Very Impressed by fast motor winding with gear reduction vs. Slow motor Winding without gear reduction

[Chalo]

If your route starts on a hill, with the battery fully charged, then that's the only time you'll have an issue, due to overcharging, not overcurrent.

He'll have an issue when the axle nuts loosen, or the torque arms wallow out, and the axle spins. At that point it'll be new motor and new frame time.

 

[MadRhino]

Very few small folders are reliable. I have broken some in a 10 minutes test ride on the street here, that are pretty rough with potholes and speed bumps. I would never ride one off road, let alone on DH single tracks.

 

[ebike4healthandfitness]

Here is what 500W to 800W of regen flowing into the battery looks like:

https://youtu.be/cnaucA7qVGs?t=229

(Lightweight rider, long tail bike, GMAC, moderate hill with some speed built up before braking)

Double the weight of the rider(or riders if a child is also on board) and regen would almost double (i.e. 1000W to 1600W).

No wonder people say regen doesn't work well for ebikes.....even a relatively light load would be too much for a typical 500W factory OEM battery pack to absorb. Hence IMO we see the popularity of multi-geared mid drive and not direct drive (either locked geared motor or conventional) for efficient travel in hilly environments.

 

[MadRhino]

Regen current doesn’t have to flow through the battery, and sometimes it is not desirable depending of the battery charging capacity/c-rate. Some controllers have the option of variable regen, very useful to give better control over regen braking power. Almost every regen enabled programmable controllers can be set to ‘fake regen’, which is protecting the battery from high current charging surges but making the controller heat if the system doesn’t have an external resistance.

 

[neptronix]

Regen can be awesome if you have a strong pack.

Used to use hobbyking lipos, with a 5C charge rate. No problem dumping 1000W into them. Eliminated my rear mechanical brake because it wasn't necessary anymore :lol: great breaking!!

Of course you want to tune this for an appropriate level per your bms and battery pack.

 

[ZeroEm]

Use regen in my car and my trike. Don't give it a second thought. I'm guessing wheel size would affect peek amps. Get top speed, small wheel, small battery and hitting max regen could cause issues for a few seconds.

People who use it all the time know not to have a fully charged battery. This goes for my car as well as my trike. I don't have any hills or mountains that would max my regen out or where I could not hold back my trike's speed and not slow down. Do have a larger battery than some and a 26" wheel.

My brake pads are 3yrs old and have no plans on changing them in the years to come. Chalo's point about drop out is correct you need to clamp down the axel and expect more torque from regen. I have my regen come on soft as not to jerk my axel in the opposite direction and have my TQ arms pulling in opposing directions. Need to go to clamps.

No over charging or Amp peaks. Used to read BillVon mountain adventure's where he would over heat his motors with regen.

 

[E-HP]

Use regen in my car and my trike. Don't give it a second thought. I'm guessing wheel size would affect peek amps. Get top speed, small wheel, small battery and hitting max regen could cause issues for a few seconds.

People who use it all the time know not to have a fully charged battery. This goes for my car as well as my trike. I don't have any hills or mountains that would max my regen out or where I could not hold back my trike's speed and not slow down. Do have a larger battery than some and a 26" wheel.

My brake pads are 3yrs old and have no plans on changing them in the years to come. Chalo's point about drop out is correct you need to clamp down the axel and expect more torque from regen. I have my regen come on soft as not to jerk my axel in the opposite direction and have my TQ arms pulling in opposing directions. Need to go to clamps.

No over charging or Amp peaks. Used to read BillVon mountain adventure's where he would over heat his motors with regen.

Pretty much my experience, which is why I mentioned the OP should try a bike with regen. The example in the video is barely a hill, but even going down a 1 mile 20% grade causes no issues as long as the battery isn't fully charged. Peak amps don't really matter, since that only happens for a short window where you apply the brakes. After that, the velocity drops and therefore the regen current. It all self-regulates. You quickly come to the conclusion after using regen, even on steep hills. More of an issue with the motor than the battery.

