Hub motor swap from Bafang to MXUS

[WheezyRider]

Controllers often have solder on the shunt from the factory.

It's not the weight or hills that damage controllers, it's the speed. You mustn't go too slow with maximum power. Obviously weight affects your speed on inclines and your acceleration.

I was wondering, for a stock set up, do you think low speeds/full amps is worse for the controller or for the motor? Which would you expect to break first?

 

[Binlo]

As Vfr says, it could have come from the factory like that, but it's not a great sign, these shunts have a resistance of a fraction of an Ohm, so anything added to the shunt could have a significant effect. Hopefully the QC in the factory should have picked up any out of tolerance units. For peace of mind, you could get a fairly cheap Watt meter to fit to your set up which will also tell you things like voltage and current output and peak values.

That actually sounds like a good idea, are you able to suggest any and do I wire it upto the battery terminal or where? Thanks What is the critical reading that I need to look out for , is it the watts or amps or both, What do I see on my lcd panel is when the motor starts play up the current shoots up to max bars, I think 5

 

[RossG]

Perhaps I could come in on this one for a second, I know the bike very well I have one myself. For the benefit of the other guys helping out - The battery is hidden on these bikes, it's in the front section of the frame kind of banana shaped, the controller is hidden inside the other section.
If you wanted to upgrade to a higher voltage battery if would need to go outside of the frame unless the battery could be re-celled differently. The controller is also a problem as a higher voltage box would not fit in the frame either, so really you're stuck with 36v. I upgraded my machine with help from the guys on here to the popular KT setup with a LCD3 display and the bike performs really well. No problems with hills and an increase in speed to boot, it's a very capable bike.
As for the fault I'd still be inclined to believe it's the controller. Incidentally the controller/display set up are a matched pair, AFAIK they will only work together and they didn't perform well for me anyway hence I changed the lot and now all is well.

 

[WheezyRider]

Perhaps I could come in on this one for a second, I know the bike very well I have one myself. For the benefit of the other guys helping out - The battery is hidden on these bikes, it's in the front section of the frame kind of banana shaped, the controller is hidden inside the other section.
If you wanted to upgrade to a higher voltage battery if would need to go outside of the frame unless the battery could be re-celled differently. The controller is also a problem as a higher voltage box would not fit in the frame either, so really you're stuck with 36v. I upgraded my machine with help from the guys on here to the popular KT setup with a LCD3 display and the bike performs really well. No problems with hills and an increase in speed to boot, it's a very capable bike.
As for the fault I'd still be inclined to believe it's the controller. Incidentally the controller/display set up are a matched pair, AFAIK they will only work together and they didn't perform well for me anyway hence I changed the lot and now all is well.

Good points Ross.

I have found with the 36V controllers I have had, I can run them at 48V no problem, other than the LVC being wrong. Need to look at the ratings of the capacitors and the MOSFETS. If they are >60V, it is likely to be ok at 48V (54V max). But I wouldn't do this experiment unless I had a spare, or didn't care about the controller.

Also, I still feel this controller is suspect, so I wouldn't push it until it is known to be fine.

 

[WheezyRider]

That actually sounds like a good idea, are you able to suggest any and do I wire it upto the battery terminal or where? Thanks What is the critical reading that I need to look out for , is it the watts or amps or both, What do I see on my lcd panel is when the motor starts play up the current shoots up to max bars, I think 5

If you can (sounds from Ross it may be tricky, due to space considerations) put it between the battery and the controller. I've got one like this. I don't think it's super accurate, but it's cheap and gives me an idea. If you did have to place it inside the frame (space permitting) it does store the peak values for you to check after your ride, and tell you how many Ah you have used.

 

[Binlo]

Perhaps I could come in on this one for a second, I know the bike very well I have one myself. For the benefit of the other guys helping out - The battery is hidden on these bikes, it's in the front section of the frame kind of banana shaped, the controller is hidden inside the other section.
If you wanted to upgrade to a higher voltage battery if would need to go outside of the frame unless the battery could be re-celled differently. The controller is also a problem as a higher voltage box would not fit in the frame either, so really you're stuck with 36v. I upgraded my machine with help from the guys on here to the popular KT setup with a LCD3 display and the bike performs really well. No problems with hills and an increase in speed to boot, it's a very capable bike.
As for the fault I'd still be inclined to believe it's the controller. Incidentally the controller/display set up are a matched pair, AFAIK they will only work together and they didn't perform well for me anyway hence I changed the lot and now all is well.

