Is regenerative braking really worth anything?

[ZeroEm]

Check out Mrbill's website
https://mrbill.homeip.net/bikeBlog.php?latest

GPS track: GPX
Bike Ridden: Power Gold Rush
Distance: 107.3 miles
Cumulative climbing: 11000 feet
Total Time: 5:59:55
Riding Time: 5:29:03
Avg. Speed (moving): 19.5 mph
Max. Speed: 28.7 mph
Nominal System Voltage: 48
Battery energy available: 2400 wh
Battery energy consumed: 2155 wh
Net battery energy consumed: 1320 wh
Wh/mi: 12.3
Battery Amps-Hour Used: 41.4
Regen Amps-Hour Recovered: 16.1
Peak Forward Current: 23.5 Amps
Peak Regen Current: 30.3 Amps
Peak Motor Temperature: 88.1 C
Average Motor Temperature: 49.2 C

This is a man who get's the most out of regen. Over 700w in one ride. I think he stayed on the road and uses areo mods that are also not used in off road.

Sounds like if you don't do much road riding then regen is a waste of your time. As far as being hard to setup it's not, my trike did not come with rear brakes and it would be silly to spend money to add rear brakes that would only skid and ware out my rear tire and regen would be the sane and logical choice for a rear break.

So it seems that regen is more for road bikes and those who can reap the benefits.

 

[pwd]

Regen braking is very valuable to me. I am using two dd hub motors and frequently ride around with traffic at approximately 55-60 kmph. Regen drastically improves my stopping distance and I'm sure I save a lot of wear on the pads. I treat it like engine braking. I don't really use it for the energy recovery but it is a nice bonus (I tend to re-coup 3-6%). For the record I'm using fixed regen with separate front and rear regen.

 

[john61ct]

My understanding is that CA grossly overstates actual usable energy recovery.

A series of A-B tests over the same route, actual mileage gained with an automated LVC set lower than usual would be the way to go IMO.

The actual %gain number being unique to each route of course.

Again, to me that factor is practically irrelevant, the added braking capabilities for long descents and heavy loads is the compelling benefit.

In many landscapes big enough a rig absolutely essential for safety

in some, well worth it just for savings in replacing pads

in others at light weights, completely unnecessary.

 

[2old]

No one saying anything about a panacea, your use of that term shows bad faith.

And the question is not one of belief nor opinion, easily tested for any given scenario.

As stated, it can be a very valuable feature for those with those certain factors & use cases that make it so.

In fact as OP made clear, there are example use cases where it becomes an essential feature.

Those without a need for regen are better off leaving it out.

And of course, many people have drunk the koolaid and overestimate its benefits.

The "green" and "free energy" tropes are certainly not valid reasons IMO.

But not reason to throw the baby out with the bathwater.

Maybe you should improve your vocabulary and attempt to understand what is stated. My main point was that for my purposes as a bicyclist-oriented e-rider (relatively low power, light bike), it wouldn't be beneficial, while for others it solved a lot of considerations. BTW, your use of an idiomatic expression is so trite and exaggerated that is's ludicrous.

 

[donn]

According to my CA I'm getting 14-16% back from regen, but it's very steep here, next to no flat ground.

That's really 12 to 14%, if you discount CA regen, and I'm pretty sure you should. It's overstated, though not "grossly". The problem is that they divide the regen watts by the net watts instead of the forward watts, so they're kind of double-counting the regen. If some impossible scenario that would have to take place on the moon gave you perfect regeneration off all your downhill potential energy, we'd expect to look at the monitor and see 100% regen, but CA would either say it's infinite or die on the divide-by-zero. At normal levels, it's just a minor discrepancy. I think you should be able to verify this by doing your own arithmetic with the forward and regen watt-hour numbers.

I don't get quite that much, more like 11-13% reported. I've lived all my life in the local glacial topography, so it seems normal to me, but there sure is a lot of the world that's much flatter.

I wonder why some people are so determined to tell you you don't want regen. Per se, as a way to recover some energy, we can say about how much you can expect under ideal circumstances, and we can explain what those circumstances are - moderate speed (because you never get wind resistance back), hills, stops. You decide.

