Is REGEN, really worth it ?

General Discussion about electric bicycles.
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Chalo
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Re: Is REGEN, really worth it ?

Post by Chalo » Apr 15, 2018 10:58 pm

Bicycles that drag are a drag, is all. John rides motorcycles, and has different priorities.
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Re: Is REGEN, really worth it ?

Post by John in CR » Apr 16, 2018 8:43 am

Chalo wrote:
Apr 15, 2018 10:58 pm
Bicycles that drag are a drag, is all. John rides motorcycles, and has different priorities.
Any bike with a motor is technically a motorcycle, and anything you ride on with 2 inline wheels is technically a bicycle. If you want to talk about arbitrary legal definitions then it depends on where you are, and the definitions vary widely. While my more recent high power ebikes would need registration and plates in much of the world but thankfully no here, the benefits of regen are the same, and those are:
1. Recovering some of the kinetic energy produced by the electric drive, and putting it back in the battery instead of wasting it as heat dissipated to the outside world. There is no valid argument against increased efficiency, and the only way any ebike won't be more efficient without regen is if the ebike is just a bicycle with electric assist and the primary drive is leg power. Only then would the added drag of a motor capable of regen be a negative in terms of efficiency.
2. Reduced maintenance time and cost- I use my ebikes as primary transportation, and want them to be absolutely reliable and as trouble free and convenient as possible. Just put the key in and go, and plug in to charge upon arrival, so it's always ready to go. I put lots of time into builds, but once finished I hate fiddling with them. Despite the lower traction I even opt for longest wear bicycle tires. Most builds though I use motorcycle tires, despite the greater rolling resistance, because they result in far fewer flats and in every case so far I've been able to ride the flat home or to a tire shop for repair. That means no carrying tools or tubes on my rides, and never getting stuck in the hot sun or rain dealing with a flat.
3. Increased safety- Having fresher and cooler mechanical brakes for emergency stops is always a good thing, especially going fast or down hills.

BTW, my ebike where I've noted regen regen recovery rates of 20-25% on a regular basis is just as much a bicycle as any on the forum even by Chalo's very prejudiced definitions. It's got functional pedals that I use to assist the motor on every ride. Sure it's a drag to ride if I run out of juice, but in 10 years of service that happened only once. That was back when I knew almost nothing and miscalculated how much battery to carry for a 80 mile ride, and I came up just a mile short. I had no Cycle Analyst back then to know my battery pack's status, but had I taken a bit more time for lunch and opportunity charge, the motor drag during pedal only operation would be a 100% non-issue for 10 years. I sometimes use the motor drag for some extra exercise. I tried pedaling against regen once, but that was a bit too intense of a workout...I'm by no means a cyclist though I am an ebiker through and through.

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Re: Is REGEN, really worth it ?

Post by John and Cecil » Apr 16, 2018 9:02 am

Clutch = no drag. Someone needs to step up and design a new motor :) For an "e-motorcycle" type bicycle perhaps a mid drive electric motor with a clutch and perhaps even a gearbox. Then you can have your regen, or pull in the clutch and you have no drag. I guess weight is a factor but if someone is going to be carrying a lot of batteries it may make sense.

I am glad people are sharing opinions from both sides :) I think eventually I would like 2 bikes. One heavy duty with extended range and regen and the other lighter with less batteries and no drag.

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Re: Is REGEN, really worth it ?

Post by AWD » Apr 16, 2018 9:45 am

The Magic Pie Golden motor I used on a bob trailer years ago had a lot of drag while not under power and although the system worked well enough in general as a cyclist it was an issue for me as others have noted and kept DD motors off my radar while looking at the best system for my needs.

After looking at geared hub motors more closely I couldn't live with the noise they make nor the possibility of melting gears. I decided to go with a 9c with statorade for a front hub build and I was pleasantly surprised that it showed little to no parasitic drag upon completing the build. Sure I notice the weight of the heavier overall bike but at least it doesn't feel like the front brake is on unless I apply regen of course.

