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Old 12-22-2007, 02:01 PM   #1
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Default Need some help please

Question for you all...
Does a brushless motor blow up if the sensor wire is not attached, or does it simply not spin?
Reason I'm asking, is I've fried my motor and an Orion 3200 li-po pack.
I was binding my module & receiver, and when I finished, I pulled the throttle. The motor sparked and smoked... and now the battery is dead. I don't know if the reason was the missing sensor wire, or if the positive connector came in contact with the graphite top deck.
Any thoughts?
T2 007
LRP Sphere (Still works... at least on brushed. I don't have another brushless to try)
Orion Vortex 6.5
Orion 3200 Li-po (reads 6.1 volts + to - ... 4.2v + to balance port... 1.7v balance to - )
I don't have a balancer to try... and I'm scared to try charging the battery.
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Old 12-22-2007, 02:30 PM   #2
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That battery is no longer good. Once a cell has discharged that much it has begun degrading itself. I would send it in. To the sensor harness question; I have had my sensor harness come off during a race. The only thing it did was not run. As soon as I fitted back into the esc it worked fine. As far as the positive touching the graphite chassis, this should only cause a problem if the chassis is grounded to the negative, either battery motor or esc.

I would hazard a guess that something is wrong with the brushless side of the esc, as even wiring the motor backwards shouldn't cause what happened. If the battery were reversed the esc should have fried, or shorted out the board in the battery.
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Old 12-22-2007, 03:22 PM   #3
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battery?---toast, done,cooked, fried. Never had issue w/sensor shorting. Quite possibly are the connections from batt to sensor sealed properly? Any open hot wire touching anything could short out the batt.
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Old 12-23-2007, 09:09 PM   #4
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I've had other people tell me the motor simply wouldn't have turned. Thanks for confirming it.
The ESC works okay in brushed mode, although it doesn't seem to have the top speed that I'm used to... this could simply be a matter of wrong gearing etc.
I'm scared to try another brushless motor... I've picked up a Novak 5.5, so when I get brave, I'll wire that up, and see what happens.
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Old 12-23-2007, 09:25 PM   #5
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If I was to take a somewhat (but not really) wild guess...I'm pretty sure the LRP senses what mode to run in based on whether the sensor wire is plugged in or not.

The "party foul" would be to have it wired to a brushless motor without the sensor wire, because it's going to fire two phases at once, the motor isn't going to turn (very far)...you overheat the windings (dead short) and burn the motor up. I bet the ESC is OK, but I wouldn't try that stunt again...LOL

For the battery...I know that everyone says it's toast...but it probably isn't. The connection where the cells are soldered to the board will melt when you short the pack. The cells are probably fine and you can just re-solder the joint IF YOU EXERCISE THE CARE THAT A CHARGED BATTERY DESERVES.

Just split the case halves apart slowly (just taped together) and CAREFULLY heat up the joint (don't add more solder, it's a different kind), just heat it up and hold it down until it cools...good to go. Been there, done that several times.

If you're wondering if you have the skills necessary to repair the battery...you probably don't. If you don't want to do it, I'll buy it from you as-is and I'll do it. You just don't want to short it out, because it will make big sparks and melt (more) stuff.
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Old 12-23-2007, 11:13 PM   #6
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Good batt info, Thanks a bunch! Never even thought of that.
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Old 12-24-2007, 04:35 AM   #7
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The main worry would be the 1.7V across one of the two cells.

Anything below 3V causes damage.

Maybe it's the joint mentioned, just be carefull.

You could try charging ata very low rate with a balancer, probably best to try that outside though!

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Old 12-24-2007, 09:33 AM   #8
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You measure at the terminals...when the cell tabs melt off the board, they rest against it, but they're not really connected. It causes the voltage to show as low.

If you think about it another way, there's no way he could have blown out one cell by what he did. No way aside from shorting the ESC and doing what I said. The cell is fine, it's just not connected to the board.

Quote:
Originally Posted by Skiddins View Post
The main worry would be the 1.7V across one of the two cells.

Anything below 3V causes damage.

Maybe it's the joint mentioned, just be carefull.

You could try charging ata very low rate with a balancer, probably best to try that outside though!

Skiddins
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Old 12-24-2007, 03:15 PM   #9
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I'll open up the battery, and have a look... and I'm almost brave enough to try the new b/l motor.
Thanks for the replies.
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Old 12-24-2007, 04:27 PM   #10
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Quote:
Originally Posted by Thistle View Post
I'll open up the battery, and have a look... and I'm almost brave enough to try the new b/l motor.
Thanks for the replies.
Just be very careful when attempting to fix the battery. Don't touch the foil envelope with the iron, although it is a spectacular sight.
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Old 12-28-2007, 04:19 PM   #11
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Well, you were right about the battery. A little heat to re-solder the tab was all it needed. Thanks.
One down, one to go.
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Old 12-29-2007, 06:37 PM   #12
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And... (drumroll please)... the ESC still works on Brushless. I guess it was the missing sensor wire that caused the motor to smoke. (Won't be doing that again)
Thanks again to everyone, for their thoughts and advice.
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