Going alternator less

So for the past few weeks I have been pouring through thread after thread on https://ecomodder.com/forum/fuel-economy-mpg-modifications.php

The complete forum can be found here https://ecomodder.com/forum/

Anyways one of the threads which stuck out to me was the alternator delete. This is not so much a "Removal" as it is making the alternator optional. The way I did it on my 1997 Toyota Corolla was by interrupting the IG wire/Field wire. This meant the alternator still had a belt, still was hooked up close to normal. It now meant you can turn your alternator on when you need to. I have a switch mounted in my dash which is convenient to use.

The Idea behind it is to replace your starting battery in your car with one which is a deep cycle battery. These batteries typically can be discharged deeper than starting batteries and they act similarly to a battery found in a off grid system. Now that you have the deep cycle battery installed. You can now start using your car without the alternator being on. You will need to interrupt your field wire. This might also not work for every vehicle and situation.

For me since I drive at most 50 kilometres round trip, I can easily use the car without having the alternator drag on. The hope here is that car MPG will increase. It seems some are seeing as high as 10% gain in MPG. Quite the upgrade.

Now its easy to make it more complicated, its easy to try and introduce a regen braking setup. So the sky is somewhat the limit. I chose to go the simple route and just use a switch. When I see the battery voltage at around 11.8VDC I will turn the alternator on. This is likely to happen when the lights are on and the heater is on.

So when I get home from wherever I was, I now plug my car into a battery charger and charge it up to full.

I could definitely see people living in the city/or those who drive short distances regularly switching to a system like this. It is also easy to go on long trips because all that is needed is to turn the alternator on.

In my instance my old battery was at least 8-10 years old. I will find another use for it. So it made sense to upgrade to the deep cycle battery.

Related threads https://ecomodder.com/forum/showthread.php/test-alternator-vs-no-alternator-10-mpg-gain-98.html

It's an interesting angle.

I wonder if the computerized bits of newer cars would have a conniption fit if they saw no voltage from the alternator.

Love those old Toyotas by the way. Those drivetrains were indestructible, but the bodies didn't fare well in our winter/salt environment. I still see some in perfect shape when I travel out your way. Very cool.

If my memory is still firing on a few cylinders, I recall getting very interested in 'soft hybrid' modifications.  Again, if I'm remembering correctly, the idea was to have an electric motor replace.....hmmmm....the alternator?  And it would alternately (no pun intended) work as an in-line, belt-driven part of the vehicle drive system to assist during cruising speeds, but act as a battery charger during times of high speed acceleration or, perhaps as you noted, regen during deceleration or braking.  The batteries were beefed up from what a car normally has, but using the main serpentine belt to transmit drive seemed to be something one needed to work out carefully.  Seems like so many ways out there to improve upon what get sold from the car lot.

jordan barton wrote:So for the past few weeks I have been pouring through thread after thread on https://ecomodder.com/forum/fuel-economy-mpg-modifications.php

The complete forum can be found here https://ecomodder.com/forum/

Anyways one of the threads which stuck out to me was the alternator delete. This is not so much a "Removal" as it is making the alternator optional. The way I did it on my 1997 Toyota Corolla was by interrupting the IG wire/Field wire. This meant the alternator still had a belt, still was hooked up close to normal. It now meant you can turn your alternator on when you need to. I have a switch mounted in my dash which is convenient to use.

The Idea behind it is to replace your starting battery in your car with one which is a deep cycle battery. These batteries typically can be discharged deeper than starting batteries and they act similarly to a battery found in a off grid system. Now that you have the deep cycle battery installed. You can now start using your car without the alternator being on. You will need to interrupt your field wire. This might also not work for every vehicle and situation.

For me since I drive at most 50 kilometres round trip, I can easily use the car without having the alternator drag on. The hope here is that car MPG will increase. It seems some are seeing as high as 10% gain in MPG. Quite the upgrade.

