2 vs 3 battery operation

I note that some torches come with 3 x 18650s - with the option to take out one battery. Sounds all very good. I was wondering what this does for current/voltage at the driver board.

I ask specifically with the Trustfire TR-3T6 triple in mind, but I guess it makes no difference. With 2x18650, you will have around 3A and 7.4V at the driver, giving some 3000 lumens and some 22.2W. Anyway, let us use these figures as an example.

With 3 batteries, you have 2A at 11.1V to give 22.2W (and I presume the same lumens). Is this correct? I am presuming that the driver will regulate the current out to the emitters to give basically the same current (wattage) no matter if 2 or 3 (or 1) battery is used.

Or do you still get the same 3A, but now at 11.1V, giving the increased power of 33.3W?

In this case I think the driver is regulated - at least I think the Skyray version of this torch was. Do not know much about the Trustfire. If the unit is not regulated (ie it gives the full 33W), is this what is called a Direct Drive (DD) system?

If anyone knows - are the emitters usually in parallel or in series? I suspect in series, otherwise the driver would have to be putting out 9A, which seems a bit much.

Nobody has the light so don't know what driver's in the TF. The led's are likely in series just like the SR, and with 3 cells it might be run on DD since it's rare that cheap lights use boost+buck driver.

DD just mean the led's are hooked up directly to the cells, or no reg. Current consumed is directly dependent on what the battery can push out, in accord w/ the led's response curve (cree publishes this, but it varies by led). More voltage = more current.

I just got TR-3T6. I can’t test it yet cause it’s still daylight here. But I wonder if anyone knows the answer to the OP’s question

It’s an old thread all infos are now there, no need to further test.

The light has a real nice regulated driver, so current through the LEDs is the same but the runtime increases with 3 cells.
Stock current throu the 3 parallel LEDs is about 4-4.5A.
There is a long review thread with a lot I formations and modding tips.

OK Great! Thank you for your reply Werner