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Does IMA battery factor into car starting up?

9K views 31 replies 14 participants last post by  fotomoto 
#1 ·
Hey guys. Just a quick question. Does the current charge in the IMA battery matter when it comes to starting up the Z or is it just the 12V battery under the hood that's involved?
 
#2 ·
The IMA starts the Z which is why you don't hear a starter and current charge doesn't matter, the computer will make sure you can start it. If the IMA malfunctioned (or other reasons, too cold) it will use the regular starter. You still need the 12V battery regardless to start the car.
 
#12 ·
Yes that would sound like a drain, the car is not very tolerant of after market items like head units. As an aside, and I know Speedbump will comment on this :)). I fitted a remote controlled breaker on the earth side of the battery. It works really well you get all the operations but you also get good security and it stops the battery from flattening. However, and i hate to bring another car manufacturer into this, the new Hyundai Kona offers the user the ability to start from a dead 12V battery using a button to energise the 12V side from the IMA equivalent battery. I will try to get a cct diagram to see what it does, but it is a bit of an obvious option. Has this been considered before?
 
#14 ·
Do you lose all your presets in your radio when you use your breaker?
I'd imagine he does if it cuts power to the whole car. The stock radio on the base model would definitely lose presets.
In my case, I've left my car sit for up to 2 weeks with no problems starting, so sounds like there is a parasitic drain. A few weeks ago my dad got a new radio for his car (2004 Mazda 6). It's one of those chinese head units that are basically an android tablet with a small amp, similar to the COHO head unit for the CR-Z. With that one, after letting the car sit for 3-4 days, the engine turns over noticeably slower.
 
#15 ·
I'd imagine he does if it cuts power to the whole car. The stock radio on the base model would definitely lose presets.
In my case, I've left my car sit for up to 2 weeks with no problems starting, so sounds like there is a parasitic drain. A few weeks ago my dad got a new radio for his car (2004 Mazda 6). It's one of those chinese head units that are basically an android tablet with a small amp, similar to the COHO head unit for the CR-Z. With that one, after letting the car sit for 3-4 days, the engine turns over noticeably slower.
Maybe it isn't connected properly and is getting constant +12V instead of ACC? The COHO unit goes to sleep if you turn the car off and in this mode drains a little bit of current, but after few days of sitting (I think it's around 4 day) it turns off completly. If that's not the case, he can use a relay to forcibly turn off the unit when there's no voltage on ACC line. Or just use this automatic circuit breaker that you install on 12V battery and it detects if the battery is almost discharged and cuts the power completly, so it doesn't discharge to the point where you can't start the car anymore.
 
#5 ·
While on the topic here about the IMA battery, is the "Auto-Stop" function supposed to kick in every time I come to a complete halt and put my gear in neutral? I have a short commute to work, and was driving in Normal mode this morning and noticed the auto stop did not kick in during the two times I came to a complete halt on redlights. It also did not kick in when I parked.

Haven't really noticed any other misbehavior in the week or so I've had the car, but I've been driving in Eco mode prior.

So I guess in summary, does the auto stop only work in eco mode? work differently in other modes?

I was thinking also maybe while idle on an uphill, it doesn't kick in?

Please I'd appreciate any feedback!!!
 
#6 ·
Auto-Stop looks at many factors before kicking in, it will kick in less often in Sport than Normal than Eco. If Virgina is getting cold like NH is then Auto-start will not kick in if the heater is on and the inside temp is a decent amount off from the set temp for the HVAC
 
#7 ·
^ Agreed - Internal environmental settings probably play the largest role in autostop behavior..
 
#8 ·
sweet deal. yeah it has started to get a bit chilly here in the mornings as my cr-z always starts up with the low temperature indicator

well i got off work and drove back home on eco mode and whatta ya know voila we have instant auto-stop!

glad it wasnt my electronics acting up, thanks for the insight!
 
#9 ·
Interesting topic. I was curious about what battery starts the engine as well.

Re: Autostop

It engages much more freely in ECON mode and nearly never engages in SPORT for me unless I've been driving for awhile.

I'm still working out the mechanics of having it engage/disengage with the 6MT. Here is what I've noticed:

1) It will not engage if the car is left in gear with the clutch depressed.

2) It will not engage if road speed is above ~15mph or so.

3) It will not engage unless brake pedal is pressed.

4) It will disengage if clutch pedal is pressed in (sometimes).

5) It will disengage if shifted into 1st gear (if it hasn't already engaged from pressing in the clutch).

I'm not sure why it disengages when pressing in the clutch and other times when shifting into 1st. Anyone know?

Most of my driving is done in ECON, btw.
 
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#10 ·
#2 is slightly incorrect the system is designed to engage at 19 or under mph. I can always get min to engage when slowing down at 19mph. In sport mode I never have problems engaging the auto-stop. As for #4 after being in auto-stop for a certain amount of time you will notice the auto-stop light flashing faster then normal at this point it will reengage the engine as soon as you put the clutch in. I think it is because the system says "ok after x amount of time the red light should be turning green so if the clutch gets pressed in it is probably green and the driver is getting ready to go so I better turn the engine over."

To add to your list for HVAC settings:
#1 Auto-stop will almost never engage when the A/C compressor is in use (defrost mode does use the a/c compressor)
#2 if there is a significant (I think it is 3 degree F or more) difference between the registered internal temp and the tmep setting for the HVAC Auto-stop will not engage.
#3 if set to auto and the humidity is high in the car auto-stop will not engage in order to continue running the A/C

These guide lines are for Normal mode, as stated before ECO mode will engage the auto-stop function more. The developers have stated the Sport will though MPG out the window for performance, Normal is a good balance between comfort and MPG, and eco mode will sacrifice some comfort in order to gain more MPG.
 
#23 ·
To answer the Original posters question: YES the IMA factors into the starting process and under most condition the car starts using the IMA battery but process is kicked off by the under hood battery so we can use a much more dead under hood battery than other cars but the margin between able to start and not able to start is a very small one.

The cool thing is under very low temperatures the car uses the back up starter to start rather than the IMA but for that to work you need a working under hood battery and charge in the IMA(Not sure on that).
 
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