RC-ESC vs E-Bike controllers

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jbond   100 W

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RC-ESC vs E-Bike controllers

Post by jbond » Dec 27 2010 3:22am

I'm trying to understand the differences between the RC style controllers from people like Turnigy and the E-Bike style controllers like the one's that Lyen modifies. Now clearly the E-Bike controllers have a lot of extra capabilities with cruise, regen, brake cutoffs, PAS sensors and so on. What's puzzling is that the RC controllers seem to be designed to run at lower voltages but much higher continuous currents. However, they don't seem to be able to cope with high throttle low speed.

I'm guessing here that the problem is to do with the phase current multiplication. An RC duty cycle normally involves limited torque but very rapid spin up. This is very different from a bicycle duty cycle where it's easy to find yourself accelerating from standstill or struggling up a hill. So an RC motor typically gets through the high throttle low speed period very quickly, where a bicycle can be stuck in that regime for quite long periods. So an RC ESC can have FETs and heat management designed around 24V-70A continuous but doesn't have to handle the 24V-200A that the phase current will peak at. Where a 36v-20A e-bike controller must be able to handle 36v-45V for quite long periods.

The high end Turnigy ESC are programmable. Is there any detail on the web of what can be programmed? Do they have LVC, battery current limiting, phase current limiting and so on?

[moderator edit to fix title]

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Jeremy Harris   10 GW

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Re: RC vs E-Bike ESC-controllers

Post by Jeremy Harris » Dec 27 2010 4:13am

The main physical differences are:

- RC ESCs are usually sensoreless, ebike ones usually use Hall sensors
- RC ESCs use large arrays of low voltage FETs, with minimal heatsinking, ebike ones use smaller numbers of higher voltage FETs fitted to moderately sized heatsinks.
- RC ESCs rarely have true current limiting, the majority have no means of measuring current (there are one or two high end exceptions) whereas ebike ones all implement some form of current limiting.

The practical differences are:

- Because of the focus on low voltage, high current, there are few RC ESCs that will run above about 50V.

- RC ESCs tend to be designed for maximum torque (which corresponds to maximum current) at maximum rpm, ebike ones have to be able to deliver maximum torque at any speed. This means that, without effective current limiting, some RC ESCs will attempt to generate very high phase currents at low rpm, high throttle. Switching these high currents then generates voltage spikes on the supply rails that the commutation capacitors cannot cope with, leading to either commutation capacitor failure from excessive ripple current or FET failure from the high voltage spikes.

- Ebikes controllers always have current limiting, so they shut down the PWM duty cycle, even though the throttle may be demanding 100%, when the current exceeds the set limit. This has the effect of limiting phase currents to values that the controller components can handle, whilst still delivering maximum torque. In effect, an ebike controller will safely deliver it's set maximum torque (current) from zero to full rpm.

- Hall sensors allow better control of commutation at start up and low rpm, as they are not speed sensitive. RC ESCs usually rely on the back EMF of the non-powered motor phase wire to determine rotor position and this signal is very low at low speeds and non-existent at start up. The effect of Hall sensors is to increase starting and very low speed torque, by allowing the controller to accurately time the phase outputs from a virtual standstill.

- Because RC ESCs are designed for use with PPM signals from radio receivers they don't have a throttle input that connects directly to the voltage output throttles common on ebikes, so some sort of converter is needed to turn the throttle voltage into the PPM signal the ESC needs. Ebike controllers will accept Hall or resistive throttles directly.

The two different controller types are essentially very similar, but optimised for different roles. Model aircraft and boats have a cube law relationship between torque and rpm, so there is no need for an RC ESC designed for use with them to be able to handle high current at low rpm. Ebikes need high torque at near zero rpm to accelerate quickly and have good hill climbing performance, and will most probably not run at maximum torque, maximum rpm very often.

Some high end RC ESCs do have features that mean they can be adapted to ebike use more reliably, but there remains the voltage limit. An advantage of high end RC ESCs is that they tend to be designed in the West (principally places like the US and Germany) so we have better access to the design limitations and more information on what they will and won't do. Ebike controllers are virtually all designed and manufactured in China, for their indigenous ebike market, so we rarely get more than a glimpse of the way they work.

