RE: What AMP do I charge battery with?
It sounds like your battery is not taking a charge. It may just be a bad battery. They do not last forever and you don't know what kind of life it has had. Charging it hot, storing it in a hot car or crashing it can damage it.
I am not trying to insult your intelligence, but sometimes it is the simple things that cause problems. Are you leaving your car key turned to the accessory position while charging? Does your car have some kind of battery cut-off device in it (like a "Priority Start")? These things would cut power to the charger.
Also try charging it at .3 Amps and see if it fully charges like that. It will take 3-4 hours, but might get you around a false peak detection problem.
You could take the battery and plane to your local hobby shop and ask them about it. They might test the battery or drop a new one in your plane to try and diagnose the problem for you.