Test: Alternator vs. no alternator = 10% MPG gain @ 70 km/h
 

(Note: this thread originally written October 2006.)

Preliminary results

Speed 70 km/h / 43.5 mph

A: alternator belt ON - 71.16 mpg (US) - avg of 3 bi-dir runs (6 one-way runs)

B: alternator belt OFF - 78.08 mpg (US) - avg of 3 bi-dir runs

A: alternator belt ON - 70.2 mpg (US) - avg of 2 bi-dir runs

Or about a 10% improvement, sans alternator

When people read about this, one of the first questions that inevitably comes up is: "can you just use a solar panel?"

Short answer: not really (for reasons of cost & potential aerodynamic penalties).

If you drive a normal amount, it will cost you a lot of money to get enough panels to keep your battery topped up, and you'll probably destroy your car's aerodynamics mounting them on top http://www.gassavers.org/images/smilies/biggrin.gif.

The only reason I can get away with solar recharging is because I don't use my car very much (less than 200 miles in May). It could easily take a couple of days for my panel to replace the electricity I use from the battery in half an hour of driving.

The panel I have is equivalent to a 1 amp trickle charger, and it cost $160 CDN (I got it to keep a boat battery charged):

http://tinyurl.com/fw77y

A typical electric battery charger "trickle" setting is 2 A (twice the power of my panel), and they cost a fraction of what solar panels cost.

I've updated metrompg.com with an article on this topic, summarized and describing my experiment in more detail:

http://www.metrompg.com/posts/photos...ternator-s.gif

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

Thanks to Brock for corroborating the results with his Jetta.

For this approach to make sense financially, you would neither either (or both) of:

1) fuel that is much more expensive than it is now;

2) a supply of free or cheap batteries.

Fortunately, I've found (2).

Today, with two 6v "junk" batteries (from the forklift company) in series to make 12v, then in parallel with the existing 12v starting battery, I did a 46 mile / 74 km alternator-less round trip.

Starting voltage: 12.68
Ending voltage: 12.40 (batteries resting for 1 hour)

11.7v is "empty", so I used 26% pack capacity in that trip, with light accessory load: wipers occasionally; heater fan occasionally; lights; occasionally; plus engine overhead, turn signals & brake lights.

Assuming similar electrical loads, my total range to 100% depth of discharge is about 177 miles / 285 km.

UPDATE:

My home-made water pump belts were enough of a pain in the butt that I hadn't been doing much alternator-less driving since last summer (2007). The belts would work for several hundred km, and then fly off or fray and wear out (and then fly off).

I once missed hearing the belt fly off, and pegged the temp gauge. So I was looking for a way to electrically shut off the alt, and leave the reliable OEM belt on to drive the water pump.

But because the Metro uses a "1 wire" alternator (senses battery voltage and feeds current through a single fat wire), there's no easy external way to tinker with the "control" wiring to shut down the field.

So I took the plunge yesterday and simply cut the output wire. Put two golf cart batts into the back of the car, and headed to Ottawa for the EVCO meeting. (I'll add a switch in the wire later.)

Predictably nice results - and one of those super rare situations where I had a tail wind on both directions (moderate on the first leg, light on the return)!

78 mpg (US) on the way there, strictly DWL with an avg speed of 36 mph, (that speed includes city driving at both ends, and passing through one town in the middle). My "target" highway speed was around 45 mph.

84.5 mpg (US) on the return trip, DWL again with an avg speed of 37 mph, max of 57.

Compare that return leg to a previous winter trip on the exact same route where I got 75 mpg (US), with an average speed of 28 mph, using 3rd gear pulse and glide the entire way. The winter differences being: alternator on, no Kammback, no tail wind, wet/slushy roads, and it was 2 C instead of 19 C.

You crazy 1L drivers...


Very nice though.

Great info.

Recharged (mostly) the batts today via an 80w solar panel.

I have another couple of short-ish trips tomorrow. Will post back on the MPGoodness of them as well.

Now I just need to go find myself either a beefy switch or male/female connector so I can reconnect the alternator wire next time I need the dino-powered electricity.

62 km round trip (about 38 miles).

90% on secondary highways, 10% sub/urban, light crosswind, 22 C.

First leg: 78.8 mpg (US), 39 mph avg speed, 60 mph max speed, strictly DWL except EOC to stops in the sub/urban stuff on each end.

