If the manufacturer set the controller just so, obviously it's not meant to give a higher amperage.

Yes and no. The same controller can be sold to different customers with the current set differently depending on what the customer wants. Some controllers have a range of current that can be set in the settings. It might typically be set to 15 amps, but the setting allows up to 20A. The controller manufacturer wouldn't have put that in if they thought it was going to kill their controller. I heard it's only Apple that does things puts things in their products that kill them, and people are still happy to buy them

 

Apart from that, we have empirical data about what works and what doesn't. It was Fordulike that soldered his whole shunt to get no current limit, and he found that his motor worked, but it got so hot that the hall sensors blew, so we know that you can't run for long with no current limit. I reckon I must have personally soldered at least 50 shunts, and I know of probably another 50 or more other people that have done it. Nobody burnt anything - not one! It's a cost-free method of getting more torque for hill-climbing, and it works on all controllers with a wire shunt that you can get to. People can make any theory they want and get all hysterical to. That's up to them. We practical guys just get on and do it, and live with the inconsequence.

 

1....If the motor current is vastly different from the battery current, are controllers rated in terms of what they take from the battery rather than they supply to the motor?

2....... the 48V system will perform better in terms of speed between 20 and 25 kph than the 36V system.

3... they don't specify any particular voltage for their motors.

1 ..I think most controllers (on the label) are rated in terms of battery current (often both continuous and maximum). By the way,motor current and battery current are the same once the motor is spinning fast e.g greater than 70%-80% of max speed. Its when the motor start to slow down under load and with pulse width modulation that this changes and motor current increases. That why its important not to bog down motor and why paradoxically increasing battery current (e.g shunt mod) sometimes only slightly increases motor current but can get motor back into the efficiency zone quicker.

2..The overvolted 48v system is way ahead of the 36v in terms of speed and especially torque at high speed.( increasing the voltage by 30% also increases the motor rpm by 30%) But here (I think) lies the potential problem, especially for manufacturers and suppliers. The lower voltage setup(lower RPM) will start to self limit at a much lower speed due to motor back emf and this reduces the likelihood of damage, especially by say an overweight and unfit enthusiastic naive user.

3...If you click on 'show advanced', there is an RPM per volt setting. That's because a motor may be used over a range of voltages and its rpm changes proportionally but its rpm/volt does not normally change. You can estimate the rpm/volt of your motor from its unrestricted top speed (wheel off the ground) using simple arithmetic to convert speed to rpm by taking wheel diameter etc. into account and dividing by actual battery voltage.

Edited July 6, 20205 yr by Sturmey

By the way,motor current and battery current are the same once the motor is spinning fast e.g greater than 70%-80% of max speed. Its when the motor start to slow down under load and with pulse width modulation that this changes and motor current increases. That why its important not to bog down motor and why paradoxically increasing battery current (e.g shunt mod) sometimes only slightly increases motor current but can get motor back into the efficiency zone quicker.

as it is said in your booklet, the controller is a DC to AC inverter.

The current in the motor is AC, the current from the battery is DC.

The efficiency of the motor is principally a function whose main variable is the RPM. How can overvolting a 36V controller make the motor more efficient? Would you plug a 12V car inverter into an 18V battery instead of buying the right inverter?

as it is said in your booklet, the controller is a DC to AC inverter.

The current in the motor is AC, the current from the battery is DC.

The efficiency of the motor is principally a function whose main variable is the RPM. How can overvolting a 36V controller make the motor more efficient? Would you plug a 12V car inverter into an 18V battery instead of buying the right inverter?

 

Unfortunately, you are comparing apples and oranges there

 

Ok, so you asked, why would anyone want to over volt their bike unless they want to do illegal speeds?

 

I've been playing with the simulator and hopefully, if I've done this right, it should explain why.

 

https://www.ebikes.ca/tools/simulator.html?motor=MXUS_XF07&cont=cust_20_100_0.008_A&wheel=700c&mass=100&hp=0&bopen=true&cont_b=cust_15_100_0.008_A&motor_b=MXUS_XF07&wheel_b=700c&mass_b=100&hp_b=0&batt_b=cust_59_0.2_12&grade=4.5&grade_b=4.5&throt_b=80&batt=cust_36_0.2_20

 

This compares a 36V battery and a 59V battery on the same motor.

