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

[vacationtime247]

Here's how I'm trying this mod, or at least tried it today. Took the serpentine belt off before going to work, during daylight hours. I work 2-10:30p. The drive to work really didn't use the battery hardly at all. Started with 13.07 volts by the time I was at work it read 12.7 volts. Hooked the belt back up once I was at work. Took 5 minutes. Have to drive home in the dark, when I'd be using the most volts to run the lights. I'm hopeful of some kind of gain not having to run the serpentine belt at all going in to work. The water pump is driven off the timing belt.
VT247

[steffen707]

As some have said, doing this will net worse mpg for you because the alternator is not very efficient at recharging your battery. So on the night time trip home the alternator is going to be working extra hard because the battery was already drained (not fully, but partially) on the way to work.

You might find better results in driving to work with belt on, then taking the belt off at night where the alternator works a lot harder.

I did a test with the alternator on and a full load of electrical (lights, defroster, blower, radio) and then another test with the same loads, but this time with my alternator in low charging mode and i got 13% better mpg on a flat road .5miles and cruising at 40mph.

The same test with no load was like a 1-3% difference.

[vacationtime247]

Here's my rational for why I'm trying this the way that I am. But, I could be wrong and it may not net any gain. Been wrong before, it was on a Wednesday in '89, lol

Taking off the serpentine belt before going to work. The engine won't have to turn the a/c, the idler pulley or the power steering, there is another belt from the ps to the alt. So none of them will be turning. Other than to charge the glow plugs, start and brake lights, the battery won't get much use except to keep the injector pump on. When I tried it yesterday, it still had what most would consider a full charge, 12.7 volts after getting to work. If for nothing else, I'm going to try this for one fill up or @ 350 miles. See what my mpg is then. No gain, I'll try something different. Would really like to use 2 deep cycle batteries for to and from work. Charge it once at home on the grid. But haven't got to that point yet.
VT247

[dipstick]

OK, I gave up reading all of these posts, because most everyone is doing the same thing and making the same mistakes and errors in logic. Spoken like a true know it all huh.

I rebuild alternators, DC motors, starters, etc. I am an AC motor repair shop and wholesale distributor as well. If it is electrical I fix it. So... I think I know it all, lol.

Actually, my intent for posting here was to give everyone a solid atta-boy for effort, and to suggest the one thing that I did not see anyone posting... but then I did not read beyond a few pages, so if I missed it, then I'm just a jerk for being a jerk and thinking I know it all.

I also wanted to express the info you guys need to know to prevent problems.

OK, item number one... stop disabling your stock alternators and then re-enabling them to charge depleted batteries... modern alternators are not engineered for the high temperatures resulting from extended high output charging periods. If you are not careful you will burn them up faster, and negate fuel savings with repair costs.

Also regular auto batteries cannot handle the deep discharge and recharge cycles you are putting them through... you ARE destroying them which again costs you the money you were hoping to save by doing all this stuff in the first place.

Also, the recharge required to replace the lost electricity requires just as much energy as it would otherwise so you are saving at most 2-3% maybe, due to the regular friction losses of the bearings and belt on pulley from regular driving.

I know, I know, I am too negative, and you all have evidence to prove me wrong... so what do I know.

Here's what I would recommend if you want to remove your alternator loads successfully. First, change battery types to golf cart batteries, and use a minimum of 4. They are roughly 60# each plus additional cabling and you gain an additional 190# or the weight of a second person in the car. A loss for certain, but consider the gain in durability of batteries, and the overall trip distance.

Also, I recommend keeping the Alternator installed for a backup, and for belt use because, without an alternator installed in the car at all you will need a plate with a pulley on it to be able to continue using the belts and the other equipment, such as power steering which can be a safety issue in the wrong situation. Also I am fond of a backup plan.

OK, lastly, get a good golf cart style battery charger, and use it every night when you get home. Install professional heavy duty quick disconnects like they use on forklifts, to make connecting and disconnecting more expedient and safe.

