See my signature for WA re-rating.

For bulbs from other manufacturers you can use the following formulas for re-rating:

The formula for halogen lumens re-rating is as follows:

Lr = (Va/Vd)^3.5*Ld, where Lr is re-rated lumens, and Ld is design lumens, and Vd is design voltage and Va is applied voltage.

The formula for halogen lamp life re-rating is as follows:

Lr = (Vd/Va)^12*Ld, where Lr is re-rated life, and Ld is design life, and Vd is design voltage and Va is applied voltage.

The formula for halogen current re-rating is as follows:

Ar = (Va/Vd)^0.55*Ad, where Ar is re-rated current, and Ad is design current, and Vd is design voltage and Va is applied voltage.

The formula for halogen CCT re-rating is as follows:

CCTr = (Va/Vd)^0.317*CCTd, where CCTr is re-rated CCT, and CCTd is design CCT, and Vd is design voltage and Va is applied voltage.

To find voltage sag:

Va = (Aa/Ad)^1.818*Vd, where Aa is applied current, and Ad is design current, and Vd is design voltage and Va is applied voltage.

To find applied voltage from lamp life:

Va = Vd/((Lr/Ld)^(1/12)), where Lr is re-rated life, and Ld is design life, and Vd is design voltage and Va is applied voltage.

To find applied voltage from lumens:

Va = (Lr/Ld)^(1/3.5)*Vd, where Lr is re-rated lumens, and Ld is design lumens, and Vd is design voltage and Va is applied voltage.

I'll let JS chime in on how they arrived at 65% for the torch lumens.

Sigbjoern