 

The controller for 36V is 20A, which is what you would recommend over a standard 15A controller for having more oomph for hill climbing.

 

The second controller is 59V at 15A, so essentially a 15A "36V" controller over volted to 59V.

 

When climbing a 4.5% incline, which isn't incredibly steep, the 36V powered system can't even maintain 20kph at 100% throttle.

 

However, the 59V powered system has no trouble maintaining 25kph at 80% throttle (which is effectively what the limiter will do, throttle the output).

 

It's using more Watts, but it's well within the tolerable range for these motors and it's likely that the hill will be climbed faster, so putting less stress on the motor as RPMs are higher and it is put under pressure for a shorter time.

 

In addition, because 100% throttle isn't necessary, efficiency is higher for the 59V system, by about 2%.

 

Imagine if you are going into a strong headwind, it would have a similar effect. The 36V powered system would not be able to maintain 25kph.

 

Most controllers labelled as "36V" these days are perfectly capable of running at 48V, or even higher. Also, just swapping to 48V is a modification that doesn't need any shunt soldering or changing other system components, so long as the user is aware of the LVC difference.

 

For a someone who is a complete novice about this sort of thing, it may not be recommended, but to users who have some knowledge and are well aware of what may or may not happen, I think over volting is a sensible option.

 

If I've not used the right parameters somewhere, please let me know, but from my experience, this does seem to back up what happens in the real world.

wheezy, you stick a higher voltage to a lightbulb, it will glow brighter but you know already by experience why you wouldn't do that nor would you want to connect that lightbulb to a flat battery.

The argument about motors will run and run because people have all sorts of idea what a BLDC motor is, including those who want to apply Ohm's laws and Kirchoff laws to a circuitry that contains capacitors and coils.

I can go into details formulas and equations but they are of no use here because you don't want formulas and equations.

Put simply, I optimise the bike for legal use, 15mph is a known quantity, 36V Lithium Ion battery is also a known quantity. When choosing a motor for a wheel diameter, I can specify the motor winding code. The normal winding code for 36V on 26" wheel is code 13. The normal winding code for 48V on 26" wheel is 16.

If I want to optimise for 20mph, I smply ask for code 16 on 36V, code 12 or 13 on 48V. They are clearly printed on the motor's label by the motor manufacturers. These things are certainly not mystery.

If you want to build your bike for your 52V battery (which requires certification because the nominal DC voltage is more than 48V, electrocution can cause serious injuries) - which motor winding code would you like?

Once you find the answer, you will understand that using the motor outside its optimised voltage is foolish.

 

edit: my 48V motors have code 16.

If I want to optimise a 48V motor for 20mph, I simply ask for code 13.

Edited July 7, 20205 yr by Woosh

wheezy, you stick a higher voltage to a lightbulb, it will glow brighter but you know already by experience why you wouldn't do that nor would you want to connect that lightbulb to a flat battery.

The argument about motors will run and run because people have all sorts of idea what a BLDC motor is, including those who want to apply Ohm's laws and Kirchoff laws to a circuitry that contains capacitors and coils.

I can go into details formulas and equations but they are of no use here because you don't want formulas and equations.

Put simply, I optimise the bike for legal use, 15mph is a known quantity, 36V Lithium Ion battery is also a known quantity. When choosing a motor for a wheel diameter, I can specify the motor winding code. The normal winding code for 36V on 26" wheel is code 13. The normal winding code for 48V on 26" wheel is 10 or 11.

If I want to optimise for 20mph, I smply ask for code 16 on 36V, code 12 or 13 on 48V. They are clearly printed on the motor's label by the motor manufacturers. These things are certainly not mystery.

If you want to build your bike for your 52V battery (which requires certification because the nominal DC voltage is more than 48V, electrocution can cause serious injuries) - which motor winding code would you like?

Once you find the answer, you will understand that using the motor outside its optimised voltage is foolish.

