What determines how many amps an alternator puts out? Is it the actual stator/rectifier assembly or something in the voltage regulator?

The reason I ask is because there is a higher amp alternator for my Civic that I'd like to swap in, the only difference being the number of pins in the plug (1 extra). It looks like the same regulator assembly for both, so could I just swap the voltage regulator assembly and have it work?

In case it isn't completely obvious, I know little to nothing on the subject.

Here is what I have, and what I'd like to swap in. (Napa may ask you to pick a store, but the alts will show after you do)

The answer is "none of the above".

Power/current/amps are determined by the size of the rotor and stator - and to an extent, how fast the assembly rotates.

The rectifier converts the AC electricity produced by the rotor/stator to DC before it goes to the DC storage battery.

The voltage regulator is a voltage limiter to protect the battery from overcharge.

The rectifier and regulator must be robust enough to withstand the power output of the rotor/stator, but increasing the capability of either does not produce more power; however, it might allow the rectifier or regulator to run cooler and possibly last longer.

If you want more power (amps), you'll have to have the alternator rewound or replaced. OTOH, if the cases of two alternators are different and the guts of a higher-powered one will fit into the case that fits your mount, that might be a way to upgrade the complete internals and derive more power from the same case fitment.

Frank

So there are 2 alternators, same manufacturer, same case. One is 55 amps, one is 70. The only other difference between the two is the connector on the voltage regulator (3 pin vs. 4 pin). Can one regulator be substituted for the other safely?

More than likely you can use it - but you need to make certain you have the correct wires going to the proper terminals on the alternator or you risk damaging the alternator, battery, vehicle - or all of them.

There are conversion adapter plugs available, but make sure you get the right one. Better yet, if you aren't familiar with electrical stuff, take it to an alternator shop and have them do the job the right way.

Frank

The manufacturer and case may be the same, Main difference is the number wraps or turns of wire on the rotor and or windings of the alternator. just swapping the lower rated regualtor into the higher amp alternator may work for a time but IMO you will blow that regualtor out when reaching the higher output of the other alternator. They may look the same on the outside but the guts are different.

I would recommend you sick with the regulator thats in the alternator and adapt your harness or plug like Frank said.

Lame, but I don't want to risk that. I'll try to find a plug to adapt things over. Any suggestions on a source?

I already checked the manufacturer diagrams, the extra pin on the other alt is to tell the ECU how much load is on the alternator. The other pins all match up to the existing ones no problem.

I'd suggest that you go to a local auto electrical shop. They specialize in what you're trying to do and can do the job in a matter of minutes - or sell you a plug adapter to install it yourself.

If you want to ask the question on a forum, I'd suggest asking it on the Toyota technical board - perhaps someone on that forum is familiar enough with your truck to answer your question from experience.

Frank

Frank, he said it's for his Civic.

I agree with the advice to swing by a shop and see what they've got. You could also head to a local junkyard and grab the connector you need.

Oh - in that case I'd do one of the following:

1) Ask the question on a Honda forum.
2) Buy a JY plug and rejigger the harness with it.
3) Go find an auto electrical shop.
4) Trade cars.

Frank