[fscott]

Is it possible to disable the IMA system on an Insight and drive it as a normal internal combustion vehicle? I know I would have no charging system for the 12 volt battery anymore, but that's not a major concern.

I'm interested in doing this because I want to compare milage with and without the IMA. I'm curious to see how much of the Insight's fuel economy comes from hybrid tech and how much comes from light weight and low friction.

Fred

 

[rtm242]

Delta Flyer posted the following on an IMA replacement thread (http://www.insightcentral.net/forum/viewtopic.php?t=4794):

The Feburary, the infamous IMA light appeared, and sure enough, autostop, assist, etc, stopped working. I still managed 80mpg the next day dropping the Insight into the dealer. I strongly suspect they were in the "legal CYA mode" when they said you can't drive this car with a dead hybrid batter pack. I had nearly 95,000 miles on it.

The Insight also does have a auxillary starter that works off the 12v battery in cases where the main battery lacks enough power to start the engine...

But both of those are with an attached, poorly performing or failed battery, I haven't seen a post of someone with a disconnected battery.

-Shawn

 

[b1shmu63]

Fred, When you are cruising on the highway at a constant speed the IMA does nothing to improve mileage. However........Your steering, computers, lights, radio, and all the small motors in the windows, mirrors, heating, radiator, hatch release, wipers, etc. draw power from the 12 volt system. The 12 volt system is powered off the IMA motor/generator which is much more efficient than the typical belt driven alternator.

Honda attributes a third of the fuel savings in the Insight to the hybrid/battery system. The rest they attribute to aerodynamics, friction reduction and various improvements to the ICE drive train.

Removing the IMA batteries would reduce weight, but again at a stedy highway speed the difference in mileage would likely be too small to measure, given the "noise" created by other factors such as road, weather, and driver variables.

There is another factor I've noticed. If you think a particular change will gain you better mileage it usually does. No kidding! Hypermilling is mostly a head game once you have mastered basic techniques and setting a reasonable goal seems to work for me. My personal average of 72.3 would be better but I try not to impede traffic and occasionally "backslide" into aggressive maneuvers.

 

[Insightful Trekker]

I know I would have no charging system for the 12 volt battery anymore, but that's not a major concern.

Huh :?: Okay...but as Kip pointed out you'll be walking within a dozen or two miles without replentishing the lost 12v current. (no 12v power for the ignition system either)

 

[trunkout]

wow

I've been driving 100 miles a day for like three weeks with no IMA.
No real problems to report....lost 5mpg.

Yes.....5 Miles per gallon.....and it's been really cold here in KC lately.

:roll:

 

[joecvt]

It is not really possible with the flick of "the switch" in the back to maintain a reliable vehicle. Like others have already said, without the ability to charge the small 12V battery, you will be walking soon. If you remove the IMA "guts" in the back, you will only save probably about 68 lbs. (the battery pack weighs 48 lbs but I added another 20 for the other stuff). Now the problems that will happen when you do:

Upon turning on the ignition, you will get a check engine light and an IMA malfunction indicator. (some inspection places will not pass your car) Assuming the 12v battery upfront is in good shape, you may be able to startup and drive for a couple of days before battery depletion. Your timing may vary based on headlight usage, etc...I guess you could hook up your battery to a charger every night but that would mean that you can't take the Insight on a long trip. If you put an alternator in the car yourself, that would probably take care of the charging system but it may rob more power away from the engine just when you may need it. (most of the time, the current design will stop charging the IMA battery if you really need the power to accelerate) You will also lose auto stop functionality. (If you use the key method as a forced autostop, you will wear out the backup starter motor within the first or second year.) Lastly, you will not have the same performance that you currently do. Not that the Insight is a screamer, it performs very well considering the size of the gasoline engine (slightly less than 1 liter). Since I have never turned off "the switch" (or removed the IMA "guts"), this is only my best quess as to what will happen.

I may have gone a bit too far in the description after reviewing your question again. If you are only wanting to try this as a temporary experiment, then that's a different story although I wouldn't drive too far from home during the test

I did see trunkout's post about the 100 miles per day for three weeks but I can only say that the IMA system must still be charging his battery. I do not know for how long though. The only thing that I know from reading trunkout's reports is that his battery did not fail, an electronic part has failed within the IMA components (according to Honda) but it doesn't mean that his IMA system is completely disabled. I don't think that the battery circuit breaker has been turned off either. My best guess answer is based on if the IMA system was completely disabled.

JoeCVT - Just your average CVT owner

 

[Insightful Trekker]

Yah, trunkout's generalizations can run you the long lap around the barn.

While he dosen't have IMA Assist or Charge there's no doubt that his IMA alternator function is still working. In "other" type IMA failures "bad" IMA batteries will also ultimately cause the 12v alternator function to fail.

Depending on many specifics the car will be "dead" in less that 30 miles without additional 12v current available. With headlights on or most any other accessory it will be _much_ less than that.

 

[trunkout]

yeah

and the stereo and amp and high beams never come off either.
thanks for the vote of confidence, trekker.
Still going strong

 

[joecvt]

Trunkout,

I think that your IMA problem is much different than most others. It appears that Honda found a problem with a part in a controller (not the battery itself) ... IF your battery is still charging, you may be able to drive around for a while without walking or perhaps never fail you....But that is a big IF.... It is very possible that only one portion of the IMA system has shutdown and the charging portion responsible for the charging system is still working.

I think that this is much different than someone disabling the IMA system as a temporary test or long term (if possible)....

JoeCVT - Just your average CVT owner

 

[fscott]

Thanks for the replies, guys.

To clarify things, I'm not trying to make a permanent change to the vehicle. I just want to to a short highway trip with the IMA totally off and see how I do on mileage. Then I'll reactivate the IMA and do the same trip again. This is just an experiment to get some real world numbers.

What I'm still unsure of is, if I switch off the IMA's main breaker in the back of the car, will the darned thing even start up and drive?

I'll be monitoring voltage via the cigarette lighter, so I can abort the experiment if the battery voltage falls too far.

Lacking anybody telling me that I'm going to damage the vehicle, I guess the best thing to do is just wait for a day with good weather and no traffic and give it a try.

 

[Insightful Trekker]

I wouldn't want to be one to discourage someone learning but this isn't exactly ground breaking science we're proposing here. And several members have tried it in the past.

MPG is only lower _due_ to IMA operation during a forced charge. Else it is an MPG booster. Its biggest contribution is in a city drive cycle when Auto Stop & Assist work a greater percentage of the time. On flat & level highway runs its probably a 1-3 MPG loser (its added "dead" weight).

During your test you will notice what its like to have 30%-+ of low end torque taken away. Drive accordingly.

HTH!

 

[trunkout]

During your test you will notice what its like to have 30%-+ of low end torque taken away. Drive accordingly.

HTH!

only 30%?!?!?!?
sure feels like 100%!!!

 

[chrs]

What I'm still unsure of is, if I switch off the IMA's main breaker in the back of the car, will the darned thing even start up and drive?

I'm pretty sure the answer is yes.

Charlie