Ok let me explain what I have and what I want to do. I currently have four 3w led fixtures in my soffit, each of them has 3 smd of 1watt @3.3v. So each fixture is 9.9v and 3 watts! I use to run them from a regulated 12v ps, so I has a resistor on each fixture(all 4 fixtures run off a standed 14awg wire running into basement approximately 30' in length. ) I now have a lipo4 280ah battery pack that gets charged from solar pv panels.The battery pack I currently have set to 13.6 charge voltage, but would like to turn it to 14v. I know I can charge a maximum of 3.65 per cell for a total of 14.4v but no need to totally top. Alway I winded up burning out the fixtures so I have replacements. I'd like to have one large resistor in basement instead of the 4 in soffit. Which resistor should I use? Each fixture is a total of 3 watts and 9v-9.9v . Keep in mind that the battery voltage starts at 13.8 but can drop as low as 12.6. (My settings) so not sure what would work? Any help, very much appreciated..

 

LEDs have a range of voltage. One or two of yours might be 3.3V when conducting 303mA.
Your voltage of 3.65V x 4= 14.6V then minus 9V= 5.6V to throw away heating a resistor plus the wires.
Each soffit needs a resistance of 5.6V/303mA= 18.48 ohms at 5W (including resistance of the wires).

 

5.6V/303mA= 18.48 ohms at 5W

Probably an 18 ohm will be close enough. Even a 22 ohm.

 

LEDs run on current, not voltage. The goal is to control the current and tolerate whatever voltage drop results. Each string of 3 in series needs some form of current control that is independent of the other strings, that's what the 4 resistors did when used with the 12V supply. I suggest keeping those resistors as-is, and adding a single resistor that, with all 4 fixtures on, drops the (solar charged) battery down to 12V when the battery is at its maximum you expect/want/choose. Drop 13.6V to 12V at 1.21A using a 1.32 Ohm resistance that safely dissipates 2W. I'd consider a series string of four 0.33 Ohm 1W resistors to do the job conservatively. If you want to run the battery voltage higher add 1 or 2 more of the same value resistors in series.