Tip 7: Do NOT overcharge your car battery Never overcharge your car battery. Lead-acid batteries release oxygen and hydrogen gases when they’re overcharged. This causes two problems: 1. It can be explosive. 2. It also breaks down the composition of the water in the battery – which shortens its lifespan. Tip 8: Check your car’s alternator If you’re doing everything we’ve recommended in this article but your car batteries are still dying early, you’ll want to check your car’s alternator (or get a mechanic to check it). If your alternator is bad it will results in ineffective recharging of your battery and dramatically shorten your battery’s lifespan. View our Free Presentation to learn how to bring old batteries back to life again