[Nagorak]

My Insight was purchased used and came with a Kenwood amp and some so-so Kenwood speakers, connected to the factory head unit. Anyway, the sound quality, while better than that of a stock car, still left something to be desired. So, I recently bought a car stereo from a friend and was planning on using it to replace the basic Honda stereo that came with the Insight, along with buying some new speakers.

The only thing I was sort of concerned about is the affect this might have on my gas mileage. As we all know, running the AC can seriously impact gas mileage in cars (although running in econ mode is supposed to be better). So, I was thinking, if the AC can do that just by drawing more power, couldn't a stereo and amp and more power hungry speakers do the same?

I tried searching on the internet for information on this, but couldn't find anything. My initial instinct is the amount of power required for a stereo and amp should be pretty negligible in comparison to the amount required to electric motor (such that it wouldn't have much, if any effect), but does anyone know for sure? I've never heard of not running the radio to get better MPG, but then again most factory head units and speakers are pretty anemic.

I'd especially like to hear from anyone who might have done before and after MPG comparisons in their Insight after installing a stereo and AMP. Also, if a stereo/amp does lower MPG, will it only occur when it's actually running, or will it reduce it all the time (more concerned about the AMP in this case, since the receiver should be obviosly powered down). If gas mileage is impacted, are there more energy efficient stereos/amps out there?

 

[Delta Flyer]

I can't give statistics for the Insight, but it would make sense a stereo with greater ampage would affect fuel economy.

I remember driving to college one Sunday night. On the way, the cassette player got slower and slower. I later turned off the headlights and my speed increased at least 5 mph. It turned out that the alternator had failed and the battery was running completely

 

[Atheos]

I just today finished up my amp installation (one of them anyway),
and I'm running a mixed-mono setup with 3 speakers on a 330Watt amplifier.
When I left work, I was at 75MPG on around 300 miles (trip), and after my 30 mile trip home I was out 76.1MPG which is about normal for the route I take.
I had the sterio up about as loud as I could stand it, and the amp was about
as hot as I can imagine it getting before a thermal shut-down.
Basically, I don't think it had much of an effect on my fuel milage.

I'll report back when I get the second amp installed, which claims to be rated
at 2000W. (Eclipse DA7232)

 

[Rick]

2000 Watts? How much power is that going to pull off of the electrical system? You only have about 30 amps to play with before you start damaging the DC/DC converter.

 

[Atheos]

The 2000W amp claims a max current draw of 200Amps.
I will in no way be able to acutally use this much power with the
speakers I have in mind, but I will be using far more than 30amps at times.
check out this device:
http://mainstreet-caraudio.com/car/audiobahn/acap50.htm

this capacitor bank will offer my sterio the power it needs, and average
out the current draw from the electrical system.
Yea, I know the amp is mega overkill, but I gotta impress the kids.
heh heh

 

[Armin]

amp power

I'd like to make a couple comments:

Atheos,
2000W found on the marketing literature for an amplifier usually doesn't equate 2kW of electrical power consumed. I don't kow what strange formulas they use, but the actual continuous power is much, much lower. A key giveaway is that my 300W amp has a 20A fuse. But manufactures have caught on to this and provide oversized fuses now to hide that. An audio-geek friend of mine differentiates between real watts and japanese watts. Maybe they have korean watts, too?

Rick,
our DC-DC converter (which supplies the 12V system) is rated 70A. Considering you will need some of that for ignition, lights, etc. You should still have at least 50A continuous power available. That's likely enough for that 2000W amplifier (600 real Watts = 2000 japanese Watts?)

Nagorak,
back to your original question:
Theoretically, any extra use of power consumes more gas (ultimately, gas is the only power source in the Insight). But for most audio amps and other accessories, the total power consumption will be too small to be measurable compared to the power needed to move the car. I would be really surprised if you noticed a difference, but you can try: just drive with the stereo off. Even if you do notice anything, I'll suggest that it is due to changing driver behavior with and without music and not because of amp power draw

 

[Atheos]

Atheos,
2000W found on the marketing literature for an amplifier usually doesn't equate 2kW of electrical power consumed. I don't kow what strange formulas they use, but the actual continuous power is much, much lower. A key giveaway is that my 300W amp has a 20A fuse. But manufactures have caught on to this and provide oversized fuses now to hide that. An audio-geek friend of mine differentiates between real watts and japanese watts. Maybe they have korean watts, too?

