You can have the battery and the charging system tested. Check for any lites left after vehicle is turned off, interior, under the hood, anywhere. Best time to check is in the dark. You can take battery cable loose, use testlite between cable and battery post. If the lite comes on bright, you have a drain. If the problem is on a fused circuit, you can remove/replace fuses one at a time. When you pull the fuse on the faulty circuit, the lite goes out.