I have a 80Amp alternator and I intend to try and use all 80 possible Amps. My main question is, "What is the minimum amount of RPM's does my engine need to be around to produce a steady 80Amps?"

 

Tryin' to run that extra large microwave?

Seriously, if you run the alt at full capacity, you will shorten it's lifespan; it may even be measured in minutes.

Get an ammeter and install it. Put your 80 amp load on then read the amps. You could also monitor voltage; if the volts are not 14.1 or better, the alternator is not carrying the load you have applied.

BTW, the FSM specifies that the S5 alt should put out 60 amps at 2500-3000 rpm.

 

So would it be wise to purchase a 200AMP Alternator (figuratively), so that it wouldn't apply that much stress on the alternator if I were to try and get like 80AMPs from it? Also, wouldn't that mean that it would require less work (RPM's) to produce those type of numbers? In my case, less work will probably be best in which to make higher numbers.

 

What are you running to pull that 80 amps?

And I don't know if a 200 amp alt would put out at lower rpms. Sounds good, but keep in mind that it takes a given amount of mechanical work to product that electrical output, so if it makes the amps at lower rpms, the load on the engine will be pretty high. Keep good belts on it. Make sure your idle is stable and the BAC is working.

 

FD alternator is 100 amps,but has been shown to put out more.So,really it would be at 75%..NO too bad a load for the alternator.

 

Thanks for the input you two, but now lets discuss Volts.

I know all car batteries range from 12-14 volts, and the alternator is regulated by the voltage regulator to cap around or at 12 volts so that it doesn't overcharge the battery.
1)Do modern alternators have the regulator built within itself or is it part of an outside connection?
2)If the regulator is removed, will this increase the amount of 'out' volts?
3)What is the maximum amount of volts a standard alternator can produce before trouble hits, or is there even a maximum amount?
4)Is there a way to produce higher numbers than 12-14 volts? For example, the US standards of 120V and 240V?

 

Without a voltage regulator the alt will make more power the higher you rev. I don't know what the limit would be but it will make over 100V if spun fast enough. I've seen them used as welders with a kit that takes the regulator out of the loop and then you run a specific speed.

Oh and don't confuse 120V or 240V AC with the DC that comes out of a standard alternator.

 

jgrewe, I've read of a 'special box' that can get the regulator out of the loop but i don't know what product that is. This is pretty much what I'm looking for.

Also, just to make sure I'm in the right state of mind... is this correct?
Standard alternators produce DC, but is converted to AC so that it can be stored in a battery of some sort. Standard appliances run off DC correct?

 

Youve got it flipped around. Batteries we use are DC. Stuff at home is AC. You wont want to take out your voltage regulator and have your alt running constantly. I dont think the alternator will last very long and your cables might need to be thicker. And many many more reasons.

Why do you need your alterntor to pump out so many amps? A portable Kegerator?

 

You need an S6 alternator. Don't go monkeying with the voltage regulator. You will burn up sensors & other electrical components. I believe the voltage regulator is built into the alternator. Check the FSM.

You'll be sorry when your electrical system goes POOF!! Again - why do you need all that power? You could add an additional alternator if the S6 100+ amps is not enough. Get a double pulley for it if you have removed the airpump as well.

Ramses666

 

Okay, so now I understand I need a converter to convert the high pressure of the DC to the AC to run standard appliances.

Part of the reason why I'm yearning to learn about alternators is because I want to know as much as I can about electricals, and alternators/generators are a huge part of it since they produce energy (not create, since energy can not be created or destroyed).

I'm thinking, since jgrewe stated that they are capable of reaching 100+Volts without the regulator, I'd just get a new regulator that caps around the numbers I'm looking for and wire that to the alternator. Sound good?

 

Nope... Thats sounds terrible. If you want to monkey around add an alternator that is all by itself & insulated from the rest of your electrical system. Put one in place of your airpump and have fun playing with it. If you want AC you need a solid state DC-AC inverter. These are widely available in various sizes & power capacity & would work well running from a second alternator. Don't kill your cars electrical system.

