Stop Idle never seems to work?

[AMigaJAzz]

I've never had this feature on a car before.
But I've only been aware of it working once.
But my friends car - newer model does it lot in traffic etc

1) how do I know it's switched on?
2) what could cause it not to function - I've heard various things about certain conditions need to be met etc?

[ColinB]

Everything you need to know is in the handbook, search for "auto idle stop".

Yes, it's very picky about whether it'll work or not. Mine worked for the first couple of years of ownership then only in the summer, now not at all. The handbook has a long list of conditions that'll inhibit it, the main issue seems to be that it needs a battery in absolutely tip-top (ie new) condition.

It is turned on by default every time you start the car (although if any of the inhibiting factors apply, it may not operate). You can turn it off by pressing the button near the gear selector, you should then get an amber light on the display to tell you it's turned off. Otherwise, it's on.

[pebbles]

mine only works in hot weather or after charging the battery overnight.

the car is only used for short journeys which doesn't help.

[embee]

Mine only works after a long run,  at least an hour. The battery is 6yrs old now but starts the engine perfectly. I nearly always turn it off anyway,  I find it annoying for the type of journeys I  make.

[inchlook]

Mine didn't work for around 2 to 3 years, main short journeys, engine failed to start few times when temperature was low.

This year service they told me the battery failed the test. I got the battery replaced and idle stop is working again.

[Anochrism]

I tend to find that if you have music playing often, like I do, the infotainment system must drain the battery a fair amount, even when driving? i will have the volume between 15-20, so the stop-start wont work unless on longer drives.

[FarNorthJazz]

I have auto start/stop on the Jazz EX and Mrs FarNorthJazz has auto start/stop on her Subaru Forester.  Battery health on both cars is good.

On both cars the operation of the system can best be described as erratic.   

I think the main factors are that when the car is stopped,  the computer has to check how much load is on the car electric systems - this will vary on conditions (wipers on/off :  aircon running : running lights or headlights : etc).  It then has to compute how much drain there will be on the battery if all of these stay on but the engine is off and not pumping amps into the system.  There also seems to be some sensitivity - particularly on the Forester -  to brake pressure - both cars are automatic CVT transmission - and with the car stopped the system seems to work more often if the footbrake is being pressed firmly.

Basically,  if all the stars line up, the auto stop kicks in.   Otherwise it does not.  If it works - good : and if it does not I would not worry about it.   Unless you are in a lot of slow town traffic the fuel saving is marginal

[AMigaJAzz]

Wow just thank you everyone for your replies. 

There seem to be a lot about this on Honda forums in general.
I did do some testing today and got the "A" crossed out battery symbol.

The car is 2019, I know.someone with a 2018.and it seems to work and also someone with a HRV and that does it every time.

So not best pleased but then again not the end of the world - are my only options replacing the battery?

[ColinB]

I did do some testing today and got the "A" crossed out battery symbol.

Yup, that's what I get. Despite that, I've never had any problems starting, even in cold weather. My car was in for service just last week and the battery was reported as being in good condition (original battery, 9 years old). But the auto idle-stop seems to want a battery that's better than good. If you really want it to work then yes, a new battery should fix it. But it's not really essential.

One thing to try is to remove the negative connection from the battery for a few minutes. This is supposed to reset the system. This might work if, for example, a previous owner has boosted the battery incorrectly bypassing the battery monitor sensor on the positive terminal.

[AMigaJAzz]

Ok thanks I guess it's quite common as there seems to be many forum posts on the subject

It's just a matter of do I want a new battery and is it worth it etc.

[embee]

If you are not noticing any signs of slow cranking or reluctant starting then I'd suggest there's no real reason to get a new battery.
I don't "do" tired batteries,  first signs of struggling and I get a new one,  assuming I haven't done anything silly like leaving the lights on etc. It'll usually be the first really cold spell which shows them up. But if it's performing well,  wait and see,  it might go on for several years yet.
I replaced my Yaris battery this summer because I had mistakenly left the lights on and didn't realise for several days,  by which time the 8yr old battery was totally flat (0.25V), it did eventually charge but it's not going to be reliable after that. I got a Yuasa EFB.
If you do need one,  then get the right "type" , most Jazz stop/start batteries are EFB, Cox Honda spares now list the correct ones at competitive prices,  not cheap but worth it for a quality item,  and it'll be good for 7 or more years. The mk.3 Jazz uses a slightly unusual size so not many suitable options.

[Lord Voltermore]

It's just a matter of do I want a new battery and is it worth it etc.

Depends on how many miles you actually drive in the right conditions - car nicely warmed up, and in the right kind of  urban traffic that  you get useful  periods of idle stop  but not so many the engine doesnt run long enough to keep the battery well enough charged for frequent restarts.   

The idle stop hardly ever works in my daughters Ford fiesta

[AMigaJAzz]

Another thing is when you are stuck for a long period it is quite quick to turn the engine off then on.

[jasonevans]

Another thing is when you are stuck for a long period it is quite quick to turn the engine off then on.

Yes, that's perfectly normal as the car detects a battery voltage drop so restarts car while it has enough voltage left.

[Kremmen]

A friend had a 10G Civic with stop/start and had the same problem

What he found, but may not always work, was to turn on the ignition but not start the car immediately. More often than not that allowed the battery voltage detection to work before the starter motor was used and therefore seemed gave a lower reading so stop/start didn't work