I think you've got your code numbers mixed up. The code number is the number of turns in each coil, so the lower the number, the faster it goes. A code 16 at 36v will barely reach 15 mph, and a code 10 at 48v will do 420 rpm, which is over 30 mph. That's for a 26" wheel.

 

 

Once you find the answer, you will understand that using the motor outside its optimised voltage is foolish.

Good point, but the question is, what is the optimal voltage? If you have a 36v system and you want more speed and torque, the optimal voltage for you is going to be higher than 36v, like 48v.

 

I keep saying it, but I'm not sure you understand it, motors don't have a voltage. There's no such thing as a 36v or 48v motor. Instead, motors have a Kv, which is how fast they turn a per volt. The only thing that will burn the motor is current, and you normally use less current at higher voltage for the same power.

Edited July 7, 20205 yr by vfr400

agreed.

I re-order the same code times and times again, so easy misquotes.

My 48V motors have code 16.

 

wheezy, you stick a higher voltage to a lightbulb, it will glow brighter but you know already by experience why you wouldn't do that nor would you want to connect that lightbulb to a flat battery.

The argument about motors will run and run because people have all sorts of idea what a BLDC motor is, including those who want to apply Ohm's laws and Kirchoff laws to a circuitry that contains capacitors and coils.

I can go into details formulas and equations but they are of no use here because you don't want formulas and equations.

Put simply, I optimise the bike for legal use, 15mph is a known quantity, 36V Lithium Ion battery is also a known quantity. When choosing a motor for a wheel diameter, I can specify the motor winding code. The normal winding code for 36V on 26" wheel is code 13. The normal winding code for 48V on 26" wheel is 10 or 11.

If I want to optimise for 20mph, I smply ask for code 16 on 36V, code 12 or 13 on 48V. They are clearly printed on the motor's label by the motor manufacturers. These things are certainly not mystery.

If you want to build your bike for your 52V battery (which requires certification because the nominal DC voltage is more than 48V, electrocution can cause serious injuries) - which motor winding code would you like?

Once you find the answer, you will understand that using the motor outside its optimised voltage is foolish.

 

So from that, can I assume you can't find a problem with the simulation results?

 

I can understand, as a kit re-seller, you need to cover yourself in case anything goes wrong, so you have to stick with what the manufacturer recommends.

 

But you can't call people foolish if they are prepared to experiment and investigate something you don't want to look into.

 

These code numbers are all very well, but go to Grin, they will tell you, voltage "ratings" for motors don't mean all that much.

 

Optimisation for one set of limited parameters does not mean a perfect solution for all situations.

wheezy, you misunderstand my position.

When you optimise, you consider compromises.

That's why I asked you to select your motor winding for your 52V or 59V battery.

Vfr400 posted the motor winding table for us to use. I use of course the same table because I buy the motors from Bafang themselves.

Choose your motor winding then explain why you choose that one instead of a higher or lower code.

Alternatively, imagine you shop for a 36V kit. The OP's Fat Boy has Bafang G06 code 13.

Which motor winding would you like? Would you like me to supply you with another code?

The argument is the same, if you optimise for one voltage say 36V, it's not going to be as good using a battery higher or lower voltage, 24V or 48V.

Edited July 7, 20205 yr by Woosh

now let's consider the financial argument. As I posted earlier, it would cost the OP about £400 for a battery, controller, LCD and wiring loom. In fact, it's the same stuff as in my 48V SWX02 kit minus the motorwheel.

https://wooshbikes.co.uk/cart/#/product/uid-188-swx02-48v12ah/bafang-swx02-48v-250w-rear-hub-kit-with-48v-12ah-battery

I sell the kit for £569 - the wwheel is worth £170, the rest £400. It's a drop in replacement for his Fat Boy.

What would you get for £400?

To me, it does not make economic sense. If it's high speed you want, you would have to derestrict it anyway, 36V or 48V makes no difference.

If it's hill climbing you want, change only the controller for a 25A controller for about £40.

