Really easy to set Powa up for this purpose. This is the set I use, you can just install the addon and "Export Set" - copy/paste. Then you can play around with the position/size and animation settings.
Code:
Set=Page 3@
Aura[49]=Version:4.22; b:0; g:0; thresholdinvert:true; icon:spell_holy_lightsgrace; r:0; begin:3; x:-32; bufftype:10; texture:72; PowerType:9; threshold:1; size:0.15; y:-202; texmode:2; finish:3@
Aura[50]=Version:4.22; b:0; g:0; thresholdinvert:true; icon:spell_holy_lightsgrace; r:0; begin:3; bufftype:10; texture:72; PowerType:9; threshold:1; size:0.15; y:-202; texmode:2; finish:3@
Aura[51]=Version:4.22; b:0; g:0; thresholdinvert:true; icon:spell_holy_lightsgrace; r:0; begin:3; x:31; bufftype:10; texture:72; PowerType:9; threshold:1; size:0.15; y:-202; texmode:2; finish:3@
Aura[52]=Version:4.22; thresholdinvert:true; icon:spell_holy_lightsgrace; begin:3; x:-32; bufftype:10; texture:73; PowerType:9; threshold:1; size:0.15; y:-202; texmode:1; finish:3@
Aura[53]=Version:4.22; thresholdinvert:true; icon:spell_holy_lightsgrace; begin:3; bufftype:10; texture:73; PowerType:9; threshold:1; size:0.15; y:-202; texmode:1; finish:3@
Aura[54]=Version:4.22; thresholdinvert:true; icon:spell_holy_lightsgrace; begin:3; x:31; bufftype:10; texture:73; PowerType:9; threshold:1; size:0.15; y:-202; texmode:1; finish:3@
Aura[55]=Version:4.22; b:0.498; g:0.9255; thresholdinvert:true; icon:spell_holy_lightsgrace; begin:2; x:-32; bufftype:10; texture:72; PowerType:9; threshold:1; size:0.12; y:-202; texmode:1; finish:2@
Aura[56]=Version:4.22; b:0.5059; g:0.9373; thresholdinvert:true; icon:spell_holy_lightsgrace; begin:2; bufftype:10; texture:72; PowerType:9; threshold:2; size:0.12; y:-202; texmode:1; finish:2@
Aura[57]=Version:4.22; b:0.7255; anim1:4; g:0.9255; thresholdinvert:true; icon:spell_holy_lightsgrace; begin:2; x:31; bufftype:10; texture:72; alpha:1; PowerType:9; threshold:3; size:0.12; y:-202; texmode:1; finish:2@
(As with most of my Powa warnings they have multiple layers - like a dark backdrop, etc - to make them easier to see in an environment of any colour. Hence it's 9 warnings for the 3 charges (3x3). If you wish do go minimal you can copy only the second three or the last three (probably not the first three as those are the dark, semi-transparent backdrops).