LED Driver for 8.4V Battery

[rschultz101]

always looking for the perfect or alternative LED Driver .

recently built a 2 x 4XPG, with an HBFlex,
and wanted to run it of 2S batter (6cell).
unfortunately , does not work with that low a voltage.
3S+, works fine.
Want ~30Watts on Leds.
Why not use 3S or 4S ? because I don't want to build batterie packs,
and the mainstream is 2S Battery packs. and my buddy has a 2S battery,...
Do let me know, if you know a source for 3S, /4S, battery packs, nice and sealed.

for the lookout, for a BOOST, LED Driver 6V-6.4V+ input, , 2S, ~30W !?
around ~1.2A at led
any suggestions ?
thanks, Rob

[Vancbiker]

An expensive, but nice solution IMO, would be two maxflex drivers. One for each string of LEDS.

[troutie-mtb]

what about doing two 2s2p strings of leds and two Lflexs for a slightly cheaper option

[rschultz101]

thanks !
think 2x maxflex, will get me 2x 12W, at 1A,
still short, on getting to ~30W on LED's.
the Lflex is linear, at 2s2p leds, that be 2.5A at driver,
at voltage drop to 7.9V with fresh batteries, 6.2V on less, 1.7V drop X at 2.5A ,
be around ~4.25W heat, each, ~8.5W heat
as much , as I don't like linear drivers, it looks like the 2x Lflex, be better , than 2x Maxflex.
Hmmm. close to 74% efficiency on Lflex ?! like to be 85% or better.
then there are those cheap AX2002,... 1.2A step down, 4x of those, be in the 92% efficiency.
but no UI, and no temp throttle.
A new Lamphead, is one think, a whole new setup at 2.5x price, and adding a new battery system and charger, is a lot harder.
For me a home-brew Lipo setup is fine. For everybody else, paying for shipping, across the big Lake, for hazmat, is not so nice.
Any nice sealed 3S or 4S bike batteries out there ? niterider ? funky charger and cables !?
maybe trail tech, don't like the connector, no extension cables, and it's kinda heavy and square.

[Vancbiker]

Since the maxflex will go to 1.2A you would get about 15W per string of LEDS. That would make your goal of 30W for 2P4S of XPGs.

[rschultz101]

thanks !
2x maxflex it is. need to figure out how to stack it . for 2S battery

now for 2 LEDs , solder them together, and use a B3flex ?
2x 1.5A max is fine with me. any alternatives ?
Lflex be 28% loss/heat at full battery, 7.9V - 6.2 = 1.7 *1.5A = 2.55 W heat at 9W led
guess the Lflex will work too, but burn more juice.