I don’t have an extender, I have an insert and a different spring so that I can run 4 c cells in the 3d configuration. I’ve tried 3 d cells alkaline, 4 c cell alkaline and 4 c Nimh cells. That’s the brightest configuration I can do with mine as I don’t have an extender. 4D tenergy Nimh cells would give a lot more runtime and a longer burst of Max lumens in the turbo mode and the 4 c Nimh cells.
As for brighter ? That’s news to me, but possible.
Are you using good Nimh batteries in both tests?
im using the blue tenergy nimh’s for both the C and D cells.
at the time, the blue one’s outperformed the white one’s from several testings. the white ones had just came out, maybe 4 months prior.
now, they are saying the white ones are better.
darn it.
Runtime is determined by current draw. Simply put, for batteries in series, regardless of the actual number of cells, higher current draw means shorter runtime. I myself have measured 1.8 amps with three cells and 2.7 amps with four cells. So I would expect to get 50% greater runtime with three vs four cells.
I think the source of confusion here lies with the driver. Lots of lights that can accept varying numbers of cells in series have a buck/boost or buck regulator. This brings the voltage to a specific level, regardless of the number of cells. So with more cells, current draw goes DOWN. However, it would appear that the Malkoff drop-in probably uses a direct drive. So current draw goes UP with more cells. I’m guessing that Malkoff probably figured an elaborate regulator was unnecessary for a drop-in that is intended to be run by NiMH batteries (since NiMH batteries alrady have a well regulated output compared to alkalines or ICR).
As for running 4D vs 4C, 4D will DEFINITELY give you more runtime. For a given brand and type of battery (ie LSD vs HSD), you will generally get around TWICE the mAH rating from a D cell vs a C cell. This means twice the runtime.