Ramses666

 

Oh I know, I wasn't going to test it on my car without knowing all possible outcomes. I will be testing this on something else

 

Maybe we could help more if we knew what you are trying to run.

Yes you can run an converter to make the DC from the alt into AC but for any big amp draw this can get expensive. You can run small appliances with no problem with a stand alone system running off your alt but getting into a big home stereo sound system would be very expensive to set up. It would be cheaper to just buy a generator.

I just did a little digging, if you are going to have a stand alone alt that doesn't run anything on the car you could probably have one rewired to get rid of the rectifier. That is what converts the 3 phase AC power produced by the alt into DC for the car. It would still be RPM dependent but it could be done.

 

Keep in mind that Ohm's law applies along with % loss due to conversion to AC. For example - A coffee maker draws 8-10 amps of current at 120 volts AC. Thats 960-1200 watts of power. If you change that to 12 volts the draw in amps is 80 to 100 amps of power from your 12 volt system. thats with zero conversion loss. If you want to run a 120 volt audio amplifier and it puts out 2000 watts of power your looking at 167 amps with no compensation for transforming the power from one voltage to another or inefficiencies in the amplifier. So you will fry your electrical system trying to do something like this with a stock alternator.

Ramses666

 

1) For the Rx-7, they are all internal.
2) You will have no voltage. Look at the FSM or haynes manual for the wiring diagram of the alternator. The voltage regulator is the set of transistors in that drawing. It supplies current to the squigly thing on the bottom via brushes and slip rings. That squiggly thing is the rotor winding. When current is applied to this winding, it creates a magnetic field with two poles. This rotor is connected to the pulley. When you spin the alternator, you spin the rotor. Now the three squiggly things above the rotor winding is the stator. When the rotor's magnetic field passes across the stator windings, it produces a voltage that is equal to the cross product of the velocity and field vectors. Since the field rotates around 360°, you get areas that are inducing a large (+) voltage, an equally (-) voltage and zero volts (ie when the velocity and field are in the same direction). It forms a sine wave of voltage, also known as Alternating current, or AC. To the right of the stator windings, you have the solid black triangles with hats. These are diodes and form the rectifier. A diode is the electrical version of a check valve; it allows flow in one direction. This causes the (-) part of the sine wave to be zero. Since the stator windings are 120° apart, when added to each other, fills in the 'gaps' of the sine wave, and you result in a relatively steady DC signal. That's how our alternators work.

Remove the voltage regulator and no rotor field exists. Without that field, you have no generating action, and no voltage is induced on the stator. No voltage on the stator means the alternator ain't doing anything.

I guess you can replace the rotor windings with a magnet or hardwire it. That'd get you your big voltage, but not in anyway controllable.

3)Sure. A problem can exist with your regulator. I had it happen on one of my chain-store alternators. Pegged the voltmeter, overcharged the battery, and I got to spend a lot of time dumping baking soda over the engine compartment to try to nuetralize the battery acid that sprayed everywhere.

4)Yep. There really is not much difference between your car's alternator and electric generators at a power plant. Both work functionally the same.

 

The alternator peaks out at 4000rpm. You get about half power at idle. The alternator puts out AC, not DC. The regulator regulates the voltage down to 14.5V, not 12V, and that is the voltage at the battery when the car is running. When the car is off it drops to 12-12.5V. If you see that while the car is running, the system is draining power from the battery (high load and/or weak/dead alternator). The battery, diodes and regulator give the system DC power even though the alternator puts out AC. Old cars had DC generators, but the voltage at idle was under 12V so the car had to drain the battery instead.

If you have a busted voltage regulator the system voltage will be much higher than normal, maybe ~18V. This will eventually damage certain electronics and overcharge the battery.

 

dude it sounds like you want to run a 120 or a 240V appliance. you can just buy an inverter that will convert the 12v to 240v etc etc

http://www.jaycar.com.au/productResults.asp?FORM=CAT

If you talking sound systems, you want amps. as its all to a 12v design.