4s XM-L driver question

[incivil]

i plan to run four xm-ls in series from one 12v SLA, with pwm control 0-5A (theyll be run at 1A mostly). Ive read a
heap, but not what to do when the combined LED voltage drop (plus driver) equals the battery voltage, or at least
will be just above/below depending on battery charge and odd voltage drops? I dont really want to run SLAs in series, if Im going to carry two
of those things I want longer runtimes. Size or diy is not an issue but cost is however. The main thing is brightness
control, which ideally could be set between adjustable presets, remotely if possible if anyone knows of such a thing.

The leds will be on MCPCBs for now, fanned al sink smaller than half a brick, i shouldnt be asking 70w
of it for more than a few seconds at a time. And while im here i might as well ask, how can the wires on in leds be
so small for the amps?

i had another profile from a year ago when i first started to think about this light, forgot email/pass tho so start from 0 again.

thanks all.

 

[wquiles]

Remember that a 12V SLA is not really sitting at 12V, but more like 13-14 freshly after a charge, so you should consider that higher voltage as the worst case scenario. True, once you put a load the voltage will sag, but keep the higher, no-load voltage in mind.

The 4x XM-L is still close enough for a direct drive solution, so I would recommend the LFlex from www.TaskLED.com. The LFlex has various current tables (max. 3.5A) and it can handle up to 17V on the input.

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LFLEX V3.0 Linear Driver:

V3.0 released January 6, 2012, hardware current regulation (versus V1 and V2)
Linear dimming driver. Utilizes a high power FET run as a linear regulator
Maximum input voltage 17V, nominal minimum input voltage 2.7V.
Ships with UI-UNI3 firmware.
Non-volatile storage of brightness level.
Maximum drive current 3.5A (choice of 7 current tables, 500mA/1000mA/1500mA/2000mA/2500mA/3000mA/3500mA).
uController based design.
Momentary action switch controls User Interface (UI).
Draws ~50uA in sleep mode (less than 0.04 Amp.Hours per month).
STAT output. If an optional 3mm or 5mm status LED is connected, the user can configure the status LED to warn when the voltage reaches Medium (status LED lights constant) or Low (status LED flashes). With on-board 100 ohm series resistor.
Temperature monitoring of driver board. If closely coupled with the light's body, it can be user configured to force the current output to reduce. Optional trip points of 50, 60, 70, 80, 90C or off.
Protected against reverse polarity connection, output open circuit protected.
Board is 0.780" in diameter (<20mm). Maximum thickness 0.120".
****************************************************************************************************


Will