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Old 04-10-2009, 08:52 PM   #861 (permalink)
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Perhaps even with pull-down resistors from the mosfets' gate to ground, for a very brief time while the control section is just shutting off (and hence no current limiting anymore), the mosfets could be "on" while the gate voltage drops, allowing power from the batteries to dump through for even a couple milliseconds! murdering them instantly! That's what happened with the bike version awhile back. So, by the time I turned on the controller the next time, the mosfets were already failed shorted.

The controller could have died just by turning it off out of the sequence below...

The smoke could have indicated lots of power through the stuff inside, rather than indicating the moment everything broke.

It's just a guess at this point, but possibly the only completely safe sequence for that version was:

ON:
1. Turn on 12v power.
2. Pre-charge resistor.
3. Close Contactor

OFF:
1. Open Contactor.
2. Turn off 12v power.

It would make me really happy if that's all that the problem is. Man! I love a mystery! By the way, I just ordered all the new parts for the newer, and much more robust and fancy and professional control board section. Ya!

Well, it would be good to incorporate the pre-charge resistor and contactor stuff as Roger suggests. I might have to order from them again to get that stuff. Dang it! hehe.

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Old 04-10-2009, 09:13 PM   #862 (permalink)
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And, it took several times of doing things out of that sequence before the bike's mosfets failed shorted. hmmm..... Oh the mystery of it all!

Me gustan los mysteries!

Having the controller control the contactor and pre-charge resistor would eliminate that potential problem.

I feel pretty sure that's what happened. The mosfets have a capacitive component to them. Each one had a 10kOhm resistor leading from gate to ground, so the overall resistance to ground was 1kOhm. I wonder what the time constant was?
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Old 04-10-2009, 09:26 PM   #863 (permalink)
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When I turned off the car....the last time BEFORE turning it on and having the POOF!, the contactor sounded funny. It makes a very particular sound, and sounded different that time.

I think that's when the controller actually failed. I had turned the key off rather quickly, and I think the contactor didn't release quick enough. Then, the 12V power would have been OFF to the controller while the main contactor was still on.

Then, when I went to turn the car back on, the controller was already stuck in a "full-on" situation. When I turned on the main contactor the motor started spinning right away.

I got the box apart. Man, that Loctite makes it hard to get those heat sink screws out!

It was the mosfets! The 3 closest to the B- bar have their little legs blown off. I think those were the dog mosfets. Darin's and my mosfets are over on the other end.

The smoke and ick in there made it look like maybe it was the capacitor on that end. It was hard to see through the enclosure.

The couple of resistors on that end are gone too!


If timing and order are so important that the controller will destroy itself if you do it wrong, maybe some sort of contactor control DOES need to be built into the controller.

I might even worry about the possibility of accidental loss of 12v power to the controller while driving to cause it to blow!
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Old 04-10-2009, 09:42 PM   #864 (permalink)
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I've been trying to be nice to the controller! Really!
Other than a few burn-outs, a couple rides up some big hills, and 65 mph joy-riding, I have been treating the controller like a lady.

I even installed the 12V fan!


Heres the controller in the car right after I towed it home.


You can see the capacitors, but not the mosfets.

Once I got the controller apart, the view was much more clear.




I hope it's clear enough in the photo. The poor little mosfets look like they stepped on a landmine.

What did I do in damage? $50 in parts and countless hours in labor?



PS: I double-checked the wiring diagrams for the Curtis controllers, and they turn on the main contactor and power to the controller at the same time.
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Old 04-10-2009, 09:47 PM   #865 (permalink)
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OUCH!!! Boy, these electric cars can be as complicated as the ICE ones.

I was about 2 pages behind, with these upper-level classes I'm dealing with. I decided to do some catch-up this evening, although it means doing homework on a Saturday...

Whew! A few hours earlier, and I'd have felt the blast!!! Well, if that was my mosfet that went, it's no surprise: I'm so hyper and stressed from everything myself!

If I don't get economically un-stimulused this month, I'll see about adopting another mosfet. A nice calm, cool, collected one...

