RE: Battery is dead.....help!
The battery tender is a float charger, once the battery is fully charged it will go into float mode. The battery tenders and battery minder type of chargers should not be used to charge up a very discharged battery. You should put a charge in them with a bigger charger first, one using 2-10 amps.
Then go with the tender to maintain the battery. The circuts in the float chargers can overheat and ruin it if it overheats. I use to repair those things, they are only meant to maintain batteries, and it states that in the instructions. Thats why they will not activate with low battery voltage, they do not want people using them on big automotive type batteries that are too discharged.