 

[trackebike]

According to my CA I'm getting 14-16% back from regen, but it's very steep here, next to no flat ground.

But I don't get why you would be braking on the downhills? It would have to be a long decent full of switchbacks, hairpin turns, and stop signs all the way down for you to get 16% back.

How fast would you go if you were to just coast on your downhills?

I'm not doubting you, but either your CA is BS'ing you or your situation is so unique that it is not relevant to the rest of us. Like you live in the Alps or something...

 

[E-HP]

I'm not doubting you, but either your CA is BS'ing you or your situation is so unique that it is not relevant to the rest of us. Like you live in the Alps or something...

Are you speaking for the forum now?

 

[Limbs]

I cycle in Tenerife and wore through a bike set of brake pads (Magura MT5-E) in 500km and they're around 25 Euros (30 USD?) a pair; I'm looking forward to trying regen!

 

[E-HP]

I cycle in Tenerife and wore through a bike set of brake pads (Magura MT5-E) in 500km and they're around 25 Euros (30 USD?) a pair; I'm looking forward to trying regen!

I've had the same pads since last March, well over 1000 miles with lots of hills, and I've only had to adjust the calipers twice, one click each time, so barely any wear.

 

[AHicks]

Getting back to the original question "Is regenerative braking worth anything?".

My vote would be no for most people. A big ywn from a flat lander...
Those that live in an area with large hills, especially those hills with stop signs at the bottom of them, I'm pretty sure they'll not only use them, they'll be grateful for them.

Point is, it depends!

 

[trackebike]

Getting back to the original question "Is regenerative braking worth anything?".

My vote would be no for most people. A big ywn from a flat lander...
Those that live in an area with large hills, especially those hills with stop signs at the bottom of them, I'm pretty sure they'll not only use them, they'll be grateful for them.

Point is, it depends!

Exactly, If you are live or trek through very mountainous regions then you might want to consider it, but for the remaining 95% of us it is meaningless.

But I will concede to one little caveat. A kit that implements good regeneration probably has better overall software/system quality. In other words, someone who goes to the effort/detail of implementing regeneration has probably done a good job on the other features of the kit.

I still can't fathom you folks who brake on the downhills... I'll happily do 40-50 mph on a downhill, coasting, instead of braking and doing 35mph in order to charge the battery...and I'm pretty sure it is more efficient.

 

[JackFlorey]

My vote would be no for most people. A big ywn from a flat lander...
Those that live in an area with large hills, especially those hills with stop signs at the bottom of them, I'm pretty sure they'll not only use them, they'll be grateful for them.

Definitely. Where I am (San Diego) there are enough hills to make it worthwhile, although I only see about 5% energy recovery. Only downside is constantly having to tighten the axle/torque arm that keep trying to work loose from the constant changing of torque directions.

I'll happily do 40-50 mph on a downhill, coasting, instead of braking and doing 35mph in order to charge the battery...and I'm pretty sure it is more efficient.

Well the guy who uses regen still gets to the bottom of the hill, and his battery will be at a higher charge state than yours - so from that perspective it's definitely more efficient in terms of miles per watt-hour. But you'll go faster.

 

[E-HP]

Exactly, If you are live or trek through very mountainous regions then you might want to consider it, but for the remaining 95% of us it is meaningless.

But I will concede to one little caveat. A kit that implements good regeneration probably has better overall software/system quality. In other words, someone who goes to the effort/detail of implementing regeneration has probably done a good job on the other features of the kit.

I still can't fathom you folks who brake on the downhills... I'll happily do 40-50 mph on a downhill, coasting, instead of braking and doing 35mph in order to charge the battery...and I'm pretty sure it is more efficient.

Really, no reason to concede anything. Congratulations, you win!! I concede that it's worthless to you!!
Or were you looking for a majority vote?

 

[donn]

Exactly, If you are live or trek through very mountainous regions then you might want to consider it, but for the remaining 95% of us it is meaningless.

No, you're way off, on the "very mountainous" and the 95%. Why is it so urgent to discount regen, that you'll make a fool out of yourself to do it? I don't get why this is so important to even a few people.

