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Ninebot One P...same control board as the E+


Cranium
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27 minutes ago, playdad said:

Wow, I don't know what to say. That is a little worrisome! Please take care when pushing it in the Summer. :o

There's enough news about exploding/burning "Hoverboards".

Well, the P should be safer for it will explode out in the open as compared to hoverboards which explodes inside the houses. :D But mind you, my E+ roasted in front of our door.

Edited by SlowMo
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It was sure for the mobo... If you put a "P" serial number in your "E" model, your mobo will give you an extra power...

But I'm not sure taht the motor can dissipate more power... Certainly a bit more, but not all the extra power for a long time (like in Uphill per exemple).

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  • 2 weeks later...
On 2.12.2015 at 5:57 AM, Cranium said:

...

I did some back and forth balancing in my house to see how fast it would heat up.  I loved the additional power which allowed it to be much snappier and for me to feel more confident.  After a bit of time, I got the beeping from the unit overheating.  I checked the app and it showed 158°F.  It took more work than this to get an E+ to overheat doing exactly the same thing (but with less confidence).

So either the 1.3.1 board is either completely underutilized and over engineered OR the E+ or it is over-utilized and under engineered for the P.  My experience with the blown board on the E+ and the overheating on the P leads me to believe that it is the later.  But time will really tell for sure.

 

V1.3.1 board on the left (E+ & P) and V1.3 board on the right (E+)

P1020358.thumb.JPG.2a5668894059812e53b69

 

With the P board (1.3.1) shown in the picture on the left side the heatsinks are not screwed togeter? Or was that just from your disassembly? It also seems (from different fotos and videos) that between this two parts of the heatsink no heat paste is used?

Since plastic is a nice thermal insulator the only real thermal exchange can happen through the hole below the metal plate below the motherboard leading to the wheel. There i have seen two different versions in the vides - one hole about 2/3 as big as the board and one very small (maybe from a one C?). 

For a rough approximation i assumed PWM Frequency 25khz, Mosfet switching time 200ns, 1500 W (was the E+ peak motor power imho?) and the thermal resistance of a 80x80x2mm aluminium plate, which should be around 10 K/W.

This should lead to a total power dissipation of the Mosfets of around 9W. This heatsink so could keep the Mosfet Junction temperature below 175°C up to an ambient temperature(heat sink temperature)  of ~75°C. (If the heat sink plate was outside with free convection.)

But the plate is inside the wheel and maybe the venting of the turning wheel is not sufficient to bring the warm air outside? From the tear down videos it seems, that there should be enough place inside to put some kind of "bar" onto the wheel to create a real airflow? There are also low profile heatsinks which one could use to replace/improve the plate?

Or paint/anodize the plate black (for IR) to improve the irradiation.

Could also be, that just the heatsink parts/mosfets are not connected properly and by this increase the thermal resistance too much. Additionaly the contruction with the heatsink for the "upper" 6 Mosfets screwed to the heatsink of the lower 6 mosfets which again is screwed on the plate which finally conducts away the heat seems less then ideal...

 

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4 hours ago, Chriull said:

For a rough approximation i assumed PWM Frequency 25khz, Mosfet switching time 200ns, 1500 W (was the E+ peak motor power imho?) and the thermal resistance of a 80x80x2mm aluminium plate, which should be around 10 K/W.

This should lead to a total power dissipation of the Mosfets of around 9W. This heatsink so could keep the Mosfet Junction temperature below 175°C up to an ambient temperature(heat sink temperature)  of ~75°C. (If the heat sink plate was outside with free convection.)

