[dfiore]

Since the electric motor on my Insight is only 8hp, would increasing the available battery voltage increase the horsepower of the electric motor? It is a brushless motor made of rare earth magnets. This would obviously make for better gas mileage! :idea:

 

[Guest]

Hi Difore:

___The Insight’s hwy mileage in particular comes from the extremely efficient ICE, not the pack and Hybrid assist drivetrain. In fact, except for the pack providing charge to the 12 V system and acting as a quasi balance shaft, the entire setup probably hurts hwy mileage given the drag the MG set places on the drivetrain when hidden or non-hidden charging occurs.

___Maybe city mileage might be improved somewhat by using less of the ICE for acceleration but all mechanical and electrical power eventually comes from the 30 - 40% thermally efficient ICE anyway. (Does anyone have a labs thermally efficient map of the Insight’s ICE?). Second is that you are modding what some very good Honda engineers spent quite a bit of time on already …

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:8wj7jecr][email protected][/email:8wj7jecr]

 

[Foxpaw]

Increasing the voltage of the pack should increase the horsepower of the motor. However, I wouldn't count on it increasing the efficiency of the motor. Also, though the motor is probrably running below it's capacity, so the risk of catastrophic failure is low, the more voltage you use, the shorter it's lifespan.

 

[dfiore]

lifespan?

If the motor is brushless, should it even have a lifespan? unless you mean the bearings

 

[Insightful Trekker]

Re: lifespan?

If the motor is brushless, should it even have a lifespan? unless you mean the bearings

I believe you already correctly understand that there are no bearings in the IMA motor. With your theoretical improvement increased heat would become a durability factor.

Higher voltages would only increase the magnetic field in the windings, and if they are already at or near 100% saturation then there is little room for improvement.

But the limiting factor in this scenario is that the fixed magnetic field cannot be increased. Therefore what you have to "push" or "pull" against will not be correspondingly stronger and little of no performance improvement will result.

An interesting site that shows several graphs in regard to the Insight and its use of the IMA system is:

http://www.ctts.nrel.gov/analysis/hev_test/data.shtml

Figure #2 is most applicable to this issue.

Perhaps the most interesting mod for the Insight's IMA would be to install a Civic Hybrid's IMA system. It is designed for more power. You'd definitely get better acceleration. But given the design use of the IMA system this would likely translate to little or no MPG improvement.

HTH!

 

[Tim Maddux]

Re: lifespan?

given the design use of the IMA system this would likely translate to little or no MPG improvement.

Actually by increasing the power of the IMA you would decrease 0-60 time and hence reduce the time burning the relatively vast amounts of gasoline you burn under acceleration (when compared to cruising).

However, I would instead just get a newer car, because any successor to the Insight would have additional improvements, such as the ability to shut down cylinders during regen, already present in Civic Hybrid.

 

[Insightful Trekker]

Re: lifespan?

Agreed that gasoline consumption under acceleration would be reduced. But as a function of overall MPG it is a small percentage. See the referenced website and graph.

The Insight also goes into "fuel-cut" mode on deceleration. The injectors are turned off. This has been a feature of all Honda multi-port injection cars for many years now.

Are you referring to the new hybrid Accord multi cylinder function? (VCM) AFAIK dosen't apply to the Civic hybrid.

http://www.hondacars.com/info/news/arti ... ory=Accord

Since this topic was multi-posted in both MPG & Problems maybe consider combining the threads and moving it to the most appropriate forum Mods & Technical issues.

 

[Tim Maddux]

Re: lifespan?

Are you referring to the new hybrid Accord multi cylinder function?

I was referring specifically to the "cylinder idling system" mentioned here and in general to the other improvements of Civic Hybrid's IMA:
http://www.insightcentral.net/KB/compar ... train.html

I find that low mpg gotten during heavy acceleration (like up to highway speed) is difficult to overcome. If I could somehow magically get rid of that consumption but still get up to speed just as fast, I would be getting over 100 lmpg, based on repeated highway segment mpg observations. One magic way to do that would be a lighter IMA system that packs more HP and torque and can recharge more during braking.

 

[muffin]

what about connecting two IMA batteries in PARALLEL? That would make keep the carge twice longer!!

