[RedDevil]

Originally Posted by James O'Neill

Alright, I see your points on the drive shaft alternator not working when the car isn't moving.
But in EVs there are no traditional alternators on the count that they use more power than they generate. So what if you build an alternator around the drive shaft on EVs and hybrids? Would this be an efficient way to generate power to recharge the batteries?

You can never generate more power than you put in!
Hybrids and EVs use their motor as an alternator on braking, a fairly efficient one at that too. There is no need for another alternator.

As a hybrid owner I can tell you there are many more opportunities to use the hybrid battery's power than to regenerate power towards it. So in practice it spends a lot of time mildly charging the battery, at the cost of a somewhat higher temporary fuel consumption.

I am building a parallel hybrid battery pack to charge at home and constantly feed the system while driving, so it does away with the recharge while driving and will use EV mode and acceleration support more.

In a non hybrid you can gain maybe 10% by removing the alternator and lead acid battery, replacing the latter with a big lithium 12V battery to be charged at home.
You can have 3 times the capacity of the lead acid battery and still have less weight, especially without the alternator.

Or you can just disconnect the alternator with a smaller battery and reattach it when you suspect the battery is getting low, like on long trips.
A LiFePO4 battery does not suffer from being discharged over its entire range, as long as you do not deplete it completely.