Why driving can’t bring back a dead battery
It sounds perfectly logical, right? Too bad it’s totally wrong.
Mostly Dead vs. All Dead
True, the alternator can give a dose of electricity to a weak battery. But weak batteries are only slightly alive.
If heat or severe discharging has damaged the battery, it may have lost the capacity to start a car more than a few times, no matter how much power the alternator gives it.
That’s why you can jump-start a car, drive it, park for a few hours (or longer in warm temperatures) and start the engine from a weak battery – only to have to jump-start it again.
Alternator’s Too Busy
Auto shop technicians who have replaced an alternator might recognize this warning printed on the part’s box: “The alternator isn’t designed to charge a dead battery. Premature alternator failure can occur and may void your warranty.”
That’s because the alternator is running all the other onboard electronics.
To fully recharge a dead 12-volt battery, you’d have to drive about 2,000 miles faster than 70 mph without using the radio, AC or headlights.
And then you’d have to buy an alternator.Your alternator isn't designed to charge a dead battery. Click To Tweet
The ED-18 to the Rescue
Battery damage is hard to diagnose without the Interstate Batteries ED-18 Battery and Electrical System Analyzer. It’s even harder if the alternator is the actual problem.
Good thing the Interstate ED-18 can test the starting and charging system. Step-by-step prompts help auto techs provide you the right service the first time around.
Find an Interstate Batteries Dealer near you and ask for a battery test with the ED-18. You’ll be glad you did.
Have fun storming the castle.