Now its easy to make it more complicated, its easy to try and introduce a regen braking setup. So the sky is somewhat the limit. I chose to go the simple route and just use a switch. When I see the battery voltage at around 11.8VDC I will turn the alternator on. This is likely to happen when the lights are on and the heater is on.

So when I get home from wherever I was, I now plug my car into a battery charger and charge it up to full.

I could definitely see people living in the city/or those who drive short distances regularly switching to a system like this. It is also easy to go on long trips because all that is needed is to turn the alternator on.

In my instance my old battery was at least 8-10 years old. I will find another use for it. So it made sense to upgrade to the deep cycle battery.

Related threads https://ecomodder.com/forum/showthread.php/test-alternator-vs-no-alternator-10-mpg-gain-98.html

Interesting. I do not think you could get away with it on newer vehicles as the computer controls the alternator field feed to optimize charging and it would throw a fit if you did this. My understanding was you could save about 5% of fuel costs cutting out the alternator it might be closer to 10% on smaller vehicles as the electrical loads stay fairly consistent vehicle to vehicle but the engine is smaller. You could feed the battery current from an onboard solar panel though. If the car detected full voltage on the battery it would not energize the field and you would save fuel in that way. You could also change out your headlights for LED bulbs saving some power there. The joys of older cars! I don't modify my family mover as its newer and I would face serious backlash!
Cheers,  David

Some of the newer vehicles will identify a field interuption. This might show as a PO622 code.  Dodge/Chrysler especially use the PCM/ECM as the voltage regulator. in newer rigs. I don't know that turning on and off the field would hurt the ECM/PCM but procede with caution until someone can say there would be no issue. We wire around the PCM/ECM with an older style regulator often when the charge regulation component goes wonky on a Dodge pickup. It saves having to buy an expensive computer component. Older rigs I see no issue but newer rigs might have issues that might show up as an inocuous code but might have down the line issues. What happens if through distraction one fails to flick the switch? Larger diameter pulley might reduce the peristaltic draw on the sytem.

You could also switch to a six stroke engine and thereby get rid of the water pump and radiator.

Like Robert, I worry about distraction, and the consequences. There could be some "simple" mods to make it "fool proof" such as a lighted switch, or the switch being reset to ON after the ignition switch is switched OFF (or driver's door), or on a timer, or automatically ON/OFF at set battery voltages. The last one could even become an aftermarket product!
A 10% savings is interesting, and I know I can realize that if I unload my back seat full of tools, and thin out what's in the tool boxes in the bed of the truck. On that same path, running on less than half a tank, means carrying less fuel weight. (for me 12 gallons = 1/2 tank) Keeping tire pressures up helps as well. I've even thought about removing the rear seat altogether, seeing as it hasn't seen passengers in three years! I personally wouldn't drive without a spare tire (full size on a truck), but for sure fuel economy is part of the reasoning for the "donut" spare tire as well.

My last truck was a manual transmission, and it was also interesting to play at hypermiling, specifically since it was an engaging activity. Coasting in neutral (out-of-gear), lower RPMs in higher gears, anticipating stops WAY in advance and coasting rather than braking, sometimes getting too close to the cars ahead.

Two trucks before that, I threw my alternator belt one night driving home in the rain (felt and heard it leave the truck). It was probably the worst conditions: lights, wipers, heater all ON... I got about 3 miles tops, to a gas station where I managed to use the 10cm shorter power steering belt after adjusting the alternator as far as it would go, using a Gerber tool, and a reluctantly loaned adjustable wrench and screwdriver from the station attendant. Drove home with lights, no power steering. I keep tools in my truck these days.

Makes me wonder about other engine loads. How much of a load is a power steering pump versus an alternator? Is a non-power steering vehicle more efficient (all else equal)? Or an electric cooling fan (on demand) versus belt driven (always driven).

Adding a vacuum guage and driving in a way that keeps the vacuum at it's highest reading for each gear helps.

Many of the newer vehicles have a clutching pulley on the altrnator to reduce drag and increase mileage.