Hi Ross, your post has added more weight now for me to change the controller and display unit. I was also looking at the KT-LCD3 setup, what controller did you pair it up with and did you also add the throttle function to it? If you able to provide me any links of what you purchased and from where, then that would be most helpful.

I'd also be interested to know of other issues or upgrades you have done on the bike, besides this motor issue I have had, I am overall very happy with the bike especially its build quality and features etc.

 

[Binlo]

If you can (sounds from Ross it may be tricky, due to space considerations) put it between the battery and the controller. I've got one like this. I don't think it's super accurate, but it's cheap and gives me an idea. If you did have to place it inside the frame (space permitting) it does store the peak values for you to check after your ride, and tell you how many Ah you have used.

View attachment 36252

Okay great, you all have been so helpful, really appreciate everyone's time and effort here. Thanks all!

 

[Binlo]

If you can (sounds from Ross it may be tricky, due to space considerations) put it between the battery and the controller. I've got one like this. I don't think it's super accurate, but it's cheap and gives me an idea. If you did have to place it inside the frame (space permitting) it does store the peak values for you to check after your ride, and tell you how many Ah you have used.

View attachment 36252

I've had a look, i'll be able wire that in and then run the cables up to the handle bar from the bottom cut out of the bottom hole. Is there a certain gauge cable I should use for this ?

 

[WheezyRider]

I've had a look, i'll be able wire that in and then run the cables up to the handle bar from the bottom cut out of the bottom hole. Is there a certain gauge cable I should use for this ?

You want to be as thick as you sensibly can, and keep it short as you can as it is carrying a fair bit of current. I mostly use 12AWG, which is probably overkill, but if you've got a fairly long cable run, I wouldn't go less than 14AWG.

 

[Binlo]

You want to be as thick as you sensibly can, and keep it short as you can as it is carrying a fair bit of current. I mostly use 12AWG, which is probably overkill, but if you've got a fairly long cable run, I wouldn't go less than 14AWG.

Okay thanks, it looks like the cable run will be less then 1.5m to get to the handle bar.

 

[RossG]

I got my controller/LCD3 from PSW power, a Chinese company but some of their stuff is shipped from Germany.
I also added a throttle which you can't do with the controller that comes with the bike so I have all three options of control, Torque, PAS & Throttle. Remember the controller would need to be the smaller 24/36v version or it won't fit inside the frame. Running cables from the controller and attaching a meter is problematic because of the way the battery connects up. You have to have the bike folded shut to have power so I found it easier to put the bike on a jig I built myself that allowed me to carry out tests with the bike powered up but still unfolded.
That required a lot of very thick cable and some cable clips I fashioned myself from crimp terminals, it's all possible but not easy. I'd still like to know why the original setup is failing though.

 

[WheezyRider]

Where possible, use Amass XT60 connectors instead of crimp fit bullets etc. I assume that's 1.5 m there and back, total length?

 

[Binlo]

I got my controller/LCD3 from PSW power, a Chinese company but some of their stuff is shipped from Germany.
I also added a throttle which you can't do with the controller that comes with the bike so I have all three options of control, Torque, PAS & Throttle. Remember the controller would need to be the smaller 24/36v version or it won't fit inside the frame. Running cables from the controller and attaching a meter is problematic because of the way the battery connects up. You have to have the bike folded shut to have power so I found it easier to put the bike on a jig I built myself that allowed me to carry out tests with the bike powered up but still unfolded.
That required a lot of very thick cable and some cable clips I fashioned myself from crimp terminals, it's all possible but not easy. I'd still like to know why the original setup is failing though.

Okay great, I will check that site out. If they do not ship from Germany and only China I will prob have to pay VAT & Duty to UK ? Was it the Brainpower controller you got as that seems to be the perfect pair for the KT-LCD3 ?

Did you have problems with the wiring or did you cut off the wire connectors from the original controller and then paired them up the new one with the same connectors? Did all the color of the wires match up or was it alot of guess work ?

I think my money now is on the controller, heating up and then causing the motor to malfunction, there prob is nothing wrong with this motor now that I have learnt alot from all on this thread. However I jumped the gun and now have a MXUS XF15R motor on this bike, which fits well and is 250w/350w motor does def look much more beefy then then the Bafang one that came with the bike.

