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-   -   ACTUAL home-brew EV regen braking (

bennelson 04-25-2009 09:18 AM

ACTUAL home-brew EV regen braking
I ran across this video of a CitiCar, which the owner added regenerative braking to.

The video doesn't say exactly how he had it wired up, but it appears to be an alternator that kicks on when he lets off the GO pedal.

Maybe you guys can figure out exactly how it works.

Daox 04-25-2009 09:32 AM

Yeah, it is probably just a higher output alternator. Pretty cool. :)

Matt Herring 04-25-2009 09:54 AM

Would have been interested to see Ben's facial expression (and/or sounds) when the "Don't worry about a speeding ticket" comment was made...

...And love the horn!

MetroMPG 04-25-2009 11:59 AM

Neat find, Ben.

He mentions it's from an old Cadillac (suggesting a high amp unit in its orig 12v state), but he must have modified the field so it pumps out 48+ volts.

I wonder if he's got it running off a belt to the rear axle. The orientation of it makes me think so.

Ryland 04-25-2009 04:03 PM

I think he has it running of a belt to the rear hub, he axle is inclosed, you can also adjust the output of the alternator by changing the voltage regulator.

taffy 04-27-2009 08:40 PM

Since i am building a DC EV i am interested in the feasibility of doing this. Some kind of clutch engagment, either pedal off gas or when brake is applied.
You dont want it on all the time!

Anyone have any more links to were it was done + a breakdown of how it was applied.

DonR 04-28-2009 12:24 PM

My stupid computer wouldn't let me view the video but the engagement should be easy to set up.

I know they make some 12v 300 amp alternators they put into cars with huge stereo's. How you convert it to the voltage you need is beyond me.

Similar to an alternator disconnect switch.
Have a relay that goes closed when current stops flowing through it so when you let off the throttle it engages the alternator. When you get back on the juice alternator disconnects.

If you power the relay off the brake light switch it will let you coast with out resistance. I don't know which one is better for range.

Automotive air conditioning clutches are electrically activated. Swap the pulley from an a/c compressor onto said alternator & Sha-zam.

MetroMPG 04-28-2009 12:56 PM

Coasting to a stop is ultimately more efficient than using regen to stop.

But the world isn't perfect - sometimes you misjudge and have to brake. Or there's following traffic, and you don't want to hold them up. Or you're going downhill and want to rein in your speed.

I'd love to have regen ability on the ForkenSwift. Even if it only makes a small difference (given the way I already drive to minimize brake use), it bugs me when I do have to get on the binders. Don't like converting electrons to brake dust!

MetroMPG 05-30-2009 09:18 AM

Hit the jackpot and posted a new thread with very detailed information about DIY regen with an alternator:


watt-a-mezz 05-31-2009 09:22 PM


Originally Posted by MetroMPG (Post 107135)
Hit the jackpot and posted a new thread with very detailed information about DIY regen with an alternator:


Hello. I hope this thread is still active, I did some reading about this diy regen, and I wanted to make sure I understood it(in case I want to try it.) If I had an alternator with an external voltage regulator, (like a Ford product), and I do not use the regulator,and I use GND, wire Field to 12v from the brake pedal switch, Stator not used, and Battery turns into HV wire going to main pack, would I have a simple form of regen braking, or a smoking mess? I will be using a 96v battery pack(8 12v). Also, if you do use regen, do you measure in volts or amps? Sorry it is so ong, but any feedback would be helpful. Take care, Watt:D

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