- My model of MX-5 is: ND2 2.0
- I’m based near: Guildford
- I’m looking for technical help or recommendations on: Istop
Can anyone tell me how long it takes for istop to start working. My battery has been on charge all week (Ctek CT5). Fuel economy monitor display says engine blue A/C blue but battery remains grey and istop NOT READY message. I don’t think I’ve ever noticed istop working as car only gets short runs. Any ideas would be useful before I go back to the dealer. Thanks
Top marks for finding the correct screen to asses what is the culprit.
I know of at least 2 ND2s that were ‘fixed’ by disconnecting the negative battery terminal for say 15 minutes and then reconnecting.
You will only lose some trip data so there is nothing to worry about doing this.
The stop start can work within 1 mile but does depend on outside temperature and how full the battery is plus a myriad of other criteria.
It is worth a try as it costs ‘nowt’ and may save you a trip to the dealer.
2 Likes
Thanks I will try that tomorrow, does this reset next service date data?
1 Like
I had my battery disconnect when I took the air bag off to change the steering wheel. All I lost was the trip data, service information remained.
Mine is an ND2 2.0l.
I agree! 
As far as the main problem is concerned, it is may be due to the short trips you referred to. You need to take it on a decent 1 hour run on the A3. The good news is that while iStop is not working the battery is being charged.
Because my ND RF often sits for a week without use, the condition of the battery concerns me. I have a cheap voltmeter plugged into the 12v “cigarette lighter” outlet. Something like this will do. I bought three different ones and returned the two that were not giving the same reading as my multimeter. You need to attach a plug to fit the 12v socket. I stuck the device to the dashboard with double-sided sticky, below the info screen and above the a/c controls. It can be left permanently plugged in as the socket is only live when the ignition is on (or ACC). Montoring this will tell you the voltage of the battery at all times and you can see when it is fully charged (>13v) or not (> 14.4v) because the alternator will put out the lower voltage when the battery is charged.
David
Interesting David I put a meter on the battery when I got home and with engine turned off I have 12.75 volts
No.
2 Likes
That is a ‘normal’ reading and would/should be enough for the stop start to work. It’s little brain is confused which is why the old IT trick ‘turn it off/turn it on’ can work.
Why not see what you have in the morning before you start it.
3 Likes
Will try, thanks for quick response.
I stop works fine for me but I have given up trying to work out the parameters for it operating! It certainly doesn’t do anything until the engine is warmed through. Then it’s randomly what heater vent settings, AC, did you go to the cinema last night and a million other checks. Sometimes it will only I-stop for a few seconds before cranking back into life. So trying to see if it’s working could be a challenge!
1 Like
I also have an ND2 that’s connected to a CTEK CT5 charger. Whenever I take the car out of winter storage, i-STOP starts working after doing an initial average of 400 miles (assorted journeys).
I seem to remember reading on here that to resolve this issue, the charger’s negative eyelet should be connected to the chassis instead of the battery’s negative terminal?
1 Like
400 miles sounds like an awful long time to get to the point where it works, considering that you have just disconnected the charger; but unfortunately, I have no idea why it should be so, except to wonder how long the individual assorted journeys are. As I suggested above, take it for a 50 mile run on the A3 and it should be working by the time you hit the traffic lights on the way home.
David
1 Like
The iStop on our similar vintage Mazda3 only works if
- the battery is close to full
- the engine is fully up to temperature.
So on a cold day with a short journey, almost no chance, as with our local London driving over winter.
But on our trip to Bridport last week in it and cooking in the sunshine despite the stiff on-shore breeze at Burton Bradstock it was popping on an off whenever we paused for a junction, almost an annoyance.
Is there not a switch to disable it, as on the ND?
David
2 Likes
The journeys are usually around 50 to 100 miles. Also, the CTEK charger is connected to the car for the entire winter storage duration which can be up to 6 months.
If it helps, when i-STOP starts working on my car, it triggers almost a minute into start of a journey when at a complete stop with the handbrake on and gearbox in neutral. I usually turn i-STOP off since the car is not used for commuting.
I had this problem on a Mazda 6. Tried charging the battery, tried a new battery but the only thing that made it work for a while was disconnecting and reconnecting the battery. I’ve had no issues with it on the CX-5. I believe the software can erroneously detect a tired battery when it is actually in good condition.
2 Likes
Yes, it’s exactly the same as ND. It wakes up again next time the ignition is switched on.
After seven years we tolerate it or ignore it.
I worry more about its clutch. Main driver, SWMBO, often keeps her foot on the clutch to prevent briefly iStop-ping the engine while waiting at the lights.
Recently that Mazda3 clutch has begun to feel ‘not right’ to me, and the car has only done 21K. By contrast her previous car lasted 20 years and 120K on its original clutch.
The i-Stop on my Mazda6 has never bothered me. It starts working after about 5 minutes of driving and saves me money and reduces emissions. What’s not to like? I miss it when stopping at lights in my NB.
1 Like
If I use a charger on my ND, istop stops working completely until reset per the instructions link below.
Even then it could be a couple of 100 Miles before it mysteriously starts working again. New battery last year.
In fact, I have to do this tomorrow as the car was on the battery Minder whilst we were away for a while over winter.
1 Like
I’ll say up front that I have no knowledge of the system or much of electronics - but, I have some experience as a user of a battery monitoring system (on a boat) which leads me to speculate.
I don’t think it’s possible directly to measure, statically and non-invasively, the state of charge of a battery with very much accuracy. Voltage only provides an estimate. It will read higher just after the charger has been removed than it will half an hour later, despite the state of charge (SOC) not being materially different. In addition, any parasitic drain, which we know exists on the ND, will affect the measured voltage.
One the car is running, the voltage is not a useful measure of SOC because the volts on the terminals is the charging voltage.
My speculation is that what is happening is that the monitoring system is measuring power in and power out. For power in it will make a charging efficiency adjustment. On this basis, once it has a datum point at which the battery is fully charged, it can calculate the charge remaining by adding power in and subtracting power out.
After a period of non-use, if the system hasn’t been active for days or weeks before start up, it’s possible that it simply doesn’t know the state of charge. Perhaps it makes a minimum estimate based on voltage. If not then it will probably want to see what is going in and out of the battery (which is in use and being charged) for some time before its algorithms permit iStop to function.
Maybe it will behave differently if the charger is disconnected a few hours before start up.
I’m certain there’s more going on than this but I think the estimation/calculation of SOC is a factor in what looks like odd behaviour.