I have my FM 9 timer setup for throttle compensation mode , which works fine

with my ESC, Stuka, 2300mah 4 cell battery, 4:50 flight time, 65% power

and compensation of 15 but is drawing 81-82% of battery, I want to keep the

time and power settings , would the compensation factor of 15 , if reduced to
 
say 10 or 12 make a difference to battery usage ?

not sure if that represents 15 steps of compensation or what ?

need to find that 2% somewhere without losing power or flight time

Vincent

Vincent,
I'm not sure that the 2% over the 80% battery usage is all that significant.  If you want to reduce battery usage, I'd look at reducing the prop diameter a little or going up in pitch a little while reducing RPM a little to keep the same lap times.

It would slightly (to moderately) reduce the amount that the RPM is ramped up to compensate for battery sag - so turning it down would very slightly reduce the current draw over the latter part of the flight and the plane would (very slightly) lose some RPM over the same parts of the flight.  If you turn compensation to 0, then the battery sag MIGHT become an issue, but since your power setting is only 65%, it MIGHT not also.  It very much depends on all the external factors - prop, plane, battery size (and quality), weather, etc. - that make up your 'normal' results.  Since it doesn't look as though this constitutes actual Stunt Pattern flying (at least at a runtime of only 4:50), you could just turn the time down 10 seconds also, that would represent roughly 3% of your flight time and, presumably, 3% of your total draw.

Here's how the "Compensated Throttle" mode in the FM-9 adds throttle during the flight, based on the chosen compensation factor of 0 to 15.

(It originated with the earlier FM-1a timer, before the governed/constant-RPM mode was available, and was made available for those still using ESCs without that mode. It could be used by those who use a governed mode by switching over to the throttle mode after achieving the desired starting RPM, which will allow them to see what throttle setting gives them that starting RPM, and then choosing the compensation factor to get a real increase -- not just compensation -- later in the flight. But I don't know if anyone has tried this...)

      Compensated throttle mode: Value vs. time

Factor   30s   1m   2m   3m   4m   5m   total
0   0   0   0   0   0   0   0
1   0   0   0   0   0   1   ½%
2   1   0   0   0   0   0   ½%
3   1   0   0   0   0   1   1%
4   0   0   0   0   1   1   1%
5   0   0   0   1   1   1   1 ½%
6   0   0   1   1   1   1   2%
7   0   1   1   1   1   1   2 ½%
8   1   1   1   1   1   1   3%
9   1   1   1   1   1   2   3 ½%
10   1   1   1   1   2   2   4%
11   1   1   1   2   2   2   4 ½%
12   1   1   2   2   2   2   5%
13   1   2   2   2   2   2   5 ½%
14   1   2   2   2   2   3   6%
15   2   2   2   2   2   3   6 ½%