How to wire multiple 2 volt flickering LEDs to work on 12V auto system
Five LEDs in series will have a total voltage requirement of about 10V. This is closest to your supply voltage, so you would wire two such series runs in parallel. Each series run should have a current limiting resistor. The following schematic represents one "panel":







simulate this circuit &ndash; Schematic created using CircuitLab

Assuming all LEDs have a \$V_f\$ of 2V, the current-limiting resistor would drop the remaining 2V. Since you want 20 mA, the value of the resistor is easy to calculate using Ohm's law (R = E / I):

$$\frac{2}{0.02} = 100\,\Omega$$

You should determine what actual voltage drop your LEDs have, but this gets you close.

There are other things you may want to do, such as add some overvoltage protection. If you're running this from a motorcycle battery that's not also connected to, say, a motorcycle, you shouldn't have any problems. However the alternator on a motorcycle (if it's like a car) may bring the voltage up to 13.8~14.4 volts.