Just picked up a Civic(thankfully in the 200000+ vin range for the control arms) for a ridiculously low price won't even mention it. However, it wasn't returning the numbers I hoped, bout 32 city 39 freeway. I had done some research and found that the 12v battery was way underpowered as far as amp hours goes. So I wedged a huge brand new battery in there from my celica gt good fit btw.

Now I am averaging 42 city 54 highway. Not sure if it was the hard restart from switching batteries or the new battery with 2x the AH rating but it also seems to have more vigor and the auto shut of kicks in way more!

These are fun cars and since they are smog exempt I'm going to have a great time molding mine with my EE degree =)


Btw. i'm pulling those numbers with 215/45/17 michelins and civic si rims and tires so I don't think the tires are HUGE as far as mpg goes, plus they look way better lol



added pics

 

Nice looking wheels – congrats on your great find.

 

Great clean looking car. Good FE for wide skins! They are a fun car to drive. H

 

Oh, and I forgot to mention my 06 is still on the originally 12v battery. Checked the output the other morning at -10 and still had the blue ring with red center and it put out 12.5 Volts. My car has been great other than rear control arm replaced by warranty. H

 

You do realize that the 12v battery does not start the car (ok maybe if it gets cold enough, I have seen below 0 and never used the starter/12v battery) it also has nothing to do with auto stop that is a function of the big battery and many other factors.
That said, I seem to recall somewhere that a bigger battery should never be used due to changes imposed on the draw from the big battery (remember it has no alternator either).
It is possible removing the old battey reset the system because it was disconnected. it will be interesting to see the long term effects of making this change.

 

Yes of course, I do have the better part of a degree in electronics engineering =) … I am also interested in the long term effects of installing a larger(almost 2x) AH rating battery in the HCH II.

I'll keep this post updated if there are any new developments as far as the IMA system is concerned(staring at the IMA schematic right now =)

So far the change has resulted in:
Updated(1/31/2011)
1. More frequent auto stops/////1/31(update) I still get way more auto-stops now than I did in the first 500 miles of my ownership of this car.

2. Gas mileage increase of 9 mpg "has since vanished"//////1/31(update)must have been the recal, that's ok I'm still pleased with my mileage at 32/40+"considering the weight of the car" and i know part of it is due to the non-LRR tires I have on the car right now.

3. Seems to take longer to run the whole system down as a whole(may be subjective more testing needed)/////1/31(update) This I have found to definitely be true I can run up a much longer grade @ 3+ bars of assist than I could before, again part of this may be still from the recal.

4. Slightly more aggressive boost signature (so we will see the impact of that over time as well)//////1/31(update) This is still working the same I have more power with the bigger battery/recal than I did in my first 500 miles.

5 Feb 28th update, Still going strong, actually saved my butt one day when I forgot to turn off the headlights for 2 hours and it just barely started… old batt would have been flat by then lol.

…..I am 37 years old and a light-footed driver most of the time, drive about the average 10-12k per year. I live in sunny, but temperate southern california.

 

Interesting data points. I'd be curious how this all works out long term for you - please keep us posted if you don't mind.

Also, some additional information about where you live (conditions now vs summer), how you drive, how much you drive, etc. would be useful.

Cheers,
-ag

 

I'll chime in on this thread as well. Enjoying my second week with my '08. This cold weather is killing my mileage in the morning, but I've knocked down a 47.5 tank and a 50.4 tank so far. Couldn't be happier with it.

 

Woohoo, congrats. Can't wait to see your results once you get the hang of it and the weather warms up! Hehe.

 

where are you MLTTASK? cold is relative, in AZ 40 is cold, in MN not so much :-)