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ACM now uses 12 MOSFETs instead of 6


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The thermal paste looks like it might be something like Arctic Silver rather than the cheap white stuff? That would be a step up too. If that connector is for the motor it looks like it is better than the cheap single-lead barrel connectors that most other EUCs use, it's gold plated for one thing. 

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Do you happen to know how long they have been using these new boards for? I got mine last week after it was held for changes the week before - I hope this was it :)

 

I'll be interested to hear your thoughts on the trolley handle too please.

Edited by TremF
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38 minutes ago, dmethvin said:

The thermal paste looks like it might be something like Arctic Silver rather than the cheap white stuff? That would be a step up too. If that connector is for the motor it looks like it is better than the cheap single-lead barrel connectors that most other EUCs use, it's gold plated for one thing. 

Not sure about the thermal paste.  I also have no idea what that connector is for but boss Lin said something in Mandarin that I didn't quite understand but emphasized how good that connector is like he was very proud of it. :P Sorry I didn't investigate more but at least you guys have this photo.   :D

21 minutes ago, TremF said:

Do you happen to know how long they have been using these new boards for? I got mine last week after it was held for changes the week before - I hope this was it :)

 

I'll be interested to hear your thoughts on the trolley handle too please.

I'm not too sure about how long they've been using these boards for either but I suspect a couple of weeks.  Will update you on the trolley when I have more chance to use it.

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3 minutes ago, John Eucist said:

I'm not too sure about how long they've been using these boards for either but I suspect a couple of weeks.  Will update you on the trolley when I have more chance to use it.

 

Brilliant! Cheers. If it's been a couple of weeks then mine will have the new board. Very happy  :D

It will be interesting to know how well the trolley copes in a crash too. I don't want anyone to crash but sometimes things happen out of our control - like mine flipping on me over the weekend.

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54 minutes ago, OliverH said:

Fix or work around?

I didn't follow the ACM problems, if any, prior to getting mine because I was simply waiting for them to make a trolley first.  I was told the extra mosfets would better handle any current spikes. 

Edited by John Eucist
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32 minutes ago, OliverH said:

Fix or work around?

As far as I am aware the ACM was having a problem where, if you travelled slow then hit a bump/pot hole and the ACM needed more power to get over, the board couldn't cope with the current and was frying so was modified.

 

I could be wrong but this is my guess from what was being reported before the fix. I was told I was getting an updated version but not the specifics - here we go.

Edited by TremF
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1 hour ago, TremF said:

 

Brilliant! Cheers. If it's been a couple of weeks then mine will have the new board. Very happy  :D

It will be interesting to know how well the trolley copes in a crash too. I don't want anyone to crash but sometimes things happen out of our control - like mine flipping on me over the weekend.

What happened to cause the ACM to flip you over?  :huh:

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30 minutes ago, HunkaHunkaBurningLove said:

What happened to cause the ACM to flip you over?  :huh:

It didn't flip me over. I got on the ACM outside a shop then as I leaned to set off (slight lean to set off slowly) it suddenly flipped from under me as if the wheel itself didn't move but the body spun maybe.

I remained standing and somehow the ACM caught my right shin as it flipped. When I looked at it on the ground I saw smoke and thought the board had fried but it still works perfect so not sure if smoke was from the ground as the pedal hit it maybe or from a stone stuck inside.

I really don't know anything other than I was stood on it, it flipped on me and I saw smoke but it works perfect still with no issue since.

Edited by TremF
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3 hours ago, dmethvin said:

If that connector is for the motor it looks like it is better than the cheap single-lead barrel connectors that most other EUCs use, it's gold plated for one thing. 

 

2 hours ago, John Eucist said:

I also have no idea what that connector is for but boss Lin said something in Mandarin that I didn't quite understand but emphasized how good that connector is like he was very proud of it. :P Sorry I didn't investigate more but at least you guys have this photo.   :D

The connector's MT60, kind of like a 3-pin version of XT60:

http://www.aliexpress.com/item/MT60-3-5mm-Motor-Plug-Connector-Set-for-RC-lipo-battery-FPV-Multicopter/32686641236.html

Just ordered a couple of those few days back ;)

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11 minutes ago, esaj said:

 

The connector's MT60, kind of like a 3-pin version of XT60:

http://www.aliexpress.com/item/MT60-3-5mm-Motor-Plug-Connector-Set-for-RC-lipo-battery-FPV-Multicopter/32686641236.html

Just ordered a couple of those few days back 

Yeah I have bunch of those here as I use those to connect motors to ESCs on multirotors ("drones"). They're clearly used for mottor connection in the picture. I prefer those on large models to individual bullet plugs despite higher weight and larger size a it's much faster and easier to swap faulty motor or ESC in field and also avoids possibilit of swapping the phases around by accident.

