[ GXB172 - 50W Single Cell 17mm Boost Driver! ]

[moderator007]

@Texas_Ace

@moderator007

I went back and read through this thread. Looked on loneoceans site. Read the dataSheet for the ic. Well looks like the driver can only be used with a led at or above 6 volts vf or series leds. I had thought this would run a single led (such as a xpl) at a constant current through the entire run time until a single cell was depleted.I know see that the led must have a vf of 6v or more to work. So while there is interest still there for this driver, it is limited from its output voltage.
Loneoceans have you tried to see how low the output voltage can actually go.

A boost driver can only increase voltage above that of the input voltage. So if you input 4V, then then lowest it can possibly go is 4V.

A buck driver would be needed for an XP-L, although it would fall out of regulation fairly quickly with only one cell.

So what is actually needed is a more advanced buck/boost driver. These are hard to come by and would be very challenging to fit on a driver this size.

A 30q cell can only do 4v for seconds at 5 amp load. At 4v a xpl v6 would see 5 amps, nothing crazy. So if a boost driver was set at 5 amps output it would run direct drive for maybe a few minute and hit the vf of the xpl at 5 amps and then switch to boost through almost the entire discharge, at least theoretically speaking.A xpl v6 needs 3.8v to run at 5 amps according to djozz’s graph. Cree XP-L V6 2C led, tested against XM-L2 T6 3C, edit23/7: I repeated the test and measured a dedomed XP-L
Fet and amc7135 drivers would fall out of regulation about 1/3 the way through at this current and reduce current as the battery voltage decreases. Probably to much for a xpl2, but a xpl or xml should be fine.