That's why I said the only economic reason for overvolting the Fat Boy to 48V is to ride it at 28mph. At that speed, a £120 direct drive motorwheel is a better choice.

wheezy, you misunderstand my position.

When you optimise, you consider compromises.

That's why I asked you to select your motor winding for your 52V or 59V battery.

Vfr400 posted the motor winding table for us to use. I use of course the same table because I buy the motors from Bafang themselves.

Choose your motor winding then explain why you choose that one instead of a higher or lower code.

Alternatively, imagine you shop for a 36V kit. The OP's Fat Boy has Bafang G06 code 13.

Which motor winding would you like? Would you like me to supply you with another code?

The argument is the same, if you optimise for one voltage say 36V, it's not going to be as good using a battery higher or lower voltage, 24V or 48V.

 

 

The point of the exercise of over volting is to get more real world utility out of existing kit.

 

"Optimisation" all depends on the manufacturer, which from my experience, the parameters that are optimised are often not ideal for many real world situations.

 

Please have another look at the simulation. I have taken the same motor and done a side by side comparison, with 36V 20A and 59V 15A setups. The 36V system can't maintain 25kph on a slope, whereas the 59V system can.

 

Ok, let's go to a 25A 36V system as you suggest:

 

https://www.ebikes.ca/tools/simulator.html?motor=MXUS_XF07&cont=cust_25_100_0.008_A&wheel=700c&mass=100&hp=0&bopen=true&cont_b=cust_15_100_0.008_A&motor_b=MXUS_XF07&wheel_b=700c&mass_b=100&hp_b=0&batt_b=cust_59_0.2_12&grade=4.5&grade_b=4.5&throt_b=80&batt=cust_36_0.2_20

 

It doesn't help, still stuck at less than 20kph on an incline.

 

If I've overlooked something on the simulation please let me know, I'd really like to see if this is wrong.

 

In terms of financial cost, if someone can keep all their original kit and just change their battery, that is a major win. With your controllers, it may not be possible to over volt, I've never had one to play with, but with all the other 36V controllers I've had, they have operated at 60V without modification or even up to 72V (with cap upgrade) without issues.

 

For me, with my limited budget, I would find it hard to justify spending getting on for £600 on a kit. That's more than my bike is worth. My Bafang kit cost £170 and then I spent another £165 on the original 36V battery. Since then I have been making my own packs at a much lower cost to suit the voltage I want.

 

My second bike cost £117 for the Voilamart 250W kit and I bought another 36V pack initially, but I also use my own packs with that now. This kit only has 15Nm torque, so it really benefits from over volting.

 

So I have two e-bikes for not much more than the cost of one Woosh kit and if I want to try over volting and having a better riding experience I can do that and know it's not the end of the world if something goes wrong.

So I have two e-bikes for not much more than the cost of one Woosh kit and if I want to try over volting and having a better riding experience I can do that and know it's not the end of the world if something goes wrong.

 

I've been watching this discussion with interest and I've already learned loads (thanks everyone).

 

On this point though [mention=26000]WheezyRider[/mention] you're not comparing apples with apples. You're (I assume) a guy working in his shed who clearly has a huge amount of knowledge and confidence in that knowledge. You're fully aware of the risks and consequences of your modifications and willing to "give it a go". I salute you for that.

 

I suspect you're very different however to most ebikers, and most of [mention=6303]Woosh[/mention]'s customers who want to buy a finished product and just ride it.

 

Also consider that [mention=6303]Woosh[/mention] has to put a warranty on products, after sales care and support, pay tax, rent, NIC's and pension contributions to employees and all the other overheads of running a UK business. This is partly where the price difference lies....

It doesn't help, still stuck at less than 20kph on an incline.

the motor on the OP's Rio fat boy is a Bafang G06. It's twice as big a the MXUS07.

Here is the simulation:

https://www.ebikes.ca/tools/simulator.html?motor=MG60_500&cont=C25&grade=4.5

 

this is with the supplied 17A Lishui controller and 17AH battery:

https://www.ebikes.ca/tools/simulator.html?motor=MG60_500&cont=cust_17_70_0.03_V&grade=4.5&batt=B3617_35E

All my bikes climb hills very well. Would you want to overvolt it?

