DIY COB turn indicators for an e-scooter - Page 1
Forum section: electronics / projects

author: e100
author_rank: Frequent Contributor
timestamp: December 16, 2021, 09:35:40 am
content: Prior to buying an e-scooter I assumed that you would use hand signals like you do on a bicycle, however the thumb throttle system and rapid deceleration when off throttle incentivizes you to keep your hand on the bar making hand signals impractical. The small wheels, high center of gravity and short wheel base also make for an unstable platform that makes you want to keep a firm grip of the bar at all times.Most e-scooters don't have indicators as there is no legal requirement to have them fitted, and those that do are usually underpowered making them near useless in bright sunlight.I searched for after market turn indicators but they are underpowered and only useful in twilight or dark conditions.So in desperation I purchased some 25mm square COB amber LEDs which arrived today. The specs say 2 amps at 12 volts. They don't have a series resistor. Testing with a constant current power supply they seem plenty bright enough at 0.2A, which is 2.4 watts, or 1.2 watts with a blinking 50% duty cycle, which is probably Ok with a small heatsink.This is the basic concept with a bar and a light on each end. I have some Meanwell LDD-500 H 0.5 A drivers from another project and these have a PWM brightness control pin.My first idea was for each light to to have 2 panels arranged at 90 degrees to make them visible from the front back and side.I'll probably use a 24v battery and put the COB panels in series.Has anyone done anything similar?Alternatively I could use a single panel and use some kind of reflector/diffuser to redirect the light in multiple directions. I only have hand tools so it cannot be too complicated. As for weather proofing and UV resistance, I'm thinking of just painting a layer of silicone or polyurethane sealant over everything. I have some Raytech silicone gel used for potting electrical junctions and some FulaSeal flexible acrylic sealant normally used for acrylic/polycarbonate glazing applications.

author: Whales
author_rank: Super Contributor
timestamp: December 16, 2021, 10:52:06 pm
content: EDIT: I notice this is in the "Manufacturing & Assembly" forum. I assume you're only making one for yourself, not trying to mass manufacture these?Sounds like it could workMy only concern is fragility when falling over1.2W per COB is probably fine without heatsinks, assuming their rear face is exposed to air and they are as big as I'm imagining (5x5cm?). Try running them continuously on the bench and take their temperature over time.Sealant: a clear one will probably look nicer. You'll probably want to test applying some on a spare/broken COB just to make sure nothing weird happens (eg the sealant bunches up into balls instead of staying a nice spread-out coat).Wiring: if you're running them at a low wattage then they won't need the full 12V each. See what your current limited power supply says the voltage is when running them. It might only be something like 9 or 10VNot sure if having 24V batteries is any harder than having 12V batteries. Running the LEDs in parallel is fine as long as you put some ballast resistors on each. You could put resistors on each LED to perform the current limiting too, killing two birds with one stone, or you could go for more advanced current limiting circuits (eg little switchmode PSU boards off eBay) if you want the extra efficiency.

author: thm_w
author_rank: Super Contributor
timestamp: December 17, 2021, 01:40:24 am
content: I agree 1W is likely fine without a heatsink, considering how rarely they are on. Also, yes, hand signals are quite difficult and dangerous to use.Many scooters do come with turn signals (usually garbage), but you may use your own controls or adapt a bar mount control like this:https://www.aliexpress.com/item/1005002776916425.htmlMay also want to have these LEDs solid on, at a lower brightness, to give good visibility at night, if you don't have other good lights.I've done this before with COBs as well as off the shelf LED lamps (eghttps://www.aliexpress.com/item/4000971797049.html).I would be tempted to use either 4V 1S li-ion with boost regulator, or a 3-4S pack with buck regulator, and LEDs in parallel as noted by Whales. Finding a 24V battery is not that easy, compared to a 1-4S li-po pack.I'll ask to move this to the Projects section.edit:I would recommend for power, either:- USB power bank -> 5V goes to arduino, and to aboost module-> ~12V to COB LEDs- Single cell lipo -> charge/protect board -> power switch -> boost module -> ~12V to Arduino/COB LEDsHave some low side FETs driving the LEDs with ~5-10R series resistance. Adjust the boost module voltage to the point the LEDs are pulling 1W.Very simple design, commonly available parts, and cheap.

author: Zero999
author_rank: Super Contributor
timestamp: December 17, 2021, 12:53:48 pm
content: If you're taking about the law. It varies, depending on your jurisdiction.In the UK, private e-scooters are illegal to use on any public highway, cycle track, or footpath. They only place they're permitted is on private land and even then if you injure someone, or damage their property, due to an accident involving your scooter, you can be sued and face criminal charges, if you're using it in a dangerous manner.The indicators need to be amber and flash at a circuit frequency. I remember my motor cycle failing its MoT (annual road worthiness test) because I replaced the incandescent indicators with LEDs, causing them to flash at a higher frequency.I'd just use a cluster of amber 5mm LEDs, or circuit board, with loads of surface mount LEDs, inside a suitable enclosure. The flash circuit can consist of a 555 timer, micro-controller, or even a self-flashing LED driving a transistor.