On/off for ebike using ssr

Discussion in 'The Projects Forum' started by Scubasteves, Jun 21, 2016.

  1. Scubasteves

    Thread Starter New Member

    Dec 11, 2015
    20
    0
    Hello!
    I'm in the process of rebuilding my 48v 30a ebike and wanted to have a key on/off (ignition)for main power instead of (un)plugging it all the time.

    So would the appropriate circuitry involve a ssr-100dd on a heatsink controlled by a key ignition between the +relay and + of 6.4v battery (2x 18650 in series)?
    (with load side of relay separating + on 48v lifepo4 and + on motor controller)

    I read inductive loads sometimes require 6x current surge during startup. All the ssr-100dd that I looked at never mentioned a surge rating. Is a 100a relay sufficient?

    Are SSRs themselves a resistive device? Enough that, with just a ssr in a circuit, will it short the battery? Do I need to add resistors or something? How much current should a relay draw to control(close circuit)

    Another relay wiring guide mentioned adding a diode across the load with cathode to + if the relay is going to be used with an inductive device. But because this relay will never be used as a killswitch does that matter?( The controller handles throttle etc.. Keys only get turned during parking) the supposed risk of using as off with inductive device is because the mechanical energy still in the tire inducting power into the wires after relay is shut off
     
  2. TheButtonThief

    Active Member

    Feb 26, 2011
    219
    38
    Why bother using a relay? Just use a key switch in series between the battery and it's load.
     
  3. Scubasteves

    Thread Starter New Member

    Dec 11, 2015
    20
    0
    So an ignition with 20awg wiring is sufficient to handle 1500w? 40 amps? I don't think so. Even if it could, the contacts in an ignition probably aren't designed for that kind of spark probably corrode very quickly. Please provide constructive input
     
  4. Scubasteves

    Thread Starter New Member

    Dec 11, 2015
    20
    0
    Any other support? Are my questions the right ones to ask?
     
  5. Lestraveled

    Well-Known Member

    May 19, 2014
    1,957
    1,215
    @Scubasteves
    Google "battery disconnect switch" They are good for hundreds of amps, and cheap.
     
  6. Scubasteves

    Thread Starter New Member

    Dec 11, 2015
    20
    0
    Thank you
     
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