Is it okay to connect up a battery charger and leave it overnight to charge?

The instructions advise to take the battery off the car. Is it unsafe to leave it all connected up?

I would like to fully charge it as it's not getting much use at the moment.

many thanks

 

I have one that I can leave connected for up to a month on trickle, If you remove it you might upset the radio codes and alarm etc. Once the indicator charge level has dropped and maintained a level you might as well disconnect it and put it on a week later. It will be OK overnight as batterys can take a while to reach full charge.

 

Thanks..

I suspected it would be okay, just wondered why the manufacturer (Halfords one) suggested removing it...

Was planning on just using it to top it up once a month or something overnight.