# Alternator Idea



## Lordwacky (Jan 28, 2009)

omonoid said:


> 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.


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## omonoid (Aug 30, 2009)

Yeah sounds a bit too complicated for my first conversion


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## Sunking (Aug 10, 2009)

Regenerative braking comes to mind.


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## omonoid (Aug 30, 2009)

Sunking said:


> Regenerative braking comes to mind.


Yeah i guess thats basically what i described


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## Frank (Dec 6, 2008)

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.


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## CroDriver (Jan 8, 2009)

I believe that new BMWs are doing something similar to charge the SLI battery...


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## DavidDymaxion (Dec 1, 2008)

Google on "Roland Wiench" he is a fan of using an alternator for a bit of regen.

If you don't care about speed, you can get a Kostov sepex motor and a Kelly sepex controller that'll give you regen, for about the same price as series. Caveat: I love my sepex Kostov motor but can't vouch for Kelly myself.


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## hans j (Mar 31, 2008)

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!


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## omonoid (Aug 30, 2009)

wow amazing


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## jk1981 (Nov 12, 2010)

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.


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