To answer your questions first:  

  1. Yes, the screws missing were from my disassembly.  I was trying to remove the heatsink completely to better expose the MOSFETs underneath and to replace them.  
  2. There is thermal paste between the lower heatsink and the bottom plate that the board attaches to but there is not any thermal paste between the upper and lower heatsinks.  I have measured the thermal temperatures directly on the board and the heatsinks and the temperature drops rapidly across the upper heatsink and has little heat dissipation to the lower heatsink.    I have not measured the heat on the back of the plate.  
  3. The hole that helps dissipate heat from the plate under the board is about 2/3 the size of the plate.  It does not appear to help a great deal while moving.
  4. I would be very hesitant to place anything on the wheel to increase airflow that would be rigid as this would increase the likelihood of a rock, stick or other item to get stuck in the wheel.  And before even considering this, I would want to see what temperature the back plate is reaching to see if this would even be worth considering.

Now for my questions to you:

  1. What is the 25kHz PWM assumption based on?  I have wanted to measure the true value on my Oscilloscope but have not yet.  
  2. How does the rated MOSFET switching time affect heat dissipation calculations?
  3. What are the equations you used to calculate the heat dissipation of 10 K/W?  I've never done this so am quite curious.  What assumptions does this calculation make?

I would like to look at improving the heat dissipation once I understand where the heat is being trapped.  

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Yes, fins, wipers and all that stuff could maybe help to repair a design issue, but could easily cause negative impact as you pointed out.

The heatsink, the mosfets are mounted to directly, mainly heats up the closed compartment. And the heat capacity of this compartment is very limited. The only real way to conduct away the heat is to the outside, which happens by the plate covering the hole. My idea was that directly mounting the mosfets on the plate (with the other side beeing in fresh air flow) avoids the thermal resistances resulting from the connections between the different heat sink parts.

Imho thats the reason why for the E+ the hole to the outside is much bigger then with ?earlier/the C? modell. Maybe thats the way ninebot also will choose for P v2 or P+.

Or maybe you really just got a model from a bad charge. Ninebot should have done enough tests before releasing the P modell to detect thermal problems and solve them. But on the other side, they are also releasing some firmware trials and destroy their products. And this not only once.. ;(

Unfortionately it seems there are not enough One P Users around to share their experience.

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@Cranium, thank you for sharing this informative comparison of the Ninebot types. As the output power increases, this issue of control-board heat build up is going to become an ever more frequent & relevant engineering problem.  

In the case of the King Song, the battery pack is over double the capacity & number of parallels over the 9B1 P, with the result that overheating can be even more problematic if ridden hard (with a high proportion of acceleration & braking). Even though the aperture to the Wheel housing has more surface area than the Ninebot, it is still less than optimal. 

On the new 16", I suggested that they integrate an internal cooling fan that is activated when the board temperature rises above a defined set-point. It's an enclosed space & of course air is not great heat-conductor, but at least it's better than passive cooling... Pleased to say they've taken up my suggestion & are intending to implement on the production product. 

What's your opinion about contoured or curved fins like the below? Surely Ninebot have the engineering expertise & resources where they can design something clever that minimizes the risk of foreign objects striking during use. At least there is physical space in which they can add the appendages to the inside of the board, but will it be enough to have any effect?

P1010496.jpg

 

A couple months back while doing some limit testing with a number of different Wheels & a datalogger attached, revealed that the average load, over say a minute, is not anywhere near the max rated output, & that the Wheels (in the example below is an 9B1 E) are not very resilient when stressed.

Regen_on_9B1.thumb.png.09611d75ac30249fa

Also power output can experience enormous swings over the course of even a single second.   

LC_Precision_Z2.thumb.png.b86494a37df0fe

Edited by Jason McNeil
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8 minutes ago, Jason McNeil said:

On the new 16", I suggested that they integrate an internal cooling fan that is activated when the board temperature rises above a defined set-point. It's an enclosed space & of course air is not great heat-conductor, but at least it's better than passive cooling... Pleased to say they've taken up my suggestion & are intending to implement on the production product. 

What's your opinion about contoured or curved fins like the below? Surely Ninebot have the engineering expertise & resources where they can design something clever that minimizes the risk of foreign objects striking during use. At least there is physical space in which they can add the appendages to the inside of the board, but will it be enough to have any effect?

