Take it home and plug it on a smartcharger like this
http://www.amazon.co.uk/Ring-Automot...9248118&sr=8-7
I use a similar one to maintain my car battery as I use it all the time to charge the lipos only. A smart charger will not overcharge the battery and will maintain it until you next need it. They are also great for your car if you leave it for weeks on end.