Is it possible to use one battery pack as this one (LINK) to power one RGB LED stripe (12v) + 1 raspberry pi (via a voltage regulator like this) + 1 micro servo SG90 (THIS) ??
What would be the perfect diagram? LED straight to the battery, then step down circuit then servo and rpi in parallel? Would I need two step down circuits to ensure that peak consumption in the servo does not reboot my raspi?
Will the battery be able to provide enough mAh for the three things ?
My 12V LED strips use about 6W per meter, and the Pi will use about 2.1-3W depending onload. So expect a 9W load. It's certainly possible, but it will be more reliable with a 47uF decoupling capacitor on the input of your buck converter. Since you drive the LEDs from 3V3 transistor control (I presume), make sure the gate/base is saturated completely, or they will get too hot.
The IRLZ44N HEXFET may be a good choice. Make sure you have overdischarge protection on the battery - it can be done with a single 10V zener, or (better), a 10V zener and a NPN/PNP pair to prevent leakage when not sensing voltage. http://www.bristolwatch.com has plenty of useful schematics.
IIRC the SG90 used ~4.5V - you could get by with 4.3V I'm sure. Use the 5V rail on your Pi through a diode, and use a 2N7000 MOSFET to drive it. A catch diode may be necessary.
This "6.8Ah" battery pack can readily supply much more than the ~12-13W your hardware needs.
Input voltage: 12.6V DC
Output voltage: 12.6-10.8V DC
If the LED strips use simple resistors instead of current regulators, the battery voltage might be a bit low when partially discharged to fully light the LEDs. I suggest you wire your LED strips to a bench supply set to 10.8VDC to check if you still have enough light.
