not using radio?
 

does anyone actually know how much using the radio affects your mpg? I'm starting to think it's not worth it...:confused:

Unless you have a huge aftermarket system with a big amp and a back seat full of subs and you crank it really loud all the time, the amount of energy it uses is small.

Radios mostly effect FE by using electricity, which usually has to be generated by alternator drag on the engine. So not running the radio can help FE a small amount, by lowering the total electrical power used, and therefore lowering the alternator drag on the engine.

However, (electrical) "power savings" from (not using) a radio are no more (or less) significant (to FE) than any other electrical power savings. And in general, I don't think the radio uses a large batch of power (especially compared to things like car lights and car fans), unless you are someone that has one of those stereo systems with big (power drawing) sound amplifiers (although how much power a radio uses does vary a lot with radio brand/model, with some using much more power than others). So if you like listening to the radio, I'd say "go for it" and just deal with the very minor FE hit. After all, you will probably get a better FE gain by other electrical savings in the car (such as switching your secondary car lights to energy efficient LED modules, not using the fans when not needed, etc), than you will by not listening to the radio.

Now, one thing that you can do (that seems to help), is to disable any "backlighting" features of the radio you don't need. For example, my stock CRX radio used to always "light up" whenever my car lights were on (even if/when the radio itself was "off"). Not only did this waste (electrical) power, but I actually found the additional cabin illumination (as a result of the radio's backlighting) slightly distracting when I was driving at night (i.e. I generally prefer a darker cabin at night, so that my eyesight is more easily focused on the road and the illuminated instrument panel). So what I did was test for (find) the specific wire (leading to the radio) that powers up only if/when I turn my lights on, and cut that one (radio harness) wire (while still leaving the other wires leading to the radio as-is). The result is that now my radio no longer has any "backlighting" (that comes on with my car lights), but the radio still works normally otherwise (including having its display light up when the radio is actually turned on). IMHO that (saved electricity from no lighting up of the radio with the car lights) probably saved more power overall (and therefore more FE), than any attempts to "not turn the radio on" if/when I was in the mood to listen to it. And the only thing I "lost" by that modification, is that my radio no longer lit up when the car lights are on but the radio itself is off. And IMHO that radio "backlighting" was really a "feature" I was more than happy to lose anyway!

Think people! :)
A good sounding stereo consumes maybe 100W at maximum.
That's about 1/6 of a horsepower.
Average power draw will be much lower, unless you're trying to induce permanent hearing loss.

Enjoy the music and try not to obsess about the 0.05 MPG you are sacraficing! ;)

I feel the same way about the backlighting. That reminds me -- I need to remove that little light bulb inside my center storage area that activates when the door is open. Not a lot of power but still wasted (especially when the dash "door ajar" icon lights up or I can activate the ceiling door light).

But to the radio -- stock sound players shouldn't be a major hit on the FE (ie. too small to detect). It would take a lot of miles and gas before I would notice any difference on my puny Scion but then again I'm not taxing the system by blasting it at obscene levels either.

Actually the 700 watts is approximately 1 HP rule, is really only true for systems that are 100% efficient. And since car alternators, batteries, etc, are generally not even close to 100% efficient, you are probably looking at something closer to 300 watts (of usable power) in the car causing a 1 HP drag on the engine.

Also, keep in mind that most small (fuel efficient) cars use/need very few HP at highway cruising speed, so even a somewhat "small" HP drag from the alternator (due to the electrical power used) can (in some smaller cars) easily be enough of the total drag on the engine (at cruising speed) to make a quite noticeable (sometimes even a few MPG) difference in FE.

While I think the hit on FE is often greater than you are estimating, I do agree that the radio load is often not anywhere near your most significant electrical load on the engine, much less your most significant load on the engine from all sources. And driver comfort is worth something too IMHO.

So while we might disagree "on the numbers", we do agree that it's probably not worth it for someone to sacrifice the radio (assuming it makes their drive more pleasant), just to try to squeeze a little extra FE out of the car. Yes, technically the radio is fully "optional" (in that you don't "need" to run the radio when driving), but it none-the-less can add to driver/passenger comfort at only a small cost (to FE).