 

[MadRhino]

Yep. Repeated hard regen combined with hard accelerations doesn’t leave much chances to the motor to cool down. But, variable regen is pretty easy on the motor, battery, and dropouts.

I don’t use regen in the nice season, only in the winter. I prefer the brake because it is more precise, and I don’t mind replacing brake pads twice in the summer. I use fast wearing, extra grippy racing pads because they are silent and consistent in all trail conditions, making them predictable thus giving excellent modulation.

 

[ebike4healthandfitness]

Based on what I learned so far (assuming moderate size batteries) I could imagine heavier riders doing better on flat ground compared to a light rider for Regen percentage, but on hills (with the same moderate size batteries) I could see the lightweight rider doing better with Regen percentage.

Trouble with a heavier rider (or load) on hills is that I takes so much energy to go up it, but then the moderate battery size severely limits how much energy can be reabsorbed.

 

[ebike4healthandfitness]

Some cells / chemistries are fine with higher than 2C charge rate

but they do need to be depleted enough to accept it.

LTO can go to 8+C no worries, full refill in 6min.

But they are low density, as I mentioned maybe just use big braking resistors for drag brakes.

Would be nice to have a smaller high C charge rate battery in front of a larger low C charge rate battery for optimizing Regen of heavier riders on hills.

P.S. Those LTO batteries are not much more expensive per watt-hour compared to lion. So 400 wh of LTO + 600 wh of lion is close in price to 1000 wh of lion.

 

[E-HP]

Trouble with a heavier rider (or load) on hills is that I takes so much energy to go up it, but then the moderate battery size severely limits how much energy can be reabsorbed.

You'll never recover more energy going down hill than you expended while climbing up the hill. If you could you, then you'd never need a charger, just go climb a hill and ride back down until the battery is fully charged.

 

[Chalo]

Brakes are better at braking than non-brakes. You're bending over backwards to do things sub-optimally.

I argue that flatted axle torque retention as used in almost every Chinese made hub motor is unsuitable for regen braking. It barely works for non-reversing torque transfer.

 

[ebike4healthandfitness]

I argue that flatted axle torque retention as used in almost every Chinese made hub motor is unsuitable for regen braking. It barely works for non-reversing torque transfer.

Splined torque arm. Problem solved.

 

[markz]

Who is doing that?

Other then Grintech - https://ebikes.ca/shop/electric-bicycle-parts/torque-arms/grin-hub-torque-arm-assembly.html

Splined torque arm. Problem solved.

 

[DogDipstick]

Regen can be awesome if you have a strong pack.

Used to use hobbyking lipos, with a 5C charge rate. No problem dumping 1000W into them. Eliminated my rear mechanical brake because it wasn't necessary anymore :lol: great breaking!!

*Braking.


I LOL @ hobbyking lipos. They are weaksuace. Sure they say 5C charge but thats just to get them sold and last two months. NOT a DURABLE COMMODITY ( GOOD) .

Hybrid cars man. H Y B R I D.

 

[DogDipstick]

Brakes are better at braking than non-brakes. You're bending over backwards to do things sub-optimally.

I am actually trying to destroy my brakes at the time being ( ready for replacement ) and the front is holding its own.. Shminmo 4 POT.. BUT the rear is trashed. Lil Shimano. Big 8" hub motor. . .. Its not looking good for that one. I do plan to modify both designs for better braking power, with better rotors and other.. Caliper designs.

The rotor or the p[ads gonna take the other with it soon. It just does not stop anymore. Squeeals like a pig.

Tha Front Shimano will turn my rotor to a nice soft red color ten twenty times per ride and hasn't died yet. I should take a pic. This next bike is gonna be a REGEN bike. Steel 1" thick combined, of tork arm on lever arm, 1/2 in plate per side . Already got the steel lasered.

