Woodfarmer
Some chargers do draw a current from the batterty if there not pluged in.
There is some charge in that battery, but is it getting the amprage load to the starter?
Charge it and find out!
Just a simple test, that dosant tell you everything, but gives you a place to start,,,,,,,
If you turn the lights on and look for a spot on the wall or were ever there shinning, (sometimes hard to see in bright daylight) note the color of the light, a very good, charged battery will cast a near white light. A half dead battery will cast a some-what yellow light and a close to dead battery will berly cast an amber glow.
If you can see the color of the lights, hit the starter just to see if there is a change,,,,, note: this test didnt cost you anything, so dont expect much,,, but if the lights stay bright, but the starter just grunted, there is a chance that the connections in or too the starter are weak.
Chances are that the lights will all but go away when the starter trys, and come back a little dimmer after the attemt, telling you that the battery needs help.