phone switching off unexpectantly

[sallypw]

  I'm starting to hate my  G1 google phone, problem  I've found with it is that  it
Keeps switching itself off even when the battery is still charged  up. When I switch the phone
back on it say: running low on battery connect the charger. Seriously I  actually  thaught  I charged up the phone long enough,  I'm using a pay as you go
G1. Internet needs updating.