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Mitaka 10-05-2005 07:03 PM

What is the pattern behind IMA charging
On numerous occasions I was coming down a big hill (thinking YES perfect recharge) and when I lifted the gas pedal the IMA did not start recharging. Even if I put the brakes on nothing was happening. It happens often. Sometimes I have to tap lightly on the gas pedal and upon release the IMA wakes up and charging is activated and so is the brake charge. What is up with that? Does it depend on RPM, gear or what? Cannot quite figure it out or... may be I got a LEMON :confused:

lakedude 10-05-2005 07:23 PM

Re: What is the pattern behind IMA charging
Mine does the same thing but not very often. I guess it would not charge if your batt was already full.

doppler 10-05-2005 07:54 PM

Re: What is the pattern behind IMA charging
That happens to me, too. I'm pretty sure it only happens when I've just changed gears and not touched the gas pedal. Tapping the gas pedal briefly will activate the regen, as you've noted.

ilan22 10-05-2005 08:59 PM

Re: What is the pattern behind IMA charging
Happens to me too. It happens only rarely though, I'd say around 5-8% of the time max. Especially if I have it in neutral and shift back into D. I know that you think that is harmful to the car Mitaka but in that situation it always happens that it does not recharge unless I accelerate and then let go of the pedal.

livvie 10-05-2005 09:42 PM

Re: What is the pattern behind IMA charging
I would suspect that because your engine can more than handle your car by itself that you will be carrying a full charge more often then an HCH would.

gonavy 10-06-2005 04:02 AM

Re: What is the pattern behind IMA charging
Unless you are always at 6 bars, it is not becasue of the battery charge state.

If the engine was in neutral (incl. gear shifts) at all, IMA will not regen until the transmission is fully re-engaged- i.e. the engine has to spin faster than the tranny to re-engage, which usually means tapping the gas to kick up rpms for a sec. Just putting the gearshift back into D does not fully engage the gears- the torque converter attached to the engine side has to spin back up and couple the fluid again.

The IMA is directly connected to the engine side of the tranny via the engine itself. IMA will not regen when the engine is unloaded (neutral). A full re-engagement to the tranny has to occur before the engine feels enough load to meet the condition. If a gearshift occurred just as you crest the hill, I can see how regen would not occur.

I see the 'no-regen' all the time as I go back into D after a neutral coast. My pack manages to stay at 3-4 bars nevertheless.

Mitaka 10-06-2005 08:08 AM

Re: What is the pattern behind IMA charging
So as I thought a quick tap on the gas is the wake up call whenever regen. is sleeping. Thanks

Dale B 10-07-2005 07:48 AM

Re: What is the pattern behind IMA charging
Mine too, probably 30% of the time. It's unrelated to the state of charge, and appears to be more random. However, I think there's a relationship to how much throttle I'm using before I let off the gas. If I'm driving "conservatively" with barely any throttle, say, at 35 mph down a slight hill, and then let off the gas gently, it will usually not go into regen. If I'm on the highway and quickly let off the gas, it will almost always go into regen. It acts like the throttle position sensor is either not sensitive enough to the small movement or the IMA system is programmed to ignore the small movements. Like others have said, blipping the throttle generally wakes the system up.

It gets annoying when it does this because I let off the gas expecting the regenerative braking to slow the car down, in anticipation of a stop light or stop sign. Then, when it doesn't do this, I have to either "waste" the braking (use the brakes without regen) or blip the throttle (which actually wastes a small amount of gas, I suppose). Having the system be completely predictable would be much better.

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