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Regen braking on 2 wheel EVs - a good idea or just fluff?
Submitted by jdh2550_1 on Mon, 08/11/2008 - 14:46.
Over on another (very long) thread regen (and the lack of it) was being discussed. In order to stop that thread getting way too long I'm starting another thread here...
Mik, if you read this do you have any tests showing how much regen can extend the range of your Vectrix?
http://visforvoltage.org/forum/2547-vectrix-reports#comment-14284
http://visforvoltage.org/forum/2547-vectrix-reports#comment-14331
There are some more that I cannot find right now.
Overall, in my regular commute the difference is hard to detect.
But Regen makes a good ABS for the rear wheel!
I would definitely not want a "Binary", "All-or-nothing" Regen system.
Mr. Mik
Mik - I agree a binary regen is not a good option.
However, I'm curious as to your comment about ABS. Does the regen really make an anti-lock braking system? Isn't it just another braking force and thus could lock up the wheel if applied too quickly? Or is there some form of override to prevent lockup?
I've now heard of three benefits of regen:
1) Range extender. This appears to not pan out in the real world for either the Vectrix or when implemented on the XM bikes. Is it that these implementations of regen are sub-optimal or that it's just not possible to regain enough energy?
2) Save on brake pad wear. Does anyone care to quantify this? It seems like the savings would be pretty insignificant. Do folks agree or disagree?
3) As a good ABS for the rear wheel. See questions above. I'm not sure it's really ABS rather than a smoothly applied brake. If it's the latter then is it still worth it as an addition?
Am I missing other possible benefits?
(Note for the skeptics out there I'm not trying to apologize for it's absence from the XM line, I'm trying to figure out if it's worth adding as a feature for the "ideal" 2 wheel EV. I'm interested in hearing folks' opinion on whether they want regen or not)
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| John H. | Ann Arbor, MI, USA (Summer is over - I wonder what next season will bring?) |
| My bikes | XM-3000 & XM-2000 (for sale) (small, SLA powered moped), CB-750 84V (big, SLA powered motorcycle conversion) |
| My business | rEVolution Electric Vehicles, LLC - X-Treme electric bike, moped and motorcycle sales |
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Re: Regen braking on 2 wheel EVs - a good idea or just fluff?
For regen to work, the wheels must still be turning.
it is not however automatic ABS.
it is possible for regen to cause the wheels to turn slower than they should be for a given speed.
The result is similar to locked up wheels, even though they're still turning.
If the regen does cause the wheels to lock up completely, the regen torque will disappear, and the wheel may start to rotate again, but it still wont reach the correct rotational speed.
Matt
Re: Regen braking on 2 wheel EVs - a good idea or just fluff?
I found it:
At the link below is much more on the subject, including explanation of the regen-brake-ABS behaviour:
http://visforvoltage.org/forum/3369-vectrix-real-world-regen-braking-testing
Mr. Mik
------------If this is part of a closed thread but you want to comment please do so via my blog!
There is always a way if there is no other way!
Re: Regen braking on 2 wheel EVs - a good idea or just fluff?
In my opinion, it sort of gets a thumbs up by default. Saving on brake wear via motor braking is nice, and why just throw that energy away to a heating coil instead of putting it back into the battery?
You don't really see much of an increase in range, of course, but, hey, it might save you from having to push your bike that last mile back.
However, if the system ends up costing you much more than one without it would, then it's no big deal to not have it.
------------The author of this post isn't responsible for any injury, disability or dismemberment, death, financial loss, illness, addiction, hereditary disease, or any other undesirable consequence or general misfortune resulting from use of the "information" contained herein.
Re: Regen braking on 2 wheel EVs - a good idea or just fluff?
In my opinion, it sort of gets a thumbs up by default. Saving on brake wear via motor braking is nice, and why just throw that energy away to a heating coil instead of putting it back into the battery?
You don't really see much of an increase in range, of course, but, hey, it might save you from having to push your bike that last mile back.
However, if the system ends up costing you much more than one without it would, then it's no big deal to not have it.
I agree. Regen should be used, even if it is only to increase experience and expertise in building it in. Undoubtedly it will be a central feature of advanced vehicles, particularly aerodynamically sensible ones...
About the above link to the Vectrix regen braking thread: http://visforvoltage.org/forum/3369-vectrix-real-world-regen-braking-testing
My summary back then on regen:
It appears to me that the effect of regen braking is not large enough to make it easily detectable amongst the variables that the real world conditions keep shuffling.
(These are road and traffic conditions, ambient temperature, wind, battery voltage and temperature and rider behavior, tire pressure etc. etc.)
.
To be relatively certain about the effect a larger number of rides is needed.
This I can only do as part of my usual commute, which strongly increases the influence that traffic volumes have on the results.
.
I have already done many commutes using regen braking almost exclusively, and because I usually make it home with full power but very little range left, I should be able to determine if it makes a real world difference.
After all, that test ride I just did four times is not what I would usually be doing - it's just for fun when I have some time!
.
If regen braking is adding between 5-12% range, then I should frequently arrive home from my commute with less than full power if I do not use regen braking.
I shall try that out...
No, I shall not try that out!
Because I can now charge at work, and know more about Ni-MH battery treatment, I'll avoid frequent deep discharges and frequent full charges by using the ABCool 12V power supply to semi-automatically keep the Vectux battery between 25% and 90% charge level, and as cool as reasonably possible.
Todays summary on regen:
If you have a heavy vehicle, with a range only just enough to get you where you need to go, and hilly or mountainous terrain, then regen braking is very useful because it avoids having to push your heavy vehicle up those hills.....
If you have a light vehicle with high wind resistance, flat terrain, and more range than you usually need, then regen breaking is next to useless.
A very heavy rider will also get more out of regen than a very light rider, at least if it is hilly.
Mr. Mik
------------If this is part of a closed thread but you want to comment please do so via my blog!
There is always a way if there is no other way!
Re: Regen braking on 2 wheel EVs - a good idea or just fluff?
I added some relevant info at the below link:
http://visforvoltage.org/forum/3369-vectrix-real-world-regen-braking-testing#comment-26120
Mr. Mik
------------If this is part of a closed thread but you want to comment please do so via my blog!
There is always a way if there is no other way!
Re: Regen braking on 2 wheel EVs - a good idea or just fluff?
I would definitely not want a "Binary", "All-or-nothing" Regen system.
Mr. Mik
Mik - I agree a binary regen is not a good option
I have fixed/binary regen on my Z20 via the Kelly controller. Although binary, it can be setup to brake at different levels. Mine is set at 60%, but I could change it higher or lower via a pot. It's activated on the same circuit as the brake light, so a light pull on the front or rear brake lever will activate regen. I don't find the fixed level to be a problem at all. I usually anticipate my stops, and will try to start braking such that most of the speed reduction comes from the regen braking. If I ever need more stopping power, I just squeeze the levers harder. There is no mental switch to be made like there is on the Vectrix. I've never driven a Vectrix, but their regen control method of turning the throttle backward sounds goofy to me. Given the choice between a fixed/binary regen braking level with no increased complexity in controls, and the Vectrix method, I'd pick the binary approach.
I've become interested in the Vectrix lately, and their regen controls is one of the things keeping me away from buying. People actually swap the front brake over to the left side to partially get around this. No Thanks.
Regen probably does not add significanty to range, but I like having it anyway. The difference in cost for the Kelly controller is $30 (KEB72601), plus $5 in parts if you want to use a pot to be able to vary the regen level. That's worth it to me - I'm guessing that with careful application, you could double the time between brake pad replacement. Hey, maybe it will help resale value too!
------------Z20b
Fort Collins, CO