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its prolly old news that the alternator ELD shuts off battery charging to improve alternator life and gas mileage, but i never knew all the conditions needed to do this. basically if you try and maximize how long the car runs without the alternator working, you could gain some mpg. it all adds up. hardcore guys can remove the alternator and install several deep cycle batteries in parallel to power the car for a given distance, then recharge them. a voltmeter is essential to monitor when voltage drops to 12v but these guidelines will help. this may not be possible at night due to just the lo beam headlights using 10A of power alone.

 
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full article here with lots more info.

http://www.metrompg.com/posts/alternator-optional.htm

 
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lately i have noticed while im driving when i give my car gas the cluster lights will dim and when i let off the gas they get brighter could this be because why and i just didn't notice it before or is my alternator going bad ???

 
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I never knew that the alternator really placed a load on the engine. Besides running a pulley and parasitic drag and whatnot. The jetta guy said he just pulled his main fuse to turn the alternator off and got 5% better gas mileage. To me it makes no sense. I dont get how the alternator actually consumes that much power when on

 
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eh, our civics are pretty efficient enough. too much work for 1-2 mpg. just dont floor it when u get on the onramp and you're good to go....

...although it might take a while to get on the on ramp

 
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the ideal solution would be an ELD kill switch that you can mount in the cabin and turn off the alt when you are coasting in fuel cutoff mode like down a hill, when it is not really needed. then turn it back on again. but gotta be careful not to leave it off too long or the battery will drain enough to make the alt have to work harder when you enable it.

the alternator is very inefficient, most are only around 50% efficient. that means you need double the engine power to get 1/2 the electricity. there are also internal losses and belt/pulley losses. it all adds up and most of this is explained in the link i posted. i was pretty surprised at the crazy amount of power the blower motor uses, esp considering we have an energy saving radial model. i usually try to keep the fan off and just let the outside air blow in and its hot enough to heat the car over time. esp on the freeway it can sometimes even get too hot with the temp at max heat.

 
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our standard leadacid batteries are not designed to be deep cycled like that. its a really fast way to shorten their life.

now, if u were running a deep cycle, dry cell, or the new LiFePO4 batteries, that would be a different story (especially the LiFePO4 ones)

 
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?
think about how much is required to transform energy.
try running a hamster wheel for a day and see how much electric energy can you convert
a few miliamps with luck

 
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I've never understood the obscene obsession with fuel efficiency, unless perhaps a person actually competes in the events dedicated to it. You save infinitely more fuel than will ever be possible through all these strange modifications by just taking the transit once a week, riding a bike occasionally, planning trips slightly better and you don't need to constantly obsess with these strange little things hindering your enjoyment of the vehicle. Aside from that, I have a hard time believing that anyone could reliably improve efficiency for free more than 5-10%, which for most people I can't imagine is more than two-three litres of fuel each week..

Some things just don't make sense to me..

 
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I've never understood the obscene obsession with speed, unless perhaps a person actually competes in the events dedicated to it. You save infinitely more time than will ever be possible through all these strange modifications by just giving yourself a few extra minutes, planning trips slightly better and you don't need to constantly obsess with these strange little things hindering your enjoyment of the vehicle.




If someone enjoys hypermiling or tweaking their mpg - why not? ;p

 
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me can have both
not obsessed for MPG, though. What it gives me is good enough - 31MPG/+20HP (?) now with stage 1 cam (up from 28MPG before overhaul, when i installed the cam)

 
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I don't understand it, but that doesn't mean I think there's anything wrong with it

I understand desiring extremely high fuel efficiency, I originally wanted to purchase a Smart or hybrid civic, but they were selling for well over $20k when I purchased my car and that was out of my budget. I settled on a Si, because it was still extremely fuel efficient and that is my highest priority when purchasing a car (not for the financial benefit).

Now, I modify my suspension, because the improvement and change over stock is dramatic and noticeable every moment I am driving. It doesn't feel sloppy and loose any more, but rather tight and refined.

When I imagine modifying my for fuel efficiency, I only see the reward being when you calculate the efficiency at fill ups, nothing but a moments gratification from looking a few numbers. The theoretically possible improvements being extremely minimal, nothing dramatic, like the base lines that can be seen through the choice of vehicle.

