I know with volume you can only have like 7(IIRC) levels and if you use more it doesn't work. The same for battery perhaps? Like maybe only 4/5 levels?...
Actually, Volume is 11, as in "But ours goes up to..." (Actually, it's 0-10 but I love that quote). Battery is 5 (0-4).
Looking though the Wiki just now, I noticed that the text doesn't actually say that, which is odd. Either it changed very recently or I just haven't looked at it... Ever.
My battery on my currenty WPS is:
"Check if it's charging. If so, display the charging graphic of "m", otherwise, show graphics "n" "o" "p" "q" or "r" which are the 5 normal battery icon grapics"
BigMac, all I can suggest to you is try putting it on its own line. It doesn't "have" to be, but maybe there is some weird interaction. Make your WPS code look something more like:
%ac%bt - %cH:Mc
And put all your image precaching at the top, but all your image displaying at the bottom. It makes the WPS far easier to read than having stuff all over the place.