Yes, I understand the marketing aspect of rating amplifiers and I know
the figures are thoretical at best. The amplifier I'm drooling over is an
Eclipse DA7232 developed by Bang & Olufsen that comes with a list price of 1499 (ouch!).
Car audio manufactures are under no obligation to list honest figures related to the exptected wattage of their amplifiers, but I've noticed that
they are usually more honest with their current draw figures, if they bother to publish them.
If I were to take Eclipse by their word, I would assume that this amp can draw up to 200 Amps of current.
If I were really dreaming, I would say that I had a car that can deliver this kind of current at or around 12 volts.
A quality class D amplifier is said to have an efficiency of greater than 80%, so with that figure, I'm sending about 160 amps into the equation.
tossing those figures into my calculator, and I'm getting back about 1,920 Watts.
Of course, this is all based on my amp drawing 200 Amps of current, which will never happen in my own car. (especially with only 2 small speakers)
My goal is to get a few hundred watts from this amp, turn some heads and have some eye candy to boot.

oh, and to stick with the thread:
drove quite a few miles yesterday (mostly city) and I'm still keeping my
MPG right near 75, but I have noticed my battery level a little lower than normal.
I'm usually filled up to about the last 2 bars, and today I'm down about 4-5 bars.

 

[glitch]

I've worked with John Wayland on this. You have to be very careful about the amps you choose. For my subwoofer I chose a MTX Class D amp as Class D amps pull less power from the batteries. They're output though is not good for high end speakers like mids and highs but is perfect for subs. So go with a Class D amp for your sub, it's much easier on the battery. As for my mid's and high's, I'm going with BlaukPunkt's new Class T amp. It's supposed to have the quality of a standard Class AB amp but the power efficiency of a Class D amp. So between these 2 amps the drain on my battery should be minimum. Ohh, and don't overkill your wattage either. I mean, my sub's RMS is 300watts so I chose a 350watt RMS amplifier for it, I could have gotten the 500 or 650watt RMS amp but that's just an overkill, I'd have to turn down the amp and the power drain on the little 12v battery isn't good. You have to remember we dont' have alternators but DC-DC converts instead which are very very expensive to replace if damaged, a lot worst than replacing a alternator.

As far as the A.C hurting gas mileage. I never considered the power drain from the A.C as the reason. Are you sure it's the power drain that hurts gas mileage? It's because the A.C requires the belts from the gas motor to turn the compressor or whatnot, which steals horse power from your motor and makes it work harder, thus hurting your gas mileage. If your A.C is off you'll notice the car is much quicker. I don't think the A.C hurts gas mileage because of power drain but because it has to use a belt to turn it. On a side note, Toyota's new 2004 Prius powers the A.C off an electric motor. This means it doesn't steal Horse Power from the Gas motor, it won't turn off when the car is in idle-stop mode (the A.C will stay on like normal unlike in our cars), and it doesn't affect the gas mileage of the car. Good job Toyota. I think Honda should consider this for the Hybrid system in their Civic's. From the front page of insightcentral.net it does look like there will be a 2004 Insight but no major technical updates. I guess all their technical improvements and updates will go into the civic's hybrid system.

 

[Armin]

AC

I don't think the A.C hurts gas mileage because of power drain but because it has to use a belt to turn it.

Ah, and what do you think you need to turn the compressor via the belt? - Power!

 

[amplifiedmouse]

Re: amp power

Maybe they have korean watts, too?

i have a korean girlfriend (insert rimshot here)

 

[Will M]

Three issues:

First, realize that any current going through your "200 amp" amplifier has to go through the 80 amp fuse for the car's 12 volt electrical system. Yep. the Big One is 80 amps. It's 80 amps in my 1992 Civic and it's 80 amps in my 2000 Insight. I know, 'cause I reversed my jumper cables jumping the Civic with the Insight and blew the 80 amp fuse in the Civic, and temporarily replaced it with the 80 amp fuse from the Insight. You won't find a higher-amperage fuse in the 12-volt system. Maybe you guys bypass the fuse box?

Second: Don't compare air conditioners to stereos. The MPG loss caused by the air conditioner is mostly not electrical. It is mechanical, created by the compressor that the gas engine turns with a drive belt in order to compress the coolant enough to turn gaseous coolant (it used to be freon, but I'm not sure what they use these days) back to liquid, giving off heat that is disapated by the second radiator added to your car for air conditioning. This compressor requires significant torque from the engine.

The liquid is then pumped back to a smaller radiator inside the car where it is, at the beginning of that small radiator, sprayed through a nozzle. This pressure release turns it back into a gas and that sucks heat, creating the refrigeration effect. Through heat of vaporization, the heat inside the car gets pumped out to the radiator in the front of the car.

Air conditioning adds heat to an engine that is already working to get rid of the heat that combustion generates and adds mechanical work to the engine that moves the car. That's where it causes extra gas to be burned, and the extra wear and tear on the engine. The electric fan blowing the chilled air is not a signficant burden to anything.