I still can't fathom you folks who brake on the downhills... I'll happily do 40-50 mph on a downhill, coasting, instead of braking and doing 35mph in order to charge the battery...and I'm pretty sure it is more efficient.

1. Those speeds are so ridiculous I have to wonder if you've ever ridden a bicycle. You might be able to hit 40 on less than a 10% grade, in a full tuck, but long hills that steep aren't a common feature in my "very mountainous" area, as in nonexistent. A much heavier quasi-motorcycle ride might be able to get to 50 under some relatively conceivable circumstances, but ... you're the guy who speaks for "95% of us"?
   
2. If you're so new to bicycling that you aren't sure what brakes are for, here's one example: there's an intersection at the bottom of the hill, and you will have to stop. Or, you're going to have to turn. Inspired by these examples, you may be able think of other reasons why you might use your brakes. Each one is an opportunity to recover some watts via regenerative braking.

I'm in the city, where I will have to stop every few blocks. That's most of my regen braking. I don't normally brake to bring the battery level up, I brake when I have to slow down or stop, on grades rarely over 4%, which gets me in the range of 10-12% recovery, 12-14% in CA math. I don't think it's meaningless.

 

[Hardergamer]

According to my CA I'm getting 14-16% back from regen, but it's very steep here, next to no flat ground.

But I don't get why you would be braking on the downhills? It would have to be a long decent full of switchbacks, hairpin turns, and stop signs all the way down for you to get 16% back.

How fast would you go if you were to just coast on your downhills?

I'm not doubting you, but either your CA is BS'ing you or your situation is so unique that it is not relevant to the rest of us. Like you live in the Alps or something...

You do not understand why we have to brake? WTF is wrong with you? If your not a troll your missing some IQ.
As I told you it is all hills here, and many Uk riders train for the Tour de France here, I live on top of a 1.3-mile hill with a drop of 600 feet with a river at the bottom, and then we have speed limits of 30mph in towns and cites with cameras on many roads, so if I didn't use brakes or regen freewheeling I would be doing 50-60mph! on the first hill alone, then you have things called road junctions where other road users can pull out into the roads in front of you, you have road crossing with children crossing going to school.
You sound like someone giving us ebike riders a bad name, do you ride through traffic lights at speed too?

Back on topic going work yesterday on my normal route I turned off regen. Work and back is 38 miles with 3400 feet of altitude changes and 6 hills of more than 7% incline. without regen, I had a voltage drop of 6.2v when normally when on it is 5.3v starting at 96v 81ah battery.

 

[Bigwheel]

thumbnail_IMG_1982.jpg

Bigwheel,
What's with that mounting position of your CA...doesn't that get in the way for using your drops?

Not at all, I primarily ride on the hoods but the drops are easily accessible. Riding the flat section is still possible but I rarely if ever ride from there.

I made some alu plates with a 1 1/8" hole and enough to mount the CA to in order to get it there and out of harm's way. Been using variations of them for three years for all my bikes displays also for my Garmin.



Keeps the bars clean so I can flip the bike over in case of trail side repair.

 

[ZeroEm]

trackebike » Sep 14 2020 9:57pm

AHicks wrote: ↑Sep 14 2020 6:54pm
Getting back to the original question "Is regenerative braking worth anything?".

My vote would be no for most people. A big ywn from a flat lander...
Those that live in an area with large hills, especially those hills with stop signs at the bottom of them, I'm pretty sure they'll not only use them, they'll be grateful for them.

Point is, it depends!

Exactly, If you are live or trek through very mountainous regions then you might want to consider it, but for the remaining 95% of us it is meaningless.

But I will concede to one little caveat. A kit that implements good regeneration probably has better overall software/system quality. In other words, someone who goes to the effort/detail of implementing regeneration has probably done a good job on the other features of the kit.

I still can't fathom you folks who brake on the downhills... I'll happily do 40-50 mph on a downhill, coasting, instead of braking and doing 35mph in order to charge the battery...and I'm pretty sure it is more efficient.

I have to question that 95% of the people here happily do 40-50 mph downhill on a bicycle, some might make it to 40 if lucky.

Have 2,500 miles on my current brake pads and they may last the life of the trike unlike my tires. Regen is free and it saves me money.