The only RC ESCs that have current limiting that is programmable (and even then I think they use FET Rdson current measurement, which is OK but very temperature dependent) are the Castle Creations HV series, plus maybe one or two of the very high end European ESCs. I've not seen any sign of a current measurement capability on any of the cheap Chinese ESCs.

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Re: RC vs E-Bike ESC-controllers

Post by jbond » Dec 27 2010 5:21am

Great summary, Jeremy, thanks. Even though the RC ESCs are small, light and cheap, they seem like a bad match to bicycles. Watching the experiments people like Kepler and Adrian_sm are doing it seems like this is a major limitation to using RC components. Lyen seems to be experimenting with using his controllers with RC motors but not entirely successfully. The RC motors seem to be sufficiently different in terms of inductance and windings that it almost works but not quite. I wonder if there's a possibility here of scratch building a Bicycle style controller to match RC style motors. Or perhaps Lyen will work out how to modify a stock controller to work well with an RC motor.

Comparing the RC approach with geared hub motors. The actual motors are very similar being usually sensorless, brushless, outrunners. In both cases quite large gear reduction is needed before we get to turn a bicycle rim. Hub motors build the gearing into the hub, RC motors need external gearing or the inherent gearing of friction drive. By the time you add all the gearing and mounting components, there's not a lot of difference in weight between a small Bafang, Cute or Tongxin and the RC approach.

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Re: RC vs E-Bike ESC-controllers

Post by Jeremy Harris » Dec 27 2010 6:41am

jbond wrote:Great summary, Jeremy, thanks. Even though the RC ESCs are small, light and cheap, they seem like a bad match to bicycles. Watching the experiments people like Kepler and Adrian_sm are doing it seems like this is a major limitation to using RC components. Lyen seems to be experimenting with using his controllers with RC motors but not entirely successfully. The RC motors seem to be sufficiently different in terms of inductance and windings that it almost works but not quite. I wonder if there's a possibility here of scratch building a Bicycle style controller to match RC style motors. Or perhaps Lyen will work out how to modify a stock controller to work well with an RC motor.

Comparing the RC approach with geared hub motors. The actual motors are very similar being usually sensorless, brushless, outrunners. In both cases quite large gear reduction is needed before we get to turn a bicycle rim. Hub motors build the gearing into the hub, RC motors need external gearing or the inherent gearing of friction drive. By the time you add all the gearing and mounting components, there's not a lot of difference in weight between a small Bafang, Cute or Tongxin and the RC approach.
I've been running RC outrunners on ebike controllers for a year or so now, with great success (not had a problem so far with any of them) as have a few others. I've also been testing my DIY controller with an RC outrunner and it works just fine. The controller needs to be capable of dealing with the low time constant of a typical outrunner, but that's really just a matter of making sure it has decent FETs and commutation capacitors, plus that the current limiting circuit is altered to deal with the high peak current without tripping the controller. I'm not running at particularly high power levels, but gwhy has been happily running his outrunner/6 FET XieChang controller set up at a kW or two for a while now without problems. The XieChang is the controller that Lyen buys and mods, so there's no issue with getting them to reliably run outrunners. They do need Hall's fitted, but that's a pretty easy job.

As for the weight difference, I think you're right. The advantages that an external motor system has is in being better able to match the gear ratios to the bike, and the possibility of driving through the gears to enhance efficiency under a broad range of speeds and loads. Hub motors will always be optimised for a particular speed, so if geared for high speed they will tend to be inefficient at low speed hill climbing and if geared for hill climbing maximum speed will be limited.

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Re: RC vs E-Bike ESC-controllers

Post by liveforphysics » Dec 27 2010 2:25pm

jbond wrote:I'm trying to understand the differences between the RC style controllers from people like Turnigy and the E-Bike style controllers like the one's that Lyen modifies. Now clearly the E-Bike controllers have a lot of extra capabilities with cruise, regen, brake cutoffs, PAS sensors and so on. What's puzzling is that the RC controllers seem to be designed to run at lower voltages but much higher continuous currents. However, they don't seem to be able to cope with high throttle low speed.

