I notice that sometimes when I brake the recharge indicator doesn't light up. Do other people experience this? Does the force with which you brake affect whether or not the recharge occurs?

As a side - question, can someone explain how deceleration can be taken advantage of to charge the battery?

Thanks for any insight,
Wes
Houston, TX

 

Brake force does impact amount of regen, but some regen should occur with no brake- just foot off the gas (answering your 2nd question). Having said that...

Regen is related to engine load/power. If the engine didn't get above X rpm/throttle then regen won't occur- the generator would be too much of a load at that instant, I suspect. Haven't determined what the magic # is, but its somewhere around 1300ish with near-idle fuel? I run into this when neutral coasting, then going back into gear just as I stop- no regen unless I tap the gas and nudge the tach over ~1300, then regen occurs on the way down (if I gotta stop, might as well charge the pack a bit, after a nice long coast in)

You should also notice that a little regen may occur the moment you crest a hill or cut back on the gas quickly- any time there is more engine power available than is needed to push the car and keep the engine itself spinning.

 

There is also probably some logic in the computer that determines if the battery needs a charge or not. There are all sorts of factors that get calculated, so it may seem random, but it's probably the various systems figuring out the most efficient thing to do at that moment.

 

true.

As for needing charge- unless 6 bars are showing and have been for awhile, there's 'always room for one more' from my experience. Its very hard to even get to 6 bars without a lot of stop/go braking, nevermind keeping it up that high. My vehicle seems to take a charge as greedily at 5-6 bars as it does at 3, but I don't know if that is strictly true. Below 2, the car will charge even more frequently- staying in 6cyl mode longer, for instance, to provide power to regen for a few extra seconds.

 

Wes, to follow up on this and from your previous post in the parallel thread:

I tried a real world test on this during my drive in today and I can't tell if the recharge indicator is ocurring during braking or if fit is just deceleration. In other words, I couldn't brake without first decelerating, even ever so slightly. As soon as you take your foot off the gas to apply the brake, the car is instantly decelerating and the charge indicator shows. I could not figure out a way to apply the brake without that initial deceleration from lifting foot from gas pedal, so I can't determine if the recharge indicator works for braking as well as for deceleration. I finally tried using both feet to keep foot on the gas while applying the brake. The recharge indicator did not light, but the assist indicator did light momentarily. So your HAH should be OK as you have experienced (no problems).

 

So it could just be that I'm really babying the car and my engine load isn't always high enough, so I don't see the regen very much.

I could swear I saw the regen during very slow acceleration too - don't know if anyone has seen that.

I rarely see the assist - I assume it's because I'm not driving it very hard at all.

I got about 28.8 mpg on the way to work this morning on surface streets with a fair amount of stop and go but lots of "ECO".

I've decided that the power of this vehicle to save gas is really two things:
1) The will of the driver to save gas
2) The constant feedback so that the driver can retrain for gas-saving behavior.

I think if we just added a real-time mpg update to every regular car, you would see gas consumption go down for people who wanted to save gas. It's just that right now, they don't know how to do it.

I'm confident that I will be able to make 40 mpg without a problem if I want to.

Also, on a slightly unrelated note:
I did discover that the reason my Auto-Stop wasn't working yesterday was because I was using the defroster setting for the A/C (it probably assumes that if you're using the defroster, it's very cold outside and disables the auto-stop). By the way, the auto-stop is great! I'm already getting used to it and the lack of noise is welcome - I'm sure the first time I idle in a regular car I will notice the idling.

Only 36 hours with the thing and I'm already starting to feel like I know what's going on .

Wes

 

 

Regen is independent of braking- it occurs anytime the engine is making more power than is needed to move the car at that moment. IMA will take a cue when brakes are sensed to go into 'full regen,' however. Thus you see some regen as soon as you remove pressure from the gas pedal, and more bars lit up as you press the brakes.

Conversely, IMA assist occurs only when the engine needs more power than it can provide at that moment, given current cylinders, gear, throttle, etc.- exactly the case for that moment when you had the brakes on with gas.

 

I've found that if I'm using very, very little throttle (foot barely on the gas), the system will frequently NOT go into regen when I let off the gas. If I'm using more throttle, it almost always will go into regen. I think it should regenerate at the low throttle conditions also, but it doesn't seem to realize I let off the gas. If this happens, and I "blip" the gas pedal, it will frequently go into regen afterwards.

 

Regarding braking behavior I noticed that when I let up on the gas the regen occurs with a bar length of about 30% to 50% of the available display bars. If I then just depress the brake pedal, the regen indicator immediately maxes out to 100% ie goes all the way to the left. So there must be logic that lets it take some charge with letting up on the gas and then detects brake pedal and maxes out. Note that I don't have to actually brake to slow the car, just depress the pedal a little.

The other thing I've noticed is sometimes regen doesn't occur when I let up on the gas.

My car rarely gets 6 bars showing on the battery indicator. Going up an down mountain passes it will charge to 6 but then it bleeds it off quickly by using the IMA assist more. It is difficult to get more than 4 bars on mine. Actually, the assist motor doesn't run much at all and when it does for a very brief time. The ECON is on most of the time.

I wish there was some technical info on this available. I wonder if an ODB II reader connected to a laptop would show anything. Any theories?