Had a battery that kept discharging and it checked ok at the battery shop, one day I took it to another shop and told then what was going on. when the guy put the load on it it read good but he said I'll leave it a little longer and about 30 sec later the battery started showing bad. bad cell in battery. this battery was only 3 months old and failed. just bought a new battery from the shop the found the problem. Yes I hate battery/electrical problems