 

Edited July 7, 20205 yr by Woosh

Interesting debate....out of curiosity and talking of motor codes, does anyone know what this code relates to winding wise ? It's on the 36v Bafang Motor that's fitted to my 20in folder.

I've been watching this discussion with interest and I've already learned loads (thanks everyone).

 

On this point though [mention=26000]WheezyRider[/mention] you're not comparing apples with apples. You're (I assume) a guy working in his shed who clearly has a huge amount of knowledge and confidence in that knowledge. You're fully aware of the risks and consequences of your modifications and willing to "give it a go". I salute you for that.

 

I suspect you're very different however to most ebikers, and most of [mention=6303]Woosh[/mention]'s customers who want to buy a finished product and just ride it.

 

Also consider that [mention=6303]Woosh[/mention] has to put a warranty on products, after sales care and support, pay tax, rent, NIC's and pension contributions to employees and all the other overheads of running a UK business. This is partly where the price difference lies....

 

 

Yes, I get that Gavin, and I think I've made those points several times already. Some people will want to buy off the shelf, others will want to tinker and DIY (out of personal interest or just necessity).

 

But, say you'd bought an off the shelf kit second hand. Had it for a while and learned some things and find it doesn't quite do what you want, and to get it to do what you want, you're expected to shell out for a lot of new kit. At that point, it's got no warranty any more, so you might be prepared to experiment and see what you can do to make it more suitable.

 

Either approach is fine, splash the cash and buy all new stuff off the shelf, or experiment and try and get a better experience from what you have. But someone can't just say to someone else "Don't do that! It's foolish to do anything other than what I say" when their are many people on the web who have successfully adapted their kit to their requirements.

Edited July 7, 20205 yr by WheezyRider

the motor on the OP's Rio fat boy is a Bafang G06. It's twice as big a the MXUS07.

Here is the simulation:

https://www.ebikes.ca/tools/simulator.html?motor=MG60_500&cont=C25&grade=4.5

 

this is with the supplied 17A Lishui controller and 17AH battery:

https://www.ebikes.ca/tools/simulator.html?motor=MG60_500&cont=cust_17_70_0.03_V&grade=4.5&batt=B3617_35E

All my bikes climb hills very well. Would you want to overvolt it?

 

 

 

Ok, but 500W that's illegal for use in the UK isn't it? So why have you been so concerned about going over 15.5 mph in your other posts in this thread? The simulation shows that this will do 34kph on the flat.

Edited July 7, 20205 yr by WheezyRider

Ok, but 500W that's illegal for use in the UK isn't it?

You misunderstand the nominal power.

500W on the simulator is the capacity of the copper and magnets, not the nominal power which is 250W and is used on flat roads. If you respect the speed limit, the bike uses only about 200W to maintain 15mph on a flatish road. There is absolutely no need to mess with the electrics.

 

As I said many times, if you don't derestrict your bike, there is no need to mess with the electrics. I made all my hub bikes so that even if the bike is derestricted to 22mph, the electrics is still within its operating margins. The only reason to overvolt the Fat Boy is to ride it at 28mph.

Interesting debate....out of curiosity and talking of motor codes, does anyone know what this code relates to winding wise ? It's on the 36v Bafang Motor that's fitted to my 20in folder.

 

A production code, probably year date (2018 March) , H is probably the factory. 10002 s/n & 1 line number.

So if the 17A Lishui controller could be over volted to 59V with the same motor set up, this is what you get when climbing an 8.5% incline:

 

https://www.ebikes.ca/tools/simulator.html?motor=MG60_500&cont=cust_17_70_0.03_V&grade=8.5&batt=B3617_35E&bopen=true&cont_b=cust_17_70_0.03_V&motor_b=MG60_500&batt_b=cust_59_0.2_12&grade_b=8.5&hp_b=0&hp=0&throt_b=100

 

The 36V system can't maintain 25kph, while the 59V system can, with an efficiency >3% higher.