Emboldened by this I built another similar bike with a Grin AnyAxle front hub motor attracted mainly by it's lighter weight and ability to use different axle types. After dealing with the 9c's nutted front axle and the need to carry a large enough wrench to remove it on the road in case of a flat and the overall cumbersome wheel removal with the AA motor I am able to just unplug the wires and remove it without any tools. I still only use a standard quick release system as I haven't found a thru axle fork yet to meet my needs that is affordable but the way the torque arm is built into the AA motor has proven to be enough to hold it all together. All I need to do to drop the front wheel now is to undo the connectors and flip the QR and it comes right out easily. But in the 2500 miles I have on it never once has it displayed any movement in the drops while under power or regen.

Grin's site claims that the AA may be louder due to the casing being thinner to achieve lighter weight but I have not found this to be the case at all. In fact it is quieter than the 9c which produces a light whir while under power and the AA does not have any noticeable noise. The AA is running Statorade as well and it has absolutely 0 drag which along with the capacity for regen has me pretty much sold on the concept.

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Re: Is REGEN, really worth it ?

Post by craneplaneguy » Apr 16, 2018 11:32 am

After two years of driving the PluginPrius, I still giggle about every time I come to a full stop, and watch the EV range click up a couple tenths of a mile. I'm averaging high 50's mpg, without even trying hard, thanks to regen.

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Re: Is REGEN, really worth it ?

Post by Chalo » Apr 16, 2018 2:15 pm

craneplaneguy wrote:
Apr 16, 2018 11:32 am
After two years of driving the PluginPrius, I still giggle about every time I come to a full stop, and watch the EV range click up a couple tenths of a mile. I'm averaging high 50's mpg, without even trying hard, thanks to regen.
In the meantime, even stinking two stroke gas bikers are doubling or tripling that mileage, by not having so much inertia and drag.

Easier than recovering energy is not spending it to begin with. Not spinning a motor when you're not using it is one ingredient of not spending unnecessary energy. It works best when combined with other efficiencies like low speed, light weight, and low rolling resistance. But once you throw away those other energy saving opportunities-- sure, regen is probably better than coasting. Tanks don't coast very well anyway.
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Re: Is REGEN, really worth it ?

Post by amberwolf » Apr 16, 2018 2:45 pm

John and Cecil wrote:
Apr 16, 2018 9:02 am
Clutch = no drag. Someone needs to step up and design a new motor :) For an "e-motorcycle" type bicycle perhaps a mid drive electric motor with a clutch and perhaps even a gearbox. Then you can have your regen, or pull in the clutch and you have no drag.
Several years back, Thud did a 2speed dog-clutch shifter that could also have been modified to use a neutral center. Was designed to use with RC motors, IIRC, as a leftside middrive, so if no freewheel was used at the rear wheel or motor, then it could also do regen.

There have been discussions on a manually-clutched geared hubmotor, using a cable or solenoid to switch it from freewheeling to locked. Dunno if anyone ever made one, though.

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Re: Is REGEN, really worth it ?

Post by lester12483 » Apr 18, 2018 7:21 am

From my experience regen is not worth it. Having to carry the extra weight put more stress on the wheel spokes.
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Re: Is REGEN, really worth it ?

Post by miro13car » Apr 18, 2018 7:37 am

what extra weight?

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Re: Is REGEN, really worth it ?

Post by John and Cecil » Apr 18, 2018 8:37 am

The place where you are riding really effects this discussion. We went on a bike trail the other day. It was a very slight upgrade that went on for a few of miles. We rode up the very slight grade at 10mph, then coasted all the way back down at 10-20mph with almost no pedaling at all. We got over 12 miles out of our 2ah battery that day. Chalo has a point about low rolling resistance, especially in situations where you are riding up and down very slight inclines/declines. But if you are using your brakes a lot and wasting energy the regen is obviously going to be much more helpful.

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Re: Is REGEN, really worth it ?

Post by Alan B » Apr 18, 2018 9:28 am

Regen is basically a little firmware on a DD system. Pretty weightless.

If you are talking about geared vs DD hubmotors then the weight difference is due to a lot of factors, not just regen.

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Re: Is REGEN, really worth it ?

Post by Ianhill » Apr 18, 2018 9:38 am

If I spin my back wheel while it on the stand with a mxus 3k dd hub and spin that wheel with all my might It will spin for say 10 seconds max then stop due to the magnetic Linkage, when I peddle the bike with me on it on the flat it rolls decent enough it's much less than a rubbing brake but it's there, if I spin the wheel on my peddle only bike it spins for minutes easy and the wind alone can push me so there's added drag no doubt.

