trouble with charging

[jetab]

hi, my tablet does not work without charging. charge level is - 27%. for update rom i need 30%

battery condition: good
version android 4.0.3(release5a).
kernel 2.6.39.4

can someone help me?
problem like this http://forum.xda-developers.com/showthread.php?t=2524935

 

[jetab]

battery fully charged. measured voltage using a multimeter shows 3.52v.
but the it still shows 27%, and not working with out charging
antutu tester shows 27% - 3.8 v