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Hello all!

Yesterday I had one of those charging episodes that happens occasionally. I had a long straightaway that ends at a stop sign with no one behind me so I decided to decelerate gradually in neutral. Speed at the start of this is around 65mph. While "gliding" in neutral, I noticed that IMA was charging...about 4 green bars worth. This has happened to me before, but usually on extended down-grades. This last occurence happened on a relatively flat road. I was wondering if anyone else had this happened.

I've been away from the forum so I don't know if this topic has been discussed. Sorry if this is a repeat.

Thanks all,

Tonpilot1

2002 red MT 73,250 mi LMGP 69.3
1990 wht Honda CRX Si 193K 35MPG
1978 Cessna A152 7K hrs 22MPG
 

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I have not seen that. Sometimes a brief flash of a few green bars immediately after shifting to neutral but it quickly vanishes. I believe that some background charging does occur in neutral at idle, but I do not see four bars. Was your SOC low at the time?

Assuming that this is a safe location to glide engine-off, you would save a bit of gas by switching the engine off and then turning the ignition back to the "on" position. If slowing down down more quickly is OK, letting up on the throttle while in gear will cut off the fuel and earn you some regen at the same time. You might even downshift to a lower gear as the car slows because regen cuts off as the car slows, and this cutoff point is at higher speeds in higher gears.
 

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^ i agree wholely

slowing down very slowly while in gear will give you "infinite" mpg as you will be in fuel cut mode, and you will get some regen...if you need to slow down a little bit quicker, then lightly pressing the brake will give you max regen and that will slow you w/o using the physical brakes

if you SOC is low, then you will get a few bars of charge while idling
 

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Discussion Starter #4
Thanks for the tips. I use your methods also. That's what's cool about the Insight is that you can get max regen by lightly pressing on the brake pedal and not use the physical brakes.

You guys will have to excuse me...what is SOC...State of Charge? If so, yesterday's SOC was not low at all...just 2 or 3 bars below the top. On those other occasions when I am gliding in neutral while going downhill, the SOC is, yes, on the low side...like right after climbing an extended hill.

I usually go into neutral to glide when I want to slow at a rate even slower than being in gear...Like on an extended straight like yesterday's event. If I need to generate some juice, then I will not use this technique. Of course if there are the usual fast drivers behind me, I'll have to keep my speed up and brake later, which I hate since I am being more wasteful...heating up the brakes more and regen less.

Thanks for the replies!
 

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This is a case where it's useful to change over to the metric gauge settings, because you can tell whether the engine is in fuel cut mode. Sometimes it's better to have it in fuel cut mode, but other times it's better to be able to coast that extra 1/8 mile to a turn.

If I hit the lights right, there's about a mile of gradual downhill slope on my commute that I can coast all the way down--no brakes and no gas needed. Usually there are busses and red lights and traffic, but sometimes it works out.
 

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I've seen the charging behavior you noted. I suspect it is normal.
 

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Tonpilot1 said:
Hello all!

Yesterday I had one of those charging episodes that happens occasionally. I had a long straightaway that ends at a stop sign with no one behind me so I decided to decelerate gradually in neutral. Speed at the start of this is around 65mph. While "gliding" in neutral, I noticed that IMA was charging...about 4 green bars worth. This has happened to me before, but usually on extended down-grades. This last occurence happened on a relatively flat road. I was wondering if anyone else had this happened.
Charging in neutral happens to me all the time. I "glide" in neutral alot. It happened with the original batteries and BCM, and it is happening with the new ones. The IMA charge indicator is almost never more than four bars from fully charged, and it happens then and also when it is fully charged. As b1shmu63 stated, it appears to be normal.
 

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Back before I got the unmentionable 4 letter mod, this sometimes would happen to me before I got a recal. I'd see a trickle charge when my SOC was high enough to not need it up to a minute before the recal. Since my mod, I don't have a recal problem...
 

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It seems like most observant 5 speed Insight owners have noticed this rare phenomenon.
Since installing additional instrumentation, I've learned that the stock "CHRG" display (which indicates the variable component of the battery pack regeneration current) has a significant fictional component. In other words, you shouldn't believe what you are seeing on that display in all cases, because sometimes it's just bogus.
I'll forego offering specific examples to preclude any discussion of MIMA
It's possible that this "coasting in neutral" regen display phenomenon isn't really happening as the display would indicate.
 

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I have had similar charging experiences. I have even seen charging occur during uphill drives with a light foot on the pedal. These experiences have seemed to become more frequent as the wear and tear on my car and battery have increased (I have about 115K on it now). As far as maximum regen braking, I have come to realize, albeit to late, that since brake jobs are far cheaper than battery pack replacements, perhaps I should have paid less attention to regeneration than to battery conservation.

