Does anyone know the gauss amount of a automotive rotor winding?

sparky 1

Joined Nov 3, 2018
If it is an automobile alternator at a given rpm you could adjust the number of turns by measuring the temperature that works for your application being concerned not to overheat the enamel on the wires. I will take a wild guess : 14,800/3.125 = 4,736 Gauss
A physics person that worked for Chrysler Corporation electrical division R&D in 1960 (61 years ago) might be able to point to the very specific information about alternator rotors. Probably certain public library archives located near closed down electric motor factories might have books on the subject. Those who rebuild alternators might also know. Some like the older GM heavy duty alternators I think they were rated at 60 Amps.
The later electric motorcycle hubs are well designed have some advantages for it's end use. Also the electric car pre-Musk had many electrical engineers that got dumped and would rather not talk about what they spent time learning.
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K OBrien

Joined Nov 28, 2020
Gauss is a cgs (centimeter gram second) unit used in the theoretical system as opposed to the Tesla in the MKS (Meter Kilogram Second) practical system. A hall effect chip used to measure DC current in a clamp meter would be a practical use of directly measuring magnetic flux. In transformers, motors and alternators you'd be more interested in knowing things like hz, rotation speed, amp-turns, air gaps and the type and amount of iron used. There is a residual magnetic field in an alternator with no current flowing and a strong field when maximum current is following in the field windings.

K OBrien

Joined Nov 28, 2020
We may talk a lot about magnetic fields, inductors, and electromagnetic radiation but seldom does anyone actually measure a magnetic field. We most often measure current, voltage, and resistance. Other things we either calculate like wattage, already know or are specialized such that we don't usually need to know them. I'd seen IC's and calculators before I saw a hall effect chip. A reluctor used for position detection is not a hall effect device. Plus they can only measure the field strength in a certain area. You would still need to do a calculation or build a special device to actually measure the field in a specific alternator on a claw at a certain current and outside of someone building alternators I'm not sure what use it would have.


Joined May 15, 2009
The problem you are asking is difficult. The magnetic field strength in an alternator rotor is not just dependent on the rotor but the air gap between it and the field coils as well. However, a clue is that the iron used has a saturation of about 1.4 T (why are you still using gauss by the way?) and designers will be trying to get as close to that as possible.
If you've not looked into transformer design that may help you to start answering your question.
You could also look at an example rotor. Typically you need something around 10% of the output current to go into a rotor. I've never designed an alternator, so I can't tell you how close that is to modern designs, just that that is what I have measured on some.