alternator load vs fuel economy

not many studies done on alternator loads effect on fuel economy. i attended a class on gm's new strategy to turn off the alternator under cruising conditions and the results are nil on an individual basis as far as fuel economy goes. tenths of a gallon in the name, but on a national scale equals alot of savings. which means alternator load does very little to fuel economy. the extra load a hho generator puts on the alternator does not lower fuel economy enough to negate the generator but may cause the alternator to fail prematurely.

not many studies done on alternator loads effect on fuel economy. i attended a class on gm's new strategy to turn off the alternator under cruising conditions and the results are nil on an individual basis as far as fuel economy goes. tenths of a gallon in the name, but on a national scale equals alot of savings. which means alternator load does very little to fuel economy. the extra load a hho generator puts on the alternator does not lower fuel economy enough to negate the generator but may cause the alternator to fail prematurely.


Wait a minute if that was true then you could run your car on HHO. NO CAN DO. I think you should test it and report back. There is no free power!! Just try putting a load on a generator set and see how it pulls the engine down and requires more fuel. This does not take a rocket scientist.

putting a load on the alternator does load the engine down. but it is a small amount. just by running the fuel pump and the coils is around 8 to 10 amps, running the blower motor is around another 8 amps and the wipers is another 5 amps, and nobody complains of getting worse gas mileage at night when its cold outside. gm says they save around 1% fuel mileage. i will test it with my car. hard to do because it is a base model and only has a heater headlights and wipers. and i don't see hho generators as free energy because water is the fuel, its not from nothing. i just think modern engines need more r & d to harness the hho enough to run completely on or at least get more mpg. i think of it as instead filling the car with gasoline, building a small refinery and converting crude oil into gasoline in the car. yes it would lower efficiency, added weight and electrical load. actually i don't even know if that would be possible but is sounds good enough. i think there's alot more we can get with hho on demand.

If you are planning to make only a couple hundred milliliters a minute then it will not make much difference just using 3 amps. The average reactor takes 15 amps or more to make 1 liter a minute and if you are going to make 3 LPM then 45 amps will be required. Many have experienced a loss in mileage when not done right or no gain because of the drain on the engine by the alternator. I suggest you do some testing and report back.

alright ran into a little problem. with my car being base model and all, i looked up the fuse ratings for everything electrical. turns out everything added up is only about 30 amps and that being optimistic. im gonna have to find an old blower motor in the shop and rig it up to do this test. my alt is rated at 60 amps so i thought a good safe range would be 45 amps. im going to make this test with the least amount of variables as possible, so im going to use a pulse width calculator to calculate fuel consumption as i drive and i'll use my shops oscilloscope to monitor injector pulse width so it will be real time. ill do 2 runs of each loaded and unloaded alt, and in 3 different rpm ranges idle 40 mph and 60 mph. gonna be busy this week so ill probably wait until the weekend to do the test

Alternators have a peak rating designed to withstand said peak amperage for X amount of time. This is important because if you are constantly hitting that peak or "pushing the edge" you will potentially end up with a dead alternator and you probably know where things break down from there. That being said, I think your approach is the right approach and I could almost bet money that many individuals here are overdriving their alternators right now (asking why they are losing MPG). I say this because not much talk happens in the direction of pre-install alternator condition on these forums. You could have a 60A peak rated alternator and it could only be capable of 45A peak because the brushes are worn, ect ect. Post the test results back as any info is helpful info for noobs here.

Related: http://www.hhoforums.com/showthread....4007#post54007

ok, had a quick second and did a idle test. took some pictures but i haven't been able figure this dang thing out so ill just tell you. the car was fully warmed up used an inductive low amps probe to measure current and back probed my injector and put them side by side on the two channel scope. first snapshot was at idle with no alternator load amp clamp shows 6.8 amps and my pulse width is 32.6 ms. next snap shot was showing 31 amps and 38.9 ms. my next snapshot was at 2000 rpms amperage jumped up over 40 amps which was my limit so all i know is that it was over 40 amps pulse width is 17.2 ms. and the last snapshot was 2000 rpm with no load 12.1 amps and 10.8 ms. im not the biggest expert on tbi so im gonna assume that pulse width is so high at idle and lower at 2000 rpms because its pulsing 2 cylinders at once at idle and going to each cylinder at 2000 rpms. now since i was at idle and was not moving i really can't use these numbers for mpg. but i can compare them. so thats a 19.35% increase in pulse width at idle and 59.3% at 2000 rpm. another thing to note is that my car is a 91 honda civic with a 1.5 liter engine with honda's version of throttle body injection and a distributor. it has 295,000 miles on it. the test at idle showed that the alt was fully loaded at that rpm because the output increased when i raised the rpm to 2000. also the alt will have its biggest impact on the engine at idle because the engine output is low. also my car is a small 4 cylinder so alt load will affect it more than really any other engine in the world. and i plan on doing this test with our high amps probe too because i don't fully trust the low amps probe its been messing up lately.

