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Marty Backe

My 84-volt Nikola Triumphs, Tribulations, and Failures

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I am assuming the glue issue will fix the problem; but the lack of proper overheating monitoring is crazy. The wheel should have overheated and tilted Marty off.

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Posted (edited)
10 minutes ago, fryman said:

I am assuming the glue issue will fix the problem; but the lack of proper overheating monitoring is crazy. The wheel should have overheated and tilted Marty off.

Yeah i think its  just how a pc works but in this case there was nothing monitoring the heat so it shut down (faceplant) and damaged mosfets because of the heat sensor placement ,, correct me if I'm wrong I'm still learning

Can you use a CPU without thermal paste? 
So a bad paste job can do a lot more harm than it does good. Your CPU will run hotterwithout paste than with, but it will still run. All modern CPUs are designed to throttle themselves if they sense they're overheating, to prevent damage
Edited by stephen

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Anyone know how widespread this issue is, does it effect the newest Tesla?

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A late thanks to @Marty Backe for uncovering this issue and @Phil McLaughlin for the confirm and insight.

For those more knowledgeable than I, do people think maybe using thermal paste, ala computer CPU-to-cooling connection, might transmit heat much better? And would this last long-term, or need occasional re-application? Or is there a better solution?

The one time I ripped into an EUC board itself, I don't remember seeing much in the way of some intermediary agent between MOSFETs and heatsink.

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1 hour ago, mrelwood said:

There are ZERO wheels (or any other product) with hot-glued Mosfets of any size in the market without issues.

I MARVEL at the IGNORANCE of Gotway and/or the outsourced company that built these boards! Doesn't this show a TOTAL lack of understanding about the heat transfer needs of MOSFETs?? I know less about MOSFETs than most people on this forum, but I wouldn't dream of using hot glue!!

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7 hours ago, Michael Tucker said:

This type of problem should be of no surprise as its from a first batch. Every first batch run of every model has problems. The glue was simply used because they were in a hurry to rush their new 16 incher to market before KingSong, many elements of the Nicola seem rushed. The glue is not really the issue anyways, the small MOSFETs are the issue. The glue can simply be skipped for future batches, but those small MOSFETs are there in the design of the 84V.

Future buyers may not be able to see if glue was used, but they can see the small MOSFETs. Who will trust them now...will it blow after 100 miles, 500miles, 1000 miles?!!! Small MOSFETs are a KNOWN problem and again right out of the gate we see a faceplant captured on camera. Marty's hill test only accelerated the burning up of the small MOSFETs before they would have blown later anyways, glue or no glue.

Small MOSFETs should be reserved for casual riding only, and with glue as a new possible risk, who would buy/ride a first batch 84V Nicola? Gotway Daredevils of course!!!

I totally agree with what @mrelwood wrote above, responding to what you wrote here. Sorry but I disagree with you on all fronts. I won't repeat what @mrelwood already stated so elegantly. 

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3 hours ago, fryman said:

I am assuming the glue issue will fix the problem; but the lack of proper overheating monitoring is crazy. The wheel should have overheated and tilted Marty off.

In a perfect world, yes. But even if their temp sensor was better placed, the board probably would have fried. There are 12 MOSFETs in play here. Only 2 or 3 were burning hot. So it would have been a hot spot among a relatively cool board. Boom!

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3 hours ago, stephen said:

Yeah i think its  just how a pc works but in this case there was nothing monitoring the heat so it shut down (faceplant) and damaged mosfets because of the heat sensor placement ,, correct me if I'm wrong I'm still learning

Can you use a CPU without thermal paste? 
So a bad paste job can do a lot more harm than it does good. Your CPU will run hotterwithout paste than with, but it will still run. All modern CPUs are designed to throttle themselves if they sense they're overheating, to prevent damage

Only if there were temperature sensors for each MOSFET would this have been detectable by the controller software. Otherwise, the 2 or 3 MOSFETS with the hot-glue appear as a localized hot-spot on the control board, but the overall control board appears relatively cool.

As has already been stated, thermal paste can't be used in this situation because the MOSFETs must be electrically isolated.