The third issue is that I have to admit that I don't understand the desire to put huge amps in cars, converting them into rolling speaker boxes. It turns mirrors into decorative objects without function and destroys your hearing. Nothing in nature creates that kind of sonic pressure wave, and ears were not designed to take that strain. It's tough on me just walking near one of these cars. How can you stand to sit inside one of them?

I'm 48. I have had tenitis (ringing in my ears) since my early teens. I didn't listen to particularly loud music, though I did have a couple episodes around very loud sounds, like the time in my late teens when I accidentally came within 15 feet of a factory steam-turbine-powered electric generator, when I had forgotten my hearing protection.

I can hear well through the ringing, but its presence make me feel protective of my hearing. I wear hearing protection when hammering nails. How can you guys willingly do this to your ears?

 

[Atheos]

First, realize that any current going through your "200 amp" amplifier has to go through the 80 amp fuse for the car's 12 volt electrical system. Yep. the Big One is 80 amps. It's 80 amps in my 1992 Civic and it's 80 amps in my 2000 Insight. I know, 'cause I reversed my jumper cables jumping the Civic with the Insight and blew the 80 amp fuse in the Civic, and temporarily replaced it with the 80 amp fuse from the Insight. You won't find a higher-amperage fuse in the 12-volt system. Maybe you guys bypass the fuse box?

I've never used the fusebox as a source of power, where any substantial
current draw will be taking place. The expected current draw at any point
in your fusebox is already being appropriated for other equipment (oem radio/blower motor/lights/etc) and you shouldn't "borrow" from any of these sources unless the current draw is minor -- like, a radar detector or something.
When adding an aftermarket amplifier, you take it straight to the battery.
Oh, and you can certainly find a fuse/fuseholder in excess of 80 amps.

The third issue is that I have to admit that I don't understand the desire to put huge amps in cars, converting them into rolling speaker boxes. It turns mirrors into decorative objects without function and destroys your hearing. Nothing in nature creates that kind of sonic pressure wave, and ears were not designed to take that strain. It's tough on me just walking near one of these cars. How can you stand to sit inside one of them?

It's for the same reason you would have a car that can go 100+ miles an hour when the speed limit is 55 (or 65/75 depending).
It's a hobby that some people take very seriously, and it's also quite a challenge to produce quality audio in a car, which isn't a good enviroment for an audiophile to work with.
As far as pure volume, I personally don't crank anything up unless I'm at
a car show with a sanctioned sound-off.
The few I have been in required ear-plugs for anything with considerable volume, and most of the contenders tweak their sterios back to a reasonable setting when it's over.

I like big sound, and most of my friends like big engines.
Guess who is most likely to be harmed from their hobby

 

[Randy]

Effect of Power Draw on Gas Mileage

You can calculate the approximate effect of a power draw on gas mileage.
A gallon of gas has about 140,000 Btu of chemical energy.
1,000 W = 3412 Btu per hour (therefore 1 kWh = 3412 Btu).

Assume that you get 75 mile/gallon at 60 mile/hour with out the amp running, therefore you are using 60/75 gal/hour = 0.800 gallon per hour.

Assume also that the conversion efficiency of the Insight, from gasoline, through the motor, to the alternator, to the amps, etc. is about 25%.

At 1,000 W continuous, you would be using about 3412 Btu/hr /0.25 = 13,648 Btu/hr.

13,648 Btu/hr / (140,000 Btu/gallon gas) = 0.0975 gallon/hour.

With the stereo running at 1,000 W continuous, you would now be using 0.8975 gal per hour, at 60 miles per hour.

Your fuel economy would then have dropped from 75 mpg to (60 mile/hr)/(0.8975 gal/hr) = 66.85 mpg.

If the stereo is only drawing 100 W continuous, you would be getting (60 mile/hr)/(0.8098 gal/hr) = 74.1 mile/gallon.

 

[Atheos]

Randy,

Great post!
I'd like to add that the hybrid regenerative breaking adds a new twist
to your formula. Properly driven (IMHO), you can have more energy
available from regenerative breaking than you use with the assist.
I think I'm in this catagory, cause my battery level never falls below a bar or two,
which means I'm getting some "free" power for my audio system that would have otherwise been wasted.
Yet another thing I love about this car!

 

[Armin]

no free lunch

Properly driven (IMHO), you can have more energy
available from regenerative breaking than you use with the assist.
I think I'm in this catagory, cause my battery level never falls below a bar or two, ...

Hi, Atheos,

while I agree with your first statement, I must caution you: if you actually drove like that, you'd have to make a real effort: accelerate in rich-burn just before assist kicks in and then brake regeneratively, repeat.