ps ok i figured this dang thing out heres pics of the scope

You are headed in the right direction and I will be interested in your findings. I have always used 1 HP for 40 amps. Now how that relates to fuel economy is another matter and is much more involved. The actual figure is slightly less than 1 HP. This was a calculated figure and I would be interested in seeing how your tests match up. There is more to this game than one thinks. There are a lot of variables. Electrical power on a vehicle is not free. It comes as a direct result of consuming fuel within the engine to drive the alternator. With a typical engine efficiency of 40%, a belt efficiency of 98% and an alternator efficiency of 55%, this leads to an overall energy conversion efficiency of only 21%. I am not a math person and can only relate to this in my testing and the above mentioned is from those who are math orientated who are recognized as experts or at least supposed to be. LOL

ok so did a quick test on my lunch break because i was feeling frisky. the numbers are a little confusing because i don't deal with tbi very much and i can't find much info on the computer strategy yet. fully warmed up engine first test 60 mph no load 2900 rpm tried to maintain cruising speed for 5 seconds hard in my car because it doesn't have cruise control and i was trying to keep an eye on the cars in front of me. so 60 mph no load 2900 rpms pulse width 4.9 ms. next test 60 mph 2900 rpm fully loaded bounced between 5.0 and 5.1ms. i did the 40 mph test but now looking at my results i did one at 40 and one at 45 so im going to have to redo that one. but at 60 mph the load should be the smallest on the engine so i did both ends of the spectrum so far and i can speculate what the middle would be. any one know how to calculate this my lunch break is ending and i don't have time. or i will do it later at home

i searched forever it felt like and still didn't come up with anything i think i might know. i looked for an algorithm to calculate mpg with pulse width fuel rpm etc. turns out that isn't a very popular algorithm. i found one but im not sure what i've actually come up with. here is my results


X/(C*0.0000212*Y*Z)

Where:

X = Vehicle Speed
Y = Engine Speed
Z = Base Pulse Width
C = Injector constant (lbs/hr)

2900 rpm
60 mph
4.9 ms pulse width no load
5.1 ms pulse width + 40 amps load
235cc/min injector max flow


60 mph / 6.7480448 = 8.8914643838760525122773340212561 - 4.9 ms

60 mph / 7.0234752 = 8.5427795060769916294429287655205 - 5.1 ms

now i have little to no idea of what i just calculated. unless some one here knows im going to spend the next few days figuring out what i just figured out.

all i know is it was between a 2%-3.9% fuel consumption increase. but really it's more likely that it is a 2-3.9% increase in engine load so my car would show the most increase since its old and the engine is small. being a diagnostician i have a wide range of vehicles i come in contact with. i plan on continuing this study with newer vehicles that i can use a scan tool on instead of a lab scope and have more data to look at one time and i can take a snapshot of the entire data field and record it.

still haven't found a proper calculation yet. but looking at injector duty cycle makes it a little easier to understand. at the given rpm and pulse width the injector duty cycle with no load is 11.84%. with over 40 amps applied to alt injector duty cycle went to 12.08% - 12.33%. that means it only went up .49%. thats a pretty small number and i do believe my hypothesis has stood. the power to make hho will be greatly overcome by the power it gives the engine when burned in the combustion chamber especially on a newer engine and a bigger engine. but it must be done properly if i had to guess it would be the hho is causing it to be too rich thus lowering engine power output and raising fuel consumption and/or not altering ignition timing enough for the amount of hho. just a hunch

