Z
z_matty aus
Guest
Hi,
I had seen another thread from Techjunkie about the xml-t6, but I thought it best to start a new thread rather than attempt to hijack his!
Im a machinist and wanting to make a canister dive light from scratch with cree xml-t6 450 lumen 1-mode drop-in module from DX... 8 of them! One of the problems Im having is choosing batteries. The three I have considered are NiMH, Li-ion and LiFePO4. It says on DX that the module input voltage is 2.8v-4.2v so I plan to have my battery pack voltage within that range (as opposed to higher and then employing some sort of reducing/regulating circuit) and a minimum of 20Ah.
I considered having 3 NiMH cells in series to get 3.6v, then arranging those in parallel banks with others to bring me up to the 20Ah. I thought of using F size cells for this. However I dont like having to charge the individual banks separately for reasons of convenience.
I thought about Li-ion, but the idea of having to supervise the charging of them, armed with a fire extinguisher inside a bomb shelter has put me off. My fears on this are probably a bit paranoid but the warnings which come from some of the vendors of these cells are hard to ignore!
The LiFePO4 cells sound promising; safe and able to be charged in parallel. However, and finally my questions:
These cells are at 3.2 nominal voltage, which is not far off the 2.8v minimum operating voltage of the drop-in modules I've chosen.
*What sort of brightness loss will I experience running them so close to their lower limit?
*DX says the current is regulated to 1.4amps. Is that fairly constant over the voltage range?
*How quickly does the discharge of LiFePO4 cells drop below 2.8v?
If there is anyone with experience or knowledge of this particular xml-t6, LiFePO4 cells or both together I would appreciate any comments.
cheers,
Matt
I had seen another thread from Techjunkie about the xml-t6, but I thought it best to start a new thread rather than attempt to hijack his!
Im a machinist and wanting to make a canister dive light from scratch with cree xml-t6 450 lumen 1-mode drop-in module from DX... 8 of them! One of the problems Im having is choosing batteries. The three I have considered are NiMH, Li-ion and LiFePO4. It says on DX that the module input voltage is 2.8v-4.2v so I plan to have my battery pack voltage within that range (as opposed to higher and then employing some sort of reducing/regulating circuit) and a minimum of 20Ah.
I considered having 3 NiMH cells in series to get 3.6v, then arranging those in parallel banks with others to bring me up to the 20Ah. I thought of using F size cells for this. However I dont like having to charge the individual banks separately for reasons of convenience.
I thought about Li-ion, but the idea of having to supervise the charging of them, armed with a fire extinguisher inside a bomb shelter has put me off. My fears on this are probably a bit paranoid but the warnings which come from some of the vendors of these cells are hard to ignore!
The LiFePO4 cells sound promising; safe and able to be charged in parallel. However, and finally my questions:
These cells are at 3.2 nominal voltage, which is not far off the 2.8v minimum operating voltage of the drop-in modules I've chosen.
*What sort of brightness loss will I experience running them so close to their lower limit?
*DX says the current is regulated to 1.4amps. Is that fairly constant over the voltage range?
*How quickly does the discharge of LiFePO4 cells drop below 2.8v?
If there is anyone with experience or knowledge of this particular xml-t6, LiFePO4 cells or both together I would appreciate any comments.
cheers,
Matt
