[NSRCA-discussion] Arming Plug/Receptacle Problem

[James Oddino]

1) A half Watt resistor will be fine.   The voltage across it drops  
very fast as the caps in the ESC charge.  It is Watt-Hrs that create  
heat that burns out resistors.

2) Yes the ESC will be on and will draw some current.  About 200 ma as  
I recall.  A little less than if there were no 100 Ohm resistor.   
Therefore I wouldn't want to plug in my batteries too long before I  
fly or leave them connected too long afterward.

3)  The spark does let you know that the pack has some charge and the  
caps are still good.

I flew this configuration on my Impact and had no problems and of  
course no damaged pins on connectors.  I did not install an arming  
plug on my Abbra as I wanted to save weight.  I use 5.5 mm bullets and  
I do see degradation but it is confined to the tip of the male and  
edges of the female.  The long length of the pin and socket is where  
the contact is made after they are connected and that area stays  
bright and shiny.   I do observe the rules for when I plug and unplug  
the packs as described in 2) above.  I also have a very safe turn on  
and off sequence that includes use of the kill switch on the  
transmitter so the motor can't turn on accidently .

Jim

On Feb 9, 2009, at 10:14 AM, Ron Van Putte wrote:

> Good.  I will try it.  What wattage 100 ohm resistor?  Let's see,  
> doesn't sustained power equal voltage squared, divided by the  
> resistance?  If so, 42 squared, divided by 100 is 17.64 watts.   
> That's probably overkill, since the current surge is transitory.   
> How about a 100 ohm, 10 watt resistor?
>
> Just thought of something:  With the 100 ohm resistor across the  
> arming plug receptacle, won't the ESC be on whenever the batteries  
> are plugged into the circuit?
>
> BTW, what about Castle Creation's statement that the "spark is your  
> friend'?
>
> Ron
>
> On Feb 9, 2009, at 11:55 AM, James Oddino wrote:
>
>> Put a 100 ohm resistor across the arming plug receptacle.  Then the  
>> capacitors in the ESC will charge without a spark as you connect  
>> the batteries.  When you connect the arming plug, no spark.
>>
>> Jim
>>
>>
>> On Feb 9, 2009, at 8:08 AM, Ron Van Putte wrote:
>>
>>> I have a problem which I am sure many other E-powered airplane  
>>> owners have that I'd like to solve.  I use an arming plug to  
>>> connect the two 5S Lipo packs to the ESC.  On initial contact of  
>>> the arming plug with the receptacle, there's a big spark thrown.   
>>> Eventually the contacts on the arming plug and receptacle get  
>>> burned to the point where the electrical contact is very bad.   
>>> Yesterday I had to land my airplane deadstick because (I think)  
>>> the ESC saw what it thought was low voltage out of the battery  
>>> that was actually due to the burned arming plug/receptacle  
>>> contacts.  BTW, I am using high-amp Anderson Power Pole  
>>> connectors, which are probably more susceptible to having the  
>>> contacts burned than would Deans Ultra connectors.
>>>
>>> I have thought about putting a BIG capacitor in parallel with the  
>>> arming plug, that would damp the initial current surge which  
>>> causes the spark.  The capacitor could be removed before flight.   
>>> However, I'm wondering if there's a more elegant solution.
>>>
>>> Ron Van Putte
>>>
>>> _______________________________________________
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>>> NSRCA-discussion at lists.nsrca.org
>>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>
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