A-B-A Lights on vs Lights off
 

I'm sure this test has been done a million times, but I wanted to see for myself. I ordered LED's to replace all auxillary lights on my '97 s10 2.2 liter, as well as the 10 additional 194ll marker lamps on my tool box. But before I went and installed them I figured I should get some really good data points so I could quantify my results. So, here I am almost 4 hours later and 180+ miles driven with some suprising results (suprising to me at least).

Testing method: A outbound/inbound B outbound/inbound A outbound/inbound

My new Scanguage II cam in yesterday and I've been playing with it a ton. Drove about 300 miles on it when we went houseshopping so I got a handle on it. I calibrated it (needed very little adjustment) at 1/4 tank yesterday and verified that with a fillup this morning.

So I wanted to see what kind of mileage difference running all of them bulbs did. This morning I got up early and found a nice, flat, and smooth stretch of 4 lane out of Omaha that is not very well traveled. I decided to use from one turn around point to another turn around point as an easy test ground.

My grilfriend set the scanguage trip at the designated mile marker on the outbound trips, and the desgnated lightpoll on the inbound trip. Verified distances with GPS (15.5 outbound, 15.7 miles inbound). I was going 60 for about 1/8th of a mile before she hit the trip.

We did one trip with headlights/marker lams on. (A1 outbound, A1 inbound)
Then we followed up immediately with no lams on as I disconnected the DRL. Fuse 15 for fellow s10 owners without factory fog lamps. (B1 outbound, B1 inbound)
We then reinstalled the fuse and turned on the marker lamps for a verifying run (A2 outbound, A2 inbound).
The B test was then duplicated again.

Results were suprising. According to my limited data all of those bulbs combine to suck about 1.05mpg at highway speed. This is about 3x's as much as I expected.

See graph below:

http://i244.photobucket.com/albums/g...adlightMpg.jpg
Edit to add: 32.5 - 31.55 = 0.95 (not 1.05) Thanks Darcane!


Now I realize that there are several areas that made my testing less then perfect. First, because it took over 3.5 hrs to complete, the temp had changed about 15 degrees from begining to end. However, the final "B" run still came in about the same below the "A" runs.
Also, there was some traffic (maybe 2-3 cars per run both directions). All of these cars drove by at a pretty steady rate and none of them gave me a "draft." I did not get affected by any semi's on my runs this morning.
There is some slope to the course. According to the GPS the course drops about 60 ft during the inbound run. Of course, this should effect both A & B equally.
I don't have cruise control. I tried to hold a steady 60, but that is impossible without a perfectly flat course. According to the GPS, my avg speed for all 3 runs was exactly 60. I did get up to 61 on all the runs, and even 62 on the "B inbound."
Wind. There was some wind this morning, but my course was parallel to it for the most part. This is Nebraska, and if I waited for a day with no wind I'd never get any testing done.
Weight. I burned about 4.5 gallons of gas from begining to end. This seemed to have no impact on the results, because the last A run still fell in under the B run. Even though run "A2" should have had all of the same advantages it still fell well under the "B1" run.

Conclusion:
Having the headlights/marker lights off improves gas mileage 1.05mpg @ 60mph. I am really shocked that 1.05mpg went to powering all of my lights!

I wanted to make my test as valid as possible, but this was my first time out. If there is something I did wrong, either in the test or data collecting please let me know. I want my results to be valid, but I don't have lab equipment to play with.

I learned alot from this expirment. The DRL is getting permenantly deleted, and I'll just run with 100% LED's driving/maker lights on during the day. This should cut about 98% of the wattage I am using currently (DRL's+marker on).

Nice work, kir_kenix!

I, too, have wondered about the DRL question, as my Corsica has automatic DRL that switch between the high-beams on low power and low beams on regular power, depending on external lighting. My car also has installed aftermarket driving lights (110W together). I have tried switching on and off various lights, the blower, and opening and closing windows while maintaining load on flat ground, to see if any of these had an effect on the instantaneous MPG reported by SG. However, I have found that none of these produce any noticeable change in reported MPG. Although, it is possible that since engine load can fluctuate so easily at highway speeds that these are more likely parasitic loads that produce only minuscule immediate changes, but have a significant cumulative effect.

Again, nice work on this experiment! This is good information here, and finding any inefficiency provides the opportunity for improvement!

I'm hoping most of my gains from the LED conversion are not instantly negated by the e-fan I picked up today. I think transferring the parasitic load on the engine to the charging system would have made some gains, but now I think I'll really be able to realize the full benefits of the e-fan conversion.


I'm glad I did the experiment, and I think the DRL delete & LED conversion will allow me to have some more leeway with future mods (deep cell battery, alternator on/off switch, and solar panel...).

If I had to start over from scratch, I think DRL delete and LED conversion would be on the top of my list. The gains are pretty big, and the conversion is too easy. Swapping out bulbs and pulling 1 fuse will probably be the easiest mod I'm likely to come accross.

e-fans will save gas providing the thermostatic programming doesn't have them engaging all the time. The fuel saving trick with e-fans is making sure they do not need to be working at speeds above 25mph.

Promising results, i recently installed LED-DRLs which allows me to drive with 8w of lights instead of ~140w in the daytime(low beams or DRL's mandatory, and the low beams activate parks, rears, instrumentation and licence plate lights!) and my commute averages much lower than 60mph! (somewhere in the 30-range)

Do you have an estimate of how many watts your lights consumed together?

I estimate all my lights together were drawing about 175-185 watts before on DRL/parking lamp. I have just about switched everything over, and I will be running about 10-12% of the original amount. Of course, when I do run my headlights I'll still be drawing an additional 110 watts, but thats still a heck of alot better then close to 300 I was drawing at night before!
Well I got my e-fan partially wired up tonight and it certainly cools the motor down on demand. I've been thinking of a way to kill the fan at a certain land speed, but most of what I've come up with have been too complicated. I'm thinking now some sort of switch on the gas pedal that will shut it off when I'm at about 1/3 throttle or more. Should be easy enough to figure out.
I never did get around to finishing the job tonight (girlfriend brought down some refreshments and the truck was forgotten). Anybody know of a good/easy place to wire up the lead that goes hot from the ignition switch? I was thinking of using the ignition coil since its right there (no trailing wire halfway accross town, no drilling holes into the cab to run wire if I can avoid it). I will probably end up getting out the testlight tomorrow and hunting something down if nobody's got a good idea to shoot this way :)

Why would you like to kill e-fan in certain speed?!
It comes on only if temperature is too high. So higher speeds you get more airflow and e.fan should not turn on anyway. If it comes on, then it is needed

You are probably right. My truck has plenty of cooling power, so I doubt the fan will see much use. Only on hot days when I pull a trailer around the metro (Omaha) will I proabably ever need it.

I ended up wiring the snap switch into the winshield wiper motor. Works like a charm. I had a tough time testing it out today because of the crummy weather, but I did get it to kick on by putting a sheet of cardboard behind the radiator and revving the motor.

Seems to like to kick on at about 203-204*F and kick off at about 195*F. I think that is probably close to ideal...won't overheat, won't run too much.

A minor math note:
32.5 - 31.55 = 0.95 (not 1.05)

Right you are! It even says that on my spread sheet...turns out I'm lousy at looking at one piece of paper and typing those numbers on another. Thanks Darcane, I feel like an idiot.