Return leg: 86.4 mpg (US), 37 mph avg speed, 53 max, mostly DWL with about 10 P&G cycles thrown in for good measure around hills.

Batteries are recharging via solar...

That's Ironic that you started this thread up. I've been reading your tests and have been thinking about it for a while now. Just this past Sunday this is what I did. I'm doing this in preparation for some wild ideas I have.....Anyway. I cut that battery cable going to the altenator. My plan was to use a plain old bosch relay and throw a toggle in on the dash. But when I flipped the fuse cover and saw that massive 70amp fuse in there I instantly decided to use a Continous Duty Solenoid. Like a Ford starter solenoid. Well I wired it up and it works great. It makes a big difference at idle. I can't really tell at 55 mph....I don't see a difference on the vacuum gauge or tach. If I get a chance this weekend I'll post some pics on this thread.

Question: What do you think the % gain mpg wise would be If the Altenator was to be driven off of the right rear wheel?

Has anyone ever made an altenator spin just from air/wind speed?

[QUOTE=RacerX; Has anyone ever made an altenator spin just from air/wind speed?[/QUOTE]

An Automotive altenator that is....

Assuming it's turning at the same speed as when driven by the engine, it'll use the same amount of fuel regardless of hooking it up to a wheel or a turbine (which won't work - it would require a really big swept area). There's no free lunch.

The wheel-driven idea would cause it to be under-driven at low speeds, so battery voltage may drop and you may save fuel at those times, but the load on the alternator will be higher as the RPM increases and it puts the lost energy back into the battery, so fuel consumption will go up. I can't see any real savings from that approach.

Also worth emphasizing again: discharging a starting battery will dramatically shorten its life. Going alternator-less may be an effective efficiency mod, but it's definitely not a money saving mod unless you have a source of free or cheap batteries.

MetroMPG,
there is an existing thread here in EM:
http://ecomodder.com/forum/showthrea...roof-4097.html
AndrewJ also did a similar thing, and he saw a similar 10% gain in FE, on page 8:
http://ecomodder.com/forum/showthrea...ics-312-8.html

Larry

Hi Larry - thanks for posting the links. I've participated in both those threads.

It's worth noting that Andrew also found a source of cheap used deep cycle batteries before he started driving with the alternator disconnected.

Bad news for me, apparently I have a "serpentine belt" that goes through EVERYTHING including power steering, water pump, air pump, yadda yadda so I can't take that out :(

I wonder if I can buy a smaller belt and take off just the alternator...

You could buy a shot alternator and tear the guts out to make a sort of idler pulley.

blackjackel: my alternator is not physically/mechanically disconnected, it's just electrically disconnected. The stock belt is still turning the alt pulley.

When I originally wrote this thread in 2006, I had removed the belt entirely and fashioned a replacement to turn the water pump because I wanted to remove ALL alternator losses including bearing and pulley fan. This time, I just disconnected the alternator wire.

Battery's aren't a problem.....Thank's for the info MetroMPG

As far as a switch is concerned take a look at these.

Battery Cut Off Switch - Compare Prices, Reviews and Buy at NexTag - Price - Review

Good stuff, thanks. That gives me some ideas of what to look for. I'm just headed out to see what's at the local auto parts store. I want a non-energized, manual switch / disconnect like some of those, rather than a relay/contactor setup. I won't be switching the thing on/off very often, so I don't need the convenience of a remote dash mounted solution. Opening the hood and flipping a simple switch is fine.

this is a sweet thread!

aren't the alternator leads really thick? how are you going to have a remote switch for that -the amps will melt it?

a diesel would be best for this purpose then you don't have electrical ignition to worry about! once a diesel is started you can disconnect the battery completly and still drive it.

how much juice does it take to keep the spark plugs sparking on a petrol engine? isn't the alternator controlled in some way or is it always running?

The lead is fairly thick - not sure what gauge (less than 1/4 inch dia.), but I cut it easily with a pair of needle nose pliers.

As for switch selection, there are all kinds of sizes available to handle the rated current. Check the link BBsGarage posted for examples. (I'm not planning a remote switch - it'll simply be in line under the hood.)

Good point about the diesel not needing power for ignition, but it still needs power for the ECU. And what about fuel pumps - are all diesel pumps mechanically driven?

Heey i found your topic :D

And me as a crazy one liter driver also thinking about an alternative.

