How do you think solid state batteries will change how we use hardware?

[99t4]

Therefore I can see why OEM ebikes with geared hubs don't have locked clutches when the most common battery size for them is 350 Wh to 500 Wh.

Is that the actual reason or could it be because of higher price and added complexity?

As far as the mechanical brakes go a person shouldn't have to use those except under extreme circumstances. The Regen system should be able to stop the bike in a reasonable distance without wasting energy. This so a person can ride their bike as the they normally would without compromising Regen.

This is in fact how most of us with regen set up use it. (DD hub.) Reality, for the majority percentage of our slowing requirements, we can and do accomplish using regen only.

 

[Ianhill]

I've been thinking opposite for the ultimate eco ride to yourself rather than fast charging a pack from a large charger ive been wanting to make something worthy of traveling.

Usb type c power delivery plugs can be had widely in a compact form plug with gan fets supplying 20v 65w, so a pack configured to 5s 650w would take around 10 hours to charge from empty and for me that turn around is acceptable if the bike can last a full day riding.

650wh at 15wh a mile should get around 45miles of commuting at a steady 15mph or so if i can get a decent 5s setup built then 10wh or less could be in the cards.

Even cheap hubs are designed to run at 10s so 5s will effectively half the top speed without field weakening but thats not going to be used on an efficency chasing ride be better off running a vesc with foc.

As for the hub its all about how ill assist the ride pulling off if im lazy expect high currents even with the best of intentions on the winding config and gearing, the geared hub may help me in the pulling off but if i can assist near 3/4 of the torque needed then the battery amps go down a similar amount and top speed if i can assist there too i may find myself outpacing the geared hub on occasional peddle stroke but a direct drive never feels like its chasing me i feel im pushing it when it comes to feel of the pair.

But I've never rode a complex rc drive to compare them for the merits.

 

[BalorNG]

With higher charge rate batteries it will take far less hills and stops to outregen the no load losses. On top of that remember the bike will charge faster from an outlet (assuming a high watt charger comes with it) or perhaps even be able to use an adapted ev charger.

No it will not. It will take more effective effective motors and, *most importantly*, better aerodynamics/good rolling resistance. Being very heavy also helps.
Remember, a 'legal' motor is a 250w one. Even given that they can be run at considerably higher wattages pretty effectively, battery losses are a small part of overall losses when braking - it is aero/motor drag first and foremost.

Why not use a planetary gearbox directly attached to the RC motor? Wouldn't this have the added benefit of stabilizing the RC motor's output shaft?

This way you'll be forced to use a chain as reduction, or a much sturdier belt with higher losses and pay much more attention to tensioning.
Also, it defeats the point of isolating plastic gear reduction from motor heat - that is what killing the gears in most cases, I'm quite sure of it.. and steel gears are less efficient/noisy. But yea, that has its merits, it was done before and quite effectively.

 

[BalorNG]

Oh, but when it comes to *near/sub-freezing temps*, than yea, barring active thermal management of the battery you MUST use different chemistries to have regen.

 

[ebike4healthandfitness]

With higher charge rate batteries it will take far less hills and stops to outregen the no load losses. On top of that remember the bike will charge faster from an outlet (assuming a high watt charger comes with it) or perhaps even be able to use an adapted ev charger.

No it will not. It will take more effective effective motors and, *most importantly*, better aerodynamics/good rolling resistance. Being very heavy also helps.
Remember, a 'legal' motor is a 250w one. Even given wattages that they can be run at considerably higher pretty effectively, battery losses are a small part of overall losses when braking - it is aero/motor drag first and foremost.

The calculator from gribble clearly shows even when taking aerodynamics and rolling resistance into.account there isn't enough battery charge rate to capture the braking energy in many common downhill scenarios.

 

[Ianhill]

Regen is at best 20% efficent by the time the energy is stored away in the battery it averages out around 10% recovery over the total braking speed range.

