Alternator Mods

[NiHaoMike]

Has anyone tried replacing the rectifiers with Schottkys if they aren't already? That should halve the rectification losses since the forward voltage drop of a Schottky diode is about half that of a regular diode.

[sdpflag]

what if you put an air conditioning compressor clutch on the alternator and hooked that up to an openguage or something that tracks instant MPG's and had it engage only when the MPG were above a certain amount. this would disengage the clutch whenever we accelerate or drive up hills or such when any extra load on the engine hurts us the most.

[thefirebuilds]

Originally Posted by gascort

Like others have said, reducing accessories reduces the magnetic field and thus resistance within the alternator, raising FE. My friend had a HUGE (like 2000W) stereo in his car; when he turned his amp on, it was like a "slowness switch".
FYI - a car's electrical system (necessary stuff like ecm, ignition, sensors) is typically somewhere around 300-400W without lights, radio, etc. Newer cars are more than older cars I'm sure.

Noone's mentioned using a deep cycle battery and a plug-in charger. This is what I'm planning on doing; running a kill switch on my car and when I'm commuting 15 miles to and from work, running on straight battery when I can. The alternator sees no extra duty and the deep-cycle battery is made to be discharged and recharged with minimal sulfation. Electrical power is more efficiently produced in a power plant than in your car, and with current prices, it's way cheaper too!

Agreed. I am on time-of-use so night time charging via a timer switch will be dirt cheap. I have a solar panel to integrate into my trunk that will keep the battery topped off during the day (15w). Should mitigate any issues in most commuting situations.

I plan on leaving the alternator installed so I can belt it up if need-be, but how do i go about finding a belt the appropriate length for just my water pump and main crank pulley? The tensioner on most cars is integral to the alternator bracket instead of the water pump, so i need a way to tension the belt properly. ideas?

[Denis]

Yes ! Lower amperage ones ! Use teh lowest amperage alternator possible and forgert all those "luxury" things like power windows, A/C, etc

Denis

[Curly1]

Why dont you just use an underdrive pulley system? That reduces drag on all driven components and should help with mileage while keeping battery fully charged.

[getnpsi]

Originally Posted by Curly1

Why dont you just use an underdrive pulley system? That reduces drag on all driven components and should help with mileage while keeping battery fully charged.

it would help, but not every company makes them for every car. Ford Aspires and Chevy Metros never really made it in the import racing scene. The thing is that its a confirmed 10% increase in mpg's in some vehicles to not run an alternator at all. That is a very tough number to beat with any other method, or combined methods (other than driver mod)

[ASV]

When you remove a watt from the load on the alternator you remove more than one watt from the engine load
the stronger the field the stronger the resistance to the engine
As long as the field is off the alternator is nothing but a flywheel and an extra pulley. But when accelerating you still have that extra rotating mass to contend with and even at constant rpm with no load you still have the belt friction loses

The problem with removing it is that single 12V battery is not enough power to drive with
you will go dead fairly soon
Modern cars are simply not designed to conserve electricity
There is probably a two hundred watt draw on your 12V system with out even the headlights on

You can fix that by replacing brake, dash, cab and running lights with LEDs
You can probably fit about thirty watts worth of photovoltaic panels on even a small roof
And adding an extra battery to run in parallel with your original will more than double available range

[metalshark]

decreasing belt leach is easy as lightening up a load. alternators are a must for a more efficient engine, but you can still make lighter pulleys at a machine shop even underdrive pulleys.
aluminum instead of steel always works better (depending on the car)

lighter pulleys is a lighter load on the belt.
whether a/c is on or off it will always draw from your engines power same with power steering. (always an option to remove a/c and p/s)

or you can go all out an start putting panels all over your car. might as well just convert it to electric.

[ecoxantia]

Originally Posted by gascort

Noone's mentioned using a deep cycle battery and a plug-in charger. This is what I'm planning on doing; running a kill switch on my car and when I'm commuting 15 miles to and from work, running on straight battery when I can. The alternator sees no extra duty and the deep-cycle battery is made to be discharged and recharged with minimal sulfation. Electrical power is more efficiently produced in a power plant than in your car, and with current prices, it's way cheaper too!

I have looked at this and concluded that the cost per cycle of a deep-cycle battery make it not cost effective.

For example in the UK, a deep cycle battery like the "red top" would cost £140 and if you got 500 cycles out of it, that's about £0.3 per cycle, or 0.3 liters of fuel's worth just for the capital cost of the battery. That ignores charging costs, which are low from the grid -but a decent charger will cost something.

What would make it worth it, is if you had regen. braking and an electric assist motor, and could use the energy for more than just starting the car the next day.

I was surprised that the battery would only hold 600Wh, by my calcs equivalent to 55 ml of diesel...

[whitewiz]

I found a super easy way to reduce the load on my alternator. I bought a $10 solar panel and threw it on the dash. 1W...not really because solar panels are rated at no load.
i'll just fill my dash with them...
but then where will i put all the empty McDonalds containers?

Schottky diode's can be scavenged from a computer switching power supply
hmmm, silicon carbide Schottky diodes... Now i need a Scangage and a spare alternator.