Battery Charging

I thought my battery had loads of charge left when on the display showed 11 and the dial had hardly moved. However someone on here kindly enlightened me advising it was nearly flat.  Having just purchased my safefill bottle I am trying to hold off on the purchase of solar panel for a few more pay days!! I wondered if someone could tell me what the battery charging sign on the CL actually means.  Is there just a plug where you plug in your own battery charger or are things provided. Sorry if this sounds a really stupid question but I haven't got a clue.