I left my car un-driven for 3 months when I had my vocation in China. After being back, I cannot ignite it even after running over 30 minutes by jumper-starting. Next day, after driven for 2 hours, it's OK. But when a Walmart tech used a digital multi-meter-like instrument to test my battery, the instrument displayed my battery is bad, need replacement. Since I doubt the instrument, I went to a GoodYear shop and got the exactly same result. Then I replaced my battery. My old battery is only 4 years service. Before I left for China, there is anything wrong w/ my old battery. Do you think I need to replace it or not? Thanks.