It seems there are degrees of 'deadness'. Putting a small charger on for an hour or two won't do any harm to either the battery or the charger and may make you feel better but it won't resurrect an 11++v battery...like Guy says.
I bought an instrument last year called a "conductance" (recriprocal of resistance) tester which, given that there is enough energy in the battery to even power up the device , will give you a very good idea of the condition of your battery and a prognosis. This is the same instrument used by most battery manufacturers to qualify warranty claims. It is much more analytical than a load test which can finish off a marginal battery by itself...but that's what you want to know anyway, isn't it? Sometimes when you go to a Jiffy-Lube oil change place and they check out things they think you should replace, they give you a little printout showing your battery condition...whether it's up to it's rated CCA capacity or not...what produces those data is a conductance tester.
howard keiper
SeaQuest
Berkeley