will start/stop before the engine is fully warmed up.

Maybe my vehicle control software is different from you vehicle.
Doubt it....but I NEVER use green mode >:D>:D
 
  • Like
Reactions: jeremybingham

·
Registered
Joined
·
285 Posts
Energy saving trust figures are fuel savings after 10 to 20 seconds and much less emissions too.

A large bus company who spent £1.2 million on fuel a year had their buses tracked found that £97,000 of fuel was used whilst stationary at bus stops and traffic lights. Drivers were advised to switch the engine off if they anticipated a 10 second or more stop.
 

·
Registered
Joined
·
478 Posts
I was advised by a friend that work for a car manufacture (not Mini or BMW), he advised if the stop is less that 10 seconds you are using more fuel. Also its about 1ltr per hour idling, so you can calculate the saving based on how much time you spend idling. At that rate I will pay the extra, given that I already pay extra for Shell V Power.
 

·
Registered
Joined
·
508 Posts
I read that unless you stop for a minute or more you barely save any fuel anyway.
Let me guess - this was in an article that concluded that stop/start was just plain wrong, and ungodly? It's the internet equivalent of "I was told this by a bloke in a bar, so you know it's true".

Since the Mini recharges its battery mainly when it's decelerating, most of the energy to restart the car is 'free' - sure, you paid for it in petrol but it would otherwise have been thrown away in braking, so it's 'free' in that sense.

So 'calculations' of the benefit of stop/start that don't consider this have nothing to do with Minis. And, really, would the time to benefit really be exactly a minute, or does that just tell you it's a made-up number?

It's just like the story about how long to switch off a flourescent light before the energy saved is greater than the energy to re-illuminate it - or "I'm not being lazy, I'm saving energy".

So in a Mini any fuel saved when idling is basically a net gain. I don't think it is a significant amount, since keeping an engine idling doesn't take much fuel, but all fuel economy measures are just the sum of small changes, not one great leap forwards.

Stop/start does fractionally increase the time from seeing a light change to moving off, so I think that's a downside that no-one admits. Plus there is the potential to stall the engine until you get used to how it works and I think that is such a huge badge of shame that lots of guys can't stand it.

I think what we are really discussing is something new, and we are just hearing peoples' resistance to new ideas. Now, if stop/start made the car look better, that would get everyone's interest.....
 

·
Super Moderator
Joined
·
8,822 Posts
Mmm i;m with Angib here Gogo; our mini batteries are higher capacity to cope and as Angib says, when you decelerate the battery charges; ie free energy hence in the ad they can quote brake energy regeneration-nothing comes from the pads as such! The issue of the battery not recovering isnt one that affects us as if the battery cant cope the auto stop start doesnt operate. in a traffic jam that is continually shifting i switch it off or dip the clutch for sanity; other than that i usually let it do its own thing, as i did with my last mini which as i say was 4 years old and 44000miles in with everything still operating perfectly. the car is designed for it so let it do it! we all need to do our bit!
 
  • Like
Reactions: Jm32

·
Registered
Joined
·
890 Posts
Manufactures have to try every thing they can to get the car they produce to meet more and more stringent emmission requirements, and the stop/start thing is one of these.
They are not so bothered about the customer saving fuel/money as they are in passing these emission tests, as witnessed by the current VW fiasco.

It will save fuel, marginally, depending on various conditions but the average motorist probably wont notice it, and it will certainly add wear and tear to other components.

As ever if you are trading in your car in a couple of years the wear and tear to starter motors etc won't matter, but I wouldn't be keen on buying a second hand car that had been used in city traffic with the the stop/start always active.

Toyota dropped it in the 1.33 IQ as it was causing more problems that it was worth.
 

·
Registered
Joined
·
508 Posts
Yeah, everyone can produce horror stories about what will fail - but where are all those failures? We've had stop/start in Yurp for many years, yet my dealer reckons they don't get through starter motors unusually fast. Ditto with engines and long oil change intervals.

Say after me:
"There's a good reason why I don't like this new idea and it's not because I'm an old fart (in my twenties), it's because the sky will fall in when........"
 

·
Registered
Joined
·
270 Posts
Discussion Starter · #18 ·
MINI uses an AGM type battery which is indeed designed for start/stop as it can handle 3x the cycles of regular batteries. So no surprises that the design is good.

The tough question is whether the fuel saved from start/stop outweighs the wear and tear from all those extra cycles. I am hoping expert mechanics would chime in...even if it is just an opinion.
 

·
Registered
Joined
·
508 Posts
Well, of my two Minis so far, the stop/start in both stopped working by the time they were two to three years old a lot of the time. Neither car gave any other indication the batteries were 'tired' (eg, when starting), but both exhibited the same tendency to not stop/start in cool weather except after long runs and the second one had its battery replaced under warranty. I do stress that the stop/start was the only sign that anything was wrong and so maybe Mini is too strict on its algorithm for battery health.

But it would suggest that the stop/start system assumes a perfect battery.
 
1 - 20 of 42 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top