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2023 A-Spec / Had '06 Touring/Nav
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Discussion Starter · #1 ·
OK, I'm an anti-idle-stop guy. I have it turned off in individual mode and hit the big center button every time I start up. Oh, and for those that complain about having to push a button each time, it's 1.75" away from the reverse button and 4" from D/S (I measured it). Your have to pull your hand back directly over the transmission controls after pressing the individual mode button. It's literally automatic at this point to hit the button and drop my fingers into the reverse pull. I digress.

I was at a touchless carwash today and the line was long. I purposely selected normal mode to use the idle-stop feature as I was going to be sitting there for 25+ minutes. I got the message in the instrument panel telling me idle stop was not working as it was either warming up or charging. I think nearly every time I've forgotten to hit the individual button and drove off somewhere, I get this message.

If you use idle stop regularly, is it always ready to go? Is the reason I seem to get this message all the time that the system doesn't "warm up" or charge some secondary battery/capacitor unless the feature is active?

It just seems odd to me that pretty much every time that feature should be active, it tells me it needs to charge or warm up.

What gives?
 

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2020 MDX Hybrid Advance
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322 Posts
There is no backup capacitor, idlestop relies on the car 12V battery to keep all systems running while stopped.

So anything that takes more than the 12V battery can supply disables it. In my limited driving with idlestop activated, the following disabled it most frequently:

Cabin temp too different from climate control target. Blowers will still send any leftover hot/cold air from the heater/ac systems into the cabin, but the actual heater/AC is disabled during idlestop. After a while if cabin temp sways too far from target, climate control will turn engine on. (or wont let engine turn off if target not hit yet).

12V battery hasn't charged enough yet, eg too soon after started car, or weak 12V battery.

Turning wheel while stopped. PS pump (even if electric) drains the 12V too much that idlestop almost immediately disengages.

Also, to prevent startup lag at a stop light, ACC radar will disengage idlestop if a stopped car in front of you starts to move.
 

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2023 A-Spec / Had '06 Touring/Nav
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375 Posts
Discussion Starter · #5 ·
There is no backup capacitor, idlestop relies on the car 12V battery to keep all systems running while stopped.

So anything that takes more than the 12V battery can supply disables it. In my limited driving with idlestop activated, the following disabled it most frequently:

Cabin temp too different from climate control target. Blowers will still send any leftover hot/cold air from the heater/ac systems into the cabin, but the actual heater/AC is disabled during idlestop. After a while if cabin temp sways too far from target, climate control will turn engine on. (or wont let engine turn off if target not hit yet).

12V battery hasn't charged enough yet, eg too soon after started car, or weak 12V battery.

Turning wheel while stopped. PS pump (even if electric) drains the 12V too much that idlestop almost immediately disengages.

Also, to prevent startup lag at a stop light, ACC radar will disengage idlestop if a stopped car in front of you starts to move.
Thanks. I doubt it's the main 12V battery unless I just happen to have a defective one. I've had the vehicle about 3 months and no other issues that would indicate a weak battery.

As mentioned above, I don't think there was any significant demand on climate control.

I was in a curved line of cars waiting to enter the car wash but, didn't turn the wheel while stopped. I suppose that leaves radar. The car in front of me would move, intermittently, as the line moved.

I'm just always surprised how often I see the "charging or warming up" vs. the feature actually being active. I guess it's just one of those quirky things. More software updates.

It seems a reasonable question might be, why is it so important to notify the driver that a fuel saving feature is inactive? Do people literally pull over and let the car idle long enough charge or warm up the system before driving? That seems counterintuitive. I guess what I'm saying is this seems like another overreach. If I used the feature regularly and sometimes, the engine just didn't turn off when it normally would, I'm not sure it would bother me. If I really wanted to know why it didn't work every single time, I suppose I could research it and find an explanation in the manual or online.
 

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2022 MDX Aspec / 2019 Ridgeline Sport / 2007 335i Coupe
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141 Posts
I believe I bought mine in March of 21 and didn’t have the stop/start ever work until winter and I had the heat on medium. Scared me because it just “shut off” and as others mentioned, it’s kind of aggressive and early before a full stop.
Anyway, a full year later and it’s cold again, and it did it to me again and it’s so much more frequent this winter than last time. I swear it was maybe once or twice last year and this year it’s already happened over a dozen times.
I initially thought my car was one of the broken ones that I would actually prefer it stay broken and unavailable for stop/start. But alas , my MDX now prefers to behave as designed lol .

I may install one of the disablers because I’m too busy initiating the dash cam, and setting music, confirming my garage door went down, and I sometimes ( all the time during winter) forget to press that button .
 

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Not an MDX but I have gone through bouts where my Q5 didn’t turn off on occasion a couple days. Engine temp, cabin temp within range, and battery char I believe are the biggest factors. If the hvac was trying to hit a specific cabin temp it may keep it on for example. Auto start / stop used to bug me until I got used to driving our gas golf cart around. At this point I just leave the system on and ignore it. If Audi wants to wear out the starter they can replace it. I only disable it when I’m in a lot of stop and go. Otherwise it starts and stops A LOT… like more often than not… stop signs, traffic, you name it - like a golf cart. Like yours mine also has an icon showing start / stop i inhibited but of course no details why specifically.
 

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2023 A-Spec / Had '06 Touring/Nav
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Discussion Starter · #9 ·
Not an MDX but I have gone through bouts where my Q5 didn’t turn off on occasion a couple days. Engine temp, cabin temp within range, and battery char I believe are the biggest factors. If the hvac was trying to hit a specific cabin temp it may keep it on for example. Auto start / stop used to bug me until I got used to driving our gas golf cart around. At this point I just leave the system on and ignore it. If Audi wants to wear out the starter they can replace it. I only disable it when I’m in a lot of stop and go. Otherwise it starts and stops A LOT… like more often than not… stop signs, traffic, you name it - like a golf cart. Like yours mine also has an icon showing start / stop i inhibited but of course no details why specifically.
Interesting. I know its only been a few months but, in my case, more often than not, if I forget to choose individual mode that has it turned off, it's off anyway. I was just wondering if maybe something was wrong.

Anyway, I'm taking the same approach as you on the other side. I just try to turn the system off and ignore it if I don't. Actually, the notification that it isn't active serves as a reminder that I forgot to turn it off! :rolleyes:
 

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2023 MDX Type S Advance in Tiger Eye Pearl with Orchid Interior
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As others have mentioned, anything that draws a significant amount of current will prevent auto-stop from activating. This includes the heated seats and maybe even when the massager is activated. If you don’t use the vehicle regularly and it sits for a few days, it will keep the motor on to charge the battery and it can take a while to get a full charge on it.

I don’t mind the warning as it lets me know what’s up. However, the Steering Input Required message is another story altogether.
 
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