The FM/FR series is an industry standard capacitor in FPV multirotors. They are some of the lowest ESR options on the market for the given size and do a good job managing electrical noise when used correctly. (FR series preferred for higher powered systems)
If you have random jitters, ticks or a shaky/fluttering quad on throttle or sharp movements, you may have electrical noise in the system and you can try applying a capacitor to see if it will help. Using a capacitor by default is good practice and will improve the overall reliability of most crafts.
To use any capacitor correctly, solder no smaller than 18awg wires as close to the base of the capacitor as possible and connect them to the batt in pads on the ESC/AIO board with no more than 1.3” or ~35mm length of the 18awg wire. Thicker wire doesn’t help much to give you a longer distance from the battery in pads. Ideally less than 30mm is preferred. We strongly recommend the use of a Cap Cap to improve ease of use.
The correct size depends on your drivetrain and voltage. Generally, 25v is used for 2S-4S and 35v is used for 6S. No quad in the 2”-6” range should need more than 1000uf of capacitance. If it does need more, your ESC is not a good match for the motor/prop combo. The lower power the quad is, the less capacitance you can get away with.
35v 1000uf FM Series w/cap cap and wire
Cap Cap V3 with 38mm 18awg wire pre-soldered
This is the maximum length of wire that is recommended
5.1g with all wire
25mm long (Cap Cap included), 12.5mm diameter
25v 1000uf FM Series w/cap cap and wire
Cap Cap V3 with 38mm 18awg wire pre-soldered
This is the maximum length of wire that is recommended
3.9g with all wire
25mm long (Cap Cap included), 12.5mm diameter
25v 1000uf - FR Series
3.6g
21mm long, 13mm diameter
25v 330uf - FR Series
1.3g
13mm long, 10mm diameter
35v 330uf - FR Series
1.7g
22mm long, 8mm diameter
25v 1000uf - FR Series
3.6g
21mm long, 13mm diameter
35v 1000uf - FM Series
3.7g
21mm long, 12.5mm diameter