Regenerative Braking for DC Systems?

Navitas carries a controller that can do regen. So does Kelly. Beyond that, I don't know anything about doing regen. I can imagine that you may need to install a chain tensioner on top of chain so that the chain doesn't come off during regen (the bottom will go taught, and the top will go slack). And, I think installing a left foot lever to control the amount of regen would work really well because it would keep your right foot and hand free for the brakes. The clutch lever could also be used, but I think it's better to run that to some type of disconnect that cuts the power for safety.

Anyway, I think regen is a great idea. I'd have done it, but it's not possible with the way my bike is set up.

hey Todd, how's the bike?

As far as regen, yeah, Kelly, navitas... or go AC.

electricmotorsport.com has some AC stuff.

I've got a sepex controller (that GE I scored) its 72V, but you need a seperately excited motor.

electricmotorsport has spex controllers and motors, starting around $1000

http://www.electricmotorsport.com/store/ems_ev_parts_motors_sepex.php

I'm actually going to buy one of the motors if its compatible with my GE... regen on a bike would be cool.

This subject comes up every few months so here is the truth about regen on light (less than 1000 pounds) vehicles. You get more distance by learning how to coast than you will ever get from regen. The amount of energy that can be can put back into the batteries is very small and you might get an extra 500 feet range using regen on light vehicles. Regen is NOT worth the expense, time or trouble.

Grandpa Chas S.

I can agree with Chas... for a 500lb bike, you'd be better off in putting more batteries in, or longer lasting batteries, than you'd ever get off of regen. There's just not enough weight, and furthermore, not enough current flow back into the batteries.

But the Oxygen Lepton scooters, have regen, and it rides so well. I think its AC, and boy is it cool to let off the throttle, its like downshifting.

It can be gotten with some money, but to what degree of functionality? And expense of controller/motor?

you can go sepex, for under 1500 for a replacement motor/controller, then sell the motor/controller you got. It'l instantly get you regen, and get you some higher speeds, because it can field weaken. Just don't expect alot out of range, its going to do more for stop/go though.

And as someone said above, you'll need to make sure you've adjusted the chain well, because if its slack, it'l slap back when you take load off and try to break. It'l also wear that aluminum rear sprocket quicker... but not by much.

This subject comes up every few months so here is the truth about regen on light (less than 1000 pounds) vehicles. You get more distance by learning how to coast than you will ever get from regen. The amount of energy that can be can put back into the batteries is very small and you might get an extra 500 feet range using regen on light vehicles. Regen is NOT worth the expense, time or trouble.

I have to disagree, and agree at the same time.

I did some calculations for the Vectrix at 320 kg total weight using regen to stop from 100 km/h (or 62 mph).
Regenerative Breaking. I calculated 14.9 whrs recoverable when using regen to stop from 100 km/hr once (all inefficiencies included), or .11 to .18 (581 to 950 ft) range recovered.

I agree that learning how to coast is valuable, but it can also be dangerous. It made me do stupid things sometimes. I remember riding my families renault. We would sometimes really stretch going through the lights (hoping they would hold yellow) because we were afraid that we wouldn't have charge to make it! Regen would have been nice to recover a good portion of that energy, and avoid the risk of an accident.

Also, sometimes it made us drive real slow making others on the road angry. Not good.

It is not good practice to either be on the throttle or using regen all of the time. This is the way some systems may be setup, where the regen kicks on once you let off the throttle. That's how my brothers truck was setup, and it was kind of annoying because it made it more difficult to coast. It is much better to coast whenever possible, and only use the regen when you would otherwise be using the brakes.

for a 500lb bike, you'd be better off in putting more batteries in

I have to disagree. More batteries adds weight, where regen can potentially add a significant amount of range without adding any weight.

I think it depends a lot on how fast you ride, and where you are riding. If it's out in the country on level ground at 25, than sure regen is totally useless. But if your in a very hilly area, and/or high speed in the city with stop lights to worry about than I think regen can definitely help. Just think, how much are you using the brakes? How hot does your brake rotor get? Mine get's pretty darn hot, it'll burn me if I touch it after stopping like once. That's a lot of wasted energy that can be recovered. And lead-acid AGMs are very efficient at taking charge, so they will work very well for regen (for instance, probably not too far from twice as efficient as the NiMH for the Vectrix, and my calculation was with that inefficiency included).

I did some calculations for the Vectrix at 320 kg total weight using regen to stop from 100 km/h (or 62 mph). Regenerative Breaking. I calculated 14.9 whrs recoverable when using regen to stop from 100 km/hr once (all inefficiencies included), or .11 to .18 (581 to 950 ft) range recovered.

First I think you all have some points about regen but I think Andrew made mine for me. I will use his larger figure of 950 Feet (.18 miles, .29 km) now at 100 kph (62 mph) how far do you think You could coast a 320 kg (705 pound) 2 wheeled vehicle? I would guess about 3 times 950 feet. So as you can see what I said is correct, learn to coast for a while before you hit the brakes and you will save just as much as Regen, possibly more, and save money by not spending it on this worthless ability.

As for putting in more batteries - I have done this with an e-bike and the extra weight I added makes it coast farther. Adding the extra battery also allows me to go faster, and adds to the total watt hours of the pack giving me more range. So I would say adding batteries is a good thing, however I do believe there comes a time of diminishing returns if too many batteries are added. Of course the other side of adding the extra weight is the e-bike does not travel up hill any better or worse and it is more weight to peddle when you are not using the motor.

Grandpa Chas S.

I did some calculations for the Vectrix at 320 kg total weight using regen to stop from 100 km/h (or 62 mph).
Regenerative Breaking. I calculated 14.9 whrs recoverable when using regen to stop from 100 km/hr once (all inefficiencies included), or .11 to .18 (581 to 950 ft) range recovered.

I heard that the Vetrix regen system uses only one of three phases to actually charge the batteries.
The other two phases are somehow used to make the breaking force adjustable.

I'm not quite clear about the physics of this...

Mr. Mik