Tweak these concepts as required to fit your driving style... simply and basically, short commuter trips need less power reserves or fewer batteries, and longer trips need more. Recharging at work if the boss allows, helps as well. It is far less expensive to use grid power to recharge then fuel in most cases or so they tell us right? So, if you are not ready for the complete electric swap, this is a good middle ground.

OK, getting tired... good night. Oh, please forgive me for being a know it all jerk. I'm working on it.

Dipstick

[Nerys]

First some of us are using metro's this means no power steering or anything else at all actually except the water pump. also our cars are much lower "power" than most cars. so a single deep cycle auto battery will be MORE than enough power for the average commute if you charge it up each night and don't go below 50% DOD.

Second people who turn them on and off are not draining the battery to such a degree that the alternator is going to "work" all that hard.

Third. on many of our car's alternators are dirt cheap and last a long time. even if we cut the life span of the alternator in HALF the savings of fuel will more than compensate for this MANY times over. 10% for me is $330 a year. MORE THAN DOUBLE what even a brand new alternator and battery cost if I had to replace them YEARLY.

same with the batteries. I get good batteries for $20. 10% fuel savings will save me $20 in a couple weeks. so even if I have to buy another battery every YEAR I am saving a TON of cash way more than the cost of replacing both the alternator AND battery on a yearly basis. IE worth it.

MY plan is to replace the pulley water pump with an electric water pump.

once I do that then I no longer need a belt AT ALL except to turn the alternator. so I remove the belt and use 2 deep cycle (I have a long commute) and will charge at work and charge at home as needed.

I also plan to toss a solar panel on the roof. in the summer I might not need to plug in at all to charge up.

just got to save up the cash for the electric water pump.

[oil pan 4]

Originally Posted by dipstick

OK, item number one... stop disabling your stock alternators and then re-enabling them to charge depleted batteries... modern alternators are not engineered for the high temperatures resulting from extended high output charging periods. If you are not careful you will burn them up faster, and negate fuel savings with repair costs.

I posted on a few of these alt disable threads recomending the use of a charge limiting resistor like I have.
I run LiFePO4 starting batteries on my diesel. Just glow plugging, cranking to then charging the batteries with unlimited alt power puts a full load on the alternator for the few minutes or so after starting (before I had the resistor). No matter how tight the belt is it would always squeek.

Originally Posted by dipstick

Also regular auto batteries cannot handle the deep discharge and recharge cycles you are putting them through... you ARE destroying them which again costs you the money you were hoping to save by doing all this stuff in the first place.

A few people tested their alt delete/disable with starting batteries but the fully committed are running deep cycle AGM or lithium ion boosted electrical systems. I posted that starting batteries only like about a 20% depth of discharge.

Originally Posted by dipstick

Also, the recharge required to replace the lost electricity requires just as much energy as it would otherwise so you are saving at most 2-3% maybe, due to the regular friction losses of the bearings and belt on pulley from regular driving.

That is what we have found with the alt still turning.
Most of the alt disable guys charge their battery with external power and retain use of the alt so they don't end up with a range limit like an electric car.
The guys with small cars running the alt with the belt off or the full alt delete see almost 10%.
I also encourage the use of LEDs to entend battery life and "alt off" time.
With LiFePO4 batteries I cant run an alt disable or delete because of my large electrical draw and small reserve capacity starting batteries.
I do like helping those who can run an alt delete or disable.

Originally Posted by dipstick

Install professional heavy duty quick disconnects like they use on forklifts, to make connecting and disconnecting more expedient and safe.

That is what I did with my LiFePO4 install.
This way I can quickly remove the batteries if the truck is parked or if my car needs its battery back.
(my suburban also uses my cars LiFePO4 battery in addtion to its own LiFePO4 battery)

[oil pan 4]

Originally Posted by Nerys

just got to save up the cash for the electric water pump.

Electric water pump and alt delete don't go together that well.