Setting up convection heat transfer is certainly better than conduction through stagnant air.  Good idea.  I think some sort of heat pipe to transfer the heat from the MOSFETs to the outside air would be great but I can't think of a way to do this without making it more vulnerable in a crash.    

I think the contoured fins would be excellent if they could be integrated to a heat pipe or put on the inside by the wheel if they could somehow be protected from debris buildup and damage.  Damage from rocks would be a concern but a bigger concern would be mud buildup clogging them on the inside which is why I think a better solution may be having this type of heatsink on the outside.  

If they wanted to have them on the inside and protect them, they could create something that would draw air from the outside over the fins that are protected on the inside of the wheel.  They could set up a Venturi nozzle to create the natural air flow.  But I'm not sure what speed you would need to get effective air flow for cooling.  

hmmmm.....How about a heat pipe that transfers the heat to a heat sink with fins in another protected compartment which has vents and allows airflow to the outside?  This would keep the circuit board isolated but allow good air flow for heat dissipation.  But it would require re-design of the circuit board and compartment.  Not an easy do it yourself fix. :(

 

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  • 2 months later...
On 2 December 2015 at 4:57 AM, Cranium said:

I received my Ninebot One P today and excitedly opened it.  It is sharper looking and I really like the black pads.  I'm glad I've done most of my learning so I won't be scratching up this EU right away.

I took off the pad to expose the control board.  It is version 1.3.1 which happens to be the same as the control board that came on my Ninebot One E+ that I received a few weeks ago.  My E+ was on firmware version 1.2.7 which had no reported issues when the board fried and dumped me to the ground.  I was lucky I didn't get hurt and was able to get a replacement control board in only a week shipped from Ninebot with the help of Forward California.    The replacement board was a version 1.3 board.  I felt I had been downgraded but after looking at the Mosfet ratings, I was ok with it.  It has worked fine so far.

The P uses the EXACT same control board as the latest E+ EUs.  The ONLY thing different electronically one the P from the E+ is the motor which is specified to produce 60% more power and the battery which is 12.5% higher capacity.  Everything else different is in the cosmetics (pads and black rings).  All for a 36% increase in price.

I verified that the MOSFETs are the same number: 100N8F6 (see attached data sheet and picture below).  These MOSFETs are expected to deliver up to 60% more power with the exact same heat sinks and cooling as in the E+.  This means that the P is capable at overheating much quicker than the E+ if you are using the additional power the motor allows.  

The E+ V1.3 board uses a 75NF75 MOSFET and I've attached the data sheet for this as well.  I would include a picture but it was hard as hell to get the number from the 1.3 board and had to use a stereoscopic microscope to read it.  I have a USB camera for it but my computer isn't recognizing it for some reason.

I did some back and forth balancing in my house to see how fast it would heat up.  I loved the additional power which allowed it to be much snappier and for me to feel more confident.  After a bit of time, I got the beeping from the unit overheating.  I checked the app and it showed 158°F.  It took more work than this to get an E+ to overheat doing exactly the same thing (but with less confidence).

So either the 1.3.1 board is either completely underutilized and over engineered OR the E+ or it is over-utilized and under engineered for the P.  My experience with the blown board on the E+ and the overheating on the P leads me to believe that it is the later.  But time will really tell for sure.

Ninebot One v1.3.1 control board E+ & P MOSFETs

565e728e9a716_PMosfets.thumb.jpg.bdda1e8

MOSFET Differences

565e7e6003ca9_Mosfetdifferences.PNG.a290

V1.3.1 board on the left (E+ & P) and V1.3 board on the right (E+)

P1020358.thumb.JPG.2a5668894059812e53b69

 

100N8F6Mosfet.pdf

STP75NF75 Mosfet (3.1 board).pdf

Hi, 

my ninebot dead and I'm not sure what's the problem, where did you get the control board from please? 

