question on single cell lights

i was looking up what kind of cell would power the seoul p7, and what i found out was that i don't think my current flashlight even has a beefy enough battery to fully power it.

i currently have a flashlight that uses a cree xre q5 and its powered by a single panasonic cr123a; going over the specifications, the the xre needs around 3.7V to drive the led to 1000ma whereas the cr123a only can only produce about 2.8V underload which equates to around 100ma of current on the cree xre data graph.

i have no idea how the built in circut for my flashlight works, since i'm still a little new to this but i don't think there are any built in chips that can raise voltage, so here are my questions
1. is there somthing i'm missing?
2. if not then is there a way to fully power the cree xre q5 with a single cylindral cell? (all the 3.7-3.6v batteries i found only produced about 3.4V under large load)


again sorry if i'm missing somthing here, its just that i may need to build a small seoul p7 flashlight if within the next few months and some of the information i'm gathering isn't adding up

This is what you are missing.

would you be able to source me a site that that has these premade aswell?

srry, i new i must have been missing somthing :laughing:

You should find this thread useful.

jzmtl said:

You should find this thread useful.

Click to expand...

thx jzmtl, your the man :twothumbs

There are 4 ways currently used to power the P7. Direct drive off a single Li-Ion of 18650 size or larger, direct drive off 3 NiMH cells (preferably C or D sized), with this circuit, or with this circuit setup (both with 4 NiMH or 1 Li-Ion).

A common source for circuits is here.

Marduke said:

There are 4 ways currently used to power the P7. Direct drive off a single Li-Ion of 18650 size or larger, direct drive off 3 NiMH cells (preferably C or D sized), with this circuit, or with this circuit setup (both with 4 NiMH or 1 Li-Ion).

A common source for circuits is here.

Click to expand...

wow, thanks for all the info guys, all the info is comming togeather much quicker then expected. i was thinking of useing one of the a123 batteries but hadn't decided yet. this is more info than i expected or could ask for. thank you so much for the help

I don think a single cr123a could handle the current draw from one of the new p7s. It even seems like a close call for a 18650.

srry, i ment the A123 Systems LiFePO4 battery a.k.a. the A123 cell, i found the datasheets leaked somwhere. the smaller cylinderal battery measures 18x60mm 3.6V 1.1Ah and can push out a harsh 30A contionous.

it's A123's 2.3Ah version that GM is looking to use for their e-flex system used on the chevy volt and the cadilac provoq, just a little food for thought.

anyways runtime would be low but it pushes the point i wanted to make about new techologies available in the lighting and electical storage sectors

ive read that the ssc P7 runs at max brightness at 2.8A at 3.7V right? and one 18650 cant handle 2.8A current draw can it? or can it? anyone know what or where i can find the max current draw is for all the lithium cells eg. 16340,14500,17670,17500...so 2x 17670/18650 or maybe even 17500 should be able to run it at 700 lumens? would that be right? although i guess u'd need alota heatsinking

Yapo said:

ive read that the ssc P7 runs at max brightness at 2.8A at 3.7V right? and one 18650 cant handle 2.8A current draw can it? or can it? anyone know what or where i can find the max current draw is for all the lithium cells eg. 16340,14500,17670,17500...so 2x 17670/18650 or maybe even 17500 should be able to run it at 700 lumens? would that be right? although i guess u'd need alota heatsinking

Click to expand...

from what i found, other then the smaller of the two a123 cells, the next smallest cell that could handle the currents was the 18650, most datasheets list their max contionous current between 3.8A and 4.8A. you'll need at least 3.3A continous for 3.6V batteries.

wait, srry, somone somone made a LiFePO4 chemistry battery the same size as a cr123a, but the runtime would only be like 10min on high

The P7 is rated to 2.8amp(?) at around 3.7v.

The voltage to the LED varies with each individual LED, so you can have a LED that needs 4v at a 350 mA draw while another might only need 3v.

The driver can lower, raise the voltage from the battery and draw the right amount of current to power the LED correctly(they have multiple components). Some also have different modes programmed into them (low, high strobe etc.).

Li-ion batteries are usually 4.2v fully charged.

You might be able to wire a few boost circuits in parallel to driver the P7 or use 2 A123s and use buck circuits wired in parallel. keep in mind that some circuits don't work in parallel.

The A123 might also work with the P7 in direct drive.

the larger of the two wouldn't be too bad, has a 3A load voltage of about 3.3V, but the smaller one drops to about 3.1V at the same load. either way, you don't but a 900 lumin led and power it enought to "get by"

Something like this could work, except with 2 A123 batteries. But that would make the light bigger.

18650 run from 1.8 AH to 2.2 AH. At a max of 2C draw your amps is 3.6 A to 4.4 A. So it will work.

Actually you can order a smallish P7 light now.
https://www.candlepowerforums.com/threads/194340
Or a big one.
http://www.cpfmarketplace.com/mp/showthread.php?t=177152

Hint:
DX sales page says "New stock has arrived" but my order tracking says "Waiting for supplier".