There has to be another way
Well since JBing isnt supposed to happen, youll have to live with it.
is there a firmware downgrader anywhere?Restore back to standard IPSW (anything but 3.1 if you can) choose set up as new phone, then re-JB and see if battery issue comes back.
If you have 3G, you can restore to older firmware as much as you want
These things happen sometimes with JB and sometimes you have to do it over.
is there a firmware downgrader anywhere?
Hold Option and click Restore in iTunes, choose any firmware you want, and you've downgraded. Very easy.
That wont work for the 3GS however.