I am hoping for some advice/someone to point me in the right direction for a boost+buck driver that would be suitable for my DIY bike light.
I am furloughed due to Covid-19, so I have plenty free time - and would like to put together a bike light with 3 to 6 XM-L2 LEDs.
I’ve done a fair bit of reading, but I can’t for the life of me find any boost+buck drivers suitable for a big battery pack and up to 6x XM-L2 LEDs!
My goal is to output up to 6000 lumens when required, use some good optics and properly angled emitters for a very wide beam, and have the ability to step down efficiently to something that 6 18650s in a box could power for several hours on a longer ride.
The size of the driver is less important, as I can design the body around it. I plan on using a local CNC company as they are all so quiet with the coronavirus just now.
If it turns into something genuinely good, then maybe we could make it an open-source BLF special bike light!
But for now - I am totally stumped for sourcing appropriate boost+buck drivers and would love some advice.
That’s the problem, I’ve never had or used one! I’m not an electrical engineer, so while I understand the principles behind buck and boost converters, I wouldn’t know where to start for a flashlight!
If anyone has any they would recommend for the requirements detailed above, either from good experience or having designed one then that would be great.
But the form factor and user interface are not ideal for flashlight use. Also check out Lexel’s buck drivers:
Otherwise I’m not sure how I would get that powerful regulated output without doing multiple drivers in parallel. Like you could have your battery pack 1s all in parallel then run three of these drivers for 3 2s strings of XML2s: kaidomain FX 35 4A boost driver
That’s a pretty impressive and versatile driver. :+1:
I have seen taskLED drivers linked from here a few times, but I always forget about them and hardly ever see them used here. They seem powerful and versatile, but I guess the larger than average sizes of the drivers mean they can only be used for more custom hosts/builds.
This is a very interesting board. Ideally I’d like to keep it within the housing this time, but I may use this elsewhere
That explains why I struggled to find one! :person_facepalming: I know that Zebralight and other more expensive brands use Buck/Boost drivers, but only for single-emitter designs from what I can tell!
Thank you for those links - I never thought about linking drivers up to one another. Can you use the one switch for controlling them all? I guess it just pulses them all?
The HB Flex driver looks like a very good all-rounder. Boost only, but for plug in and play I think you found the most simple solution unless anyone else has a secret buck/boost driver source :laughing:
Taskled also has buck drivers that would work for you. I don’t think you need a buck/boost driver since you can choose your configuration so the input is always higher or lower than your output.
Best to use elliptical TIR lenses vs reflectors. They come in 26mm as well as the usual 20mm.
Behind each LED+lens you can stick in the drivers of your choice, 1 driver per 1 LED (great redundancy!), even 1-mode “dumb” drivers, or use “smarter” drivers to get multiple modes.
Then, you’re just running everything off of 4P or 6P or however many cells you have.
Running any cells in series requires at least a rudimentary BMS to keep from killing the cells, whether charging or (over)discharging.
Lotta bike-lights use 2S#P anyway, so if that’s the route you want to go, have at it.
yes, but there is an easier way, use protected cells, and balance charger, build about a dozen of such packs, all work fine, as long as you do not go over 4s.
5s, and 6s are pita to charge for some reason, my charger always throws voltage error with those. i have to restart charge, it happens 5 to 10 times during ballance charge, or any other charge. it charges cells eventually, but i no longer build 5s6s that way.
i also tried several drivers, works great with 1 mode, multimode, something go out of sync, it would not happen, imo, if we had master driver\slave drivers set up, but i have not tried it,
Thanks for the sound advice, it is much appreciated Lightbringer!
I had planned on using TIR lenses, and my current 3D model angles the LEDs on each side outwards slightly - main goal is to completely eliminate those blind/dark spots without having to turn the handlebars. Having those elliptical beam patterns means it shouldn’t need angled too far.
With regard to the 1 driver per 1 LED - is there a method of hooking the multi-mode drivers up to the one switch, slaving them somehow? I guess I could use multiple switches, but just adds to the complexity.
With regard to the battery pack, been looking at cheap battery boxes on Aliexpress with charge controllers built in. Looks to be a variety of configurations for different voltage setups and I can drop high quality batteries in. Worth a shot I think!
This will be an interesting hurdle - I do need multiple modes. Wondering about 1 switch per 2 drivers, allowing me to switch off pairs of LEDs entirely… i.e. the ones on the side if I just need a bit of throw or I’m on the road.
