Rebuilt DiveRite MR11 LED500 Questions

Morning i recently changed the head of my Dive Rite LED500 to a sumpdonkey3 however i have since hit a problem.
During a recent cave dive the battery cannister opened up causing a flood of the unit and the head.

Sump donkey kits for the MR11 head are no longer available, so have had to revert to going to cutter electronics however not getting any replies from them so need to ask a few question here.

Firstly what is the difference between a buck and booster kit? I am guessing it has something to to with voltage levels of the battery but am unsure. as in between the Cutter electronics Cutter XPL-MR11 Kit Boost or Cutter XPL MR11 Kit Buck kits
Secondly as the battery is now Fried looking at replacing it with something more powerful and better duration. Currently has 10 x HR-4/3 FAU batteries in a 4500mah 12V Pack 140mm x 49mm Round pack.
So wish to reply it with a premade pack like this one from Batteries space.

Any Assistance on this would be greatful.
Paul

The difference between buck and boost is buck drivers can only reduce the battery voltage, while boost drivers can only increase it.

That means that if you have an LED array with Vf of 11V, and a buck driver, your battery voltage must be higher than 11V.

Conversely, if you have the same LED array and a boost driver, your battery voltage must be lower than 11V.

Also, keep in mind that buck drivers have a 'dropout' voltage. That means that the battery actually has to be higher than the LED voltage plus the dropout voltage. In some drivers, the dropout voltage is a small fraction of a volt, but in many it's a volt or more.

Thanks for the reply DIWDiver,
Sorry i am a newbie at building own lights, So if i would need the Buck kit with a 14.8V Battery 6800mah. If i was using a 11.1v Battery would be a booster? how do i figure out what the Vf to guess which one i need?

Hi,

A Cree XML U2 led has a typical forward voltage of 3.3V at low current and 3.7V at full current (3A). Sum up the forward voltages of your led array and see if it is below or above your battery pack. The driver will "eat" a few hundred millivolts.