The energy recovery figure is a squared figure from the speed value meaning lighter and slower you are less you get back.

Bosch shimano yamaha brose and many more use the same tyoe of system for a reason it extracts most useful energy on average out of most given scenario's you want to hang with the big boys then a freewheel takes you alot further than the regen ability ever could.

If you want to make an f1 bike then no issues you will get your little boost back as you roll on the throttle but it will soon be used up, slowing from 30mph to a stop would give you enough power to get back from stop to about 8mph before its all gone

 

[ebike4healthandfitness]

The energy recovery figure is a squared figure from the speed value meaning lighter and slower you are less you get back.

The lighter and faster you are the less you get back.

The heavier and slower you are the more you get back.

 

[Ianhill]

The energy recovery figure is a squared figure from the speed value meaning lighter and slower you are less you get back.

The lighter and faster you are the less you get back.

The heavier and slower you are the more you get back.

Lighter slower poop

Heavier faster good

Kinetic energy recovery systems

 

[ebike4healthandfitness]

The energy recovery figure is a squared figure from the speed value meaning lighter and slower you are less you get back.

The lighter and faster you are the less you get back.

The heavier and slower you are the more you get back.

Lighter slower poop

Heavier faster good

Kinetic energy recovery systems

That is wrong.

For any given kinetic energy heavy and slow will have less energy lost to aerodynamic drag compared to light and fast given both have the same coefficient of drag and frontal area.

 

[Ianhill]

So tell me why do the most grid flywheels have as big mass as possible spun at as high speed as possible?

For example dint we increase the ridgity of the rotor and spin it as fast as possible before destruction to harvest to most energy back out of the system ?

Im not dead set against your idea i like regen and used it successfully on a 10s system a mxus 3k has enough stopping power to slow my speed down a fair incline so id say just doubling the capability would be enough to stop on most occasions.

How much would be needed for an emergency stop on the other hand ia difficult to say i found 20mph plenty of regen 5mph not so much.

 

[donn]

I wouldn't mind having a three level regen brake - instead of none / 300W - maybe none / 300W / 500W. I don't think it would mean much in terms of more watts recovered, though. I don't spend much time in those higher braking force conditions.

 

[BalorNG]

For any given kinetic energy heavy and slow will have less energy lost to aerodynamic drag compared to light and fast given both have the same coefficient of drag and frontal area.

Actually, both aero drag and kinetic energy go up with square of speed.
A 100 kg vehicle travelling at 10kmh will have roughly 300 joules of energy, at 30kmh - 3000, at 50kmh - 10000!

Now, 10000 joules is 2.8wh, and there is no way you can recover more than a small part of it (most will be lost to aerodynamic resistance), and you'll spend more (if you lay on the 'gas' - *significantly* more) than 2.8wh acceleration to that speed.

When it comes to hills however, things are different.

Let's assume you want to maximise your average speed while minimising battery draw while going in hilly terrain.
This means you'll be going up hills at your preffered average speed AND going down them at same speed, so aero losses remain the same.

Assuming a decent efficient system (80%), for each 1000 meters climbed for a 100kg system weight, you'll be using 340wh to 'just climb' and recover 217wh while descending, so you spend only 122wh overall.

Given efficient and powerful enough motors, that is pretty much like more than halving your weight when it comes to hills and energy expenditure.

Now assume better aero, 170kg of weight, 4000-5000 meter ascended per trip and you'll see why I'm so keen on regen
Btw, I have 2.3kwh lifepo battery that cost me about 250$, it can give out and absorb enough power to meet my needs - no fancy new tech needed. It does weight more than a typical bicycle though...

 

[Chalo]

Assuming a decent efficient system (80%),

That's a faulty assumption. When you stack controller and motor losses to get the vehicle up the hill, aero and rolling losses while in motion, motor and controller losses when regenerating downhill, and battery charging losses when storing the recovered energy, your assumptions are wildly optimistic.

