S06S Controller Failure

I just built a Euro-spec Pedelec for my wife with her existing hybrid mountain bike and parts purchased from BMSBattery.com – no issues with the order which was fast, smooth, and accurate. I have a Bafang 500W BPM motor, 36V – 15A Li-Ion battery in a AL case, and S06S 250W sine wave controller. I am deliberately under powering the motor to maximize longevity. This spec with the PAS is perfect for my wife to keep up with her compulsive, roadie husband.

Issue

The components went together easily, worked great, and then quit after less than 100 miles. On one ride we briefly noticed (1 second) and electrical burning smell after topping a short but steep hill - no obvious negative effects were observed. On a second ride we noticed the same brief burning smell immediately in the middle of a short, steep climb after which the unit immediately failed. The LCD1 display intermittently indicated 06_Error which means “Motor or controller has short circuit Abnormality”, according to the user manual.

Troubleshooting

I have tested a number of things and now believe that one of the controller Mosfets failed. Here’s what I did:
1. Dismantled the motor and found no obviously burned wiring.
2. Tested the motor halls and observed the proper switching from 0 to 5V for each as I spun the wheel http://www.ebikes.ca/documents/HallSensorTestingFinal.pdf
3. Tested the controller Mosfet continuity per http://www.ebikes.ca/documents/BlownMosfets.pdf and found the following:

Phase Pos Neg

Green 0Ω 11KΩ
Yellow 21KΩ 11KΩ
Blue 21KΩ 11KΩ

From this I conclude that I have a blown Mosfet on the green phase. In addition, the motor is harder to turn with the controller connected which Grin also states is an indicator of a blown Mosfet. However, there is no obvious burning on the Mosfet or any other controller component.

Questions

1. Have I missed something? Am I correct that this is a Mosfet failure?
2. Was this a fluke, did I do something wrong, or did I deserve this because this is a really crappy controller. I don’t want to spend a fortune on a new controller for what is a rather power modest requirement, but I don’t want to replace it after another 100 miles either.
3. Should I just replace the Mosfets with IRFB4110s? Any advantage to getting branded ones for $5/ea. at Digikey? Or are the eBay Mosfets from China OK at about $1/ea.?
4. Controller replacement choices that I have considered:
• BMS SO6S: If this was a fluke and this is a reasonable choice I’ll buy another from BMS: $24 + $35 shipping = $59.
• BMS S12S: I’d get this if it is more robust for my application (12 Mosfets) AND I can set it with the LCD display to limit the power to ~250W: $34 + $ shipping = $69.
• Cellman 6 fet IRFB4110 Infineon controller http://em3ev.com/store/index.php?route=product/product&path=38&product_id=78 with the ability to program it using XPD open source software http://endless-sphere.com/forums/viewtopic.php?f=2&t=27927#p403201: $76 + $25 shipping = $101.

Any assistance will be appreciated.

1.S06S original chinease motfets are really bad quality. This is your unique chance to do a Frankenstein S06S. Remove the original chinease mosfets and replace them with Texas Intruments CSD19536KCS. Those are the first choice because of extreamly low RDS_on, but a bit pricey as they are a new state of the art product. Second choice is IRFB4110pbf. This was the first choice until recently, but the technology moved forward. They are now considered standard fets. Package you are looking for is TO-220. You will need 6 of them. Buy a 7,5€ hot desoldering pen tool here http://www.electrokit.com/en/desoldering-pen-30w.47090?currency=EUR, or cut the old mosfets using dremel tool before removing legs one by one.
2. You did nothing wrong. I blew mine original fets too just by looking at them. Twice .
3. Order mosfets from a well known source, as there are copies on ebay (you just blew one copy remember ). I bought mine IRFB4110pbf here http://www.tme.eu/en/details/irfb4110pbf/tht-n-channel-transistors/international-rectifier/# . Price för 12 IRFB4110pbf with P&P was less than 30€, and it took 23 hours from ordering it to arrival several countries away. DHL and TME did impressive work (opted for stardard/normal shipping).
4.Don't buy a new one, try to repair your S06S. After repair, it will became 48V compatible and work much cooler. I did this on both of my S06S, so your chances are good.

FYI , For a 36v system the IRFB3077 are a much better choice than the 4110's.

You didn't mention which speed BPM you have. The controller is rated at about 10 amps, but the BPM could be drawing the maximum 15 amp current all the time, in which case you need to get the controller out in the air flow to keep it cool. If you had it in a bag or box, it would over-heat.

