my attempt at replacing BT200x headlight with LEDs

[Kelly1005]

Hey everyone, new to the forum and minibikes in general. I've got a trip coming up this summer where I'll need to get from a OHV trailhead up a mountain and back down again, about 20 miles, and with the limitations on what my vehicle can carry (no towing, low hitch capacity with an aftermarket hitch) I've decided to use a Coleman BT200x as my ride. It's nutty, but if it fails, worst case I'm walking back to the trailhead? Anyway, we know it won't fail!

I've figured out how to carry more fuel, tools, etc and now I'm working on replacing the seemingly useless OEM headlight with something brighter.

Based on what I think I've found, I'm working with ~36 watts, and AC voltages from 9-14?

I couldn't figure out the rectifier stuff, like which one could be adapted to run lights without a battery in the circuit, but I did find these and have had good luck with stuff like this in the past on other projects:

https://www.amazon.com/gp/product/B08B3T9DX4

At 12v and under 2A I don't have enough wattage to run a big LED headlight, so I got these:

https://www.amazon.com/gp/product/B00IY3YLCI

Each one is only 18W, and with the 2 pack of converters I figure I just run one light off each converter, total draw off the engine should be 36 watts. Seems like it would work.

I temporarily wired one converter into the headlight plug, got the output voltage set and attached one of the LEDs. At idle, they do flicker a little. At ~2100 RPM (per the tach I've added) they stabilize and at more than that the bike starts moving and my wiring falls off since everything was just laying on the ground. Fortunately no one was around to see that.

I need to come up with a way to mount the lights and protect those super fragile converters. Or, if someone has a wiring diagram using one of those 'cheap ebay rectifiers' that are more solid and can be used without a battery, I'm open to that.

Maybe an aluminum project box, remount those heat syncs right to the box and turn it into one giant heat sync then fill the thing with epoxy?

 

[Kelly1005]

First attempt at mounting up the lights. Just sorta eyeballed the cuts and holes, don't have any equipment beyond a dremel, drill and a round file. It gets me the general idea, now I can 'oval' out the holes so I can aim the lights, and then cut new brackets with the holes in the right spots.

 

[Kelly1005]

The bracket is done. I made it a little taller so that the 2nd light clears the first with it's beam. I've got it painted but only had flat black, hoping to find some gloss black before final assembly.

I got a project box to house the electronics and soldered up the wiring harness, but ordered the wrong size PCB stand-offs so I can't mount anything in the box just yet. Amazon to the rescue, the correct parts should be here Friday and I can get it finished up this weekend.

Watched a few more videos on headlights, and now I see why people just mount a battery and call it good. Maybe when this dies I'll go the 'smart' route.

Rear bolt on the lower light goes in the bottom hole of the OEM mount, and that empty hole in the middle of the bracket gest bolted to the top hole in the OEM mount. It's got a little adjustability in it, but it's pretty close as is.

 

[Tom S.]

Very nice.

 

[Kelly1005]

Wiring done, got it mounted up today and it seems to work. Still getting flicker at lower RPMs, kinda bummed about that but we'll see how it works tonight if the rain is done and I can get it out in the dark.

Forgot to take a picture of the headlight switch, it's basically the same model as the kill switch, just labeled differently.

 

[Kelly1005]

Very nice.

Thanks. My first attempt at something like this and I'm hoping my documentation helps someone in the future.

 

[ole4]

FYI instead of those regulator boards for the same dough you could get a pitbike 4 wire regulator rectifier that would be able to power a lot more and is simple to mount. AC in DC out.
12V FULL WAVE 4 PINS VOLTAGE REGULATOR RECTIFIER FOR DIRT PIT BIKE SCOOTER ATV | eBay

 

[Kelly1005]

FYI instead of those regulator boards for the same dough you could get a pitbike 4 wire regulator rectifier that would be able to power a lot more and is simple to mount. AC in DC out.
12V FULL WAVE 4 PINS VOLTAGE REGULATOR RECTIFIER FOR DIRT PIT BIKE SCOOTER ATV | eBay

That's what I really wanted, I figured one of those would do what I wanted but I wasn't sure which one would work given the weak voltages coming out of the stock engine setup. None of these say they'll deal with 8v AC which is the low end of what I saw coming out on my bike.

 

[Kelly1005]

Quick test ride tonight. It's pitch black out and these are producing enough light to actually ride around, even off road a bit.

 

[SCooke123]

looks like it lights up the trail really well.

 

[Kelly1005]

FYI instead of those regulator boards for the same dough you could get a pitbike 4 wire regulator rectifier that would be able to power a lot more and is simple to mount. AC in DC out.
12V FULL WAVE 4 PINS VOLTAGE REGULATOR RECTIFIER FOR DIRT PIT BIKE SCOOTER ATV | eBay

I ordered one. Not that one since it's unavailable basically but a similar one. It's cheap enough to try, and maybe it works and I get to simplify all that wiring. Or it doesn't work, and then I know for sure.

 

[ole4]

here is one on one of my speedways.

 

[Kelly1005]

FYI instead of those regulator boards for the same dough you could get a pitbike 4 wire regulator rectifier that would be able to power a lot more and is simple to mount. AC in DC out.
12V FULL WAVE 4 PINS VOLTAGE REGULATOR RECTIFIER FOR DIRT PIT BIKE SCOOTER ATV | eBay

Wired it up today. The old setup was using spade connectors so it was easy to wire up the pigtail that came with the rectifier and plug it into most of the existing harness. It's kicking out 14v at 2600 and the lights fired right up. They flicker more than they did with the original setup, but we'll see what it looks like when it gets dark. if it's good enough... it's way better to have that solid aluminum rectifier setup vs. what I had.

Whole lotta wire loom at the moment, may have to simplify that if I stay with that setup.

 

[ole4]

Add a 2000 mfd cap across the dc making sure to match polarity of the electrolytic cap. that should reduce or eliminate the flicker.

 

[Kelly1005]

Add a 2000 mfd cap across the dc making sure to match polarity of the electrolytic cap. that should reduce or eliminate the flicker.

i've got enough smaller caps in the little kit I have for arduino projects that I could make a parallel setup to get me to 2000 mfd.

That said, I noticed that when testing the rectifier it retained voltage for a long while (according to just the meter) after the engine was off, and when I connected the lights to with it still showing voltage they lit up for a brief second. Makes me think there is a capacitor inside the rectifier already, so is it as good as it's going to get or will the extras outside help even more?

 

[ole4]

They do have small caps but on mine I have the 2000uf cap and my lights do not flicker but I have no idea if it does anything or not. I originally used a full wave bridge and the black box with fuse and 2000uf cap @ 40 volts. After a test ride I noticed the low beam was out so I switched to high beam and after a few more blocks no lights. Blew both bulbs then replaced bridge rectifier with the regulator rectifier not more problems. Here is the original setup that blew the bulbs cause of no regulation. I had used this exact setup with no issues before but depending on the led bulb some do not like high voltages. The black box has the cap and fuse.