My guess is you connected it wrong way round which is unsual as most leads will not reach if the battery is put in the cradle the wrong way round.
First look at the battery pillars for - and + marks. (Minus and Plus)
connect black lead to ( -) negative pillar and red lead to (+) pillar in that order.
try starting. if it doesn't , just 'clicks' 'chatters' take the battery off again {don't charge batteries in the car] and charge it for 48hrs, (Yes 48hrs) on a 'LOW' charge. Then making sure you re-connect correctly [Positive first then negative] try again. if it starts and ok. Then run it as normal but if the battery starts to show signs of going flat again get the motor round to a garage or car shop and have the system checked ie: a test put on the battery which checks both battery state and charge from the alternator. That will tell you if it's a battery fault ,or alternator fault, or in the worst senario both.
Never charge a battery in situ unless the book says you can but that's only if it's parked in a garage in the dry and with one or both lead disconnected.
You may already know this.
Disconnecting and reconnecting a battery.
Disconnect the Negative (-) black lead first
Disconnect the Postive (+) red lead last.
To re-connect:
Connect the Postive (+) Red lead first
Connect the Negative (-) last
Reason!! If you disconnect the Positive (+) first and you touch the body of the car with the spanner it will cause a flash which has been know to ignite leaking fuel.
but disconnecting the Negative first even if you touch the body with the spanner whilst undoing it, it doesn't flash. You can then disconnect the Positive lead second and it doesn't flash even if you happen to touch the body work.
to re-connect: connect the Positve lead first then the Negative lead for the same reason. Do this and you get no fash or short out, or get burnt.
bob, October 2005