The BPM is a strong, reliable motor, which will last for years at 30 amps, using a 15 amp controller won't make it last any longer. If I were you, I'd chuck the S06S and get a S12S, which is more suitable for that motor. You can select "torque simulation" mode and then use level one PAS if you don't want to use much power.

These are great comments!

The Bafang BPM motor is stamped 48V 500W 16(12) - this is Code 12? It was quoted to me by BMSBattery as being 328 RPM @ 48V. My intent in running this at 36V is to get a 75% slower no-load RPM – 246 RPM. The result on the bike seems about right for me.

I am running the controller in a closed box on the end of the battery case http://www.bmsbattery.com/36v/464-36v-15ah-lithium-ion-electric-bicycle-battery-pack.html. My wife really likes it because it’s really neat, but it isn’t well-ventilated. OTOH, it seems like the thermal connection from the Mosfets to the S06S case is not very good – little steel clamps connected to the case by a steel screw for each pair of Mosfets. Can this be improved?

Regarding the S12S, wouldn’t this have the same cheap Mosfets as the S06S that are subject to failure. Also, I’ve thought that my battery (listed above), doesn't have the C-rate needed to run much above 15A.

So, it looks like my choices are 1) get an S12S OR 2) Replace the Mosfets in the existing S06S with better ones. If the latter, I'm not sure what advantage I'd see from something other than IRFB4110pbf for my low-power application.

Additional thoughts?

Replace the Mosfets in the existing S06S with better ones. If the latter, I'm not sure what advantage I'd see from something other than IRFB4110pbf for my low-power application.

Click to expand...

Here are your mosfets options, in no particular order:
1. TI CSD19536kcs V_ds=100V, Rds_on=2,3mOhm. Small 6 fet controller = 30A+ current limit. Almost unnecessary military grade margin of Vds=100V. You don't need this kind of paranoia as you are using it at 36V. Expensive.
2. IRFB4110pfb. V_ds=100V, Rds_on=3,7mOhm. Small 6 fet controller = 25A current limit . Almost unnecessary military grade margin of Vds=100V. I love margins, as i'm using it at 55V, and have plans for higher than that. It gets a little bit warm on climbing at 14A, but nothing alarming (compare Rds_on as a rough guidance). You don't need this kind of margin as you are using it at 36V. Cheapest option of those 4.
3. TI csd19506kcs V_ds=80V, Rds_on=2,0mOhm. Smal 6fet controller = 30A+ current limit (S12S/12fets killer in a smaller 6fet package). Coolest controller possible, this thing could freeze in Sahara desert at 14A. This is lowest Rds_on in TO220 package. 80V is normal safety margin if used at 36V and 48V. Maybe your best choice, but I could not found it in stock in EU. Expensive.
4. IRFB3077pbf. V_ds=75V, Rds_on=2,8mOhm. Small 6 fet controller = 25A current limit. Runs cooler than the IRFB4110pfb but hotter than the TI mosfets. 75V is normal safety margin if used at 36V and 48V, but a bit to low for my taste at 55V which I'm using. More expensive than IRFB4110pfb but cheaper than TI mosfets.

Compare this with the chinease STP80NF70 copy that you blew up. V_ds=68V, Rds_on=8,2mOhm. Small 6 fet controller = 14A current limit. Very usable for frying eggs after climbing. No safety margin at all according to Fairchild semiconductor seminar. Cheaper than cheap. Works well at 24V.

The advantage of IRFB4110pbf for your aplication is in its price in EU. Dissadvantage is that it gets warm at climbing at 14A. I'm sure it is capable of 25A, but i'm imagining that it becames an egg fryer at those currents. 3.7mOhm sounds as nothing but its still almost the double of the best TI one.

Well the S12S isn't going to fit in your enclosure so you'll need to remount it somewhere too.

If it were me I'd try repair my existing unit or buy another (because spares are always handy) AND ventilate that case.

Thx for all the great information!

For now, I'm going to repair the unit with locally-sourced (not Chinese or eBay) IRFB4110pfb's. This seems like the least expensive approach that should be much more robust than the original. And I'll be sure to ventilate the unit or move it or remount it on the exterior.

The IRFB3077pbf is about the same price as the IRFB4110pfb at US suppliers that I checked: about $32/10.

IRFB3077pbf is better choice in that case (it will run cooler), as long you are under 50V. Is it 32 USD for 10 pcs with P&P? Can you please post a link?