Besides which, if saving electricity (in order to get better FE) is the goal here, there are (as I mentioned in my other post) much more effective places (in many cars) to save power (than turning off the radio). For example, both car lights and car fans tend to be real energy hogs in most cars, so anything you can do to lower their power usage (not run them when not needed, switch some car lights to energy efficient LED modules, etc) can make a big difference (likely much more significant than the radio) in total electrical power used in a car.

Stereo = 7 lbs. It's in a box. :D

You'll never notice the difference. It's probably only drawing max power during a big bass boom. That's only a momentary transient. But...if you have one of those stereos that can be heard booming six blocks away, TURN IT DOWN! Why?

1. You are probably driving it into distortion, annoying the hell out of everyone.
2. It is vibrating parts of your car. You may not be able to hear that inside, but I can outside.
3. You are damaging your hearing, probably most pronounced in the female voice range. You were wondering why your wife/girlfriend keeps saying that you don't hear them?

Now, if you want some significant power draw, perhaps a tube-type, circa 1955 AM ham transmitter, about 100 watts or so, plus a tube type ham receiver, and a dynamotor to provide the high voltage might well add up to a couple horsepower...

yea a stock radio draws less than an amp and when playing a cd its right around an amp at normal levels. so in the big scheme of things no, you wont see any fe improvement...

also i really dont think removing the dome/door lamps that liht when the door is open is really gonna do anything... i mean really in a week those lights are on what a total of 10 minutes?(prolly less, considering it takes about 10 seconds to get in a car and close the doors)

yeah I didn't really think so.... thanks guys

When I was a college kid I had two speakers right behind my ears in a partition in my van, maybe 6 inches away. Headphones were illegal.

Now my car has no radio. If I wanted one. I would get a small boom box from Wally world and plug it into the empty cigarette lighter socket.

regards
gary

Sometimes the radio can help avoid busy/stagnant traffic and hence save some gas.
As is pointed out/implied in some of the foregoing posts, it is usually the heavy bass that drains power (the sub-woofers are often the worst). One can save a little by using the tone controls to cut down the bass a bit. At least do not boost the bass level:) .
A very small difference may be noticed in a rather long trip.

haha i doubt it since those long trips are generally going 65mph the alternaters making more than enough juice....

i messed with the bass(particular headunit had a LOUD button) and maybe flucuated the amps .01 amps more when using that button. stock radios draw even less.

now a sub system yes those draw quite a bit of power but stock or near stock systems nah use it as you please.

Just use your stuff and don't worry about it.

But if you got a car full of amps, then all that extra weight you are lugging around is what will kill your gas mileage. It would be like hauling around "fat albert" all the time.

Just my opinion.

Just try not listen to "I can't drive 55" or "Ace of Spades" or other uplifting music as it could affect you psychologically and make you go faster thus wasting gas.

As far as wasting gas via electrical - you might as well go #2 before you ever hop into the car each time you drive in an effort to reduce weight.

same goes w/ heat and air. a comfortable driver is a safer driver.

i have exactly a 40 mile commute. just for the sake of easy math, we'll round my FE down to 40 MPG. that's a gal/day @ ~$4(rounded up). i don't use a/c in the morning, so half of 4 is $2. so even if a/c costs me a 10% loss, i live w/ it!

anyone ever drive in 95*F @ 100% humidity and no air? it ain't fun!

throw in vinayl seats in that mix, then welcome to driving my chevette in a summer in IL:mad: the s-10 is slightly better, 5% tint on the back window and cloth seats:rolleyes:

sounds like it would improve weight reduction! :D

Most alternators create more electricity than the car needs, so a fair amount is wasted anyways.