I've got some idea's:

1) Stirling engine
2) Solar
3) Seebeck-effect
4) Some guy on a dutch forum said to change the coolliquid whit ethanol (boiling point 80C ) and power a steam engine whit it. :confused: Or just raise the pressure of the coolwater to about 1.5-2 bar will also down the boilingpoint...

But we have some 80-90 degrees hot water in the car. So i think we can do something whit that.

Or make a combined constuction.

What i was wondering, you said that u just diconected the cable and not removed the alternator. Will this also give improvement? When yes would it be possible to keep the alternator and just putt some more energy in to the circuit from outside (like with solar pannels)

We could also remove some lights (like breaking light, daylight etc) and replace it whit a Led construction. Going from 15-30 watts to 1.

I will try to get/make a small Stiling engine who can run a default alternator.

And would a new alternator be an improvement. Like mine is from 1992 (thats 16 year old).

Seems to me that the battery replacement isn't really that much of an issue. Lead acid batteries may not have many cycles but partial discharges only count for a partial cycle and for the majority of my trips it would only be a partial discharge. Then when I get home I could just plug it in with a trickle charger under the hood. I've heard of electric cars that have lead acid battery packs that will last about 3 years before needing replacing. With a 10% increase in fuel economy I believe that within the lifetime of the batteries they would pay for themselves. Taking my vehicle as an example it would yield a 5.5mpg increase and if my figuring is correct using my specific cars specs and track record I would save $14.73 per month, $176.80 per year, and $530.41 every three years if gas stayed at $3.60/gallon (cheapest it's been here in a while besides now). So unless I waste money on meaty Trojans it seems that two batteries would pay off.

MetroMPG; about your question about diesel needing an alternator.... No is the short awnser. In reality with how a diesel engine works it never needs any source of electricity once it's going.

But the long answer is that unless your car was built before 1998 it probably will need a alternator. Most diesels before then were Mechanical injection and the only electrical part running to the engine is a fuel cut off solenoid, and glow plugs (neither of which are needed). I had my alternator belt break once and drove around for a week on what was left of the charge until I finally had to "bump stat it" to get it going. Most cars after that have a hybrid mechanical/electric pump that is ecm controlled. Great for starting and "noise control" but a pain in the ass in the long run. I personally will stick with mechanical injection until I cant get parts any more.

Newton, It's working well for me and I have a 140 mile round trip and the return trip is at night. I'm running a pair of group 24 deep cycle interstate batterys hooked in parallel. I plug the car in when I get home and when I get to work. I haven't turned the Atl. on for about 2 months. Good Luck

Answer is "yes". Removing the alternator completely will give the greatest results, but the difference (of belt & bearing losses) is likely small. Probably not worth the hassle.

Sure. But solar is expensive, and you'd be hard pressed to find enough surface area on a 1L car to generate the power needed, even @ peak daylight times.

No harm in doing that. Again, the fuel savings will be very small.

you could produce electricity using the engine's heat by utilizing peltier plates. VirtualVillage.com i've got two 12v 400w plates on the way, i just have to find a spot that gets warm but doesn't exceed the plates max temp and mount them with some thermal grease somehow and put a heatsink/fan on the otherside to cool down the cold side. Not only does using the engine's wasted heat to produce it's electricity increase the overall efficiency of the engine but could possibly completely replace the alternator. Just gotta make sure to put a diode in the line so that when the temperature gradient is gone they don't become heat pumps.

Hi,

I thought I saw a thread here on EM that had a turbo-powered alternator?

it'd be tricky to connect a shaft to the turbo blades and would need gearing for sure but it would probably work. seems like it would be taking energy from the engine though seeing as how the energy is coming from the upward motion of the pistons (the exhaust just being the medium like hydraulic fluid) which is just energy from another combustion cycle.

Wow ! What a great idea.

Would it work ?

i'll be sure to keep you all posted, i'll start a thread probably when i do it seeing as how there's a bit of wiring needing to be done so that when the temperature gradient is gone they don't pull power from the battery and become heat pumps (one side gets hot the other side gets cold, they're kinda inefficient so that keeps them from being used for heating/air conditioning) the two i have on the way (probably another week or two) are 20A @ 12v each so if i wire them in parallel then i can get 40A @ 12v. The replacement alternator for my geo will produce 50A and i doubt that it's producing that constantly so i imagine at 40A i'll have some extra juice to use for the rest of the car. On paper this should work, only issues i have to tackle first is that they cannot exceed 68C (154F) so i'm going to go pick up a laser thermometer, i might have to bolt a plate above the engine at the correct height that it will get close to but won't exceed 68C

Sounds interesting but the literature states:

"Capable of generating electricity when one side is kept cool and heat is applied to the other"

It's not clear in the specs how much electricity they produce when working in reverse.

