Quote:
Originally Posted by serialk11r
Hub motors run at very low speed. Alternators run at 17000rpm. Huge difference.
Just look at the numbers for permanent magnet motor losses. It's not that bad, and you won't be spending a lot of time at high engine speed regardless. 10kW motor has a no load power consumption of 300-400W at maximum speed.
Alternators have field weakening, but they are so inefficiently designed from the start that it's not a big difference. They have inefficient cooling fans, significant rotor power consumption, and 4x the iron losses for the same magnetic field strength.
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Erm; The number I recall is 6000 rpm for max output.
And thats alternator rpm.
The alternator pulley is generally less than half the crank pulley, so we're looking at more than double engine rpms..?
Dont recall a max efficiency #??
, so I went looking and found:
Improving Alternator Efficiency Measurably Reduces Fuel Costs
https://www.delcoremy.com/documents/...ite-paper.aspx
Still need to get to it, but from a quick scan it looks
worthy of a thread of it's own!
Bicycle hub motors:
Ye much lower rpms
But my reading says motors designed for higher rpms are more efficient.
So too for alternator I would think..?
I thought of belting 2 hub motors to the inner CVs of a car.
Fabrication would be pretty easy.
Cost, control and lithium batteries; not so much.
That said
Here for example is a
Tadpole Trike powered by 2 high rpm and efficiency Radio Control motors through a reduction box.
https://www.electricbike.com/50mph-m...lectric-trike/
Looks like a damn nice Motor/Alternator to me!
Just one of those coupled to the end of the crank pully..!?
I like this mentioned
jump in efficiency when modding an alternator to 48 volts:
"...The efficiency (and power output) of an alternator can be improved markedly by moving to synchronous rectification and raising the output voltage using load dump configurations. For example a 48V 100A output may improve to almost 75% or better..."
https://electronics.stackexchange.co...configurations.
I haven't checked that yet???
A 48 volt system is nice and should simplify switching modes but Lithium is expensive.
Lead Acid for the 10?? seconds of acceleration?
Other?
Maths time.