What you are seeing in your second sentence is the normal cruise charging of the Insight. It sometimes charges the battery during cruise, without lighting any green bars. So you think it's free energy, but it's really coming straight out of your gas tank!

Sorry, there's no free lunch!

 

[Rick Reece]

I agree with Armin and the charging while cruising can be substantial. I use a constant tension on the accelerator to ensure a constant engine load. As a result I prevent the normal regen when going down a hill (In other words on the downhill I am speeding up). Meanwhile when I climb the next hill the speed will gradually drop until it hits the min speed allowed by the cruise control at which time the engine load will be increased (I also get assist at this time which is nice because without the electric assist the car would probably have to downshift to maintain the min speed on a steep hill). Anyway when I have it balanced right I can get assist on the hills, never go into forced regen (Green lights when the battery is too low), and still maintain my battery through the trickle charge. This method works because I am maximizing my time in lean burn (I can see the vacuum guage drop before the car exits lean burn). I can easily get 95+ mpg over a long distance using this method. My tank average right now is 102.4 and that is down from Sunday's 104+ range. I hope to have a lmpg average of 90+ by the end of the summer since nearly all of my driving is at a constant engine load. I doubt those that have to make short trips or city driving or multiple speed changes on their commute will benefit but if you have a long trip on the interstate to make try this method and you can get high mpg values (Just don't stop). Qualifications (I usually set the min speed at 52 and have the tension so that my max speed only goes above 70 on the steep or long downgrades. Have fun, RIck

 

[Thorian]

ok I think I can straighten out this thread
Atheos is a MECP that is the equivalent of a master electrician for moble electronics. or a MCSE for computer administrators. He is not some Idiot wiring at random. 2 the only thing IMHO that would affect the milage of the insight is the weight of the equip being installed.

Atheos cant wait to hear about the monster sound system after it is all installed

 

[Ecfool]

I did lose a little mileage when I installed the system in "MIZER", but it was more from the weight (approximately 150+lbs additional) which include subs and amps. Plus being slightly leary of the "little" main battery I run a Optima blue top just for the amps, which is run in series with the main 12 volt battery. To date no problems at all with D/C converter and the set up has been in for well over 2 years now. I did check my amp draw off the main electrical circuit and when in "normal" listening mode, which is slightly loud considering slight hearing loss and love of good music I only draw aprroximately 20 amps. I am running older Fosgate amps, a 600 watt 4 channel for all front speakers (2 pairs one in kick panels and other in doors. A 500 watt power amp for the twin 10" subs. And to me the slight loss approximately 5mpg is worth the pleasure of a decent sounding, hmmm should say great sounding system.

 

[Nagorak]

The third issue is that I have to admit that I don't understand the desire to put huge amps in cars, converting them into rolling speaker boxes. It turns mirrors into decorative objects without function and destroys your hearing. Nothing in nature creates that kind of sonic pressure wave, and ears were not designed to take that strain. It's tough on me just walking near one of these cars. How can you stand to sit inside one of them?

Thanks for the information, but I think you're unaware of just how weak car stereos are. By no means do I intend to spend many hundreds of dollars on a stereo setup, but even $100 speakers cannot be pushed adequately by the factory stereo. I'm not interested in sheer volume but quality. Unfortunately, the system is currently greatly lacking.

That said, I'm not sure I'm going to bother with much of an upgrade, because from what I've heard all car speakers are pretty much sub-par. I guess I was just expecting a little too much out of 6 1/2 inch speakers. In order to get anything near comparable to my home stereo I'd have to spend over $1000 (and even then it wouldn't measure up), and I just don't spend enough time in the car to warrant it.

Anyway, I just wanted to say it's not all about blaring sound volume. Frankly, I find most of the bloated, "boomy" bass that most people pass off as "a good stereo" to be absolutely disgusting. There's a big difference between loud, booming, overpowered bass, and good bass, which many people aren't aware of (but, if it makes them happy then eh...). Specifically a lot of the "subs" you'll find in Circuit City are just about the musical equivalent of a nuclear explosion.

 

[Rick Reece]

Nagorak,
Well put. The only way to get good sound in a Insight is to try and mask the background noise. I am still playing around with moving some of the high frequency sound away from the lower door panel. Trouble is the mounting location. So far I am leaning toward on the dash either side of the steering wheel. Another thought was the noise canceling headphones. Although you arn't supposed to drive with headphones it does seam a good way to defeat some of the noise environment of the Insight. Has anyone ever tried any of these. I havn't seen any consistently good reviews on these products other than a brand that consistently beat the airline headphones which isn't saying much. Have fun, Rick