how trickle charge the battery?

Yes you can. Go to the autoparts store and buy a trickle charger. Or you can order them on Amazon, ebay etc. They have two leads that go to the battery and one that plugs into the wall. That's about it but read over the instructions to be sure. Alex

IF you're wanting to just keep the battery charged for extended periods of time - Google > battery tender. There'll be plenty of options on the resulting page.