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8 minutes ago, esaj said:

@esaj thank you for finding those, when I eventually have a puncture or otherwise need to drop the wheel out my EUC, I think I'll fit one of those rather an trying to get the wires off of the control board. I might just be tempted to put heat shrink over it to ensure it cannot come apart in use.

15 minutes ago, esaj said:

Just ordered a couple of those few days back ;)

Don't hold your breath - "delivery 30-50 days"!

P.S. I see you are still singlehandedly keeping Aliexpress in profit :-)

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1 minute ago, Keith said:

@esaj thank you for finding those, when I eventually have a puncture or otherwise need to drop the wheel out my EUC, I think I'll fit one of those rather an trying to get the wires off of the control board. I might just be tempted to put heat shrink over it to ensure it cannot come apart in use.

Don't hold your breath - "delivery 30-50 days"!

Well, it's pretty normal that the deliveries take between 1 and 8 weeks to here, no matter what the page says ;)  Of course I'm skimpy and always use the free shipping option :P 

1 minute ago, Keith said:

P.S. I see you are still singlehandedly keeping Aliexpress in profit :-)

Ahem, my order count has just broken 400 this week... :D  Whoopsie again

Total reward points: 1871
A3 level member
Your level is higher than 99% of other users.

 

 

 

Even though I only order the "cheap stuff" and always with free shipping, it all starts to add up... ;)  But still, the price difference for basic components is so huge compared to here, that I've probably "saved" a four figure sum by now.

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5 minutes ago, Keith said:

@esaj thank you for finding those, when I eventually have a puncture or otherwise need to drop the wheel out my EUC, I think I'll fit one of those rather an trying to get the wires off of the control board. I might just be tempted to put heat shrink over it to ensure it cannot come apart in use.

They don't come apart for sure. They're quite stiff and as being used in RC flying models proved fairly secure. You can though always use small cable tie or two winds of electrical tape for the peace of mind but I'd not recommended encasing those into heatshrink tubes.

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Don't forget to get some Ebates cashback to your Paypal account when buying stuff from AliExpress!  My total cashback from eBay, Walmart, etc is about $272 over the past year or so.

BTW is there less chance of MOSFET burnout if 12 are used instead of 6?  Does that divide up the heat dissipation so it's halved for each MOSFET?

Edited by HunkaHunkaBurningLove
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21 minutes ago, OliverH said:

For one motor or for all motors? So how much per phase? And how much current does the Mosfet handle in a Tesla?

Teslas' don't use mosfets but IGBTs:

 

Damaged-IGBTs-e1442318721253.jpg

Fig.1: 2×14 IGBTs in parallel is one leg of inverter—All packaged in discrete TO247 – From Tesla Roadster and Model S inverter

http://www.pointthepower.com/on-tesla-electric-vehicles-semiconductor-packaging/

Also, I recall reading somewhere that the motors use something like 400V for voltage... thus the inverter? But not that familiar with the Tesla technology or IGBTs/inverters in general :P

EDIT: Oh, right, about the current:

  • “That design allows Tesla to ‘insanely’ run 1500A through the inverter IGBTs and then the motor”

 

Edited by esaj
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2 hours ago, esaj said:

I stopped reading the terms when it said " Member must have a valid address in the United States or Canada only. " ;) Plus, I don't pay with Paypal or credit card...

At least in theory, it should halve the heat dissipation per mosfet (as 2 mosfets "share the load"). In practice it should sort-of "auto-compensate" for slight differences in the mosfets, if the mosfets are mounted near enough each other to stay around the same temperature, if they're unequally loaded, the internal resistance should go up with temperature on the one that's taking a bigger share of the load, thus reducing it and passing more of it to the other one. That's what I've at least read about, one of my (unfinished) projects is an electronic load based on paralleled mosfets, but it's not exactly the same principle as with the wheels (for load usage, the mosfets are deliberately made to dissipate a lot of power, whereas in the motor drive you want them to dissipate as little power as possible). Still the principles hold, at least for the most part ;)

Aw that's too bad.  I didn't think there was a location limitation on the Ebates site.  I usually use the .ca one, but the .com one has better cashback rates so I've switched to that instead.  I'm not sure if they check the address as I have mine set on sending the cashback to my Paypal account.  I could have registered with any address in Canada or the US I think.  They do send cheques as an option so you have to set it to offer Paypal deposits.  In any case, it's still a handy way to make some money back from purchases I find.  I spend so much that every bit adds up.

So is it mainly a temperature issue with these MOSFETs burning up or are there problems with voltages or current passed onto them going too high and ending up frying them?  I would think if the voltage/current is kept in spec, and if the heatsink is appropriately sized, there shouldn't be a problem?  But why do we see so many reports of control boards getting fried?  What's the common root cause?

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