Dave Steele said it. And I understand that the OP already has the parts and wishes to use them.
But for anyone interested in this topic just for led lighting conversion (no need for battery, charging, or other dc accessories) consider the 'black box' concept of design. If you'd like to learn what's in the black box by all means, learn it. But this is a situation where it's not all that necessary.
Most black boxes we use well enough without knowing how they function. I don't want to learn how to convert my existing bathroom receptacles into ground fault versions. I'm happy to let the engineers do that part for me and will just go down to home depot and buy the 'black box' version of ground fault receptacles. All that engineering has been done for me. Now it's just power in - power out.
Similarly I've been using two of these as headlights on my Puch maxi...
...straight off the AC from the old 1978 E50 lighting coil. No mods. All the rectification and regulation is on a postage stamp sized circuit board right inside the bulb. I get 1240 lumens of 3000k light with a 35 degree spread. In four years of riding not a single hiccup. Slight dimming at idle. Full light beyond that.
I wish they'd burn out so I'd have a good excuse to drop 35 dollars on a pair with 1320 lumens at 4000k and a narrower 25 degree spread.
https://www.bulbs.com/product/8-5MR16-LED-840-F25-DIM-12V
I'll only vouch for Philips at this point. I tried a Feit mr16 at one point cuz it was a 4000k and cheaply on sale. Worked just fine except for a slightly annoying flicker. So between brands YMMV. (edited)