I am sure 95% of the people here that ride bikes at 50 mph have no use for regen. Regen is for people who want to reduce wear and get more miles out of a battery so they don't need to carry another one. Like slowing down to lessen wind resistance and down hill you trade wind resistance for watts. This is for people who ride more than 20 miles and can use regen not a bigger battery.

 

[fechter]

There is a pretty long topic about this somewhere with actual measurements.

On fairly typical riding I might get around 4% regen which isn't huge but it really helps with the braking. On rides in steep hilly areas I've gotten up to 15%, which is pretty significant.

If most of your riding is in relatively flat areas, regen is not that helpful.

 

[j bjork]

I sure miss the variable regen on nucular when I had it on my dirtbike.
I could use it very careful going down wet rock, or lock the wheel on the road if I wanted.

Much better precision then sometimes dry, sometimes wet or muddy disk brakes that should be maneuvered with big boots.
Absolutely worth it in my opinion.
And what is the cost? A cheap thumb throttle for variable regen? If you think that is too much, maybe you have some old button you can use for fixed regen?

 

[john61ct]

And with heavy rig, drag braking to control your speed is not an optional killjoy but absolutely essential to safety.

Without effective regen braking, never mind the Wh recouped, many designs are just inherently unsafe, as in life-threatening.

Even just a touring tandem in the mountains, never mind 400# of cargo.

 

[Balmorhea]

And with heavy rig, drag braking to control your speed is not an optional killjoy but absolutely essential to safety.

I beg to differ. Most of my e-bikes have grossed over 500 pounds loaded. None had drag brakes. All had good brakes, better performing than most new bicycle brakes even considering the added weight.

That's five e-bikes so far. It's worth noting that not one of them has had a disc brake yet (though some of my pedal bikes have them). I think if you depend on 1/4 pound disc rotors to absorb your kinetic energy, then yeah, you should consider having a supplemental drag brake.

 

[John in CR]

And with heavy rig, drag braking to control your speed is not an optional killjoy but absolutely essential to safety.

I beg to differ. Most of my e-bikes have grossed over 500 pounds loaded. None had drag brakes. All had good brakes, better performing than most new bicycle brakes even considering the added weight.

...Until you get caught on a hill in the rain where you've got a vehicle with wholly inadequate braking power. The idea that anyone who has never experienced good quality regen braking thinks it's appropriate to denigrate regen braking as not worthwhile is ludicrous and is hypocritical when they ride only ebikes with brakes that are much less effective when wet.

 

[ZeroEm]

I use regen in my leaf then the disc brakes kick in. Don't think I will ever take the disc brakes off and put shoe brakes on and quit using regen.
Coaster brakes were the big thing at one time and Caves were popular homes before houses. We must move on and embrace the future.
Here is an earlier discussion on it.
Analysis of regen on an ebike

 

[Balmorhea]

...Until you get caught on a hill in the rain where you've got a vehicle with wholly inadequate braking power.

You have inventive thinking about rim brakes. Yes, like discs they require a couple of wheel rotations to squeeze out excess water when it's present, before they deliver good strong braking. But when using aluminum rims and quality pads like Kool Stop salmon compound, you still get good strong braking. Folks who have ridden decent bikes for a long time already know this.

For most people's wheel and motor combinations, regen starts out with "wholly inadequate" braking power in the best case. And until more motor manufacturers follow Grin's lead in supplying better torque arm interfaces, it's asking for show-stopping trouble anyway.

 

[Balmorhea]

I use regen in my leaf then the disc brakes kick in. Don't think I will ever take the disc brakes off and put shoe brakes on and quit using regen.
Coaster brakes were the big thing at one time and Caves were popular homes before houses. We must move on and embrace the future.

Coaster brakes still have some advantages, and several of my bikes have them. Total immunity to ambient conditions and more than enough power to lock the wheel, with none of the vulnerability or maintenance of a cable or hose, are good things. In another hundred years, we'll still have coaster brakes, but the fashion chasers will have abandoned hydraulic discs for something more exotic sounding.

There's nothing wrong with disc brakes. I have some and I like them fine. But they don't stop better than good rim brakes; that's not one of their advantages.