BBS02 750W controller dead

I haven't reprogrammed my controllers yet. I will get to that soon. I have the display extension cable and USB serial hardware ready to go.

I'll do a repair on both and test some new settings when I get the time.

I got a load of mosfets from here.

http://www.rapidonline.com/electronic-components/p75nf75-mosfet-t0220-80a-75v-47-5622
 
Here's the data sheet for the P75NF75:
http://www.st.com/web/en/resource/technical/document/datasheet/CD00002771.pdf

75 volts, 80 amps, 11 mOhm.

There are much better choices out there these days.

IPP034NE7N3 is one, 75V, 100A, 3.4mOhm and relatively cheap ($3.41ea on DigiKey).

for a little more money ($4.16), the CSD19536KCS is rated 100V, 150A and 2.7mOhm. This makes a IRFB4110 look lame.

Having a lower on resistance lowers the heating quite a bit and will be less likely to blow.
 
fechter said:
Here's the data sheet for the P75NF75:
http://www.st.com/web/en/resource/technical/document/datasheet/CD00002771.pdf

75 volts, 80 amps, 11 mOhm.

There are much better choices out there these days.

IPP034NE7N3 is one, 75V, 100A, 3.4mOhm and relatively cheap ($3.41ea on DigiKey).

for a little more money ($4.16), the CSD19536KCS is rated 100V, 150A and 2.7mOhm. This makes a IRFB4110 look lame.

Having a lower on resistance lowers the heating quite a bit and will be less likely to blow.
Click to expand...

Wow, thanks for the information!

Have you personally tried any of these yet?
 
fechter said:
Here's the data sheet for the P75NF75:
http://www.st.com/web/en/resource/technical/document/datasheet/CD00002771.pdf

75 volts, 80 amps, 11 mOhm.

There are much better choices out there these days.

IPP034NE7N3 is one, 75V, 100A, 3.4mOhm and relatively cheap ($3.41ea on DigiKey).

for a little more money ($4.16), the CSD19536KCS is rated 100V, 150A and 2.7mOhm. This makes a IRFB4110 look lame.

Having a lower on resistance lowers the heating quite a bit and will be less likely to blow.
Click to expand...

I haven't torn into my 48v 20a (which is dead) or my living 48v 18a controller to check what FETs are in there yet. So what do you think the chances are that all the controllers are using the same ones? I ask because eventually I will open up the dead controller and order replacements. But I was thinking it might be a good idea to have spares. Especially if both controllers take the same ones.

Bob
 
A long, long time ago, I had a Crystalyte controller that blew the FETs and I replaced them with IRFB4110s. I hammered the crap out of it, running up to 100A and it's never blown. Runs quite a bit cooler than stock too.

I haven't tried either of the ones I listed since they are pretty new. On paper, they look better.

If upgrading the FETs, it's important to change all of them to keep the set matched.
 
Do mosfets blow only from a current surge or also from heat?
 
im not an expert but i guess both, although the bbs02 does have a temperature sensor mounted in to a little hole in the heatsink that the FETs are screwed to so in the case of these blown controllers it is mostly surges.
 
arc246, nice writeup and pics, thanks! :D

-JD
 
incase anyone is intterested i have replaced my controller completely for an infineon, and have so far logged my progress in another thread on here.
 
ac246 said:
im not an expert but i guess both, although the bbs02 does have a temperature sensor mounted in to a little hole in the heatsink that the FETs are screwed to so in the case of these blown controllers it is mostly surges.
Click to expand...
Thanks, ac246! I'm glad you're having good results with a separate controller. I'll go check out your thread.
 
Hi,

I have invested in a few Bafang BBS02 750 kits from Paul. I have them listed for sale here on ES.

After reading through this thread and if possible I'd like to do everythimg I can to remedy any problems my kits might have before I sell them to customers.

I'm having the controllers flashed by a local ebike company who also sells this kit. I want to make sure they do everything possible from a programming standpoint.

Any suggetions..

So what have determined?

Is this strictly a software problem?

Is it a random problem that only affect certain kits or is it one inherent to the hardware or software?
 
I ordered a BBS02 750W kit from Paul last week. Was a delay for me on the logistics shipping to an APO address but got it squared away.

I want to share what Paul stated....."Many problems on the BBS02 kits have been due to programming problems, which are now resolved, we do warranty failures, so will deal with issues that may arise."

So it looks as if there was a programming issue. I ordered the USB cable so I hope to take note of the info on the stock controller. I'll share what I can, once it arrives.

-- Ed (Jayvyn)
 
Guys, I am getting close to Madison (Wisconsin). Do you know of anybody that can fix, service a Bafang motor in the Area? It's making a horrible grinding noise and it dies now and then (starts OK after reseting it).

