Battery Simulation

Discussion in 'General Electronics Chat' started by cnguyen, Nov 11, 2009.

  1. cnguyen

    Thread Starter New Member

    Oct 19, 2009
    6
    0
    Hi,

    There are 2 series capacitors ( 70,000UF, 65Vdc each) and a big resistor put across 2 caps. My question is how do we choose the value of a big resistor? What is the purpose of this resistor, discharge?
    The input voltage is 38Vdc.
    Thanks

    KN
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Those are bleeder resistors to provide a discharge path for the charge on those big capacitors. The value is quite variable, depending on how fast you want the caps to discharge. But there is no point in wasting energy as heat, so something around 47K is probably good.
     
  3. Duane P Wetick

    Active Member

    Apr 23, 2009
    408
    19
    Well, how quickly do you want to discharge those capacitors? Remember 5 x RC (seconds) will discharge 98% of the voltage charged. Use a 20 watt resistor as some heating will occur. Avoid shorting the terminals with a screwdriver (Big Spark!) as this stresses the capacitor un-necessarily.

    Regards, DPW
     
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