 

Ok, so go to a 25A controller:

 

https://www.ebikes.ca/tools/simulator.html?motor=MG60_500&cont=cust_25_70_0.03_V&grade=8.5&batt=B3617_35E&bopen=true&cont_b=cust_17_70_0.03_V&motor_b=MG60_500&batt_b=cust_59_0.2_12&grade_b=8.5&hp_b=0&hp=0&throt_b=100

 

Efficiency is improved, but it still can't get up the hill at 25kph.

 

Am I missing something?

You misunderstand the nominal power.

500W on the simulator is the capacity of the copper and magnets, not the nominal power which is 250W and is used on flat roads. If you respect the speed limit, the bike uses only about 200W to maintain 15mph on a flatish road. There is absolutely no need to mess with the electrics.

 

As I said many times, if you don't derestrict your bike, there is no need to mess with the electrics. I made all my hub bikes so that even if the bike is derestricted to 22mph, the electrics is still within its operating margins. The only reason to overvolt the Fat Boy is to ride it at 28mph.

 

Yes, I get "nominal power", but if it has a 500W sticker on it, it's going to raise questions, compared to one with a "250W" sticker on it.

es, I get "nominal power", but if it has a 500W sticker on it, it's going to raise questions, compared to one with a "250W" sticker on it.

of course I asked Bafang to make me 250W G06.

 

Am I missing something?

 

yes, power consumption.

Use my original configuration, Lishui 17A G06 and change the gradient to 8.5% - 29WH/km

Your system A G06 same gradient: 35.7WH/km

Your system B G06 same gradient: 37.8WH/km

Your system A XF07 same gradient: 49.5WH/km

Your system B XF07 same gradient: 51.4WH/km

 

there is no free lunch.

A production code, probably year date (2018 March) , H is probably the factory. 10002 s/n & 1 line number.

Ah, that partly explains it. It's not all that fast but has quite a bit of torque, there's small wheels for you great fun

Well, you would expect to use more energy if you are going faster

 

This is interesting, if you throttle back to match the speed of the 25A 36V system, the time to overheat is longer and max temp is lower and energy consumption is lower:

 

https://www.ebikes.ca/tools/simulator.html?motor=MG60_500&cont=cust_25_70_0.03_V&grade=8.5&batt=B3617_35E&bopen=true&cont_b=cust_17_70_0.03_V&motor_b=MG60_500&batt_b=cust_59_0.2_12&grade_b=8.5&hp_b=0&hp=0&throt_b=56

This is interesting, if you throttle back to match the speed of the 25A 36V system, the time to overheat is longer and max temp is lower and energy consumption is lower:

the battery consumption is pretty much the same, 36.8WH/km against 36.9 WH/km

don't see much in it.

there may me a tiny difference in motor yield at that point but it's difficult to solve the yield equation without knowing the frequency and pulse width/duty cycle. BTW, the equations and formulas for back EMF are in the doc that Sturmey posted.

https://www.pedelecs.co.uk/forum/attachments/toshiba-pdf.36673/

Edited July 7, 20205 yr by Woosh

I've been watching this discussion with interest and I've already learned loads (thanks everyone).

 

On this point though [mention=26000]WheezyRider[/mention] you're not comparing apples with apples. You're (I assume) a guy working in his shed who clearly has a huge amount of knowledge and confidence in that knowledge. You're fully aware of the risks and consequences of your modifications and willing to "give it a go". I salute you for that.

 

I suspect you're very different however to most ebikers, and most of [mention=6303]Woosh[/mention]'s customers who want to buy a finished product and just ride it.

 

Also consider that [mention=6303]Woosh[/mention] has to put a warranty on products, after sales care and support, pay tax, rent, NIC's and pension contributions to employees and all the other overheads of running a UK business. This is partly where the price difference lies....

I can't argue with that; however, your missing a point: We advise people what to do and how to do it. I wouldn't advise anybody to do anything that I don't have confidence that it would work without problems.

 

What this thread is about, like many before it, is that somebody gives a practical solution to their problem that is know to work, then the hysterical people come along, spouting off because either they haven't got a clue of how things work or the solution doesn't suit their agenda.