I recently did a paper study of converting a 1.5 L turbo auto conversion from alternator+starter to an integrated starter generator. Preliminary, and by no means apples-to-apples, but the controller, starter-generator, and mount came to comfortably under 5 lbs, with the stator and rotor accounting for just under half of that. Plenty of compromises — 1700 W at cruise settings (around 30 A at 56 V), but power decreasing with RPM, so negligible at idle; and the parts used don’t really scale to a < 48V system.
I was assuming I would retain an alternator for my secondary power source, mostly to provide a better story for power at idle…. But off-the-shelf units sized for these power levels (assuming field coil rewinding and modified regulator for 48V) are mostly around 12 lbs, with a few possible excursions down to 7 lbs. some of this is lower level of integration… but is there anything else driving it? Has anybody updated a field-coil alternator to modern magnetics approaches? Why is there a 2x weight difference for two similar-efficiency systems thermally limited to similar power?
I’d still really prefer one alt and one ISG, and the extra weight of the alt isn’t insane since I wouldn’t have to add in a starter as well… but I’m surprised the spread is this big.
I was assuming I would retain an alternator for my secondary power source, mostly to provide a better story for power at idle…. But off-the-shelf units sized for these power levels (assuming field coil rewinding and modified regulator for 48V) are mostly around 12 lbs, with a few possible excursions down to 7 lbs. some of this is lower level of integration… but is there anything else driving it? Has anybody updated a field-coil alternator to modern magnetics approaches? Why is there a 2x weight difference for two similar-efficiency systems thermally limited to similar power?
I’d still really prefer one alt and one ISG, and the extra weight of the alt isn’t insane since I wouldn’t have to add in a starter as well… but I’m surprised the spread is this big.