 

[RossG]

I used the KT24/36SVPR-12A Controller because it matches the LCD3 Display so no compatibility problems.
You can't get a beefier one because as I said it won't fit in the frame, this one does.
Small packages from China usually get through without having to pay any extra charges I've always found.

When it came to connecting mine up I cut off all the plugs & sockets and soldered the whole lot together covering the wiring with heat shrink. It was a bit of a squeeze cramming all the wiring back into the frame space especially as in my case I had extra cables for the throttle plus I fitted a separate lighting circuit that has an LED indicator on the bars to show if the lights accidently get switched on during the day without me noticing.
With all that extra cable in the frame I decided to go the soldering route so everything is covered and no plugs can shake loose.

 

[Binlo]

I used the KT24/36SVPR-12A Controller because it matches the LCD3 Display so no compatibility problems.
You can't get a beefier one because as I said it won't fit in the frame, this one does.
Small packages from China usually get through without having to pay any extra charges I've always found.

When it came to connecting mine up I cut off all the plugs & sockets and soldered the whole lot together covering the wiring with heat shrink. It was a bit of a squeeze cramming all the wiring back into the frame space especially as in my case I had extra cables for the throttle plus I fitted a separate lighting circuit that has an LED indicator on the bars to show if the lights accidently get switched on during the day without me noticing.
With all that extra cable in the frame I decided to go the soldering route so everything is covered and no plugs can shake loose.

Thanks for all this information, really useful stuff. So I am thinking of ordering the following components, as the other stuff I have on the bike or do I need to get anything else you think which is not compatible with the bike ?

 

[Binlo]

Thanks for all this information, really useful stuff. So I am thinking of ordering the following components, as the other stuff I have on the bike or do I need to get anything else you think which is not compatible with the bike ?

@Ross - I have ordered the same controller you have, KT-LCD3, plus the light/horn and throttle. It says it should arrive in 3-5 days using DHL Express.

I don't want to damage this new motor using the existing "suspect" speed controller, so will now wait for new controller and hopefully I can start to enjoy the bike.

24V/36V 250W 6Mosfets 12A Brushless DC Sine Wave Controller
LCD/LED:KT-LCD3
Lamp and switch:with Lamp and switch
Throttle:with left Throttle

 

[vfr400]

I was wondering, for a stock set up, do you think low speeds/full amps is worse for the controller or for the motor? Which would you expect to break first?

That's where you get maximum current. when the motor gets up to speed, the current goes down independent of anything the controller does.

The controllers always blow first. I've never seen a hub-motor of the types we use burn in normal use, even when they've been substantially over-powered. Burning will happen sometimes if a phase wire disconnects with some controllers.

As I said, solder on the shunt from the factory is quite normal. they do it to make adjustments to the shunt value.

 

[WheezyRider]

That's where you get maximum current. when the motor gets up to speed, the current goes down independent of anything the controller does.

The controllers always blow first. I've never seen a hub-motor of the types we use burn in normal use, even when they've been substantially over-powered. Burning will happen sometimes if a phase wire disconnects with some controllers.

As I said, solder on the shunt from the factory is quite normal. they do it to make adjustments to the shunt value.

That's what I expected, although sounds worrying about the phase wire disconnection. Is that from a controller failure, or just a wire coming adrift?

I suppose in some factories they have someone sitting there with a soldering iron trying to "tune" the shunt. All the controllers I've taken apart and BMS units with shunts have been clean.

 

[WheezyRider]

Binlow, out of interest, what is the part number on the MOSFETS? The component that looks like a MOSFET on the end is a voltage regulator, but can't see the codes on the MOSFETS.

 

[RossG]

That's where you get maximum current. when the motor gets up to speed, the current goes down independent of anything the controller does.

The controllers always blow first. I've never seen a hub-motor of the types we use burn in normal use, even when they've been substantially over-powered. Burning will happen sometimes if a phase wire disconnects with some controllers.

As I said, solder on the shunt from the factory is quite normal. they do it to make adjustments to the shunt value.

They do that a lot in the world of consumer electronic products. In theory every item of the same type coming off of the conveyor belt is the same as the first, but because of component variation in the circuit board you get a slightly different performance so slight adjustments are made to even things up.