View Single Post
Old
  (#10)
Finnster
KillaHurtz
 
Finnster's Avatar
 
Offline
Posts: 2,958
Join Date: Apr 2006
Location: Bucks Co, PA
02.18.2008, 05:27 PM

Quote:
Originally Posted by BrianG View Post
This type of thing can be done with Deans just as easily (actually, probably easier):



Just hook the mini-deans up first, wait ~10 seconds, then hook up the main leads.

The resistor in the pic above is based on 1,000uF ESC total capacitance and an approximately 10 second charge time. The actual formula for picking the resistor value is:

R = S / 5 / C

R= Resistor in ohms
S= Time in seconds
C= Capacitance in farads

So, if your ESC has three 330uF caps (990uF total) and you want them charged in 5 seconds, the resistor to use would be 1010 ohms, or 1k.

The required resistor power rating can be found by the formula:

P = V^2 / R * 2

P= Power in watts
V= Battery voltage
R= Resistance in ohms

So, for a battery voltage of 22.2v (6s) and a 1k ohm resistor, use a 1W resistor.
That is basically what I did with mine. However I did not want to use a Deans miniplug as it leaves the possibility of the little prong on the mini connector making contact w/ the main Deans plug. ==> Dead short.

If it was wired carefully to make that impossible then I would feel ok about it. I just don't want any lipo fires in my travel bag I'm carrying my RC stuff around in. Instead I just prefer this:


You can use a smaller resistor, but then you have to get a higher watt rated resistor, and those get big and bulky. I used a 1/2W resistor (as its small and easy to find at ratshack) and an appropriate ohm value. I prolly should get a 1W resistor, but I just have it plugged in a few secs so its fine (its a 2200 IIRC.) Really you just need to take the initial "sting" out of it, and it always takes me a couple of seconds to plug in one, then grab the Deans and plug that in. Spark is tamed by then. Here's a handy calculator

BTW Brian, shouldn't it read [P=V^2/R ]?

Last edited by Finnster; 02.18.2008 at 05:36 PM.
   
Reply With Quote