Thanks!
 
I tried to replace all 9 mosfets on a blown controller with IPP034NE7N3 from DigiKey. (Could not get any support from the vendor with, learned my lesson and now will buy only from Paul at em3ev)

Typical horror story of 2nd time out and the controller went belly up on a small hill.

Spent about 4 hours getting off the potting and doing all the soldering work. It was a bear. Not recommended for the faint of heart.

In the end it didn't work. I don't know if it was because the controller was not compatible with the new mosfets, or there was something else that blew in the controller or if it was my soldering skills.

Was surprised that the heat sync for the mosfets was not thermal pasted to the metal case. Seems like that would have been a smart thing to do.

Karl
 
OD.jpg
ac246 said:
Some photos of my controller. I didn't take many photos.

There are a few un used holes on the controller which look like they were for potential header plugs which werent used such as on the second photo.
Click to expand...

Sorry ac246.. i'm trying to push the circuit out from the motor case. I've seen 1 screw on the left and 1 screw on the right side.. but after unscrewing, it doesn't move from its position. And, in order to remove rubber i've used a small screwdriver.. your work looks far better than mine, how could you do these 2 things i described?
I hope on your aid :D
 


It was a 3-hour work .. seriously.. removing all the rubber cover with a narrow screwdriver. This work revealed his risks when i made a leverage with a bigger screwdriver in order to pull up the board. These movements have broken 2 resistors. And not only.. also 2 small components on the other side of it.
11 screws (9 horizontal ones placed into the 9 power mosfets, 2 vertical in order to block the board in position) . One of those screws obligates the removal of the bigger capacitor from the board.
Under the board, another rubber strate is stuck to it, entirely. The steel ring which keeps mosfets in position can be removed only after the board removal.
It's such a risky work . Better buying a replacement part. I'm going to do that , from greenbikekit. Only € 88 , shipping included, to Italy. 3 hours on this is not as convenient as simply buying replacement part.
 
Is there a solution that the board could be soaked in to make the potting compound easier to remove? Alcohol or acetone?
 
I think DuPont Riston can be removed using Sodium Hydroxide NaOH or Potassium Hydroxide KOH (pretty nasty so be careful.!) and Mylar can be removed with Freeze spray and pulling. I know both have been used in the past for pcb protection - my guess though is its a Riston type polymer.

e.g. http://www.jaycar.com.au/images_uploaded/pcboards.pdf
 
ac246 said:
The potting compound in the motor will need to be replaced but i havent yet. i wanted to test the bike out fully first. and i need to find a potting compound that is just as easy to remove as the original.
Click to expand...

The stuff used is called 'magic rubber', and made by Raytech:
http://www.raytech.it/inglese/home-magic-rubber.php

I've used it a fair bit, it certainly has its advantages.

It peels off easily, just be careful not to tear out any wires when you remove it.
 
I retested my blown controller and was switching it out with a new controller which fixed the problem so I tried the controller that I re-soldered the mosfets on and it worked as well. I guess the replacement mosfets from digikey IPP034NE7N3 did work after all!!! What a relief.

They are more expensive but should support more power and heat before toasting.

Installing a aquarium thermometer inside the unit I can monitor myself instead of 'hoping' that the high temp shutoff will save it.

Karl
 
After research I'm going to replace the FETs blown . 5 FETs . 3 on the green phase , 1 on the yellow one, 1 on the blue one. I will take 3 genuine FETs from another BBS02 controller (FET plate: P75NF75) and the other 2 bought on an electronical stuff shop (FET plate: P80NF10) . These one can resist on bigger voltage , 100v , and the same current (80a) . Slightly different resistance and I hope this would not give problems once connected to the battery.

Here are the datasheets if you can check for me: http://pdf.datasheetcatalog.com/datasheet/stmicroelectronics/8451.pdf and http://pdf.datasheetcatalog.com/datasheet/stmicroelectronics/6958.pdf

In your opinion , do the replacement position of P80NF10 among the other P75NF75 can change something? And.. Can the PAS sensor really solve the on/off behaviour as seen for the thumb throttle? I would like to disconnect it from its cable and replace a PAS.
 
It's generally better if all the FETs are matched, but if none are paralleled it might work OK to mix types.

Unless you plan to run higher voltage, using a higher voltage rated part won't help much. What really helps is finding FETs with a lower resistance. Resistance = heat. Parts with a higher watt rating will survive better as well. I'm pretty convinced that over dissipation is the primary cause of FET failure as opposed to voltage spikes or current.
 
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