Help with new controller for MAC 12t

[Justin.Clements]

Hi,
I've not had to replace a controller in many years, not since Em3ev stopped selling them. I've only ever used 20a/9 fet Infineon controllers bought from them which were compatible with a MAC 12t hub motor with a 52v battery. I recently bought a 26-32a controller on Amazon that I thought would be suitable but although it works fine on the flat it pretty much drops to a standstill on big hills. Could this be due to a max current that is less than my motor draws on a hill?

Can anyone recommend a controller that would be more suitable?

Thanks in advance.

Justin

 

[Nealh]

Is your battery capable of delivering 26+ amps ?

 

[saneagle]

Hi,
I've not had to replace a controller in many years, not since Em3ev stopped selling them. I've only ever used 20a/9 fet Infineon controllers bought from them which were compatible with a MAC 12t hub motor with a 52v battery. I recently bought a 26-32a controller on Amazon that I thought would be suitable but although it works fine on the flat it pretty much drops to a standstill on big hills. Could this be due to a max current that is less than my motor draws on a hill?

Can anyone recommend a controller that would be more suitable?

Thanks in advance.

Justin

It would help a lot if you told us which controller you have.

 

[Justin.Clements]

Is your battery capable of delivering 26+ amps ?

Is your battery capable of delivering 26+ amps ?

I used a 30a Daly bms with 14 li-ion 20ah pouch cells. I can't remember the c rating but they were li-ion not lifepo4. The battery has always performed really well. I don't think it will be the battery as I'm using my partner's controller which is the same as my old controller and it flies up hills using that.

 

[Justin.Clements]

It would help a lot if you told us which controller you have.

Sorry Saneagle I don't know. I bought it in 2013. They we're only ever described as Infineon controllers which obviously I appreciate just refers to the make of mosfet used. My motor is a Mac 12t geared hub motor, brushless with hall sensors if that helps.

 

[Justin.Clements]

It would help a lot if you told us which controller you have.

Just found some more details. This is how it was sold, there is no manufacturer name.

9 fet IRFB3077 Infineon Controller (Motor With Hall Sensors)
63V Caps, Max input voltage is limited to 60V
36-50V operation, 60V max
30A Current Limit

 

[saneagle]

Two things I can think of: I don't see any wiring diagram or explanation of the wires. Is one connector for a three speed switch, limiter or something like that? Secondly, I've had a controller, where it had two shunts and one came unsoldered so it only gave half the current.

It would be nice to see how much current it's actually giving. You'd need an external wattmeter for that. Are you using a Cycle Analyst with it?

 

[Justin.Clements]

Two things I can think of: I don't see any wiring diagram or explanation of the wires. Is one connector for a three speed switch, limiter or something like that? Secondly, I've had a controller, where it had two shunts and one came unsoldered so it only gave half the current.

It would be nice to see how much current it's actually giving. You'd need an external wattmeter for that. Are you using a Cycle Analyst with it?

Yes, both my old and this replacement controller have wires for a three-speed switch and I had this connected on top speed. Not that I would expect to reach full speed up a hill, what I mean by that is when going up a steep hill switching between middle and top doesn't make any difference. My ride to work takes me over the south downs, not a massive hill but it's enough to slow the bike down to walking speed with the new controller. It would probably stop if I wasn't off the saddle peddling, while the old controller manages it easily.
No, I don't use a cycle analyst. I did rig up a watt meter some time ago, I'll see if I can find it. It was more to test the amp hours put into the battery. It's rated up to 100a but I don't feel the wires in/out are thick enough for my liking, even at 20-30a, but I guess a short test would be ok. Also, my kit pre-dates the use of a PAS sensor and I just use a throttle. But do you think it could it be some kind of speed limiter then?
I don't know if more recent and advanced controllers are just incompatible with my motor. I read somewhere that the hall sensors on MAC motors were set differently to others. I replaced the hall sensors not that long ago and I can't see how that could be true but I don't know enough to understand this.
Unless there is an obvious fix or test I'm prepared to write off the controller I bought recently and buy another but I don't want to make the same mistake again.

 

[saneagle]

Yes, both my old and this replacement controller have wires for a three-speed switch and I had this connected on top speed. Not that I would expect to reach full speed up a hill, what I mean by that is when going up a steep hill switching between middle and top doesn't make any difference. My ride to work takes me over the south downs, not a massive hill but it's enough to slow the bike down to walking speed with the new controller. It would probably stop if I wasn't off the saddle peddling, while the old controller manages it easily.
No, I don't use a cycle analyst. I did rig up a watt meter some time ago, I'll see if I can find it. It was more to test the amp hours put into the battery. It's rated up to 100a but I don't feel the wires in/out are thick enough for my liking, even at 20-30a, but I guess a short test would be ok. Also, my kit pre-dates the use of a PAS sensor and I just use a throttle. But do you think it could it be some kind of speed limiter then?
I don't know if more recent and advanced controllers are just incompatible with my motor. I read somewhere that the hall sensors on MAC motors were set differently to others. I replaced the hall sensors not that long ago and I can't see how that could be true but I don't know enough to understand this.
Unless there is an obvious fix or test I'm prepared to write off the controller I bought recently and buy another but I don't want to make the same mistake again.