I'm guessing here that the problem is to do with the phase current multiplication. An RC duty cycle normally involves limited torque but very rapid spin up. This is very different from a bicycle duty cycle where it's easy to find yourself accelerating from standstill or struggling up a hill. So an RC motor typically gets through the high throttle low speed period very quickly, where a bicycle can be stuck in that regime for quite long periods. So an RC ESC can have FETs and heat management designed around 24V-70A continuous but doesn't have to handle the 24V-200A that the phase current will peak at. Where a 36v-20A e-bike controller must be able to handle 36v-45V for quite long periods.

The high end Turnigy ESC are programmable. Is there any detail on the web of what can be programmed? Do they have LVC, battery current limiting, phase current limiting and so on?

It sounds like you've got a good grasp on the situation. As far as the 200amp Turnigy controller goes, of the 4-5 folks on here who got it, it didn't last more than a minute or two for anyone. The Castle Creations 160amp version seems to be the best of the RC controllers, and the only one worth spending any time/money playing with if you feel the need to try an RC controller on an ebike.
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Re: RC vs E-Bike ESC-controllers

Post by deVries » Dec 27 2010 2:29pm

jbond wrote:By the time you add all the gearing and mounting components, there's not a lot of difference in weight between a small Bafang, Cute or Tongxin and the RC approach... (AND) ...What's puzzling is that the RC controllers seem to be designed to run at lower voltages but much higher continuous currents. However, they don't seem to be able to cope with high throttle low speed.
Friction (shaft) Drive (not using motor can) is an exception regarding the weight & RC controller burnout. Using a drive shaft of 1" to 1.25" or 25mm to 32mm & having it engage & turn as it slides/moves onto the tire while simultaneously pedaling with foot power, or pedal first to 2-4mph & then engaging the motor has worked without failures. There are more ideal exceptions to what I just wrote, because EVTodd was able to start his bike from a standstill repeatedly at 36v with an HV85amp Castle Hill without any pedal assist. If you go with a bigger shaft 2"/50mm or use the outrunner motor can, then there will be more issues with start-up sync or RC ESC failure (when using partial throttle).

If you make your own friction drive, then you have to experiment with your partial throttle limitations... learn those (heat) limitations, and you won't blow the ESC. Also, with either friction shaft or motor can the battery weight will usually be much lower than what is needed for the geared or DD motors. :mrgreen: 8)

Using a "slipper clutch" on RC installs is another ESC/controller burn-out preventative, and I expect a lot more experimentation with this idea in the next year. Also, proper cooling of RC ESC has not be addressed with eBike builds. Modding the RC ESC for proper cooling will probably prove to be an excellent solution. Someone on ES needs to do heat reduction mods on an ESC ASAP & post a thread, seriously! There are some cooling experts with mod skills and they have ESC too. (You know who you are!) :twisted: :lol:

The main reason for going with a geared motor in the wheel is it's proven over many years, is "ready made" & easy to install, works well under 25mph, though some eBike friction drives were proven too in commercial use 2-10+ years ago. Friction drive with ICE motors goes back 6+ decades, so it is a well proven concept for commercial use. Friction drive is being used now on some high-performance motorcycles too. :wink:

RC (sprocket/belt) reduction drives will work with Jeremy's new controller or Gwhy! (Lyen type) modded controller with hall sensors, but this requires some electronic build skills & hall sensor installation. Also, Ricky in NZ is designing a high powered controller that is showing real promise too. (Final thought, slipper clutch and/or proper ESC/controller cooling will reduce or eliminate the chances of overload & burnout.)

:twisted:
The high end Turnigy ESC are programmable. Is there any detail on the web of what can be programmed? Do they have LVC, battery current limiting, phase current limiting and so on?
Go to HobbyKing Click Here for Hobby King :) and read the reviews on the Turnigy ESC you want. Also, some manuals or instructions are available w/links in the reviews or on that webpage to purchase the item. (There is a forum too where more info is available & you can ask questions too.)

