How much gas does the alternator take to run?

He lied.

Alternator technology has been pretty consistent since the mid 60s when they became common as replacement for generators.

If there were 15% MPG lost in the alternator, the OEs would have been all about a more efficient technology to get 5-10% improvement.

 

SERPENTINE BELT DRIVE SYSTEM

Here’s a list of the items that the serpentine belt covers:

Power Steering Pump Pulley
Crankshaft Pulley
Idler Pulley for Automatic Tensioner
Water Pump Pulley
Belt Idler No. 2
Air Conditioning Compressor Pulley
Alternator Pulley
Belt Idler No. 1
Lots of stuff to move!
Remember the old days when the fan didn’t have a clutch? Now some cars use an electric fan to further reduce drag.

 

If you really want to save fuel, take the fridge, tent, shovel, hi-lift, propane grill, jerry can, and whatever other unnecessary dead weight that you call "overlanding gear" and leave all of that shit in the garage.

That's guaranteed to save far more fuel than bypassing the alternator.

 

It has changed though. A lot of cars charge while the engine is in decel and not using gas. So they basically charge the battery with energy that would have otherwise been wasted. BMW claims a 4% decrease in fuel consumption.

 

OP, I suggest you go to an auto parts store and turn an Alternator there. They all spin pretty freely so the amount of drag on the engine is going to be minimal. Drag from the A/C Compressor (when it's engaged) and the P/S pump will be much greater. I think that's the reason why a lot of models are using electric P/S now.

 

How much blinker fluid do you use a month.

 

https://www.rapidtables.com/convert/power/Watt_to_BTU.html

There are only so many BTUs in a gallon of gas.

 

You’re talking about hybrids. Not straight gas.

 

Curious would be the typical "moderate speed Horsepower consumption of the tonka trucks RELATIVE to electrical consumption (at night)

 

The math is easy, calculating the load accurately is the hard part. Convert the load in watts to HP and you can get a very rough idea of how much energy from the engine is used to generate electricity. Don't try to figure it out to any sort of real fuel consumption numbers, though, because there are too many variables that change engine efficiency that you could never really know how much power is going to electrical energy generation and how much is going to other energy use. A ballpark percentage is probably the best your can get.

 

EVs and Hybrids use regenerative braking. In gas engines the alternator is always running as long as the engine is running and thus it is always charging. Without it the engine would likely be only running on the battery and you wouldn't be getting very far. Unless of course there's some wizardry I'm not aware of, I believe alternators are relatively simple systems.

 

I think some charging systems reduce the alternator output at high throttle and maximize it at low throttle. So you are slightly draining the battery as you get on the gas but it holds out with the hope you'll let off and slow down again. At a certain point it obviously needs to charge the battery no matter what, and I don't think these systems cycle the battery very deeply.

 

Generally speaking the alternator sucks less fuel than the added drag of solar panels on top.

 

Always spinning (I think some may even be clutched like the AC) yes but that doesn't mean its producing power. The amount of power it takes to spin the alternator is directly related to the demand placed on it. So if it's not being told to create power its only friction you have to overcome. If it's being told to produce full power it takes more power to spin.

The computer knows the state of charge of the battery and when its supplying fuel to the engine. So it will do it's best to only run the alternator when no fuel is being supplied to the engine. Of course it will turn it on no matter what if the battery starts to get low.

 

Prime example of someone who should never have purchased a truck to begin with LOL

 

Lets take a look at Max power consumption of the alternator running at 130A compared to the Max power of the 4.0L

2.5*100/278 = 0.9% (max alt load at max engine power). Less than 1%.

Be generous to say the Tacoma get 20 mpg. The alt is consuming about 0.2 mpg (at full load)..........

Where is the nit harvester?????

 

So you’re saying there’s some kind of electric clutch on the alternator pulley? I’m sorry but I’m not buying it.

An alternator is just copper wire windings spinning around magnets. There’s no intelligence to it. If it’s turning, it’s outputting 14.5 volts, and that’s that.

 

So you think its going full bore all the time? It's not and it never has been that way. That would overcharge the battery. The voltage regulator controls how much or little energy the alternator creates (and consumes). The difference is now that is regulated via the computer and can be done at times the energy would have otherwise been wasted.

 

Alternators have regulators in them that vary the output based on the load. They have had this for a very long time. Typically they just shoot for a specific voltage on the output and regulate current to hit that. But there's no reason you couldn't slap a chip in it and have it communicate with the ECU to optimize further.

If they were completely unregulated and spinning all the time making power for the rpm, things would fry - energy doesn't just disappear.