Run-Time Plot - DownBoy 400

This runtime plot is for a DownBoy converter mounted in a PM-6 with a R2H LS. Plots were done for three configurations, 6v, 9v with one SF A19, and 12v with two SF A19s


Equipment used is a photocell and a Radio Shack 22-805 multimeter with a PC interface that is using ScopeView software (V1.08)

The vertical axis is in mA and the horizontal axis is in time...30 min per division fo the 6v and 9v plots, and one hour per division for the 12v plot.

Be aware that yhour actual battery milage may vary from that indicated by this runtime plot.

PM6 with DownBoy 400 at 6V
Time to end of regulation = 4 hr 33 min
Runtime to 50% of starting brightness = 4 hr 58 min



PM6 with DownBoy 400 at 9v
Time to the end of regulation = 7hr 41 min
Runtime to 50% of starting brightness = 7 hr 52 min



PM6 with a DownBoy 400 at 12v
Time to end of regulation = 10 hr 48 min
Runtime to 50% of starting brightness = 10 hr 58 min

Roy,

Thanks for doing this! So,

2 cells = 4.5 hrs or 2.25 hrs/cell

3 cells = 7.6 hrs or 2.5 hrs/cell or an additional 3.1 hr from the third cell being added

4 cells = 11 hrs or 2.75 hrs/cell or an additional 3.4 hr from the additional 4th cell being added

Running 2 sets of 2x123 cells would give you 9 hours of regulated run time but having all 4 batteries in play gives you 11 hours of regulated run time; a gain of 30%! Wow!

I assume this gain in run time is a result of two factors; a possible increase of efficiency in the converter at higher Vin as well as an increase in the ability of the cell to provide the power for regulation at the lower level demanded (per cell)

Certainly for walkabout, extending the cell count seems to have its rewards.

EDIT: the Vf of this test R2H is 3.21 V With further review of the curve after regulation stops, it appears that with the increase in cell string, more of the cell's total capacity is consumed in the regulation mode with less available beyond regulation. If 5 cells had been tested, I would assume that the light would run even longer in regulation and just plain die at the end. /ubbthreads/images/graemlins/grin.gif

- Don

DB700 to follow as soon as the re-supply of 123's gets here! /ubbthreads/images/graemlins/grinser2.gif

Fascinating stuff, indeed. And great observation about the steepness of the regulation drop-off, Don. Makes complete sense (after somebody else points it out). The more runtime you get by adding cells, the less moon you're likely to see.

Darell,

You want moon? I show you moon! /ubbthreads/images/graemlins/grin.gif

EDIT: this post is not to be construed as "Fluff"; rather a slightly veiled threat and the veil shall fall!!

Please notice that the horizontal axis is one hour per division for the 12v plot, whereas the horizontal scale is 30 minutes per division for the other plots. The vertical rise and fall of the 12v plot will appear steaper because of the scale differences.

Well I just realised that I have made duplicate postings! /ubbthreads/images/graemlins/blush.gif

I'm going to close this posting. Any comments should be made to the "Run-Time Plot - DownBoy400 and 700 Converters .