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Re: RC vs E-Bike ESC-controllers

Post by jbond » Dec 28 2010 4:02am

deVries wrote:Also, with either friction shaft or motor can the battery weight will usually be much lower than what is needed for the geared or DD motors.
Another puzzle! A123 based RC batteries vs Ping duct tape style. The much higher C values on A123 mean that small batteries can supply much higher currents. But the actual efficiency of the whole system is not that different. So the real weight diff is due to duty cycles and usage styles. The RC helper systems expect you to supply plenty of pedal power. There's no reason why you shouldn't do the same with a geared hub. There are some Brompton conversions out there using a small Tongxin or Bafang and then using A123 packs from hobbyking of about 24v-3AHr/5AHr. You end up with a light weight bike with a range of 10 miles. The real trick here again is about controller strategy. The standard E-Bike controllers expect you to use mostly assist with only a little pedal power and they tend to be speed limited rather than power limited. That's good for ease of use, but bad for range. If you need 15AHr for range, 36v or higher for speed, you get forced into Ping style batteries instead of A123 and significant weight and bulk. The other big catch is that Ping style batteries all have optimised and relatively integrated BMS. There's another need there which is a BMS for A123 batteries so that they can be used by unsophisticated users.

I have to admit I'm still trying to puzzle out an ideal controller strategy. I tend to use the pedelec as a kind of cruise control but I've also been using pulse and glide to eek out battery power. I'm wondering about using a CA to give a 3 position power switch using it's current limiting capability. Basically, set the normal controller to max speed, and then use the CA to offer 5-10-20A max. Effectively 25%, 50%, 100% of max power assist. The aim being to add a few mph onto normal flat cruising speed and to use the big power only on hills to turn 5mph pedalling into 15mph powering up the hill. The Panasonic-Khalkoff with it's pedal torque sensor is very interesting here. It's an elegant and simple answer to the User Interface problem. Except that there's still situations where a simple throttle would be preferable.

It feels like there's a holy grail here that is tricky to do on a conventional bike, and that's the mid chain drive. The rear gear cluster let's the motor do high speed and high torque. With enough freewheels we can have pedal, motor or both. It's just really awkward to package neatly on a non-recumbent.

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Re: RC vs E-Bike ESC-controllers

Post by Jeremy Harris » Dec 28 2010 4:43am

jbond wrote:Another puzzle! A123 based RC batteries vs Ping duct tape style. The much higher C values on A123 mean that small batteries can supply much higher currents. But the actual efficiency of the whole system is not that different. So the real weight diff is due to duty cycles and usage styles. The RC helper systems expect you to supply plenty of pedal power. There's no reason why you shouldn't do the same with a geared hub. There are some Brompton conversions out there using a small Tongxin or Bafang and then using A123 packs from hobbyking of about 24v-3AHr/5AHr. You end up with a light weight bike with a range of 10 miles. The real trick here again is about controller strategy. The standard E-Bike controllers expect you to use mostly assist with only a little pedal power and they tend to be speed limited rather than power limited. That's good for ease of use, but bad for range. If you need 15AHr for range, 36v or higher for speed, you get forced into Ping style batteries instead of A123 and significant weight and bulk. The other big catch is that Ping style batteries all have optimised and relatively integrated BMS. There's another need there which is a BMS for A123 batteries so that they can be used by unsophisticated users.

I have to admit I'm still trying to puzzle out an ideal controller strategy. I tend to use the pedelec as a kind of cruise control but I've also been using pulse and glide to eek out battery power. I'm wondering about using a CA to give a 3 position power switch using it's current limiting capability. Basically, set the normal controller to max speed, and then use the CA to offer 5-10-20A max. Effectively 25%, 50%, 100% of max power assist. The aim being to add a few mph onto normal flat cruising speed and to use the big power only on hills to turn 5mph pedalling into 15mph powering up the hill. The Panasonic-Khalkoff with it's pedal torque sensor is very interesting here. It's an elegant and simple answer to the User Interface problem. Except that there's still situations where a simple throttle would be preferable.

It feels like there's a holy grail here that is tricky to do on a conventional bike, and that's the mid chain drive. The rear gear cluster let's the motor do high speed and high torque. With enough freewheels we can have pedal, motor or both. It's just really awkward to package neatly on a non-recumbent.
Ebike controllers are generally power limited, not speed limited. They all have current limiting and most will current limit whenever called upon to deliver high power, so limiting the torque, and hence power, that the motor can deliver. Speed is almost always a function of battery pack voltage, rather than any setting in the controller.