The IRFB3077pbf is actually a little less expensive.

IRFB4110PBF $30.10/10 + $4.99 US economy shipping
http://www.mouser.com/Search/ProductDetail.aspx?R=IRFB4110PBFvirtualkey57370000virtualkey942-IRFB4110PBF

IRFB3077pbf $27.90/10 + $4.99 US economy shipping
http://www.mouser.com/ProductDetail/International-Rectifier/IRFB3077PBF/?qs=%2fha2pyFadujujqg2k4hCXFWjUSs8Ag01AJb12YY3p8an44JThI31tg%3d%3d

You might look here http://parts.arrow.com/item/search/#st=irfb3077;reEEJM
http://parts.arrow.com/item/search/#st=irfb4110;re2ERQ

Dan

Arrow's prices are certainly low, although the shipping is on the high side. Do they ship from the US? It's hard to tell on the web site.

Singlespeed10 said:

Arrow's prices are certainly low, although the shipping is on the high side. Do they ship from the US? It's hard to tell on the web site.

Click to expand...

Sorry can't answer that question.

Dan

FOLLOW UP

I received my IRFB3077PBF Mosfets and proceeded to install them. Removing and unsoldering the old Mosfets was the most difficult part. Once they were unsoldered, I used a Dremel with a very small drill bit to clean out the hole.

Installing and re-soldering the new Mosfet was very easy. I powered it up and ZAP! I had neglected to remove all of the drill cuttings and one tiny was remained on the board and shorted out the battery connection. So after all that work, I fried the board. Moral of the story, use compressed air to blow off all of the drill cuttings and inspect very carefully.

NEW CONTROLLER

I had the replace the controller and I wasn’t going to get another crappy S06S from BMS. I ended up getting a 6 FET IRFB3077 Infineon Controller from Cellman. http://em3ev.com/store/index.php?route=product/product&path=38&product_id=77 I got it with the program cable and then used XPD open source software to program it. This controller works great! The most noticeable difference is that the design of the heat sinking is much better than that in the S06S. Also, the voltage regulator chip is heat sinked whereas in the S06S it had no heat sink at all and got very hot. Lastly, it was too big to mount inside the battery compartment, so I mounted it on the top of the compartment where is it gets lots of air flow. Anyway, it never gets even barely warm.

You could have gone with the S12S sine-wave. After I smoked a couple of SO6S's, that's what I went with.
I also have a 6-FET Infineon and the S12S is smooth and the motor is dead silent, where as the Infineon is rather growly.
Of course the S12S is BIG, so space could be a prob.

I assume that the S12S has the same crappy Mosfets and heat sinking as the S06S. Also, I really like to be able to program the Infinion.

You can do a lot of programming of the S12S direct from the display. I don't believe that the S12S has crappy mosfets. Lots of members have them.

d8veh said:

You can do a lot of programming of the S12S direct from the display. I don't believe that the S12S has crappy mosfets. Lots of members have them.

Click to expand...

The S12S is a great controller. Your don't hear anything about them failing.

My only complaint is that the newest version (the one that's compatible with the. LCD3) comes in a needlessly large case. The older ones were considerably smaller. (Fortunately, the circuit board is the same size, so I just swapped out the internals to maintain the smaller form factor.)

Avitt said:

d8veh said:

You can do a lot of programming of the S12S direct from the display. I don't believe that the S12S has crappy mosfets. Lots of members have them.

Click to expand...

The S12S is a great controller. Your don't hear anything about them failing.

My only complaint is that the newest version (the one that's compatible with the. LCD3) comes in a needlessly large case. The older ones were considerably smaller. (Fortunately, the circuit board is the same size, so I just swapped out the internals to maintain the smaller form factor.)

Click to expand...

That is hilarious! I imagine they did this for marketing, "Bigger = better".

Did you take a look at the mosfets that comes with the S12S?

They say;

80NF70
CZ028 6
MAR 401

motomech said:

They say;

80NF70
CZ028 6
MAR 401

Click to expand...

Is this the one, then?

http://pdf1.alldatasheet.net/datasheet-pdf/view/499214/STMICROELECTRONICS/STP80NF70.html

I think so.
Junk or decent?

motomech said:

I think so.
Junk or decent?

Click to expand...

I just read where fellow describes it above...Specs aren't so good: V_ds=68V, Rds_on=8,2mOhm