Ebike adding accessories to ignition help

Hi I have a 3000w SB running on a sabvoton 150a controller,
I have a headlight,horn, turn signals etc.. and I'm wanting them to be some how attached to my ignition so they can't be used when the key isn't inserted is there any way this can be done? Also all my accessories are running directly from my 60v battery (71.4v when charged) thanks

If your ignition switches the "keyswitch ignition" wire from battery positive to controller, then you could just make sure that the source wire from the battery, and the keyswitch itself, are all rated for the total current draw your accessories will require.

Then move the accessory power main supply wire from the battery to the controller side of the keyswitch.



If your ignition switches something else, you'll need to provide details of exactly what it does for us to tell you how to use it to switch your accessories as well.

Thanks for the reply, my ignition is from the controller ignition wire, if there's too much current flowing through the ignition what's the worst that can happen? I'm wanting horn,headlight,rear light attached to it but the lights I'm using are 72v and I'm not sure if they will work with lower ignition voltage

Hi, I've just wired the power from the lights to the ignition and it's working fine, but I also have a alarm system fitted, is there any way I could get the light to flash when the alarm goes off or gets armed? Thanks

sorry, i'm still busy with a city-ordered cleanup project so will be at least several days before i can look into it and respond.

Cam3roon2k41999 said:

Thanks for the reply, my ignition is from the controller ignition wire, if there's too much current flowing through the ignition what's the worst that can happen? I'm wanting horn,headlight,rear light attached to it but the lights I'm using are 72v and I'm not sure if they will work with lower ignition voltage

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Ok. The ignition switch on most controllers is actually battery voltage. You'd need to measure yours to find out.

It's usually a low-current very thin wire though, and the switch itself isn't usualy designed for high current either. As long as the headlight is low current (1-2A) that will likely work fine. If it's a high current headlight, then it depends on the actual rating of the switch and wires as well as the actual current draw for the results. If they're very low rated, and the current is way over that rating, you may have melted insulation on the wires, or if the keyswitch is all plastic it could warp or melt the areas around the contacts.

You can measure the headlight current using your multimeter on 10A, and the red lead on the meter 10A port, black lead on meter ground. Hook up headlight ground to battery ground. Leave headlight power wire disconnected. Then red lead other end on headlight power wire. Black lead on battery power. Headlight should light up and you should get a reading on the meter in amps.

Cam3roon2k41999 said:

Hi, I've just wired the power from the lights to the ignition and it's working fine, but I also have a alarm system fitted, is there any way I could get the light to flash when the alarm goes off or gets armed? Thanks

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Depends on the alarm system.

If it has an LED on it that already does this, then you can wire a relay controlled by the power to that LED that then controls the headlight power.

If it has a speaker that chirps, you can use that output with a bit of extra electronics to do the same thing, but the LED output won't likely need this.

If the alarm has an output meant to flash external lights (like car alarms often do) then you'd use that per whatever instructions the alarm came with (there are a few ways it may be intended to work, and it may require an external relay). (if you don't have any info on the alarm, then you'll have to do testing and guessing to find out what functions any unused wiring may have).

Hi, thanks for the reply , sorry I only just got you're message I'm waiting on a new horn and switch as my horn produced allot of smoke due to me being a idiot connecting a 12v horn to 72v isn't a good idea I've connected a 12v 10a DC-DC converter to my ignition wire that is for 72v my lights etc are made for 36-72v I think so I have them directly connected to my ignition power and works fine up to now, I've ordered a 12v motorcycle high tone horn should I comnect that to the DC converter that's connected to my ignition? Thanks

Cam3roon2k41999 said:

Hi, thanks for the reply , sorry I only just got you're message I'm waiting on a new horn and switch as my horn produced allot of smoke due to me being a idiot connecting a 12v horn to 72v isn't a good idea I've connected a 12v 10a DC-DC converter to my ignition wire that is for 72v my lights etc are made for 36-72v I think so I have them directly connected to my ignition power and works fine up to now, I've ordered a 12v motorcycle high tone horn should I comnect that to the DC converter that's connected to my ignition? Thanks

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Depending on the horn, you may need a lot bigger DC-DC; many horns take 30A or more at startup, and will just shutdown a smaller converter (or blow it's fuse if it has one). You'll have to test it and find out.

If you have a 12v car battery you can hook the horn up to, and a clamping-style current meter, you can set it to it's highest range and test the current the horn actually takes, best if it also has a peak-hold for the highest reading it detects.

Otherwise you'll just have to see if it works on the DC-DC you already have, while it is also running all the lights/etc.

For that, if you have a horn button on a control on your handlebars, you have to see how it is wired first (is it two separate wires, or does it have one horn wire and one that goes to 12v or one that goes to ground, etc), and then I can help you determine wiring for the horn.

If you use a separate horn button that's just two wires, just put it in series with the horn and one DC-DC output wire (either ground or positive, doesn't matter), then hook the other horn wire to the other DC-DC output wire.


Also note that "12v" is pretty low voltage for automotive / mc 12v accessories; they actually run on 13.6-15v, so lights will usually be noticeably dimmer and horns quieter on 12v.

Thanks for the reply, my horn switch has 2 wires coming from it and my dc converter has one yellow wire for 12v output, my lights are connected to the ignition wire but not the dc converter, thanks

Hey, just an update I've connected my horn and Dc converter to my 72v ignition with my lights etc.. and it all seems to working good apart from the horn does seem a little low on volume lol I think it might be because my dc converter is 12v 10A thanks for the help I appreciate it