Umm without the regen charging I don't see how this gains anything.

When the field cable is disconnected and battery is supplying the car circuits, electrical load goes to 0 but mechanical losses remain.
When the field cable is connected and battery is supplying the car circuits, electrical load over doubles to charge the battery and to run the car's circuits, also the mechanical losses remain.

Right now it looks like the overall efficiency is down. Regen would certainly change the balance.
Or plugging in a charger (assuming that your local grid is cleaner and more efficient. Hint, it is).


Now because the manual switching bugs me..

The pulley clutch would be better as it removes the mechanical losses but if you want to stick with electrical....

It would be fairly easy to build a circuit or even a voltage meter that would switch the f cable. A 555 timer in bistable mode with a voltage divider to set the trigger voltage is one example of a plain circuit. An LM3914 with some leds and a relay on one of the lowest leds should work (there's a way to get it to light one led at a time instead of the bar graph effect).


Honestly, I think the best way to save energy going down this route is to wear an extra jumper so you don't turn the heated seats on and wipe the windscreens instead of using the demist wire, I think those will be the biggest electrical drains but A/C will be bigger.

do you have difficulty starting the car with a deep cycle batt after running the voltage down to 11.8? or have you always had an opportunity to plug in and recharge?

consider the scenario of an unscheduled engine off eg a police stop just before you get home. it depends on how beefy your batt is but i'd be tempted to keep it above 12.4V both for confidence in starting and longevity of batt.

something to consider is flicking the switch to charge whenever slowing down with engine braking or coasting downhill.

I think the problem is that the power still has to come from somewhere to charge the battery, so you might see a savings on your fuel bill, but your electric bill goes up the same amount when you charge the car at home.  

A free spinning alternator takes almost nothing to turn, and one that’s charging hard can almost stall an engine it’s so hard to turn, so there is savings to be gained, but the best option may be a flexible solar panel stuck to the roof so that it doesn’t at wind resistance and charges the battery for you. If the battery voltage is high, the car won’t power the field coil in the alternator much or at all, so you could save money without modifying your cars wiring at all

The field terminal is not a simply on off wire, the voltage is varied based on need

Steve Farmer wrote:do you have difficulty starting the car with a deep cycle batt after running the voltage down to 11.8? or have you always had an opportunity to plug in and recharge?

consider the scenario of an unscheduled engine off eg a police stop just before you get home. it depends on how beefy your batt is but i'd be tempted to keep it above 12.4V both for confidence in starting and longevity of batt.

something to consider is flicking the switch to charge whenever slowing down with engine braking or coasting downhill.

I have yet to have any problems at all.

Where I live the furthest I could drive is from one end of the island to the other. I have yet to do this. So its mostly short drives. Lately when I have been working at the same place I have been using around 5AH to get their and back. Noted on my Victron 12v 30amp charger(awesome charger by the way)

I also do a lot of Engine off coasting(EOC), and restart the car when going up hill. I leave the car on when I know there is a need for braking.

I suspect in the winter I might have a harder time charging my battery given that I live off grid.

For the most part my battery shows 12.3v while driving. It will dip to 12.0v when the brakes are on. than return. I also have no lights on or radio(not that I get a signal)

 This might be sort of off topic but I went to the energy fair in WI and there was a guy in the parking lot with a fan on the front of his truck.
It looked like a fan off a grain bin, with the venturi still surrounding it.

He reduced the number of things running off the crank and used the air hitting the front of his truck to  
run the electric water pump, charge the battery, electric AC and power steering.
He invested some good time and money into his experiment.
It was a long time ago so I can't remember the numbers but he got some incredible smileage.

 At first it didn't sound feasible, like making energy with a wind turbine on your car,
where the drag would take just as much energy away.
But he was using air that was going to hit the front of his truck anyway and using it to replace items that cause drag on the engine.
That guy in the parking lot is the only time I've seen this idea mentioned or tested.