Looking for fast automotive relay - Please help

Discussion in 'The Projects Forum' started by emil01, Oct 29, 2012.

  1. emil01

    Thread Starter New Member

    Oct 29, 2012
    4
    0
    Hi all,

    I am new to the forum and not this is not my strongest side.
    I really need a relay that can handle automotive amperage.

    The project I have going is using a microswitch to control a 12v electric motor with 11.1v 3000mah lipo battery. Because the switch is not made for this kind of amperage drawn from the motor the switch tends to melt or burn. The microswitch is going to be used with frequent taps to control the motor and even in longer intervals which is no match for the micro switch. A must for the setup is fast response from when the "trigger"/microswitch is activated to when the motor runs and a normal automotive relay that can handle these kind of amperage and spare the microswitch is too slow and can't handle high frequency usage.

    So my question is what relay should I use if I need something that can preserve the microswitch and still have the responsive performance as before?

    The microswitch I'm using is this OMRON V7-1S17D8-022

    Specs: Ampere Rating 0.1 A
    Circuitry Single Pole Double Throw (SPDT)
    Actuator Straight Lever
    Termination Quick Connect
    Operating Temperature Range -40 °C to 82 °C [-40 °F to 180 °F]
    Voltage 125 Vac
    Approvals CSA,UL,ENEC
    Actuator Length 35,6 mm [1.40 in]
    Contact Type Gold Plated Silver

    Thank all of you who are willing to help me! It's much appreciated! :)
    and great forum btw!

    -Emil
     
  2. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    You've not told us how many amps the motor draws..
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    Told us plenty of other useless information though :p just forgot the one important piece. Other than clearly .1A is not enough..

    And you pressing a button is NOT FAST in the electrical world.

    Heck just go to the car parts store and get the standard 30A black "ice cube" relay and have fun. like this https://encrypted-tbn1.gstatic.com/...PvohMGyneuvv6icNUIJI21wQ0nrShyMxJM8-SAAHLvnzQ
     
  4. emil01

    Thread Starter New Member

    Oct 29, 2012
    4
    0
    sorry guys, it draws up to 40amps. the "ice cube" relay is too slow tried those all ready. Arent there an alternative out there thats faster?
    Larger power relays take about 0.020 - 0.050 seconds to react MOSFETS react within 0.001 seconds. thats the target.
     
  5. crutschow

    Expert

    Mar 14, 2008
    13,052
    3,244
    You could use a DC output (not AC) SSR relay such as this.

    Or if you don't need isolation and want to design you own, you could use a MOSFET. Can the load float or does it need to be grounded?
     
  6. kc5tpa

    Member

    Sep 21, 2012
    48
    3
    If you don't want to divulge too much information, understood, but as mcgyvr said you pressing the button, no matter how fast you think you're pressing it, will never be as fast as 0.020 - 0.050 seconds or 0.001 seconds. It will take you longer than that to react to whatever you're trying to accomplish.

    It takes you roughly 0.35 seconds to blink.

    If you gave more info there may be another way to do what you want. But I can't wrap my head around the need for a 40 amp motor to be used with such high switching capabilties.
     
  7. kc5tpa

    Member

    Sep 21, 2012
    48
    3
    Not to mention the inrush current...
     
  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    The "automotive ice cube" relays should operate and release in 10ms or less (.01 seconds) each way.. NO WAY that is not fast enough for a human triggered push button and a 40A motor.
     
  9. wayneh

    Expert

    Sep 9, 2010
    12,153
    3,059
    Reiterating crutschow's suggestion, if MOSFET performance is the target, why not use a MOSFET?
     
  10. kc5tpa

    Member

    Sep 21, 2012
    48
    3

    "I want to rewire my entire house but I want to use only 28 AWG runs..."
    I could do it, but you better not turn anything on.

    It's a possibility, not a capability.
     
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