Or litium-ion instead of Nimh:

http://www.thunder-sky.com/LP90A(EN).htm

http://www.acpropulsion.com/SEMAtrip2003.htm

 

[Guest]

Hi Tim:

___A bit OT and should be in a separate tips and tricks mileage thread but here goes …

___What I have found that helps my mpg from initial start and take off when cold is to let my Insight idle cruise whilst in second and then third gear up to ~ 25 mph. Since we were back into the teens and twenty’s again the past few days , my Insight likes to idle at ~ 1,500 RPM for a few minutes from initial start. Once I have her moving from second, I just use this fast warm up idle to get my instantaneous into the 55 - 75 mpg range and she will usually accelerate and then hold speed while warming up and still give a decent readout over that first 1 mile or two. I can usually reach the highway (~ 1.5 miles) with a 55 - 60 mpg readout in these colder temperatures and have some momentum (~ 25 mph) to assist in getting me up to 50 - 55 mph or so.

___Another thing that seems to help is that when I reach home after a drive, I always back into my driveway which is ~ 150’ with an ~ 5 degree down slope toward the road. This costs me some fuel to back in but the Insight is well warmed up given it is after a long drive and it doesn’t use much fuel for that 150’ or so. From the Insight’s parked position with her nose facing downhill toward the road, I can coast out of the parked position and hit the road @ ~ 9 mph when I start/light off the Insight and shift immediately into second gear to start this fast idle cruise. I know it’s not much but it might help you gain some of that lost mileage due to the highway acceleration if you do have a sloped drive yourself … I do not use the Accelerator to the Floor in First, Second, and the shift to Fifth technique anymore myself but accelerate ever so gradually to attempt to maintain the instantaneous in the 65 mpg + range in third, fourth, and then fifth until I am up to hwy speed …

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:47tqfcti][email protected][/email:47tqfcti]

 

[figgy]

I do the same in my drive. I turn her around and orient her for a quick take off.

She is warmed up always when I return, and enough to give me a little idle stop during the 3 point turn.

Then, when I depart when she is cold (to go about 1 mile down a hill from my house to the main road), she uses the absolute minimum and with a little blocker on the lower air intake is always warmed up by the time I reach the bottom.

 

[flunkysama]

Series or parellel does not matter that much, you are still raising the current/wattage. The Motor probably won't be is as big as a problem as the electronics driving it. Those have definite limits in voltage and current. Overheating them will shorten thier life. The Motor is in contact with a nice big water cooled heatsink (i.e. the engine block).

IMHO, the biggest problem with modding any part of the IMA is the electronics. From the manual you can get a pretty good idea of the function of each module, but have no idea what information they are exchanging and you have no easy way of re-programming them.

Put in a higher voltage battery and the BCM, which monitors battery voltage and determines SOC, may not let the battery fully charge. Put in a battery capable of high current at 0 ohms and you will overheat the IGBTs. Put in a battery with more Amp-hrs and BCM, which also monitors current in and out of the battery, won't use those extra Amp-hrs because it is calibrated to the stock battery.

 

[Insightful Trekker]

Re: lifespan?

I was referring specifically to the "cylinder idling system"

<snip>

One magic way to do that would be a lighter IMA system that packs more HP and torque and can recharge more during braking.

If I am reading between the lines correctly the cylinder idling system was added to improve the energy available for recovery during regenerative braking.

So it looks like another design limit is that of balancing the cars mass with the overall size of the IMA battery pack. Too large a pack and you'll be driving in forced charge more frequently and highway mileage will suffer.

Swapping a Civic hybrid's pack into the much lighter Insight would likely display this problem. The same with increasing the packs capacity.

Looks like the best we can hope for in IMA batteries is durability improvements.

 

[meow77]

The technology to bring in Lithium Ion batteries in is there... its just a matter of cost. These batteries are better and increasng the IMA power is a definite plus

 

[Foxpaw]

The technology to bring in Lithium Ion batteries in is there... its just a matter of cost. These batteries are better and increasng the IMA power is a definite plus

Lithium Ion batteries can catch fire if their control circuits fail or if they are ruptured. Given that the location of the battery and it's control circuits are in a position likely to be damaged in a rear-end collision, and they are mounted directly above the gas tank, I would not be comfortable using lithium ion batteries in the present configuration.

Besides, most of us aren't deep cycling the pack anyway, so increased storage capacity is not even an advantage. I think that the IMA motor would have to be much more powerful to gain any benefit from a larger capacity pack.

 

[james]

I think the problem with any battery mod would be in getting the control module to understand the changes. There's a microprocessor that controls charging & power, and if it thinks you have X amount of batteries, putting in 2X isn't going to change the behavior at all.

It probably wouldn't help those of you who live in fairly flat country, either. I could use one around here, but if you never drain the pack climbing your local hills, then you don't need a larger pack. Maybe upping the power to the electric motor would give you a bit better acceleration, but I think you get a better return on investment by doing a turbo conversion