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

[cosmick]

Get a bicycle crank and a passenger, let the passenger pedal up the alternator?
I doubt it would make a 3 mpg difference on a stock 94-02 Z28 with T56 (0.50:1 sixth = 1500 RPM @ 65 MPH = 30 MPG)
I doubt it would make a 1 MPG difference on a big block dually. Only a micro mini baby engine could suffer so badly, and who wants to suffer a micro mini baby engine? Maybe a V8 with a T56 and a 2.14:1 axle in a Geo?

[Gasoline Fumes]

Originally Posted by cosmick

...who wants to suffer a micro mini baby engine?...

You know what website you're on, right?

[MPGeo]

Originally Posted by Gasoline Fumes

You know what website you're on, right?

Ha, Ha... that's funny.

[teoman]

Just finished reading the whole thread. Very interesting, but i have a feeling that i may be a bit more tricky on a modern vehicle that probably already implements algorithms similar to this. If anyone know how they do this, i would be very interested in knowing.

Looking from a completely different side, the reason your deep cycle batteries cannot fire up the car once they are low is because they cannot generate enough current. If one were to add a capacitor bank in parallel then even almost dead batteries would be enough to fire up the car.

Like this guy:

https://www.youtube.com/watch?v=z3x_kYq3mHM

I am pondering, on a modern car, would it be beneficial to remove the battery completely and use capacitors instead? You would not have the problem of charging a battery that lost capacity if not used for a week or so. Also you would not waste energy on a battery that started to age. (you would need means of charging it (which is very quick ~1-3 minutes) if left for a couple of days).

[gone-ot]

You ARE aware that super capacitors ALSO loose charge, don't you? It's called self-discharge.

[teoman]

Yes I do, and I expect it to be completely dead in 3 days. However they can be charged up very quickly from a very small capacity battery (it does not hold too many Wh but it is enough to crank the car a couple of time).

A capacitor is like a mini battery that can deliver all of its charge, i.e low voltages does not stop it delivering amps, and it does not get upset if the voltage falls too low.


The advantage would be that over the long run it does not have so much loss. i.e you start your car and it thinks you have a full battery in a couple of seconds.

I plan on doing this with my car but I fear that the modern charging algorithm may be confused with what is essentially a much smaller battery.

[teoman]

Does anyone have clue on the energy consumed with say a 2010 ish passat.

The newer cars are fairly sensitive to the voltage of the battery, I do not think that they would be happy with a dropping voltage.

One could install a super capacitor bank instead of the battery, and then charge that with regulated voltage from a different energy source. This would have the benefit of keeping your car at its happiest voltage and you can use several different types of batteries in parallel. With very minor changes in voltage one could use one set of batteries and once those go low, you could switch to other sources of batteries.

On the plus side with a newer car, the power gains are more significant.

[oil pan 4]

No one I know of who runs an alt delete uses more than 2 batteries. That's a starting battery and a big deep cycle battery for the rest of the electrical system.
Most people just use one big battery.

[teoman]

One big battery will also do it. But i am stuck in traffic for 2 hours every day. And mixing and matching batteries would be a good idea.

Does anyone know what a modern car would do if if detects a voltage of say 15V at the battery. Would it stop the alternator or would it get completely confused?

[oil pan 4]

Unless you are going to remove the belt from the alternator and cut its power there isn't really any fuel economy to gain.