I'm using Sony VTC5A.
The fit is perfect.
But the reason is that these lights pull around 20 amps, which heats up a battery beyond my comfort level. The VTC5A will deliver the amps and take the heat.
As above, high drain is what you need for the D4. Along with the sony vtc5a, the vtc6, vtc5 and samsung 30Q will also work fine.
Would not use the Pany A, not a good cell for this light. If need to use it, limit the output to under 500lm ish(just a little past the 140lm when you get the blink). Also locking out then tightening tail cap gives you around the 140lm level. Using higher outputs could damage this type of cell pretty quick!