Even if the calculation is correct the .49% dose not mean much to a simple person like me. Unless you can relate it to fuel per mile or HP it is not something I can relate to. I do understand that it takes just less than 1 HP to generate 40 amps on a vehicle that is operating properly. Maybe we are saying the same thing but if we are, it is unknown to me. There are many studies out there showing that turning off the alternator saves fuel by a good bit. Now adding a 40 amp draw should make that number even bigger. The only way the small amount of HHO being used adds significant HP is if something that is unknown to most is happening in the combustion chamber that creates a fuel that is more powerful than just HHO and can push the piston through more of the power crank angle than just HHO, which is just to fast of a burn and in some cases over before the piston is at TDC in some cases. The best thing you could do is try it and report back. I will be very interested in your findings. Your hard work so far is more than most are able to do so keep it up.

FINALLY!!! i figured out how to convert pulse width to mile per gallon. ok so here goes

Alt. unloaded
injector 235/cc x 0.0049 = 1.1515 cc/pulse
cc/pulse = 1.1515
gal/pulse = 0.000303996
gal/min = 0.01823976
gal/mile = 0.01823976
mile/gal = 54.82528

Alt. loaded by 45ish amps
injector 235cc/min x .0051 = 1.1985 cc/pulse
cc/pulse = 1.1985
gal/pulse = 0.000316404
gal/min = 0.01898424
gal/mile = 0.01898424
mile/gal = 52.67527

only other thing is i don't quite get that good of gas mileage, but i guess this is just a snap shot so it will vary to my tank to tank readings.

Nice work, @motocross1550. So the data you presented is from your test at 2,900 RPM?

To recap: you mentioned in a previous test that at idle pulse width was increased by 19% at idle when load was added and then by 58% with the same load at 2000 RPM which makes sense.

It appears as though fuel comsumption was only increased by ~4% with load added at >=2,000 RPM.

thanks stevo, im trying to make more sense of the test at idle. i didn't really expect to see that because it seems my engine does better at higher rpms. i get better gas mileage at 65 mph than i do at 55 mph, go figure. so when i increased the rpm i expected to see less alt impact than at idle when engine potential is the lowest. i would still like to do one more tests at medium speed. i haven't had much time to mess around with anymore cars but a 99 Lincoln continental. but i need to find injector capacity and it doesn't appear readily available. otherwise i have the snapshots i need. you wouldn't happen to know that off the top of your head would you? lol

Quote:

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Originally Posted by myoldyourgold

Even if the calculation is correct the .49% dose not mean much to a simple person like me. Unless you can relate it to fuel per mile or HP it is not something I can relate to. I do understand that it takes just less than 1 HP to generate 40 amps on a vehicle that is operating properly. Maybe we are saying the same thing but if we are, it is unknown to me. There are many studies out there showing that turning off the alternator saves fuel by a good bit. Now adding a 40 amp draw should make that number even bigger. The only way the small amount of HHO being used adds significant HP is if something that is unknown to most is happening in the combustion chamber that creates a fuel that is more powerful than just HHO and can push the piston through more of the power crank angle than just HHO, which is just to fast of a burn and in some cases over before the piston is at TDC in some cases. The best thing you could do is try it and report back. I will be very interested in your findings. Your hard work so far is more than most are able to do so keep it up.

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i can see how turning off the alt. would save fuel consumption. but i think the draw from an hho generator gives back what it takes in amps. its like a supercharger, it takes power from the engine to run but it gives more than it takes. i read some test about removing the alt and using a high efficiency alt. with the high efficiency alt test i don't think over a year with city tractors is a good test. the variables for fuel consumption can change so much through out the year. in both tests i question the integrity of the alt they test. a worn alt or a alt with a worn diode bridge that is leaking ac current can play games with the on board computers and due some pretty funny things, the least it can due is cause the computer to operate less than normal. with removing the alt, it shows gains but shortens the distance the car can be driven and makes it even shorter if any electrical load is used. i think the best of both worlds can be achieved if you turn off anything not needed at idle. its the draw at idle that makes the most load on an engine and raises fuel consumption the most. when i get some time i am going to do a test of pulse width over a per-determined distance with no load and with 40 amps. mostly with engine under acceleration so engine load will be taken into consideration
.

after further review i figured out why i got better mileage in the calculations than in real world driving. i will re-calculate my numbers because i remembered my rpms were a little higher and my speed o meter is a little fast so it was closer to 2975 rpms and 57-58 mph.