This information will save anyone with a speed controller time and cash.....
The chances are that most of us have a few IRFB 4110 mosfets, they are to be found in most KT speed controllers.
You can get 20 x IRFB 4110 mosfets of Ebay for £7, this does not seem a bad deal, if your speed controller is £70. What if they are not real IRFB 4110 mosfets. What happens if they are 2nd, 3rd or even 4th generations copies. If your running 250w to 12kw motor it does not matter, your speed controller is going to die sooner, than later.
The real IRFB4110 mosfets cost around £45 for 20, so how can your speed controller cost £70 new ? Well they are fakes or B grade, which is a real shame, By replacing a few other cheap parts, costing about £15, and using real grade A mosfets they could be very good speed controllers.
It would cost £60 in parts, on top of the £70, that's £130, and a little time at the soldering iron. In my case its a 48v 18 mosfet speed controllers running 1.8kw. A replacement quality controller costs £300 to £700, so its still a great deal as long as you get the real IRFB 4110 mosfets.
Why IRFB 4110 mosfets ? The IRFB4110 mosfets rated upto 100 volts and can supply a constant current 120A with a maximum power disipation 370W each. Some mosfets are rated for 72v or less. Considering our controller is for a 48v system using a 1500w hub motor which can draw upto 1800w, overrating the components allows for voltage surges, current surges and a lower running temperature.
Official Inferon mosfet identification diagram (OLD)
The above diagram is from the datasheet from inferon showing the official marking and case design. The picture below is of IRFB4110 mosfets from 2 controllers we have purchased and replacement mosfets purchased from ebay and leading component manufacturers. Since then the identication diagram has been changed see later in post.
Suspected Mosfets (picture may or may not be true)
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| Original 1500w 45a speed controller | ||
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| KT45A 1500W Controller - Suspected Real KT, Mosfets - Undecided |
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| Real KT speed controller - Note website and model number on PCB |
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| ebay mosfet listing | ebay mosfet delivered | Leading supplier mosfet | Real KT mosfet |
The ebay listing picture is of 20 mosfets we purchased for £7, although when delivered the mosfets were not like the picture on the listing.
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| Inferon mosfet identification diagram | Leading supplier mosfet |
The mosfets purchased from a leading supplier, purchased as genuine inferon mosfets also did not match the inferon identification diagram.
From what we gather the mosfets that seem real have a deep inset circle, but we are not sure wether this is supposed to be at the top of the case or at the bottom. Just to make sure we emailed inferon, providing pictures, and asking them which were fakes and which were real. Inferon replied from their office in germany and we were told we would get a reply from there department that deals with this within 3 to 6 working days.
We also contacted Suzhou kunteng electronics co., ltd, the original suppliers of the KT controllers. We were passed onto one of there distibutors as they do not supply direct. We asked by providing pictures of the mosfets and the controllers to see if they were real. They replied saying that from the pictures they could not say if they were real or not, but did say that KT would never use fake mosfets in there products. We have also asked if they could supply us with genuine kt controllers and are waiting for a reply. We were asked if the ebikes were to be used on hilly areas and would ask KT to use high quality mosfets.
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| Original 1500w 45a speed controller | ||
We want to be able to to say with confidence that the mosfets we use are reliable and fall within the specification on the datasheet. We want to go on a 100 mile journey, starting with confidence that our equipment is in peak condition and not be stranded in the middle of nowhere.
As of yet we are waiting for a reply from inferon reguarding the authenticity of the mosfets.
As of yet we are waiting for a reply from the distributor from kt.
Once we have found out what is real and what is fake we will email the seller on ebay and ask tem about the mosfets we purchased from them and ask them if they are real and why the item we received is different from the picture on the ebay listing
All we are asking for the truth, we dont think it to be hard to be honest !
More updates to follow......
Email to inferon
Hi,
I have purchased some IRFB 4110 mosfets from "leading supplier name" to replace some mosfets on an ebike controller. I want to know if the mosfets i purchased are made by you (ie real). i have photographs of the new mosfets and would like to send the photos to you. many thanks james - Dark City Community Ebike project.
I added the photos of all the mosfets and a picture of serveral mosfets descibed as fake and real. turns out that what were thought as real maybe not real and visa versa, apart from maybe the mosfets we obtained from the leading supplier.
Reply from Inferon
Dear James,
I’m sorry for the late reply. Based on provided information we find no discrepancy, additional I can confirm that "Leading Supplier name" had this parts.
So if you expect any problems with parts purchased from "Leading Supplier name" an authorized distributor, you will get fully support from "Leading Supplier name".
Additional I have a question about the picture you have provided, where you show a comparison about genuine and counterfeit products (I have reattached). Did you have made this by your own or did you get this information from a test house?
Many thanks for you reply
Kind regards
They say the leading supplier is an authorised dealer and has had the parts. To me this wasnt full clarification of wether the parts were real or not.
My reply
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