LED Power vs current and voltage
LEDs have no internal current regulation &amp; require a series resistor to keep them from overcurrent that can cause them to melt/explode/die horribly.

Also, the listed "voltage" of an LED is the "knee" voltage of the diode...more of a "no light comes out below this voltage" than an ideal operating point.

Try running a series of 3 LEDs, with a 7.5ohm series resistor to see if you get the LEDs to react closer to "datasheet specs."

Something like this:







simulate this circuit &ndash; Schematic created using CircuitLab

NOTE: After testing it with a 7.5ohm resistor, you can check the current flowing through each strand, then use more/less resistance to get closer to your "goal" 700mA.