12 Volt Relay, Capable of up to 24 Volts?

Discussion in 'General Electronics Chat' started by Jesse James, Jun 3, 2015.

  1. Jesse James

    Thread Starter New Member

    Jun 3, 2015
    3
    0
    Hey guys,

    I'm working on a project to bump up the voltage on a couple motors from 12 volts to 18 volts. The last bit I need is a relay capable of 18 volts, but alas I can't find a proper one, sadly. I looked up the datasheet regarding the current relay and it specifies that it 'might' be capable of 18 Volts since it says a maximum of 24V. Here's the datasheet. http://pdf1.alldatasheet.com/datasheet-pdf/view/144774/ETC1/HFKP/0121Z5TS.html, if anyone can give me information regarding whether i'm right or wrong, it would be a great help.
     
  2. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
    2,781
    1,228


    Where are you seeing 24V? -- The linked datasheet shows an (I can only assume, absolute maximum, open circuit) "switching voltage" of 75v and a loaded spec. of 14V...

    IMO don't worry -- It'll work fine (but you didn't hear it here ;)) --- If, however, yours is a 'high stakes' application, there are plenty of 24V relays on the market;)

    Best regards
    HP
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,522
    2,369
    When working with a DC relay you can always put a suitable series resistor in series with the 12vdc coil if you find it overheats at all, it should not require one of significant wattage.
    Max.
     
    cmartinez likes this.
  4. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
    619
    Second this idea. Datasheet gives coil resistance of 120 ohms; something like a 1W 56 ohm resistor should do the trick. Just make sure you satisfy the minimum pick-up voltage.

    But are you talking about switching 18V or driving the coil with 18V?
     
    kiroma likes this.
  5. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
    2,781
    1,228
    Ooops --- I missed that you were referring to the coil (as opposed to the contacts) -- May bad!:oops:

    FWIW relay coils often feature two EMF specifications (The higher for AC and the lower for DC)

    With abashed regards
    HP
     
  6. Jesse James

    Thread Starter New Member

    Jun 3, 2015
    3
    0
    Wow, thanks for the replies everyone, much appreciation from a noob!

    I'm trying to drive the coil with 18v's instead of it's default 12v.
     
  7. Stuntman

    Active Member

    Mar 28, 2011
    181
    47
    A trick I have used is driving two 12V relay coils in series on a 24V rail.

    Then there are other options such as a ballasting resistor, diodes to drop voltage, and even a regulated 12V rail.

    It's a lot easier to use 12V coils in a 24V system than the other way around...
     
  8. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    Before you using the relay, you better to check the datasheet, different type of relay can be a big different range of max working voltage, some maybe can be reach to 110%, some can be up to 180%.
     
  9. Jesse James

    Thread Starter New Member

    Jun 3, 2015
    3
    0
    Thanks everyone again for the replies, I really appreciate the help.

    I do have one more question if someone can answer and or possibly explain how to read the data sheets so I can purchase a new relay. I found a 24v version of the relay here (http://pdf1.alldatasheet.com/datasheet-pdf/view/194434/ETC2/HFKP/0241Z5TS.html). I tried googling for the specific relay but no luck. I'm currently searching on Mouser.com, but I'm not sure how to exactly find the correct one with all the options and filters. (http://www.mouser.com/Electromechanical/Relays/_/N-5g31/). If anyone can give me advice on what too look for in comparison to the data sheet like connection type or contact termination etc that'd be great!

    Thanks again guys.
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,522
    2,369
    The majority of Automobile type are predominantly either SPST or SPDT, so are limited as to the amount of contacts.
    It depends on what you require to switch for each relay on how many contact positions you need.
    If using a 24v relay on 18vdc you may be lucky if the hysteresis point is low enough to enable it to pick up, the advantage of DC relays is that once picked up, they require less voltage to remain retained.
    Max.
     
Loading...