Will it hurt the battery? If I left it overnight would I run the risk of "exploding" the battery?

I have a 7Ah SLA battery that I need to charge, but I don't have a charger and I don't want rake out $50 for a charger. Even if I did I need to charge it by the weekend, so I probably couldn't even get it in time. 

If I use a 1Amp wall wart it should take 7 hours to charge the battery. Would it be bad for me to plug the battery in for 7 hours and then unplug it when the voltage is about 13.5-14volts or so?