This is only a small downside of the DD hub it's not going to hypermile like a bosch or shimano system or even a bafang but you will have a instant throttle response no pawls in a freewheel to engage or slack in the chain etc just silent and violent.

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Re: Is REGEN, really worth it ?

Post by Chalo » Apr 18, 2018 2:58 pm

miro13car wrote:
Apr 18, 2018 7:37 am
what extra weight?
A direct drive motor is heavier than a gear reduced free overrunning motor, all else equal. A battery that can store regen energy on demand is necessarily bigger and heavier than a battery sized only for the drive load, all else equal.
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Re: Is REGEN, really worth it ?

Post by Alan B » Apr 18, 2018 3:38 pm

Chalo wrote:
Apr 18, 2018 2:58 pm
miro13car wrote:
Apr 18, 2018 7:37 am
what extra weight?
A direct drive motor is heavier than a gear reduced free overrunning motor, all else equal. A battery that can store regen energy on demand is necessarily bigger and heavier than a battery sized only for the drive load, all else equal.
Apples to oranges. Geared hubs can have regen (leave out the fragile clutch), and there are many other differences between the motors. So the comparison is not straightforward. There are also some very lightweight DD motors.

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Re: Is REGEN, really worth it ?

Post by amberwolf » Apr 18, 2018 9:39 pm

and if you use cells that can accept higher charge rates, theres n8t necessarily any weight penalty there either.

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Re: Is REGEN, really worth it ?

Post by Chalo » Apr 19, 2018 1:15 am

Alan B wrote:
Apr 18, 2018 3:38 pm
Chalo wrote:
Apr 18, 2018 2:58 pm
A direct drive motor is heavier than a gear reduced free overrunning motor, all else equal. A battery that can store regen energy on demand is necessarily bigger and heavier than a battery sized only for the drive load, all else equal.
Apples to oranges. Geared hubs can have regen (leave out the fragile clutch), and there are many other differences between the motors. So the comparison is not straightforward. There are also some very lightweight DD motors.
I specified "all else equal". Pound for pound, no DD hub is the equal of a gear reduced motor.

If it made sense to leave out the overrunning clutch, don't you think more geared motors would come set up that way?

Apropos AW's assertion about batteries-- high current batteries aren't equal in energy density or cost to those with lower ampacity.

So to have regen, you don't only have to accept all-the-time drag. You also have to pay more, weigh more, or live with lower performance-- or some combination of the above. The compromises might be acceptable to you, or not, but they are part of the deal if you choose regen.
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Re: Is REGEN, really worth it ?

Post by MadRhino » Apr 20, 2018 1:51 am

Low power and speed, doesn’t make you feel like you need regen anyway. Accepting the extra weight of a dd hub, is then more about reliability than regen ability.

Riding a fast bike does make it interesting, to improve braking and/or efficiency.

Those who are riding light weight performance, and willing to pay for the best brakes, generally prefer a momentary switch because they are using the brakes most of the time, and regen only in some conditions where it does improve their braking distance.

Those riding fast and heavy, usually prefer using regen all the time. When they feel the need to improve, they start using controllers that have advanced regen features, to have a better control and efficiency of regen braking.

It would be easy to build mid drives with regen ability, but this would add moving parts and maintenance to a system that has a lot already. It does make sense better, on motorcycles that have a transmission and a clutch.
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Re: Is REGEN, really worth it ?

Post by Alan B » Apr 20, 2018 10:35 am

Looking at Regen alone isn't the whole question, unless you already have a DD motored bike, and are considering using DD or not there. The OP wasn't clear on this in the initial post. The initial poster, rumme, has made no other clarifications or comments in the thread that I found.

Geared motors are less reliable and the lifetime cost with maintenance is significantly higher. More moving parts, more wear, and nearly guaranteed failure long before a DD wears out. So comparing DD to Geared based on only Regen is viewing one parameter of a multiple parameter change. One needs to look at the "big picture" when making choices and consider all the factors. Let's list some of those other factors.

Motor Selection Factors

What is your application - is this a commuter application, or a for-fun role?
How important is reliability and longevity?
How important is low maintenance?
How important is ease of maintenance? Some motors require removing wheel spokes to service the motor.
What is the cost of downtime, waiting for parts?
Will you have a second ebike or spare motor wheel or parts inventory?
How important is each factor below to the application?

