Way back up the thread the question of alternator core
temperatures was raised. Here you go:
This is for a standard small-case auto alternator running at full nominal field current
and ambient temperature (on the test stand) of 23C. The case runs about 100C over ambient, and the windings about 40C over that. Note that removing the diodes from the case dropped the overall temperatures by about 20C.
The key in this (especially with LiFePO and other high-acceptance batteries) is finding a high-efficiency alternator. You bog standard auto alternator has (at best) an efficiency of about 50%, that means that if you are getting 1kW out of your alternator you are also using a 1kW heater on your alternator. Finding even a 60% efficient alternator makes a huge difference; to get the same 1kW output you reduce the heating
element by 30% just by getting a 10% more efficient alternator.
For more than you ever wanted to know about temperatures in the various parts
of the alternator:
MIT Alternator Temperature Modeling