Electric Bikes - Controller problem

My first request for help!
I recently bought two Chinese made folding bikes,that have turned out to be a bit of a mystery.
According to the manufacturers web site they should be 48volt,but on opening the battery case I found they were fitted with only3 batteries and a 36 v controller.The motor was marked as suitable for 36 or 48volts,so after some difficulty I purchased 2 48v controllers from the manufacturers in China,and added extra batteries.Our contact in China was most helpful with pictures of the controllers wired up,but I still can't get them to run properly.
With the original 36 v controllers the bikes run beautifully,on 48volts,but of course the safety cut off for depleted batteries doesn't work.When I wired up the 48v controller,everything seemed to work,but after only a couple of minutes the controller and wires were very hot,and the motor sounds very rough and noisy.I have checked the wiring and are sure they are wired up correctly.
The only difference is that the throttle has a button for 3 power settings and this doesn't work on the 48v controller.
I put the 36v controller back in and did 16klm this morning ,with hardly any pedaling,including a few hills,and at the end the battery pack still showed 48.2 volts on my tester,well above the safety cut out level of 42 volts on the 48v controller.
The bikes run very well on the 36v controllers,but I would like to set them up correctly.
If anyone has any idea what the problem is I would be most grateful to hear from them.
regards Ken.

I'm not much of an electronics expert when it comes to your 48v controllers, unfortunately. With the mention of the heat, it sounds as though the new controllers are having difficulty in handling the current - which is unexpected considering their higher rating, but it could be that there is a problem somewhere. Asking on V is for Voltage would be my suggestion, there's a large community of very skilled users there.

What could work well as an alternative, would be seeing if a Cycle Analyst is compatible with your motor system and linking it up to the 36v controller. There is a stand alone model which is very likely to work. The Cycle Analyst would be able to regulate the voltage cutoff for your 48v batteries, as well as having many other useful features to offer. Its a very useful little piece of hardware.

http://ebikes.ca/drainbrain.shtml

yes that one would be hard to nail down without a meter, could be a number of problems.
one would be amps. another could be hall wires timing is off.

if im reading this right you have two controllers righ? one 36v one 48volt? are these two controllers the same brand?

I'd like to take a stab at this...I'm either correct, or I'm completely out to lunch ( lol )

can you measure the voltage across the motor with each controller in place? I have a suspicion that the 48Volt controller is getting more voltage to the motor....bare with me, I'll explain...

you said the motor is sounding rough and noisey....I'm trying to guess what this means, and the one idea that comes to mind is that the motor isn't responding well to the higher voltage and higher electromagnetic fields...

have you ever ran a motor so long the bearings or bushings are no longer any good? well, it'll want to bind up instead of spinning freely, and if it does spin it'll often take more power to do so.

......an of course, we all know that a stalled or loaded motor draws much more current. this might explain why you are overheating after running it for a few minutes.

My first request for help!
I recently bought two Chinese made folding bikes,that have turned out to be a bit of a mystery.
According to the manufacturers web site they should be 48volt,but on opening the battery case I found they were fitted with only3 batteries and a 36 v controller.The motor was marked as suitable for 36 or 48volts,so after some difficulty I purchased 2 48v controllers from the manufacturers in China,and added extra batteries.Our contact in China was most helpful with pictures of the controllers wired up,but I still can't get them to run properly.
With the original 36 v controllers the bikes run beautifully,on 48volts,but of course the safety cut off for depleted batteries doesn't work.When I wired up the 48v controller,everything seemed to work,but after only a couple of minutes the controller and wires were very hot,and the motor sounds very rough and noisy.I have checked the wiring and are sure they are wired up correctly.
The only difference is that the throttle has a button for 3 power settings and this doesn't work on the 48v controller.
I put the 36v controller back in and did 16klm this morning ,with hardly any pedaling,including a few hills,and at the end the battery pack still showed 48.2 volts on my tester,well above the safety cut out level of 42 volts on the 48v controller.
The bikes run very well on the 36v controllers,but I would like to set them up correctly.
If anyone has any idea what the problem is I would be most grateful to hear from them.
regards Ken.

Sounds like the amps the controller is sending is more than the motor can handle. It will sound rough as it's in the process of burning up.

Email the seller and ask them what the amperage is coming out of the old controller and the new controller and go from there. My experience from some chinese manufacuters is they don't know, don't care or close their eyes and collect the money.

Good luck.

Many thanks to all those who have so promptly offered help.tomorrow is Monday for me,so it is back to work,and I shan't have time to work on the bikes again till next weekend.Meantime I will look up more information on all the points made,[and try not to confuse myself further]
The replacement controllers are a different brand but have been supplied by the bike manufacturers,so should be compatible.I will look at the Cycle analyst option,but with 2 bikes to convert I am afraid finance[or rather lack of it!!!]becomes a factor.
As regards amps,the 36v controllers are rated at 17 amps and the 48 at 18,so I don't see a problem there.The motors are set up to handle 36 or 48 volts,and are used on most of the bikes they produce.
This afternoon I had an unexpected visit from an EBike enthusiast who I met over the internet,and he has advised trying different combinations of the wires between controller and motor.[Green,yellow and blue]Apparently this solved a similar problem that he had.I have already discovered that connecting blue to blue makes the motor go forward on one bike,but backwards on the other!!!!!It seems that the Chinese assembly workers are not too fussy about how the bikes are wired up,or how the colour combinations go together.[getting the right combination could be a bit like winning lotto!]
Thanks again to every one,it is great to know there are people out there who can help.

I posted too soon. you mention multiple wires going to your hub motor that means its a brushless motor, right? brushless motors don't have a commutator. instead they use hall effect sensors to determine the 'firing order' of the power wires. So, yes, the green yellow blue combination matters, and yes, trying a different combination could solve your problem.

best of wishes to you! rgds Tyler

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