DIY Electric Car Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
168 Posts
Discussion Starter #1
I release that alternators are not as useful as they would seem due to law of conservation of energy, but what if you could rig something to only kick the alternators in while decelerating/engine braking ('throttle' at zero). Certainly possible to rig up, and would recoup a little energy while decelerating but I am not sure how much.

Has this been done?
 

·
Registered
Joined
·
141 Posts
I release that alternators are not as useful as they would seem due to law of conservation of energy, but what if you could rig something to only kick the alternators in while decelerating/engine braking ('throttle' at zero). Certainly possible to rig up, and would recoup a little energy while decelerating but I am not sure how much.

Has this been done?
Yes, this has been done. I can't find the link but there is a S10 conversion in Idaho I think that uses an AC clutch to engage an alternator for regen braking. The alternator was reround to output a DC voltage high enough to charge the traction pack. It is a good way to get regen while using a series wound DC motor, but it is a fairly major hack.
 

·
Registered
Joined
·
509 Posts
With the right alternator you should be able to de-energize the field while running so there's no output. One issue is that the 12volt negative (alternator ground) should not be connected to the pack negative.
 

·
Registered
Joined
·
39 Posts
http://www.waynesev.com/ev/regeneration.html

I have looked into this idea, but instead of using a switch on the shifter, I would use a normally open switch on the brakes and normally closed on the accelerator. That way the clutch for the alternator will only engage when there is no pressure on the accelerator and the brakes are on. It allows for normal "coasting" when you want and only applies the regenerative brakes when the real brakes are applied.

I will have to upgrade my motor first to a twin shaft motor first. I am wondering how an over charge protection circuit would run though? But this system makes sense, probably makes a huge draw on the system too, braking well!
 

·
Registered
Joined
·
74 Posts
Why would you need a clutch at all?

The alternator is basically a three phase generator (which would anyway need re-winding or boosting up to a usable charge voltage) plus rectifier and a separately excited rotor winding. Vary the rotor field (fairly simple DC current control) to vary the braking torque. No field, no drag, no clutch needed, cleaner simpler build.

What's the rated power output of a big automotive alternator, not a lot anyway.
 
1 - 11 of 11 Posts
Top