I think other folks' demonstrated and measured results of up to 10% energy recovery are more in line with what you can expect. Your estimate that you could ever recover two-thirds of battery energy is laughable.

 

[Triketech]

For most, I believe Solid State Batteries will change what you're riding.

Many may be in wheelchairs by the time they're become practical.

 

[ebike4healthandfitness]

Assuming a decent efficient system (80%),

That's a faulty assumption. When you stack controller and motor losses to get the vehicle up the hill, aero and rolling losses while in motion, motor and controller losses when regenerating downhill, and battery charging losses when storing the recovered energy, your assumptions are wildly optimistic.

I think other folks' demonstrated and measured results of up to 10% energy recovery are more in line with what you can expect. Your estimate that you could ever recover two-thirds of battery energy is laughable.

If a person is climbing a steep hill aerodynamic drag doesn't factor in much because speed is typically too low.

Also the bikes in this forum might be the worst example of what is possible in Regen. One reason is because most people here want a very high top speed for their bike. Another reason is because most Regen bikes in this forum are direct drive which are not that efficient (even in slower windings).

 

[Chalo]

If a person is climbing a steep hill aerodynamic drag doesn't factor in much because speed is typically too low.

But for it not to be a factor when going down the same hill, you have to use regen to go just as slowly downhill. Whee.

Point is, any energy lost to aero drag, up or downhill, can't be stuffed back in the battery at any level of efficiency.

 

[Ianhill]

Tom stanton just done a video where he claimed 40% with a supercap setup.

The video was long winded to get to 3 mins of decent data at the end the motor he made was poor considering his background and he never broke above 20 mph for a 30 second test so over a hill yeah thats its peak efficency and best use case scenario id say he set the test up for the best data.

Theres room for improvement on most systems no doubt but the motor will have to be over rated in my view to cope with little down time the heat load will increase but the ride i had was well underpowered and i found it great strong braking lots of torque and never got warm i think i used peak 1.4kw and thats nothing to a large hub but the torque was still decent in a 20 inch rim with a middle of the road wind 4t if i remember correctly.

 

[ebike4healthandfitness]

Speaking of the inefficiency of Direct Drive hub motors (even slow winding ones) compare and contrast the MAC 6T with an additional 2:1 reduction (i.e. geared hub motor used as a single speed mid drive) to a slow winding direct drive hub motor "C.Lyte H3525":

https://ebikes.ca/tools/simulator.html?motor=M3525&batt=B4816_GA&mass=170&hp=0&grade=0&cont=BRL10&cont_b=BRL10&motor_b=MMAC6T&batt_b=B4816_GA&mass_b=170&hp_b=0&grade_b=0&bopen=true&add=false&blue=Lbs&mid_b=true&tf_b=30&axis=mph

Both have a top speed within .2 mph of each other on flat ground (22.6 mph v.s 22.8 mph) but look at the efficiency difference at low speed and mid range.

At 10 mph the MAC 6T (used as mid drive with 2:1 reduction) has a efficiency of about 76% compared to the H3525 efficiency of around 55%......but the gap gets even larger the slower both motors go. At 6mph the MAC 6T drops down to 68% , but the H3525 only has 40% efficiency.

 

[Chalo]

You don't use a MAC motor to go 10mph unless you're unclear on the whole concept. If you did, it would be a MAC 12T laced into the smallest possible wheel.

When I built a bike for a friend of mine using a donated BMC motor (similar to MAC), I had to run it on 24V to get it down to bicycle speed. He can cruise at 24ish mph even at that voltage.

I think what you're saying is true, inasmuch as using things wrong tends to get poor results.

If 10 mph is all you're interested in, what kind of feckless weenie do you have to be not to simply use a pedal bike?

 

[LewTwo]

If 10 mph is all you're interested in, what kind of feckless weenie do you have to be not to simply use a pedal bike?

