All of those batteries are protected and based on a low-drain cell. They are not appropriate batteries for a FET quad. The protection should trip at higher output levels and it might be dangerous to the battery if it doesn’t.
5W vs 10W? Are you going off the current limits in the datasheets?
That’s not how this works. Those are advice from the LED manufacturer about power limits lights designed around the LED should use, and the D4 ignores them. Instead, current is determined by three things:
- The forward voltage curve of the LEDs; this is how much voltage is required at a given drive current.
- The resistance of the circuit, which adds to the LED’s forward voltage curve.
- The ability of the battery to deliver power. At high current, the voltage sags until it intersects the forward voltage curve for the complete system. This determines the drive current.
The 219C has a significantly lower forward voltage curve than either the XP-G2 or the XP-L HI. I was actually surprised that the XP-L HI is brighter at all. Based on this test, TK’s lumen reading and a rough estimate of optical losses, the 219Cs are getting over 12W at power on.