I think I have a 130 amp alternator on my Explorer that puts out about 60 at idle. If your AC, lights, etc. are off, there is no way you're using anywhere near 60 amps. Likewise, if I'm cruising at 70 mph, my alternator is going to be putting out near the 130 amp rating. and again, there is no way a vehicle will use 130 amps of 12V electricity. So I don't think it would affect your mileage at all.

The obvious exception would be those who have big stereos (I must admit, I am one). If you're playing it so loud that the voltage dips on big bass hits, then yeah you're energy defficient and the alternator will have to pull a little more engine power to create its power to make up. You can visually see the RPMs dip when this happens, too (at idle), so you know the alt is pulling harder.

WRONG!

Most alternators (even very big ones) only produce what electricity is currently being "used" (either immediately, or to charge the battery), so little is wasted. While it is true that many car alternators are considerably "over sized" (and therefore could theoretically keep up with much more demanding electrical needs in the car), that mostly just has an effect on the maximum power you could (if you really wanted to) use from that alternator. BUT, almost all alternators put progressively more drag on the engine, as your electrical usage goes up!

So even if/when you have a way "over sized" alternator, you will still end up using more fuel (due to the higher alternator drag) as you use more electrical power. And in the case of cars, the mechanical energy source is the engine, so as the engine "drag" from the alternator increases (as a result of using more electricity in the car) the engine needs to do more "work" (generate more mechanical energy) to compensate (which will usually result in the engine burning more fuel to accomplish this extra "work").

Of course, when you look at this from an electrical engineering standpoint, that result is really to be expected. After all, a car "alternator" is just one design for a mechanical energy to electrical energy "generator". And so the car's alternator, since it is a "generator" of this type, has to follow the same laws of nature that pertain to ALL such "generators". And since one of those laws of nature is that energy is just transformed from one form (mechanical motion) to another (i.e. energy is not "magically" created out of thin air), then it follows that the more electrical "work" (i.e. electricity) you get out the harder it will be for the mechanical source to turn the "generator".

BTW: This is the primary reason why you really can increase fuel economy some (in most cars), simply by taking steps to use less electricity in the car!

I actually said that in my post.

So, which is it...is there a baseline amount of power generation that gets wasted if it's not used, or does it only make however much is needed?

With the little I understand about it, I'm pretty sure it only makes as much power is needed.

Think of your battery as a tank of water. The alternator refills the tank until it gets full, then waits until the level drops off to refill the tank again.

Those who think the energy drain of an alternator is constant just dont understand the fact that the battery voltage level "tells" the alternator

Charge me
Dont charge me

If this was not the case all batteries would be overcharged into oblivion in a very short time, with the electrolyte cooked out of the battery.

regards
gary

KU40 most alternators do not have the capacity to charge at rate greater than all potential drains combined.

Thats why if you jump start a car and rev up the engine in the good battery car, you can fry the charging system in that car.

Maximum potential drain is far in excess of the charging systems capability. Cranking loads are generally several times the charging systems capacity.

My car runs at a higher idle speed after a hot restart for a short time until the loss from cranking is recovered.

regards
gary

Put simply: You will not see measurable FE gains as a result of turning off an original equipment radio.

yes the brakelights /tailights draw more amps than the radio does... even switching those to LED wont give you measureable results.

so really if it came stock on the car leave it and use it

I read someone's post here today who said he ran a radio off a second battery, without charging, and it lasted several days before it got low. Given that a car battery stores very little power really, I'd say the average consumption is a small fraction of a hp in the end.

Well see I guess this is where I'm misinformed. I've always just seen graphs of alternator output with only engine RPM and amperage output. So I assumed that amperage output had a direct relationship with engine speed. So RPMs go up, amperage goes up regardless and the voltage fluctuates from the voltage regulator. I thought electricity produced would be fixed at a given RPM because the bearings would be spinning at a certain speed and the amount of windings inside the alternator were fixed, giving off a fixed amount of power per RPM.

I've just seen these graphs when looking at aftermarket pieces and I guess they don't indicate the load placed on the system for the test.

yup, in lemens terms, its like saying i wont drink this bottle of water because it will affect the gas mileage from the added weight...