Alternator Hot

[MississippiJim]

I noticed today that my alternator (Vans 60 amp) was hot to the touch while I had the battery charger hooked up and the master switch on. It was hot enough that you couldn't hold your hand on it for more than 2 or 3 seconds. I have never noticed this before, but it doesn't seem right to me. Could I have something touching a ground that shouldn't be? Ideas anyone?

[molson309]

I'm assuming you had the alternator field turned on - a typical alternator field draws 4-5 amps. This is ~50 watts! If there isn't any cooling the alternator will get plenty hot. It's probably not a good idea to leave the alternator field on without the engine running because of this. Note that the heat is being generated in the rotor, which is buried inside the alternator, and also doesn't have a direct path to the outside to dissipate heat. If the outside of the alternator is so hot you can't put your hand on it, how hot is the rotor?


Mark Olson RV-7A F1-EVO

[riffelj]

Yup, just like "M..309" said. I discovered the same thing a while ago & called Plane Power in Granbury, Tx. Said to switch off the Field when charger was attached.

I put a big label on my charger to remind myself and everything is nice and cool. EIS complains if I don't switch it back on when I fly.

[MississippiJim]

Thanks for the reply Mark, and makes sense. I feel better now. I'll pull the field breaker from now on. Usually I am charging without the master on, but was working on some stuff at the same time.