ORIGINAL: laryboy
a 45 w 12v power supply is totaly different than a 12 volt wall wart. the wall wart he is using is similar to what tower hobbies recomends for it 12 volt 7amp supply. he probably has a bad battery.
That's right. The wall wart for charging the 7 AH battery is a fairly constant current source, maybe with a bit of taper to it. Starting out higher but then tappering off to 500 mA, which can be left on a 7 AH battery for some time with little negative impact, these gel cell batteries can tolerate some overcharge if it is not too high a rate. If the battery voltage is reading 12.6 then the charger should be putting out about 500 mA (as it is rated at). It should not get hot if the charger is any good. The only way you can really tell is to actually measure the current out of the charger when it is connected to the battery. I just hooked one to a 7 cell (8.4 volt) Ni-Cd. Output was essentially the same, 500 mA as it was when hooked to the 12 volt lead acid.