One with a bum leg ???
.... however I prefer about 20-25 MPH

 

[ebike4healthandfitness]

If 10 mph is all you're interested in, what kind of feckless weenie do you have to be not to simply use a pedal bike?

Efficiency at 10 mph on a 22-23 mph ebike is important because sometimes the bike doesn't have enough power to go 22-23 mph. (e.g. going up a hill and/or facing strong headwind)

 

[Chalo]

If 10 mph is all you're interested in, what kind of feckless weenie do you have to be not to simply use a pedal bike?

Efficiency at 10 mph on a 22-23 mph bike is important because sometimes the bike doesn't have enough power to go 22-23 mph. (e.g. going up a hill and/or facing strong headwind)

Right. But whenever you do go 20 mph or more (say down the same hill, or cruising easy), most of the energy it took to get up to that speed is lost to aero drag and unrecoverable. So those losses stack on top of rolling resistance and mechanical hysteresis and electrical resistance and magnetic eddy currents and whatever else, to prevent most of the energy you put in from being captured by regenerative braking.

With LTO cells, it's technically feasible to charge a battery with regen braking as fast as you can bleed off kinetic energy. But the trifling energy return is not worth the compromises in terms of weight, heat, cost, and loss of coasting.

 

[ebike4healthandfitness]

If 10 mph is all you're interested in, what kind of feckless weenie do you have to be not to simply use a pedal bike?

Efficiency at 10 mph on a 22-23 mph bike is important because sometimes the bike doesn't have enough power to go 22-23 mph. (e.g. going up a hill and/or facing strong headwind)

Right. But whenever you do go 20 mph or more (say down the same hill, or cruising easy), most of the energy it took to get up to that speed is lost to aero drag and unrecoverable. So those losses stack on top of rolling resistance and mechanical hysteresis and electrical resistance and magnetic eddy currents and whatever else, to prevent most of the energy you put in from being captured by regenerative braking.

If the hill is really steep and the weight being carried up the hill is heavy then aerodynamic drag at 20mph becomes a small percentage of the total energy used.

So in the case of a person having a really big hub motor it would be overall more efficient to go 20 mph up a steep hill because motor efficiency rather than aerodynamic drag plays a greater role.(i.e. Any aerodynamic load reduction achieved by going slower than 20 mph could be more than offset by the decrease in motor efficiency. This because when going up a Steep hill with a heavy weight the major load on the motor is from gravity not aerodynamic drag)

 

[Ianhill]

Id love to see someone average 10mph on a peddle bike while climbing the hills of any of my locals.

on the decent side of my trip id lose to the lycra brigade on a nice sunny day id be to 20mph they would be over 30mph but in the climb id be there steady 10-14mph while they drop cogs to under 5mph and scream the cadence to climb 1000ft id be calm cadence climbing away no sweat.

Feckless as it can be the ebike allowed me at the time due an operation on impacted wisdom teeth blood pissing out constant pain bad enough to have an out of body experience to get out and just enjoy what i could of the summer, granted riding in a city would hae been death of me but rural riding was just the ticket to power me up keep me active.

I learned dont hate the dentists or hub motors, its not about been the best its about taking part obsessive compulsive people stride for perfection and it costs a lifetime dont do it, i have the same urges but i block some no good for mental health and longevity.

 

[ebike4healthandfitness]

battle those losses with very thin laminations, too. 0.2mm and even 0.15mm are common on RC motors now and they do not cost a fortune!

I noticed the Astro flight RC motors are boasting up to a 95 percent efficiency.

Those are expensive, of course, but it is good to see the potential for very high efficiency exists.

P.S. It is interesting to think about how low turn RC motor with higher reduction planetary gearbox would compare to high turn RC motor with lower reduction planetary gearbox as far as efficiency throughout a speed range? Assume both combinations produce a top speed of 20 mph.

I've read that the higher the gear reduction of a planetary gearbox the lower the efficiency, but could this be more than offset by the lower internal of resistance of a lower turn RC motor?