Help! Slow Battery Discharge

gonna see if I can locate issue- but would this work in the meantime? $24 shipped from Amazon
See there are alot of options pricewise... dont need overkill. May get one for my boat as well.

[ame="http://www.amazon.com/Battery-Tender-021-0123-Junior-Charger/dp/B000CITK8S/ref=sr_1_1?ie=UTF8&qid=1354986304&sr=8-1&keywords=battery+tender"]Amazon.com: Battery Tender 021-0123 Battery Tender Junior 12V Battery Charger: Automotive[/ame]