What to use to keep battery charged while sitting?

Have you had the battery checked and serviced? It should hold a good charge if it is sitting for two weeks. I have solar and i have only used it when I put the battery in after winter. I turn the solar on and do some cleaning until it has a good charge. The battery should get charged from towing as well. Be careful with solar though, I have seen some people overcharge the battery cause its easy to forget that you are charging it that way.