Reliability - how long between failures, and how big a problem is a failure (Can you be late to work or other destinations?)
Maintenance - how often disassembly is required to re-grease or replace gears
Parts Availability and cost, and shipping costs and delays? Will it be necessary to keep spares on hand?
Power handling and Heat dissipation - how much power will it handle
Torque provided vs torque required for climbing or acceleration, and how much current does this require?
Speed - how fast will it go, and on what voltage?
Noise - how quiet is the drive, and how much does this affect stealth and annoy the user?
Drag - how much drag does it present when powered off and how much does this matter (if terrain is not flat it's hard to notice DD drag)
Size (diameter) and the effects this has on stealth
Weight
Width and Gear compatibility (rear wheel application)
Disc brake compatibility
Front or Rear wheel mounting
Difficulty to incorporate into the bike - impacts on gears, brakes, handling reaction torque, etc
Difficulty to change tires
Initial cost, shipping cost and delay, Wheel build, spokes, etc
Lifetime longevity - how long before it needs to be replaced - in years and/or distance
Lifetime cost including maintenance effort, supplies, tools and replacement parts
Regen and brake maintenance, additional range and safety due to improved braking and reduced wear
Controller and battery requirements

Selecting between Geared and Direct Drive hubmotors changes almost everything. Looking only at Regen is closing one's eyes to everything else.

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stop huffin

Post by Toorbough ULL-Zeveigh » Apr 21, 2018 5:07 pm

Chalo wrote:
Apr 19, 2018 1:15 am
I specified "all else equal".
just like the confidence-man who specifies "trust me"
you both know you're full of it trying to sell a lie.

in aspects where gearing has the clear advantage you make the direct comparison.
in the reverse case where dd shines "oh, we need to tie one hand behind its back" & make a normalized comparison.

you really need to stop cheezing
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Re: stop huffin

Post by Chalo » Apr 21, 2018 5:16 pm

Toorbough ULL-Zeveigh wrote:
Apr 21, 2018 5:07 pm
[tripe]
Once again posting nothing of value, probably while drunk. Congrats, you now own the second ever spot on my STFU list. You can chat with Dauntless over there.
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Re: Is REGEN, really worth it ?

Post by Toorbough ULL-Zeveigh » Apr 21, 2018 9:56 pm

Chalo wrote:
Apr 21, 2018 5:16 pm
Congrats, you now own the second ever spot on my STFU list.
badge of honour
Chalo wrote:
Apr 15, 2018 10:58 pm
Bicycles that drag are a drag, is all.

of course ubee talkin phatbykes :lol:
because a dd hub motor drags less than that.
and your solution is to let air out of the tires for even more drag. :pancake:
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Re: Is REGEN, really worth it ?

Post by rumme » Apr 22, 2018 6:19 pm

Well there is one more important aspect that doesn't get mentioned much. This applies to my situation.

Im using a LYEN controller and I can use a momentary on off switch to engage the REGEN on my controller, so it only kicks on when it is best suited to create energy { going downhills...this would not be brake regen, but motor regen using the magnets/motor for the extra resistance} .

In my location, the route I always take, has all the STEEP decline roads { 4 of them} going towards my destination and when I am coming home, there arent any steep roads, declines that are worthy of using regen.

This basically means, my regular route has no real benefits for the use of REGEN, because when I start my commute, my battery is fully charged at 80- 84 volts....and I dont need REGEN then . I need the regen coming home, when the battery voltage is below 75 volts but it is then, that those 4 steep roads have to be ascended instead of descended , which cancels out the use of regen. The rest of the commute home is basically road and 4 steep hills I need to go up.

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Re: Is REGEN, really worth it ?

Post by Ianhill » Apr 23, 2018 4:30 am

Rumme.
Save yourself some time and money by only charging to 80% then make your trip to top up the rest while on the way to your initial destination, then return with 90% etc.

Free energy is not to be scoffed at if there's ways of making it work for yourself to higher the speed carried and improve trip times etc.

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Re: Is REGEN, really worth it ?

Post by Alan B » Apr 23, 2018 5:17 am

In the case of living on a hill and descending first, regen will not be available for this initial descent unless charging is reduced below 100%. But every other hill on the trip would be fine.

As was suggested, charging to slightly lower max voltage, which is often done just for battery life, would allow regen to be used even on this first hill.

Using an adjustable charger would easily handle the situation.

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