I hope it works because that would be a fantastic way to power a vehicle. These could be your radiators. Can one get a 150 degree thermostat? I was just wondering if you have any experience or examples of what you are proposing.

(Fingers crossed)

Added link: http://en.wikipedia.org/wiki/Automot...ric_Generators

Why dont you use an underdrive pulley?
 

Why don't you use an underdrive pulley. From your tests it is obvious that the Alternator does have a significant draw. A solar charger would help some but I do not think they put out enough to replace alternator. Still anything you can do to reduce the load will help you.
Most underdrive crank pulleys slow the alternator, water pump and airconditioner to free up some power and increase mileage.
I do not think it is a good idea to completly eliminate the alternator but you can limit the horsepower it takes to run it and the electric draw need to charge batteries.

I don't have any experience but I do have two of these puppies on the way for me to experiment with. I do know however that they are very inefficient and that's what keeps them from cooling our food and heating our homes. It's amazing that this concept hasn't really caught on in the major automotive manufacturers. With the ability to recollect the energy lost from heat in the horribly inefficient internal combustion engines (ICE) we could see some very good numbers. Or even use the electricity to power a small DC assist motor making a small Parallel hybrid drive system. Someone in the diyelectriccar forum brought up the fact that you could easily put a small dc motor in place of the a/c compressor and use the accessory belt to assist the engine (maybe ~9kw). That would most certainly boost FE a great deal probably.

We did some research on the peltier plates and we found that they're made for either cooling/heating/generating and upon further research i found some thermoelectric generating peltier plates but they are pretty expensive. $70 for 1 plate that produces 2.5watts at 3.3volts. they'll do discount bulk orders but it's still gonna be pricey. i'll bet that theres a chinese factory somewhere that will sell them to me dirt cheap. if i find anything better i'll post it.

"It's amazing that this concept hasn't really caught on in the major automotive manufacturers."

"...upon further research i found some thermoelectric generating peltier plates but they are pretty expensive. $70 for 1 plate..."

I think you have answered your own question.

lol yeah but the company i got the price from (Hi-Z Technology, Inc.) is working with Clarkson University and NYSERDA to develop a drop in model for the GMC Sierra pickup truck. If the major auto manufacturers really wanted to do this they could easily produce the modules for dirt cheap (kinda like lithium batteries now, no mass production so they're expensive). They're only expensive on the small scale which is where it is right now. So yeah lol in a way i did answer my own question but then again it just raises more questions about why if the automotive industry knew about this, and nissan motors made a working prototype in the early 90's, why they haven't pursued it further. I could point my finger to the oil companies and it may have been them keeping ICE from getting more efficient but it probably lies in the lazy hands of the Managing bodies of the corporations. I apologize for digressing this thread.

OK I could be wrong, haven't put a whole lot of thought into it, but perhaps the peltiers wouldn't be as capable of supplying the vehicles' electrical needs as the ol tried n true, relatively inexpensive alternator systems, even if the peltiers do come down in cost with further development and acceptance. For instance, there is probably no charging when cold... on a vehicle that does frequent short trips would the charging system keep up? The manufacturers pretty much have to design things for the worst case scenario.

the one Hi-Z is developing is 300w which at 12v is only 25amps but maybe that's all the gmc sierra needs, not sure. but one could easily fan out the exhaust tube to create more surface area and put a peltier farm easily replacing the alternator. they don't produce anything until the engine gets warm but they do continue to produce after the engine is off. that might make up for the lag on startup. the alternator is tried and true but so are peltier plates. they use them on satellites to pump the suns "heat" so they don't melt and they use them because they run indefinitely under ideal conditions. you have a very good point with short trips but how hot is the actual exhaust as soon as the engine starts up? if the peltier plates were literally the wall of the exhaust then they would be in contact with the exhaust temperatures immediately, i dunno, that's just me speculating but sounds like it might work. but with all said unless you're a millionaire then we just have to play the waiting game.