The bikes that work well with electric assist, like the infamous Brompton with the Tongxin tested by A to B, tend to have controllers with very limited current capabilities. In the case of the Tongxin (a.k.a. Nano) this limit was just 12A on the original controllers and 15A on the later ones. The reason the Tongxin worked so well on the Brompton for this test is that it was very low geared, so was only providing assistance up to about 12mph. At any speed over this the motor wasn't doing anything, but because the Brompton is a pretty efficient folding bike, plus because the Tongxin has near-zero drag when being pedalled, the bike still rode well. The A to B test was by someone who pedalled a lot and they got a pretty good range because the motor was only working at low speeds and when climbing hills. Not a bad setup if you want a light, efficient commuter bike.

Battery performance is far less critical once you lower average discharge levels. Better by far than either the Ping or the A123 cells for a super lightweight pack would be a couple of small RC Lipo packs. They'd give the lightest, most compact, solution that it's possible to get with readily available cells.

Driving through the bottom bracket or existing chain with a compact, free spinning, drive system would undoubtedly be the most sensible way of providing assistance to a low to medium powered bike. The challenge is in engineering such a system to fit within the constraints of a typical bike frame. Certainly RC motors are compact enough, what's needed is a nicely engineered drive system with a free wheel that has near-zero losses when pedalled. It's not easy to engineer well, but I'm sure there'd be a market for such a system.

Jeremy
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Re: RC vs E-Bike ESC-controllers

Post by jbond » Jan 03 2011 3:43am

Jeremy Harris wrote:Ebike controllers are generally power limited, not speed limited. They all have current limiting and most will current limit whenever called upon to deliver high power, so limiting the torque, and hence power, that the motor can deliver. Speed is almost always a function of battery pack voltage, rather than any setting in the controller.
In terms of maximum possible speed, perhaps. And also in terms of max power and hence acceleration or hill climbing ability. And yet, all the controller is doing is changing average voltage via PWM and hence motor max speed. The typical 3-way power switch is just changing max speed via max voltage. The throttle is doing the same thing of providing a UI to a PWM average voltage which in turn is setting a maximum speed. Anything aimed at EU limits is speed limited to 15mph (ish). But as you say, all of this is also required to run inside the current limit. But even that is implemented by reducing PWM average voltage and hence max speed. The typical geared hub motor is also designed to work within a speed range. It may well be able to provide 350w or 500w continuous (in conjunction with it's battery and controller) but if that was actually available it would reach a speed above it's no-load rpm. If aeros, wind, slope or pedalling help you above that speed you still won't get any assist. So again we're speed limited.

What's hard to tell from the outside without some instrumentation is when the controller moves into current limiting mode. And I need some more understanding of what happens above and below that point.

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Re: RC vs E-Bike ESC-controllers

Post by Jeremy Harris » Jan 03 2011 4:28am

You'll find that the typical small ebike controller will spend a fair bit of time current limiting. Anyone who's hooked a meter up to one will see this happening pretty frequently as they ride. Even holding the throttle at a constant speed still invokes the current limit fairly often, particularly at low speeds when accelerating, going up hills or facing a stiff headwind.

I have an ammeter display on the handlebars of my folding bike and used to run at a 20A current limit on my controller. Even without trying I used to see the meter peg at 20A pretty often, indicating that the controller was current limiting. It very rarely does this at full speed, most of the time it limits when the torque demand at low speed is too great - it'll even do it when you get hit by a gust of wind on the level, for example, without touching the throttle at all.

Although you can take the simplistic view that the controller PWM is setting the voltage to the motor, the reality is that it's controlling the current much of the time, particularly when actively current limiting. The motor rarely runs at the speed determined by the theoretical mean voltage of the PWM'd battery voltage, as you can quickly determine by doing a few measurements. In practice the motor seems to always be either trying to accelerate or decelerate, it's quite rare for it to actually stay at the commanded speed for more than a second or two. This is hardly surprising seeing as how the speed control is open-loop.

The three way switch fitted to a few controllers just limits the maximum throttle voltage, so does nothing that you can't do with your hand on the twist grip. It does effectively improve the throttle resolution at low speeds, but that's only because it's turned the full throttle into a fraction of what it should be. That switch doesn't change the current limit or have any other effect on the controller output.