Chris
 

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I too have whitnessed the "phantom charge"

I cant quite figure out why it will charge in neutral, but only if rolling at a high speed. Theres no mechanical explanation for it, when in neutral there is no signifigant link between the tires and the engine, there might be a little bit of force, like if you've ever had the engine on with the wheels in the air they will spin, but you can stop and hold them easily.

So the engine is just idling on its own, but supporting charge. I would assume this indicates that the engine will support charge at stopped idle as well if you could force it. I wouldnt mind being able to tell the engine to charge when idling, so like when I start the car to defrost and warm, its doing something useful with the gas. It might use more gas, but it would also speed warming, so it wouldnt take as long.
 

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If any charging is taking place while idling in neutral, it would have to be quite low level. Even 7-10A of charge could stall the idling engine.(experience speaking).
If regen is requested when in neutral, the 4 regen green leds light, but the MIMA amp display will only show ~ 3-5 A (One dim regen led)
Bottom line as Nemystic indicates, the charge assist leds are not indicating the true charge assist current.
 

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Discussion Starter #14
Re:

nemystic said:
It seems like most observant 5 speed Insight owners have noticed this rare phenomenon.
Since installing additional instrumentation, I've learned that the stock "CHRG" display (which indicates the variable component of the battery pack regeneration current) has a significant fictional component. In other words, you shouldn't believe what you are seeing on that display in all cases, because sometimes it's just bogus.
I'll forego offering specific examples to preclude any discussion of MIMA
It's possible that this "coasting in neutral" regen display phenomenon isn't really happening as the display would indicate.
That is good info. Base on the information you have from your additional instrumentation, the charging episode is probably just a false indication. I like to say there is a "gremlin" in the system! Easy way to explain the unexplainable!

BTW, what instrumentation did you add to the Insight?
 

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Tonpilot1 wrote:

"BTW, what instrumentation did you add to the Insight?"

With the home built MIMA_L modification I installed in 2005, I used a small DVM to display a voltage that's directly proportional to the IMA current.
That was later replaced with the MIMA_C modification (links to a website with detailed information are on a sticky thread in the technical branch of this forum), which in my configuration, includes an 8 LED display, 4 amber for assist, and 4 green for regen. The most significant LED illumination intensity is variable. That display doesn't offer as much resolution as the DVM, but it's about as good as the stock bar graph display, and more importantly, it provides an accurate representation of the actual IMA current in either direction.

It's not necessary to have the MIMA modification to monitor the IMA current accurately. I had connected the original small DVM to the IMA hall effect current sensor output and the MCM logic ground. It was set to the mV scale.
A "cleaner" way to implement that would be to build a relatively simple analog circuit (as Armin has done) to create a virtual ground from the +12V and -12V connections at the hall effect sensor, and to scale the output voltage by about 0.5x to provide a display in actual amps (1mV per amp).
 

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instrumentation

Not that it has anything to do with charging, but I added a connector to the speedometer sensor wire so I can connect a TimeWise rally computer to the car. My idea was to do some coast-down testing to get some real-world data on the "A/C versus open windows" discussion. A rally computer can take many very exact readings of time and distance, which is what you need for this sort of experiment. Also what you need, though, is a very long, flat road. So far I have found that the Insight coasts so well that it is hard to get decent data--you need miles of road to coast down from 60 mph to 10 mph.

What I need is a road about three or four miles long that is perfectly level, has no traffic, and located where the wind doesn't blow. There ain't any such place in Colorado...as far as I know.
 

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'Continuing the off-topic discussion, which should probably be in the "coasting" category; I'd considered running some experiments with my Insight to quantify the effect of open windows on aerodynamic drag.
There's a hill in the town where I'd previously lived that is relatively short, but very steep and straight. On that hill, I can get to 40mph on some bicycles without pedaling while going downhill.
The plan was to coast downhill from a very precise starting point, with the windows closed; then in subsequent runs, opened in several increments to 100%, all on the same day, to ensure consistent environmental conditions.
The metric was to have been the coasting speed at a marked location around the bottom of that hill. (Even though it is a rural road, coasting to a stop may have irritated other motorists.)

Since my Insight doesn't have air conditioning, I couldn't do a quantitative, comparative study.

Since the original plan was never carried out, this may all be irrelevant, but considering that the Insight open-window-aerodynamic-drag discussion has never been resolved to my satisfaction, I'd re-consider the experiment (described above) if enough fellow Insighters would be sufficiently interested in the result.
 
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