There's always a slight drain on the battery for vehicle electronics. IMO the battery should not be dead in a week. Either your battery is failing or it's not getting a full charge. In addition, if you're running your vehicle for 5 minutes to charge the battery, that's not enough running time. IMO you need to run the vehicle until it's up to normal operating temperature & even that may not be enough to bring the battery back up to full charge. 
If you're considering a battery charger, I'd recommend this one. The price is reasonable & it has 3 LED indicators that let you know what it's doing. I actually have one mounted permanently in each of my vehicles. :wink:
Bobby...
My MODding Journal
If you're considering a battery charger, I'd recommend this one. The price is reasonable & it has 3 LED indicators that let you know what it's doing. I actually have one mounted permanently in each of my vehicles. :wink:
Bobby...
My MODding Journal