Melted battery connectors
08-21-2011, 04:40 PM
#1
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Melted battery connectors
Last weekend I was flying my Blade 400, and I was having fun, until I noticed that the EC3 connectors were melted together. I run a 30C pack in place of a 20C, but this has never caused problems before. Can connectors melt if the contacts brush against them too much? I have uploaded some pics so that someone can see if they know what caused this. Thanks.
08-22-2011, 06:27 AM
#2
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RE: Melted battery connectors
You obviously had a high impedance in that connector; could be from several possible problems. Dirty contacts, poor solder or crimp connection between the connector body and wire connected to it, loose or sloppy fit between the two connector parts, to small a cross section on the connectors for the current you put through it. Current times impedance equals watts which means heat, if high enough, you get melted connectors.
08-22-2011, 11:59 AM
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RE: Melted battery connectors
Rodney,
It seems to me the formula for watts is P=IE. Where P is power in watts I is current and E is voltage. The definition of impedance is:
Electrical impedance, the ratio of the voltage phasor to the electric current phasor, a measure of opposition to time-varying electric current in an electric circuit. So, is it not better to say that the problem was caused by to much current rather than impedance? I've always thought impedance was the resistance to current in an inductive circuit. Is this what you are thinking? I know the motor is basically an inductive circuit. But, I don't see the connection to the "plug contacts". If the contacts are rated for say 60 amps and the draw from the battery is say 80 amps would not that cause the "plug contacts" to overheat (they have some resistance) and melt?
It seems to me the formula for watts is P=IE. Where P is power in watts I is current and E is voltage. The definition of impedance is:
Electrical impedance, the ratio of the voltage phasor to the electric current phasor, a measure of opposition to time-varying electric current in an electric circuit. So, is it not better to say that the problem was caused by to much current rather than impedance? I've always thought impedance was the resistance to current in an inductive circuit. Is this what you are thinking? I know the motor is basically an inductive circuit. But, I don't see the connection to the "plug contacts". If the contacts are rated for say 60 amps and the draw from the battery is say 80 amps would not that cause the "plug contacts" to overheat (they have some resistance) and melt?
08-22-2011, 08:17 PM
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RE: Melted battery connectors
I somehow keep thinking that the contacts were too loose, and were brushing against the insides of the connectors. But, I wouldn't be surprised if the contacts were just dirty, my house gets a bit dusty sometimes. If that's what it was, it might be because I kept the helicopter on my dresser for a few weeks, I normally use the box it came in. And I still haven't ruled out the theory of too much discharge current, though I've never had any problems with my 30C lipo before. Also, I've been wondering if it's safe to fly like this, or if I should replace both connectors. Thanks.
08-23-2011, 06:27 AM
#6
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RE: Melted battery connectors
ORIGINAL: jzrf6c
Rodney,
It seems to me the formula for watts is P=IE. Where P is power in watts I is current and E is voltage.
Which is also P=Esquared/Z where Z is impedance and E is the voltage drop across the connection. Note that impedance is the opposition to current and is composed of both R and reactance which is this case is primarily R. Technically, Z can be either resistance, inductive reactance or capacitive reactance, when you say Z you are always correct, when you say R you are only correct when there is no inductance or capacitance involved which is never totally true as even a short length of wire has some component of impedance which is not totally resistive in nature. Admittedly a picky point but technically correct.
The definition of impedance is:
Electrical impedance, the ratio of the voltage phasor to the electric current phasor, a measure of opposition to time-varying electric current in an electric circuit. So, is it not better to say that the problem was caused by to much current rather than impedance? I've always thought impedance was the resistance to current in an inductive circuit. Is this what you are thinking? I know the motor is basically an inductive circuit. But, I don't see the connection to the ''plug contacts''. If the contacts are rated for say 60 amps and the draw from the battery is say 80 amps would not that cause the ''plug contacts'' to overheat (they have some resistance) and melt?
Rodney,
It seems to me the formula for watts is P=IE. Where P is power in watts I is current and E is voltage.
Which is also P=Esquared/Z where Z is impedance and E is the voltage drop across the connection. Note that impedance is the opposition to current and is composed of both R and reactance which is this case is primarily R. Technically, Z can be either resistance, inductive reactance or capacitive reactance, when you say Z you are always correct, when you say R you are only correct when there is no inductance or capacitance involved which is never totally true as even a short length of wire has some component of impedance which is not totally resistive in nature. Admittedly a picky point but technically correct.
The definition of impedance is:
Electrical impedance, the ratio of the voltage phasor to the electric current phasor, a measure of opposition to time-varying electric current in an electric circuit. So, is it not better to say that the problem was caused by to much current rather than impedance? I've always thought impedance was the resistance to current in an inductive circuit. Is this what you are thinking? I know the motor is basically an inductive circuit. But, I don't see the connection to the ''plug contacts''. If the contacts are rated for say 60 amps and the draw from the battery is say 80 amps would not that cause the ''plug contacts'' to overheat (they have some resistance) and melt?
08-23-2011, 02:48 PM
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RE: Melted battery connectors
I suppose you're right, looks like it's time for another trip to the hobby shop. Maybe I can pick up some stuff for my nitro bird while I'm at it. 