People forget tahat it takes power to speed up. but.. takes just bout as much power to slow down. Watty watty wat wat watts .

 

[Chalo]

Tha Front Shimano will turn my rotor to a nice soft red color ten twenty times per ride and hasn't died yet. I should take a pic. This next bike is gonna be a REGEN bike.
[...]
People forget tahat it takes power to speed up. but.. takes just bout as much power to slow down. Watty watty wat wat watts .

Well, as long as you're comfortable adding heat to your motor instead. Only so much of it goes into the battery, and the balance dumps into the copper.

 

[DogDipstick]

Blah I did not think of that. Oh.. yeah. Doh. Grrrr.

 

[ZeroEm]

Anyone focused on how much they get back from regen is missing the boat. Some clam above 10% recovered. It's more between 5-10% is normal.

It's better not to use the energy/watts than trying to recover them. Setting up a system to handle all of the recovered watts is a waste of time.

I like regen but try to slow down ahead of time before using it. Then use regular brakes if I must. I don't think how many watts i'm recovering, think about how many i'm losing by using any type of breaking. Going down hills, you can let the wind hold you back or slow down and recover a few watts.

 

[ebike4healthandfitness]

Anyone focused on how much they get back from regen is missing the boat. Some clam above 10% recovered. It's more between 5-10% is normal.

I've heard those same numbers (i.e. 5-10 percent for Regen on ebikes) quoted over the years, but I believe this low Regen percentage is due to the typical small battery which can only absorb so much.

For a mostly hilly route without elevation gain Regen percentage should be higher than 10 percent assuming the battery regen charging rate (i.e
through the discharge port) is not a bottleneck.

Maybe LTO is the battery that is needed.

 

[ZeroEm]

y ebike4healthandfitness » Sep 18 2021 8:45pm

ZeroEm wrote: ↑Sep 18 2021 7:31pm
Anyone focused on how much they get back from regen is missing the boat. Some clam above 10% recovered. It's more between 5-10% is normal.

I've heard those same numbers (i.e. 5-10 percent for Regen on ebikes) quoted over the years, but I believe this low Regen percentage is due to the typical small battery which can only absorb so much.

My battery is 72V 24ah or 1,800w (New). Have not tested the capacity lately. Is this small, if so what do you consider big enough to get more than 10% regen.

 

[john61ct]

No, the real numbers are like that by people really trying to make it work.

I **definitely** will do it, but only for safety, heavy tandem/cargo loads, down long steep mountain roads

likely using braking resistors

if the recouping energy can be added easily then maybe but just icing on the cake, not an expectation.

 

[ebike4healthandfitness]

So besides the increased weight and volume tradeoffs for LTO, how bad is the situation with chargers for LTO?

Let's say someone wanted to use a 500 Wh LTO battery pack how big and expensive would the charger have to be in order to charge at 6C,8C or 10C? (Charging a 500Wh battery pack at 6C needs 3000W charger).

How about LTO battery chargers that could work with a regular 15 amp or 20 amp outlet?

How about BMSes for a 500 Wh LTO pack?

 

[MadRhino]

High power charging does require big and/or expansive charging stations. You can’t pull much more than 2kw from a 120v outlet, and that is when the circuit is not feeding anything else.

LTO may have a future for cars, but ebikes have limited space and weight requirements. Ebikers who charge fast are using high c-rate RC lipo. That is expansive too, and has a very short life expectation as compared to LTO. But, they are making a simple compact lightweight battery that can supply very high power.

 

[ebike4healthandfitness]

LTO may have a future for cars, but ebikes have limited space and weight requirements.

500 Wh of LTO would weigh about the same as 1.5 kwh of conventional lion.....

.....but if I could get a higher Regen percentage and could charge at 4C from a 20 amp outlet (or 3C from a 15 amp outlet) then maybe it is better than using a 1.5 kwh conventional lion pack?