Reinventing the Alternator

[Frank Lee]

You still have a system where you are using horsepower to generate electricity. The only time it makes sense is for regen braking, and they use other systems for that.

[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.

[ksa8907]

The answer we're all looking for is charging at a higher voltage and stepping the voltage down to 12v. That way you dont have to reinvent every electrical component in the vehicle and you get the efficiency of high(er) voltage generation.

[Isaac Zackary]

Reinventing the alternator?

One idea I had was to get a high amp alternator and hook it up so that it doesn't charge until either 1) you let your foot off the accelerator pedal or 2) the battery is near dead.

I got the idea from the hybrid systems, and as a way of making a city car more efficient. When you let your foot off the accelerator chances are you are going to be slowing down. The high amp alternator would kick in and not only rapidly charge the battery but also help slow down the vehicle. If you come to a stop and idle it would be charging and putting that normally wasted fuel to use. But as you drive around it would be turned off and not charging unless your battery level reaches a low threshold.

[pete c]

Mazda is doing exactly that. They are using caps to store the power as a cap can accept a large charge quickly.

I think what we will see in the near future is a variation on what honda did with the Insight years ago. They may not use the same pancake configuration. They could simply go with a much heavier duty bolt on alternator that runs at a considerably higher voltage. I believe they are currently looking at 48V systems.

Such a system could eliminate a separate starter. Also, going with 48 volts means lighter wiring and better efficiency all around. Once such a system is used on a mass scale, it would not be that much more expensive than today's charging systems.

[mazdamx640]

http://www.performanceboats.com/part...6/topics/12876

[James O'Neill]

Originally Posted by RedDevil

You can never generate more power than you put in!
.

Doesn't an alternator use some of the power it generates to power the electromagnet??
If so, then it makes more power than it uses.
It might not make more power than it uses from the engine, but still, just an example.

[RedDevil]

Generate and reuse internally, in that sense. Yup, true.
The net yield will always be lower than 100%.