:-)
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Old 04-10-2009, 09:56 PM   #866 (permalink)
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Gentlemen -

This thread has quickly gotten way over my head, but I just wanted to cheer you on and say that you are being watched closely by all the little guys. In fact, I wonder if maybe Curtis sabotaged Ben's controller when he was shopping...

Post the link for Mosfet adoption again, I would love to help.
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Old 04-10-2009, 10:00 PM   #867 (permalink)
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Quote:
Originally Posted by MPaulHolmes View Post

It's just a guess at this point, but possibly the only completely safe sequence for that version was:

ON:
1. Turn on 12v power.
2. Pre-charge resistor.
3. Close Contactor

OFF:
1. Open Contactor.
2. Turn off 12v power.
Whoa, slow down a minute! Your starting /ON sequence is not cool! The reason why Kellys, Curtis and Alltrax kick the bucket is because the 12 volt power is activated BEFORE the Pre-Charge system has completed it's thing. I have to Precharge my Kelly BEFORE turning it on, as it's stated in the manual. Usually controller systems are always "charged" for the caps/PWM cycle to not kill itself.

When I PreCharge my Kelly, I can see it sucking up the AMPs through my current meter and I wait until it settles down. Usually I give it a minute or so, then I leave it alone.

Your listed Boot/ON Sequence is probably what destroyed the controller, it just didn't let out the smoke until it has done it a few times.
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Old 04-10-2009, 10:24 PM   #868 (permalink)
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Quote:
Originally Posted by bennelson View Post

It was the mosfets! The 3 closest to the B- bar have their little legs blown off. I think those were the dog mosfets. Darin's and my mosfets are over on the other end.
What? What?

Jake! Emma!

Where are you?

What have they done to your little legs?

Oh the sacrifices we make so that others may be happy

Guess I'll have to send a couple more dogs over to sacrifice to the good of the cause.

Eric
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Old 04-10-2009, 11:26 PM   #869 (permalink)
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Adopt a Mosfet!!

Go here:
Green Cars: Videos and More!

And click the Open Source Controller Repair fund link in the upper right corner.
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Old 04-10-2009, 11:55 PM   #870 (permalink)
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OK, lurkers: support this project! Adopt a mosfet!

OK fellow forum lurkers…(wow! – That sounds kind of creepy – but no offense intended!)
You are waiting for the completed version…time to help where help is needed….

I would like to start a challenge to raise some funds so we can buy what we need, when we need it, to continue this amazing project. I’ve been following along quietly for a while, but it’s time to speak up.

I challenge everyone following this thread to match my $20 donation so work can continue into Version 2. A little toasting was a minor setback, but it will drive improvments; we’ve all gleaned ideas for projects of our own, looking forward to the day when we can start building our own controllers based on all of the terrific R&D, and input from the collective mind of this forum.

$20 dollars might be a struggle to some in these troubled financial times, but you will save WAY more than that eventually. Think of it as a future investment to save you money. We will ALL benefit from your donation. In the big scheme of things, this controller is worth way more to you than: 2 tickets to the movies, 4 coffees from Starbucks, 3 packs of smokes, or a few cold adult beverages. (Not that I don’t like drinkin' mind you…..but 20 bucks worth of booze is only the first 4 or 5 drinks, and then it will cost me another $40 to cop a buzz….just not worth it anymore! )

Please accept my Challenge and donate to the cause……if you can't honestly do $20, then please do what you can and Thank You ; If you can do more than $20 , then Thank You! Thank You!

Click on or paste the link below: Then hit the DONATE button under the
"Help FIX the 144V Open Source Motor Controller!"

Green Cars: Videos and More - Donate to Paul & Sabrina's controller project

Ok..ok…I’ll get off the soapbox now…..Thanks for listening! (and chipping in!)

:EDIT: If the above isn't enough reason to donate, think about this: When all is said and done, and you've built your own unit; if anything breaks, you will know EXACTLY how it was put together - because YOU built it! And THAT knowledge, which is being supplied here by many great people, is PRICELESS!

Try getting all that knowledge from those other controller makers...after you've spent $1600 on a unit....are you going to try to repair it yourself?
:END EDIT:

Wherewolf


Last edited by Wherewolf; 04-11-2009 at 12:16 AM..
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