KD BD8P 17mm Single li-ion Buck 2.9a Driver Board

Flashlight Modding and DIY Parts
1

http://www.kaidomain.com/product/details.S024285

Is this a new board? It is in their latest release list. It has unusual good (but not perfect) specs. It is a 2.9A board, buck, but for max. 4.2V, and it is current regulated, no PWM. It has the usual solder bridge selectable mode group options, of which 5%-30%-100% would have my preference. Last mode memory that can be switched on by soldering a bridge (D), leave D open for no memory. The board has thermal protection. The spring is said to be copper.

The meh part: no reverse polarity protection, low voltage warning at 3V with switch to low but no switch-off. No modern UI with low low, the same old mode groups from 5 years ago.

2

Looks interesting though a little rough. It says, quote, Last mode memory: By soldering the bridge at "D", you toggle this setting (default off - disconnected).

It then adds this, D: Lo(5%) > Med(30%) > Hi(100%) > Strobe(10Hz) > SOS

Am I missing something?

3

I don't get buck with a 4.2 volt limit. Couldn't stay in regulation long with most emitters. Claims to be more efficient than 7135's. I didn't know bucks could get that efficient. Lots of questions on this guy.

4

+1 on the 4.2V buck thing. What is the point. However should we find out that is a typo, or a way around that so we could get at least 2 cells behind it I would be in for a pile.

Thanks for sharing djozz

5

I guess the main difference in efficiency would be on lower modes, due to both lower voltage sag and higher LED efficiency (and lower Vf) at lower currents.

6

The point is I guess, that unlike lineair drivers, the needed voltage for the led to get to the desired current is not made by burning the excess voltage but by buck conversion. This gets more interesting when the overhead voltage is higher, like with very low voltage leds, example 219C, or red emitters.

Edit: the red emitters we we use do not like 2.9A so that may not be a good choice. Perhaps a red XP-E2 triple?

7

Just curious if someone has put it thru the paces. Is it really on 4.2 volts or is that wrong?

8

Anyone measured max. current is this driver ?

9

I see modern component packages, it basically can’t be very old. The Chinese designs weren’t using so much leadless stuff even 1 year ago.

Offhand the inductor looks small.

The KD pics show at least two different driver revisions. The pics with words on may be of an earlier revision.

10

And zero reviews. 8(

11

Old thread I know, but does anyone have any experience using this driver they can share? Thinking of using it for triple xp-e2 red in a convoy s2 style light. Is that R100 the sense resistor for maybe a tad bit more current than 2.9? Thanks!