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8 hours ago, Nils said:

Oh man, not a one-off then.. :wacko: Thanks for looking at this and updating us, and I'd be very interested to see a video of your rework! While I don't believe I'll do this myself, it would be very interesting at any rate. Did you happen to shoot any video of your disassembly and inspection? A shame that this should be so hard to inspect without destroying the board, perhaps some tool like @Harold Farrenkopf suggested could work.

So, how widespread are we to assume that this is then? Sub-set of batches? First batch? All 84V batches? 100V batches as well? Gotway need to provide some kind of official response here. Also, as Marty noted it might be possible that same thing is happening with other Gotway wheels, and that it's just the bigger MOSFETs saving them.

Argh, another year, another wheel, another problem, I'm having a bad streak it seems. Those waiting for the KS16X should be lucky I didn't go with that, if I had it would probably be discovered that they built it out of some new cost-saving material that turned out to spontaneously combust when rubbing it wrong. 

"Mo wheels mo problems"

I would bet anything that if we looked under the middle row of MOSFETs on the MSX control board, we would find hot-glue. If only we could find someone with a dead MSX board (for other reasons maybe) and have a look under those MOSFETs.

I'm positive as to why the hot-glue was used, so by inference we know which control boards are affected.

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37 minutes ago, Marty Backe said:

As of today (Saturday), Gotway has not responded to Jason's queries, to the best of my knowledge. They appear to be playing Deaf, Dumb, and Blind.

:efef895ddd:

Well, it's the weekend, but still...

:efef895ddd:

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13 minutes ago, meepmeepmayer said:

:efef895ddd:

Well, it's the weekend, but still...

:efef895ddd:

He's been trying since last weekend

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3 hours ago, Hansolo said:

No, the metal part of the mosfets must be electrically insulated from the cooler, if not short-circuited. This is the role of the thermal pad in addition to transporting heat.

Thanks!

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5 hours ago, mrelwood said:

If you were more familiar with electronics, you would understand that this is not a ”whoopsey, missed that because we rushed a bit”. This is someone who’s unaware of how Mosfet cooling works, deciding how the GW electronics are built. Being rushed, or any other excuse in the world, doesn’t begin to explain what GW has done. Car companies don’t leave out seatbelts to get the product out faster. Air

It seems Gotway, KingSong, Inmotion, and NineBot all rush to get their first batch to market and make mistakes in that rush. I think Gotway has a long established reputation of low build quality and questionable choices in build materials. Even the mounting of the Nicola board in the cavity seems very hastily designed. Of all the brands who would be suspected of hiding/not caring about first batch problems (even if the problem is design related) Gotway would be the obvious one. Many people who are familiar with Gotway products would use the word AMATEURISH!

That is incorrect. Properly designed and properly built, the smaller Mosfets would’ve been fine. They should be able to handle the currents being used. But if they are not attached to a cooling plate, even bigger Mosfets than on the MSX would not survive.

In the past all the manufacturers used small MOSFETs because the belief was that properly designed and properly built small MOSFETs would be fine, but of course that was not the case and the move to TO-247 is much safer as real life use in MSX/Monster/MCM5/KS18X(L) has shown. The danger with small MOSFETs is that they mostly work...MOSTLY! Every once in a while they don't; hard to trust. Marty believes that the glue use is on MSX type boards as well because of the hidden second row of MOSFETs. 

You are jumping to conclusions. The size of the Mosfets used in the Nikola are not a known problem. There have been many high performance wheels on the market with smaller Mosfets without issues. There are ZERO wheels (or any other product) with hot-glued Mosfets of any size in the market without issues.

I believe the general excitement with the release of the MSX/KS18L type boards was that it was "Over-engineered" with the TO-247. Sometimes jumping to conclusions on the side of safety is better than relying on "sound principles of design and build" with little room for errors like "glue" or fan failures. Recently I have seen posts here about how motor watt rating is irrelevant, small MOSFETs are no problem, and charging your wheel at 10 amps or higher is totally safe. I think EUCs are complex and built with some secrecy and experimentation. These attributes are dangerous and I think promoting safety and over-engineering is better than attempting to apply perfect science to an imperfect industry.

 

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