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Re: RC vs E-Bike ESC-controllers

Post by hillzofvalp » Jan 04 2011 3:24am

I personally would fair for a Castle creations hv 160 because I can log data with it. My issue is whether it will be compatible with a hub motor should my friction drive setup fail. I am running A123 M1s in a 7s2p config for around 4.6Ah (going to go higher eventually) and I just don't see myself surviving 2 miles with assist if I used an ebike controller. As far as the hub motor vs friction rc motor setups go, I have no idea which will be more efficient and economical. I can't just keep adding batteries cause my goal is to be minimalist about it (while staying away from lipos)

I see a good solution to the problem of controlling RC ESCS which is pulling the trigger assembly out of a 2channel radio and wiring it into a servo tester. My pot happens to be 5K which is what is common in servo testers.

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Re: RC vs E-Bike ESC-controllers

Post by mattetjus » Mar 24 2011 4:14am

Hey, newbie question:

is it possible to add a current limiting circuit to the phase wires between the motor and (RC) esc to address the starting issue?
or would this mess too much with the controllers bemf readings/pwm signals?

/long time lurker

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Re: RC vs E-Bike ESC-controllers

Post by bobc » Mar 25 2011 1:45pm

An in-line current limit would be most unlikely to be practical, in my opinion; at the very least because of the low voltage cutout which most ESCs contain.
I have not found the RC ESCs to be as bad as many folk seem to have, I'd say try it - they only cost a few dollars, unlike the fancier e-bike specific types!

oops - re read the post & you suggested the limiter in the motor wires - I still don't think it's practical - how would the BEMF sensing work wih a series pass element in circuit?

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Re: RC vs E-Bike ESC-controllers

Post by liveforphysics » Mar 25 2011 1:51pm

bobc wrote:An in-line current limit would be most unlikely to be practical, in my opinion; at the very least because of the low voltage cutout which most ESCs contain.
I have not found the RC ESCs to be as bad as many folk seem to have, I'd say try it - they only cost a few dollars, unlike the fancier e-bike specific types!

oops - re read the post & you suggested the limiter in the motor wires - I still don't think it's practical - how would the BEMF sensing work wih a series pass element in circuit?

Every RC controller of a useful power range has been more expensive than any ebike controller I've bought.

No RC controller has survived more than a few minutes for me.

no RC controller has had good zero RPM torque for me.


Conversely, ebike controllers do everything well for an ebike.
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Re: RC vs E-Bike ESC-controllers

Post by bobc » Mar 25 2011 2:10pm

Power level dependent I'd have thought - a kilowatt or less is $15 to $20 in an RC ESC.
I must say I was also expecting it to be useless but I've tried a couple now & they've both surprised me by being eminently usable!
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Re: RC vs E-Bike ESC-controllers

Post by evaleto » Apr 02 2011 3:43am

I bought a Phoenix ICE HV 40A to test it with my 250W HUB motor. I did a short video in French - sorry - (http://www.youtube.com/watch?v=XefmIf0LApA)
First of all, the controller is really tiny and works very well for nominal scope. The issue was exactly as Jeremy say
- Ebikes controllers always have current limiting, so they shut down the PWM duty cycle, even though the throttle may be demanding 100%, when the current exceeds the set limit. This has the effect of limiting phase currents to values that the controller components can handle, whilst still delivering maximum torque. In effect, an ebike controller will safely deliver it's set maximum torque (current) from zero to full rpm.


What is the difference between getting current control directly from phases or from the battery ? Is there a safe constant ratio where current control from battery could be safe in phases?

About the Phoenix ICE HV, is there someone who knows how to hack it. I'm looking to hack 1) get 5V (40ma) VCC, ( I'm pretty sure there is one inside) 2) get the shunt resistor? Finally, I'm wondering if the capacitor are well sized (voltage is 50V for 270uf) for high torque at near zero rpm?

Cheers,
olivier

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Re: RC vs E-Bike ESC-controllers

Post by recumpence » Apr 02 2011 7:04pm

Wow, great thread!

Jeremy, you have such a fantastic way of explaining things. :D

My personal experience is pretty much what was already stated.

