Newbie direct drive question!

New to the forum, and spent a lot of hours reading it! I have had a couple of flashlights built for me by “Vesture_of_Blood”, and now I’m hooked, messing around with everything from $2 AAA lights to 6D Maglites. I also have a rather large number of Convoy S2s in various configurations, including one from RMM which was great until I blew it up! But I will rebuild…
So, my question is, what would be likely to happen if I were to build a true direct drive S2 - something like an XM-L2 U3 1A, on a copper Noctigon board, soldered onto a heavy copper heatsink, and NO DRIVER at all - and drive it with a decent IMR cell? Far too much current, instant blue smoke, venting cell?
Or just a very bright light with no modes, that gets very hot very quickly?

I have drivers on the way from RMM for a few different projects, but was just wondering what would happen if I went totally driverless on this - very bad things, or just mediocre things - and I know you are the fellas to tell me!



Hi Patrick, welcome to BLF!!

As long as the light is assembled well, particularly at the pointy end, & you bypass the springs to avoid them melting, that's exactly what you will get :)

That’s great, thanks for the answer! I don’t know what LED I am going to use yet, but just wondered if it was possible without blowing anything, assuming (as you said) that the light is put together well.
I have seen the spring bypass on the S2 that RMM put together for me, so that’s no problem - and having a mis-spent youth dabbling in electronics back before all this Surface Mount business, I can solder just fine - also Santa may deliver a hot air solder torch to complement the irons I have lying around!

Thanks again!

As long as your led is on a DTP (direct thermal pad) board, like a Noctigon, plus bypassed springs, it will be fine. Note that some nichias can’t been run straight direct drive, their forward voltage is too low so they can pull too many amps. The reason that direct drive works with cree leds is that things just happen to balance nicely, led voltage, battery voltage under load, battery amp handling.

It will work great :slight_smile: I like running many of my lights driverless, check out Driverless modes thread i did if you want to learn how to get modes from a light without a driver :wink:

That’s great, I tend to stick to Cree LEDs anyway! And thanks for the advice about altering the output without a driver - can’t get youtube at work, but I’ll be sure to watch it when I get home!

Thanks again,