Moma eMTB Motor Upgrade Issue

Moma eMTB Motor Upgrade Issue – Motor Cuts Out After Few Seconds

Hello everyone,

I’m having a problem with my Moma eMTB and I’d really appreciate some advice.

Original Specs:

• Rear motor: AKM 95RX 250W (brushless)
  
• Battery: 48V 6.25Ah (6250mAh) – although I’m not fully confident about this, based on this discussion:
  
  
  
• Controller: KZQW22A
  

What Happened:

Unfortunately, my original motor got damaged (long story ), so I had to replace it.

I tried to find the same 250W motor but couldn’t, so I bought:

• Replacement motor: AKM 95RX 350W
  

I installed it on the bike, and everything fits properly.

The Problem:

When I start pedalling, the motor activates normally, but:

• It makes a repeated clicking/strange noise (very loud/ and louder)
  
• After a few seconds, it cuts out
  
• Then after pedaling again it works again with the clicking noise and stops again....
  

I also tried another motor (500W), and I get exactly the same issue.

My Questions:

Now I’m confused about where the problem is:

• Is my controller not compatible with higher wattage motors (350W / 500W)?
  
• Could the controller be damaged?
  
• Could it be a battery or voltage/current limitation issue?
  
• Or is there something wrong with the wiring, hall sensors, or connectors?
  

I don’t have much electrical knowledge, and I really don’t want to keep spending money without knowing what the real problem is.

Any advice on how to diagnose this properly would be greatly appreciated.

What should I check first before buying more parts?

All motors and controllers work with each other as long as they have the same 9-pin connector. If they have different connectors, the motor must have hall sensors if it's a controller for a hall sensor motor.

It would have been helpful to describe what the problem was with the original motor. If you damaged the cable, it normally wipes out the controller too.

The first thing to check is that the motor connector is definitely all the way in until the outer part reaches the marked line on the inner part.

When you try to run a motor that won't run, it'll damage the controller to the point that it needs to be replaced too. You need a meter to check that. With everything disconnected, you measure the resistance between the red battery wire and the three motor phase wire connections, then repeat with the black battery wire. each group of three must be the same as each other and roughly in the range 3k to 24k.

When you run a 36v motor at 48v, it will spin 30% faster. The 350w AKM 95 is already a bit too fast, so at 48v it won't be very efficient. You should have got the 250w one, which is slower and will make more power than the 350w one in normal use.

Morning I sold Sia this motor on e bay it was surplus to requirements from a YOSE kit I put on a Carrera bike explained to Sia that I do not know a lot about his bike .

I have a Bafang 250W motor and rim coming in the next few days same one that I use on my bike that works a treat with 48V happy to sort this one for him once I have tested it .

I was not aware that Sia was using 48V until quite a few what’s app messages .

I also have a used Bird Bike Bafang that I think are actually 500W but have been restricted and labelled at 250W .

when he showed me his controller I asked him if he could reduce the amps to around 17amps would this help him if he is able to do it again I am not familiar with his controller.

He was also thinking about changing his controller and LCD I recommend 17 -18amp

LUSHI FROM YOSE OR KT FROM TOPBIKE KIT BOTH NOW DO PASSWORD PROTECTED LCD SCREENS

The motor shown in the OP is marked "C29", which I would assume is slow speed for 29" or 27.5" wheel. If he has large wheels, the Yose 350w motor would be the wrong speed.

Just about everything in the Reddit thread is wrong. It's not a fake 48v battery. It's simply a 12S 48v one. The cut-off voltage might be a bit low. If what the guy says is correct (only appears to be hearsay), it looks like Moma used a 36v controller rather than one set specifically for 12S. Run-on is normal for cheap bikes, and they should have break cut-offs to deal with it. It looks like he ran the battery flat and didn’t bother to charge it for some some time, which let it go below the minimal charge voltage. Leaving a bike with an empty battery is very risky, but even worse if his controller was indeed set to 2.91v per cell insread of a safer 3.1v.

He was also thinking about changing his controller and LCD I recommend 17 -18amp

LUSHI FROM YOSE OR KT FROM TOPBIKE KIT BOTH NOW DO PASSWORD PROTECTED LCD SCREENS

Before buying or changing anything, you should always find out what the problem is by testing with a meter, then you know what you need to replace and why.

I see , so we have already discussed the possibility of him changing out the controller and LCD screen to YOSE or KT so he would also need to change the PAS or possibly swap some wires about not sure because I’m not sure which one he has.

I’ve never done a build or do I have an experience on these bikes?

I think if it was me, I would look at KT 17 amp controller and KT LCD 3 or 4 and a correct PAS

From topbikekit he has a neighbour and a friend who is more hands-on with this type of thing helping him.

I do not think his bike has juliet Juliet plugs except motor so he would need to be careful of the wiring sequence.

Or I’ll go on the YOSE WEBSITE and buy the 18 amp Lushi Controler which is the correct one for this motor and a password protected LCD.

I think both ways should be okay with 48 V what do you think?

Then sell the parts from the bike he knows are working on eBay or on here

Or see if top bike kit have the exact correct motor that he needs have it threaded into his original rim and send me back the AKM one he bought and I’ll refund him.

I see , so we have already discussed the possibility of him changing out the controller and LCD screen to YOSE or KT so he would also need to change the PAS or possibly swap some wires about not sure because I’m not sure which one he has.

 

I’ve never done a build or do I have an experience on these bikes?

 

I think if it was me, I would look at KT 17 amp controller and KT LCD 3 or 4 and a correct PAS

From topbikekit he has a neighbour and a friend who is more hands-on with this type of thing helping him.

 

I do not think his bike has juliet Juliet plugs except motor so he would need to be careful of the wiring sequence.

 

Or I’ll go on the YOSE WEBSITE and buy the 18 amp Lushi Controler which is the correct one for this motor and a password protected LCD.

 

I think both ways should be okay with 48 V what do you think?

 

Then sell the parts from the bike he knows are working on eBay or on here

 

Or see if top bike kit have the exact correct motor that he needs have it threaded into his original rim and send me back the AKM one he bought and I’ll refund him.

Run-on is caused by the controller, not the pedal sensor.

It's not worth usuing a LiShui controller as a replacement. A KT is much better.

As I said, he needs to find out what's wrong before wasting money on replacement parts.

A KT will work with a 12S battery, but it has automatic voltage selection between 36v and 48v, so you'd have to make eure that the battery is fully charged whenever connecting to make sure it chooses correctly, and you'd need to set the cut-off a bit lower with C12 setting. The battery meter obviously won't ever show full.

Hi folks, thanks for all your replies. I’ve recorded a video showing exactly what the problem is, which should hopefully make things clearer. As [mention=3847]saneagle[/mention] suggested, I suppose a 17-amp controller might solve the issue.

Click: Here is the link to the video

Have you tried getting into advanced settings in your LCD ?

As we discussed I really do not have experience with these bikes and only do builds with kits that mostly all come together .

T that said can you show a picture of the inside of the controller i.e. where all the wires are going in? Is it full of silicone or can you actually test it in there?