[ecomodded]

2 deep cycle batteries will give you a lot of juice/ drive time.
Two 80 ah battery could provide 8 amps for 20 hrs. drive time,20 hrs by lets say 50 mph is 1000 miles a charge. Adjust accordingly for your individually cars amperage use.
Solar may come to mind for many of us when we think of ways to recharge the system, but i think the real cure is wind power.
Its something anyone can make. Made mostly from everyday items, with only a few odd pieces like couplers, a charge controller etc.
A car alternator would work for a wind generator, but is not ideal as it is a high rpm motor.
If you can find a big old heavy motor with 700 to 2000 rpm stamped on it you are in business.
I have been looking into wind power as of late and can really see the cost per watt benefit of wind over solar. Solar is expensive.
That being said i have a 15watt panel on my dash board that keeps my battery at 14 volts.

[Nerys]

yes they do. at least in a GEO they make sense together. My objective is to remove "ALL" Load from the engine except that of "moving" the car. my only two accessories are water pump and alternator.

the water pump (electric) at full tilt is 4-5 amps. I can drop that to 2-3 amps since I am cooling a wee little geo and not the V8 Racing engine they are designed for.

that amp load is SMALLER than the current amp load of my incandescent light bulbs. by a lot.

so going to LED and possibly 35w HID for the head lights will save me more than double the power that the electric water pump will consume at full tilt. 4 times at lower draw.

2 deep cycle batteries will let me go one week without a recharge (without going below 50% DOD)

except in the winter where I need the head lights more often and the blower. then every 3-4 days will need to plug in (but I will plug in nightly anyway to be on the safe side)

the water pump is a larger mechanical load on the engine than the Alternator if memory serves me correctly. though this may be different on the geo.

thats the math I came up with ecomodded. figure twin 100 amp hour batteries which meant without going below 50% DOD I had 100 amp hours to play with.

In the beginning I could even go on ONE deep cycle as long as I charge up at work and at home. (I have an optima blue top scored lucky on craigslist)

lets put it this way. I left ALL the lights on for 3 hours accidentally (2 hours 58 minutes) and the car started right up (though at idle the alternator REALLY bogged the engine down with the load of recharging that battery)

Really impressed me these blue tops. (scored it for $60 on craigslist !!) got it for my boat I use it in the geo when not in the boat.

6 amps for the car itself. .5 amp for lighting (50% usage) (once I go all led less than that but rounding up for safety) 3 amps for the stereo and surround sound (I was surprised how little power it consumed) 1 amp for misc accessories and 3 for the water pump.

13.5 amps so far MAX possible plus the head lights. 7 amps. figure 50% usage so 3.5 amps or a total max possible of 17 amps.

so 50% DOD is roughly 5.88 hours figure 6 hours so 300 miles. or about 5 days and thats worst case scenario. (except if I need the blower)

more than enough power if I charge at work and at home and more than enough power if I "forget" or the charger "fails" for some reason.

I will leave the alternator and water pump physically in place. I was THINKING about install another pulley to a small tiny efficient electric motor to very slowly "turn" the water pump and alternator. this way my belt and my bearings won't "rot away" on me. this way I can just rebelt if I need too for any reason.

[Christ]

Originally Posted by Nerys

I will leave the alternator and water pump physically in place. I was THINKING about install another pulley to a small tiny efficient electric motor to very slowly "turn" the water pump and alternator. this way my belt and my bearings won't "rot away" on me. this way I can just rebelt if I need too for any reason.

Wouldn't worry too much about that, honestly. I've seen cars parked for 30 years that the alternators and engine accessories still function perfect on. In fact, I just bought a 70's Ford big block pickup that's got the original alt and water pump on it at over 100k miles, and they both still function perfectly after it sat in a field for 10 years. It also started and ran on the 10+ year old gas that was in the tank, worth noting... yano, back when gasoline was actually made of gas.

Even the tires are still holding air after it sitting that long in the weather, rain, snow, etc. and no attention ever being paid to it other than to stack junk on the flatbed or in the cab.

If you plan on leaving the belt off for long periods, a quick blast of WD40 once a week at the alternator's front and rear sections will be more than enough to keep the bearings from getting corroded and "rotting" away.