My ninebot only 3 months old, and I bought it from eBay but stall under warranty, do you think if I contact ninebot service by email they could help me and send me new board or I have to buy one online? 

Please advice.

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  • 3 years later...
On 12/1/2015 at 8:57 PM, Cranium said:

I received my Ninebot One P today and excitedly opened it.  It is sharper looking and I really like the black pads.  I'm glad I've done most of my learning so I won't be scratching up this EU right away.

I took off the pad to expose the control board.  It is version 1.3.1 which happens to be the same as the control board that came on my Ninebot One E+ that I received a few weeks ago.  My E+ was on firmware version 1.2.7 which had no reported issues when the board fried and dumped me to the ground.  I was lucky I didn't get hurt and was able to get a replacement control board in only a week shipped from Ninebot with the help of Forward California.    The replacement board was a version 1.3 board.  I felt I had been downgraded but after looking at the Mosfet ratings, I was ok with it.  It has worked fine so far.

The P uses the EXACT same control board as the latest E+ EUs.  The ONLY thing different electronically one the P from the E+ is the motor which is specified to produce 60% more power and the battery which is 12.5% higher capacity.  Everything else different is in the cosmetics (pads and black rings).  All for a 36% increase in price.

I verified that the MOSFETs are the same number: 100N8F6 (see attached data sheet and picture below).  These MOSFETs are expected to deliver up to 60% more power with the exact same heat sinks and cooling as in the E+.  This means that the P is capable at overheating much quicker than the E+ if you are using the additional power the motor allows.  

The E+ V1.3 board uses a 75NF75 MOSFET and I've attached the data sheet for this as well.  I would include a picture but it was hard as hell to get the number from the 1.3 board and had to use a stereoscopic microscope to read it.  I have a USB camera for it but my computer isn't recognizing it for some reason.

I did some back and forth balancing in my house to see how fast it would heat up.  I loved the additional power which allowed it to be much snappier and for me to feel more confident.  After a bit of time, I got the beeping from the unit overheating.  I checked the app and it showed 158°F.  It took more work than this to get an E+ to overheat doing exactly the same thing (but with less confidence).

So either the 1.3.1 board is either completely underutilized and over engineered OR the E+ or it is over-utilized and under engineered for the P.  My experience with the blown board on the E+ and the overheating on the P leads me to believe that it is the later.  But time will really tell for sure.

Ninebot One v1.3.1 control board E+ & P MOSFETs

565e728e9a716_PMosfets.thumb.jpg.bdda1e8

MOSFET Differences

565e7e6003ca9_Mosfetdifferences.PNG.a290

V1.3.1 board on the left (E+ & P) and V1.3 board on the right (E+)

P1020358.thumb.JPG.2a5668894059812e53b69

 

100N8F6Mosfet.pdf

STP75NF75 Mosfet (3.1 board).pdf

Since 100A and 80A is relatively close considering  that each pair of transistors add up to at least 16A when the wheel would require a maximum of 100A at extreme conditions, and because both wheels are significantly below 75 V, the only real difference is the 176w vs the 300w. This said, I really don't know if the 300w seems safer... On the other hand, the axle on my Ninebot One E+ broke on the PCB side, and the wires that went through the axle also got sheered at the same time. this fried two mosfets 100N8F6 the two first transistors starting on the left of the board as seen in your pics. Obviously, their parallels remain intact; only one of the pairs fries at a time. Now, I'm looking for replacements, but they all seem to come from China or Hong |Kong which will take at least 2 months to arrive. Do you know of anywhere in the US or Canada where I would be able to get them sooner?

Mind you, I bought a KS 18XL a couple of weeks ago and enjoy it for its speed. On the other hand, I did like my Ninebot One E+ for its agility and to help other learn. I also enjoyed the Ninebot  One for practicing freestyle; its a lot easier than my heavy KS.

Ben

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