Measure current without load?

Question

just wondering can we measure current from an alternator without any load? just using an ammeter to create a closed loop circuit.

Answer 1

If the alternator is disconnected from the battery, it will not work. It is a synchronous generator and requires the dc power from the battery to produce anything.

If you could connect an ammeter across a working alternator, you will create a load, and lots of it. Its probably a way of testing your local emergency response systems

A load test on an alternator would be unusual anyway. Normally its good enough to see the voltage increase on the battery as the vehicle is started.

Answer 2

NO! Absolutely not.

With no load there is no current, so what would you be measuring? Exactly this: the ability of the current-supplying device to deliver huge current into a short-circuit, because that is what you'd be doing. You would read some huge current for a fraction of a second, then either the current source would blow, or the meter, or, if you're lucky, a fuse.

That is the only useful information you would gain: which would blow first.

NB: a clamp-on ammeter is for AC only.

Answer 3

NO

with no load, current will read zero, because .... there is no load!

And if you put the ammeter across the alternator, the ammeter will be the load, and you will get very high currents, because an ammeter is very close to a short circuit. Either the ammeter will go up in smoke or the alternator will. Or the alternator will stall, breaking a belt.

.

Answer 4

Not really because you make the load connecting the amp meter.

A alternator must have power to work as they don't' have permanent magnets built in. You don't have to load it but the coil needs power.

But if that is ok sure you can but you will have hard time finding a amp meter that will support this much power. Most max out at 20 amps. Alternator runs around 60-150 amps.

That's if your talking about a car :) And if you're talking about a car the way you test a alternator is to test the voltage. If your voltage increases from 12ish from the battery to 14ish when you start the car, it's working.

They have other types of meters the type that measure by flow. You don't close the loop with this type you just clamp it around the wire. They're rated for 1000's of amps. But you must have a load.