What needs to be addressed (and is to a certain extent) is the low speed versus high speed timing of sensored setups. That is the only thing lacking with them. Other than that, they really are better in most respects than RC controllers for bikes. If you need a hammer, buy a hammer, if you need a drill, buy a drill. Bike controllers were designed for this application. I do like the tiny size of the RC controllers, though, as I like the active timing advance they use. But, they require some specific setup items to work properly.

Oh, lastly, a comment was made earlier in the thread about cooling RC ESCs. That is not a correct statement. I have very rarely heard of anyone complain of temperature problems with these tiny ESCs. I know I have not had any temperature problems with them. In fact, they rarely heat up more than 10 degrees F over ambient temp.

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Re: RC vs E-Bike ESC-controllers

Post by mattetjus » Apr 05 2011 7:51am

evaleto wrote: What is the difference between getting current control directly from phases or from the battery ? Is there a safe constant ratio where current control from battery could be safe in phases?
well, if i understand BLDC-motors correctly (which i probably don't), they have similarities with 'normal' brushed DC-motors; simply put, voltage governs the (top) speed and current governs the torque, so, when starting the motor from stand still, the speed controller takes the battery voltage and current and transforms it to suit the above statement - from e.g. 50V 100A (5kW) between battery and controller, we could get 10V 500A (still 5kW) between controller and motor allowing 5 times larger torque than at 100A.
Since an airplane BLDC-motor can be assumed to need its maximum torque at its (near to) maximum RPM (the propeller of the aircraft turns easy at low RPM and pushed more air the faster it spins), such RC ESCs are built accordingly, not expecting high currents at lower speed. on a bike without extra protection this means that the ESC will try to run at maximum load (eg 5kW) from start and hence kills itself due to too large currents.

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Re: RC vs E-Bike ESC-controllers

Post by madin88 » May 29 2014 12:28pm

mattetjus wrote: Since an airplane BLDC-motor can be assumed to need its maximum torque at its (near to) maximum RPM (the propeller of the aircraft turns easy at low RPM and pushed more air the faster it spins), such RC ESCs are built accordingly, not expecting high currents at lower speed. on a bike without extra protection this means that the ESC will try to run at maximum load (eg 5kW) from start and hence kills itself due to too large currents.
very good explaination. this is the main reason why RC ESC are not a good choice for our ebike usage.
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Re: RC-ESC vs E-Bike controllers

Post by fredfire » Oct 11 2015 12:42am

I bring back this thread because recently we've seen Dave build the Tangent drive 80:1 reduction astro motor paired with a HV80, a shunt, a cycle analyst and a throttle.

Using the Cycle analyst to limit the starting throttle would make it OK it seems.

Is there another potential problem with this HV80 ESC?

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ferret   1 kW

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Re: RC-ESC vs E-Bike controllers

Post by ferret » Jan 27 2016 11:05am

Not really.
The Cycle Analyst can be used to limit the battery current, but it can't sense (or limit) the phase current which can be much higher.

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Re: RC-ESC vs E-Bike controllers

Post by Leebolectric » Jan 27 2016 11:51am

This uses a CastleCreations HV80, 52v20ah 25r battery, Astro3210 Tangent kit...barely warm after this ride.
...and I have it mounted in the least air flow space possible...
Is there a better device for this application? What would be "best"?
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Re: RC-ESC vs E-Bike controllers

Post by tightbox » Jan 28 2016 11:48am

Anyone tried the Vedder VESC with the Tangent yet?

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Re: RC-ESC vs E-Bike controllers

Post by DanGT86 » Dec 10 2016 9:08am

Anybody know the max Erpm for a lyen controller running sensored? I was thinking of trying an 80kv sensored 80100 motor with a 12Fet EB312 controller board at 75v nominal.. Since the 130kv motors are more readily available it would be nice to know if that would be possible too. Thats 75k erpm unloaded.

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Re: RC-ESC vs E-Bike controllers

Post by Flipsky » Aug 10 2018 2:47am

tightbox wrote:
Jan 28 2016 11:48am
Anyone tried the Vedder VESC with the Tangent yet?
My reply is a little late, but maybe you already know that vedder's ESC is perfect . I'm Grace, we're professional ESC design and manufacture base on VESC. currently, our products used in ebike is ok.

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