That's just my perspective though, and to each their own. It's far less perplexing to me than the majority of American culture, which I'm certain, I will never even begin to comprehend.

 
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its the same reason most of us here will put all sorts of bolt-ons just to gain 2hp. its more about learning and having a hobby, rather than just the benefits. most of the mods i see on this site make no sense to me either. but small mods here and there add up if you do enough of em. there is nothing wrong with making a car better, because i guarantee honda did not think of everything. and if you lose hope, just remember the 1st gen honda insight with a k20 motor that gets 200+hp and 40+mpg. i love making this car more efficient, im rewarded each time i drive and no, i almost never fill up a full tank to check mpg.

 
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i do, not for the MPG check itself, but to know how the engine is running

 
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x2

and then input the data into gascubby to see my stats.

 
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i dont drive as much and hate having old gas sitting there. not to mention the extra weight.

 
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i do 400 miles a week so i pour gas on a weekly basis

 
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Me too, plus my mpg is getting kinda bad lately too. About 400 km on 37-39 liters. Tire size is lare, so it's reading 3% slow. So i guess it's like 415km ish. I dunno. I'll check at my next fill up tonight/tomorrow :P. I last filled up on friday night and am at 360km, if that gives you an idea on how much i drive lol.

 
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Interesting..

 
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regular filament bulbs are affected by voltage swings and 2v can be a big difference in brightness. that can be a huge range for the halogen lo beams. hid does not have this problem because it uses a constant current ballast to regulate power input. halogen bulbs can lose over 500 lumens when the voltage drops from 14.4v to 12.5v and it looks like honda thought of this because at night, the lo beams will use 10 amps and the parking lights will use a bit more, putting total night use at over 10 amps (which causes the alternator to stay on all the time). so to answer your question about the gauges dimming, its possible alternator is not making as much power as it should. not bad enough to trigger the battery light, but getting there. i have seen 60 amp alternators put out between 5-50 amps when they are going bad it just depends. you can always have the amp output checked at the auto store with their machine. if you go by the alternator cutoff info i posted, your lights should get brighter when your foot is on the gas (and alt is making full power), and get dimmer when you let off the gas ( and alt is cut off with car running on 12.5v battery). this is assuming the park lights are only on. if the lo beams are on, that puts the total draw above 10 amps, and the alt would stay at full power all the time at night (no cut off will ever activate). then you would have a problem because you should always be getting 14.4v at night. unless maybe you have hids and are barely below 10 amps. i cant be sure without testing your amp draw and knowing what other accessories were being used. but it does sound like your alt is a bit weaker than it should be.

 
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i always drive with my lows on since i don't have DRLs... maybe i should stop lol. I think i'll just put on my parking lights instead so i have some sort of light up front.

 
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Between winter fuel blends, cold weather keeping the engine in open loop for a longer period of time and heavier higher rolling resistance winter tires, my fuel efficiency is not insignificantly lower during winter. Mostly highway, driving like an old lady, I'm at around 550km a tank atm.

Yay for gas being down to $109.9 a liter right now, lowest I've seen it in two years.

 
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Last i checked it was 114.9 here.
Im sure i could get 550 out of a tank, i just never let it use up more then 40 liters, and i believe we have 50 liter tanks because once i filled up 47ish at the pump.
What sucks is now im working downtown, and have to commute in from the suburbs, so the stop and go traffic there and back is whats really effecting me i think.
I have next week off, so we'll see how well my mileage is without all that highway crawling.

 
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lo beams and park lights make lousy drls because there isnt much light shining at other drivers. maybe some philips or hella LED drls are in order?

 
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Hella Led drls?? Please explain lol. Remember that i got rid of my drls because of my retrofit :P

 
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yeah i know. i was referring to those various led strips, circles, point leds, etc that philips and hella make as aftermarket drls. most are mounted in the bumper

philips 4 led



philips 5 led



philips 8 led



HELLA 3-led



hella 3 led 90mm



hella dayline 5 led



hella dayflex (individual leds)

 
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DRL's are not that much, really. parking lights are more tahn enough, never been stopped for using the parking lights (although i had the halos wired to the drl, but then they are far from what one would call visible during day