With the power you're getting, I doubt that you're going to overload the wires in the wattmeter. All you need to do is confirm the current. You do that by spinning up the wheel with full throttle, then use the brake to slow it down while you keep the full power on. It only takes a couple of seconds, so nothing will get damaged. You should see about 1A to 2A with the wheel running in air after it's accelerated up to speed, then the current will go right up when you put the brake on. You only need to brake it down to about 10 mph. Don't stop it completely.

 

[Justin.Clements]

With the power you're getting, I doubt that you're going to overload the wires in the wattmeter. All you need to do is confirm the current. You do that by spinning up the wheel with full throttle, then use the brake to slow it down while you keep the full power on. It only takes a couple of seconds, so nothing will get damaged. You should see about 1A to 2A with the wheel running in air after it's accelerated up to speed, then the current will go right up when you put the brake on. You only need to brake it down to about 10 mph. Don't stop it completely.

Thanks, I'll try that. I think the meter is in my camper van which is at the workshop atm.
What are we looking for? I don't think my motor would be demanding more than 20 amps so it just to show that the controller caps out at a lower amperage than it claims? That is what I suspect and it was either mis-advertised, is faulty or has internal settings capping the output.
Are there any alternative controllers you could recommend?

 

[saneagle]

Thanks, I'll try that. I think the meter is in my camper van which is at the workshop atm.
What are we looking for? I don't think my motor would be demanding more than 20 amps so it just to show that the controller caps out at a lower amperage than it claims? That is what I suspect and it was either mis-advertised, is faulty or has internal settings capping the output.
Are there any alternative controllers you could recommend?

The power comes from the controller. If it's a 30A controller, you should see 30A, but if you only see 15A, then something is wrong with the controller, probably an unsoldered shunt. If you get 30A, but the motor is not giving enough power, we have to find out why, like incorrect timing or false positive connection sequence.

 

[Justin.Clements]

Thanks saneagle, if it's an issue with the controller that's fixable and you are happy to guide me through then it's worth doing. The controller has been taken off my bike atm so I might just try and connect it up to my partners bike for testing. Her controller is currently on my bike.

 

[Justin.Clements]

The power comes from the controller. If it's a 30A controller, you should see 30A, but if you only see 15A, then something is wrong with the controller, probably an unsoldered shunt.

Hi Saneagle, I couldn't find my wattmeter so bought a new one. Useful item to have.
Anyway I've tested my bike which has the original controller. I applied the brake while the motor was at full throttle and it went up to 33 amps. I was a bit surprised it went that high.
I then wired the new controller onto my partners bike. The motor wheel actually stopped at about 6a when I was testing so I tried again a using the brake more gently and got it to reach 21a before stopping.
I think this shows that it's capping out too early and not reaching the 26-32a shown. I might as well open it up. You said it's likely a shunt that is unsoldered. Are you referring to a mosfet? I have tried to replace mosfets before, one successfully and once unsuccessfully!

 

[saneagle]

Hi Saneagle, I couldn't find my wattmeter so bought a new one. Useful item to have.
Anyway I've tested my bike which has the original controller. I applied the brake while the motor was at full throttle and it went up to 33 amps. I was a bit surprised it went that high.
I then wired the new controller onto my partners bike. The motor wheel actually stopped at about 6a when I was testing so I tried again a using the brake more gently and got it to reach 21a before stopping.
I think this shows that it's capping out too early and not reaching the 26-32a shown. I might as well open it up. You said it's likely a shunt that is unsoldered. Are you referring to a mosfet? I have tried to replace mosfets before, one successfully and once unsuccessfully!

The shunts are like a wire staple in the pcb. Sometimes there is only one, but higher current controllers often have two, three or more side by side. Some controllers have solid state shunts, which are like little black slabs. Here's a picture of a pair of normal shunts:

https://www.reddit.com/media?url=https%3A%2F%2Fi.redd.it%2Fa9qzii9wjja61.jpg

 

[Justin.Clements]

Hi Saneagle,
I've pulled the pcb out and can see two shunts side by side. They look OK. I've attached some pics. The controller has 12 mosfets as advertised.

 

[saneagle]

Hi Saneagle,
I've pulled the pcb out and can see two shunts side by side. They look OK. I've attached some pics. The controller has 12 mosfets as advertised.

I'd resolder them just to make sure. When you do it, use plenty of heat and don't take the iron off too soon. be careful that the solder doesn't run through the hole. I'd hold the pcb vertical when doing it.

If it was only one shunt, it probably wouldn't be the cause of your problem, but two matches perfectly because if one wasn't soldered properly, you'd get half the current. If it's a compromised solder joint, you could get anything between half and full current changing with temperature or anything else.