Ideas for controlling locking mechanism on electric scooter?

I’ve been tinkering with an idea for implementing a rfid lock for my electric scooter using the xEM. They sell an oem fingerprint lock which appears to simply connect two pins on the controller, if no lock is installed, there’s just a jumper in place which always shorts the pins. Unfortunately, in researching what kinds of technology I need to get to create the lock, I accidentally found out the pins are 60-100V DC and had a bit of a surprise with a large spark and pop, followed by magic smoke (pretty sure I shorted pins with my multimeter that I did NOT intend to).

So, I know I’ll need a vreg to bring down the 100V to the 12V the xEM runs on. My original plan was to have the signal line of the xEM trigger a relay, then have the output of the relay hold the input open with a diode to protect the signal line from not having >12 volts sent down it, but with the high voltage I’m a bit concerned. I’ve been looking at ratchet relays but I’m not 100% certain what to get or where to get it. Could someone with some more experience in electronics work give me some advice? (The pinout of the lock header appears to be Unused, V+, Ground, Lock Trigger)

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I had the same idea for my razor scooter… just haven’t had time to do this yet… it’s a sound idea… but on my scooter there is a break cable that has a switch on it which blocks the motor from running if engaged… I can short these low voltage conductors and effectively lock the scooter.

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Ah yeah, I’m doing this on my kaabo mantis, the fact that I’ve already managed to blow up my controller while just testing voltages upsets me a bit, but this seems like it really shouldn’t be that difficult a solution, I’m just lacking knowledge of the specific components I need… I suppose I could use a microcontroller to toggle a relay on the signal pulse from the xEM controller if I don’t want to figure out ratchet relays haha.

I used a dpdt relay to self-latch… can only turn off by cutting power to the whole thing but that works fine.

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I have used several different kinds of relays, but I don’t have any experience with ratchet or latching relays. You’re right, they do seem complicated. Here’s some good info I found:

Guys… honestly… just use the dpdt… it’s easy;

Here’s how you wire it up to be self-latching;


Basically you use one of the throws to self-latch, and the other to control whatever you want to control. The diode protects the XAC from current feeding back through the output wire and destroying the XAC. The switch should be the main power switch on the bike or scooter or whatever… so when you turn the main power switch on, the XAC gets power but the relay is dead. Once you scan your authorized chip, the relay will latch and begin feeding itself power, so even if you remove the chip from the XAC antenna it will remain closed. The only way to unlatch it is to cut power via the main switch, but for most vehicle style applications this is totally ok.


Great ideas guys…
Had a similiar idea for my e-mtb.
The problem i see is: only cutting power wont prevent from getting it stolen…

I’m personally just doing this for fun, I still fully intend on using my heavy duty kryptonite lock and keeping it in my apartment or a secure area whenever possible, but a little more deterrant never hurts and it’s neat.

I actually finished doing the mods to my scooter a couple days ago using a self-latching dpdt relay. I figured out the lock accessory header supplies 5v for the accessory which needs to bridge the 60v system pins to allow the scooter to move or turn on it’s lights, which is a good indicator of a successful authentication. Ignore the very professional looking zip tie mounting.


I wonder if I can make this work for my bbshd kit from lunacycle…

Haha, it looks like a TIDY MadMax mobile all the bells and whistles that you can squeeze on there… I like it.

A pity my electric skateboard doesn’t have the space

I’ll give you that! I use pretty much everything on there regularly, gotta have a light for riding at dusk/night, a horn for riding in downtown traffic and to try stopping getting sideswiped again, and my phone holder for maps for longer rides. The xEM is honestly the least functional upgrade but I love it nonetheless.

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Do you think you could squeeze some indicators on there? ( Turn signals in USA speak )

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Living in Southern California I don’t think they know indicators exist, let alone talk about them…

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Have you ever been to South East Asia? or India?
That is, Toot horn, manoeuvre… but it works. generally.
Organised chaos! lanes are merely a suggestion

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My only question with the DPDT Relay is if there is a specific amp or voltage rating that I need to search for?

Would something like this suffice?