If you want more power, go to 48V, but I wouldn't bother going to a controller with higher Amps. With more Amps you will get a lot more heating in the motor and shorten its life. A 48V volt pack (ie 54V at full charge) at 15A will give you up to 810W, which is plenty. If you are carrying heavy loads and going uphill, or firing away from standing starts with high currents you will generate a lot of heat, with the potential to demagnetise the magnets, burn out coils, or even strip the nylon cogs inside.
Hub motor swap from Bafang to MXUS
- Thread starter Binlo
- Start date
Yes, sure here they are. The 9.8 reading is on all the 3 phase wires on the black battery terminal. The other reading is on the Red terminal of the battery, repeating again 2 min later gives a 1 now constant.
Attachments
The reason is that there's a large capacitor across the battery wire that either you're charging with your meter or it's powering the probe to give a false measurement. Three things you can try:
1. Short the two battery wires to discharge the capacitor before you start.
2. Measure with the battery connected to the battery wires.
3. Reverse the probes when measuring in each of the above.
One of those 4 measurements should give you correct readings.
Okay thanks, I will try that , as the battery is concealed in the body of the bike and will only connect to the battery plate when closed could be a bit difficult to do.
Quick question, can I damage any of the electrical components of the bike using a multimeter or even if the probes are reversed etc ? Thanks
Whether the capacitor is discharged or not really matters not, if you get a 1 reading it means the fet isn't are not shorted on that side.
That's not correct. He got a 1 because he was using the wrong scale. The mosfets should always give a resistance reading.
No damage will occur with your probes the other way round.
What I meant was If the capacitor isn't discharged 1 will register on the all the ohm scales, the fact 1 registers infers no shorting so a fet hasn't failed, a 0 would indicate a fault.
Okay that makes sense, so if I get a 1 or any other reading indicates the mosfets are working and no issues with the controller. If I had a 0 reading then mosfet's could be damaged.
So with all these tests, it has to be the motor at fault then. Anyways have now mounted the new MXUS XF15R motor and it seems to be running well. Have not had a chance to get outside to ride the bike yet, but will report back if this has solved the issue.
Thanks for everyone's feedback, stay tuned for an update shortly !
If you want to see an ohm reading on the Red line then as vfr has said simply discharge the capacitor by shorting Red/Black to each other nothing will happen.
If the original motor failed after only 140 miles, it raises the question as to why this happened. Was the cause a motor fault, or because of something else in the system damaging the motor? Is the old motor under warranty still? Can you get your money back? Otherwise it might be a good idea to investigate further yourself.
Hi, yes the bike is still under warranty, just over a month old. The problem is I have to return the whole bike to the reseller, that alone would cost me around £70 just for shipping, then the other issue I have is that if they ride it the fault may not even show up, its totally intermittent. So it was easier for myself to replace the part (motor or controller) as I am pretty good with these things, just not using a multimeter to identify the fault etc.
I now have a new motor and will try it out, if I do not see the issue then it will 100% be the motor as the controller seems have to have checked out as working with the multimeter tests I have performed etc.
I will only know once I ride the bike and confirm if the fault is disappeared etc. If the same issue does occur on this brand new motor then it will be the controller as stated by vrf.
Thanks for the feedback.
Really the reseller should pay postage if they have sold you faulty goods.
Anyway...my only niggling concern is that there may be something wrong with the controller that lead to the demise of your first motor. So it would be good to do an autopsy on the motor to find out why it failed.
Yes, and even if I get the reseller to take the bike back, I wont see it a for a few months. I made a big mistake buying from just a shop that does not specialise in bikes, anyways mistake made .. time to move on.
It is a good build bike overall, and yes I agree with you that I do need to find out where the issue lies. I will open up the motor and see, can you advise on what I am looking for etc, and can I use a multimeter to test anything inside the motor?
Perhaps I may even change the controller to a more better one as this motor is 250w/350w. So will need to do that anyways maybe?
My gut feeling is still I think overloaded the motor with going on pedal assist 5 up these inclines with my 27kg son on the back, so 80KG me, 23KG bike plus another 27KG = 130KG, when this motor states 100 kg max .. also when the motor cools down it is back to normal until it tries to tackle another incline .. flats are okay.
130Kg all up weight isn't that bad really. How steep an incline are we talking?
It is a 20" wheel bike isn't it?
I had a look back at the photos you posted of the inside of your controller. I can see a blob of solder on the current sensing shunt, which bothers me. Has anyone tried to mod this controller to give more current?
They not even big inclines, they just flat road hills, with maybe about about a 10-15' degree incline. Yes it is a 20" bike, have posted a pic of the bike now.
Wow, that is such a good observation. This is a brand new bike and I only I have had it unless this is a factory issue at time of manufacturing. Should I try and remove that extra solder or I can try and put in a new shunt if easy to do.
Only I have opened it up to look inside , never modified anything inside it. Was interested to see if I could see any burning marks on FETS and vfr indicated.
Looking at the shunt pic closer, I can also see some black scorching marks too now that you pointed that out.
Attachments
Last edited:
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.
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.
What is the purpose of the extra solder then on the shunt, is it to add additional heat protection? As it does look quite messy now that WheezyRider has pointed this out.
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.
Related Articles
-
MTF Enterprises announces acquisition of EMU Electric Bikes- Started by: Pedelecs
-
Wisper 806T folding bike wins Which? ‘Best Buy’- Started by: Pedelecs
-
Sustrans calls for protected cycle lanes- Started by: Pedelecs
-
Amazon launch their first UK e-cargo micromobility hub- Started by: Pedelecs
