Back in March we replaced the battery in our 2001 Intrepid. We left the car for four months and when we returned the battery was dead. We are currently charging the battery with our friends automotive battery charger. Our question is, how long should we keep the charger on the battery.
Until the battery is fully charged.
At a 2 amp charge rate which is what should be used to properly recharge a discharged battery, it could take 12-24 hours to completely recharge the battery.
And you want to keep an eye on that battery too. A bad charger, or a shorted battery that gets charged, can cause overpressure in the battery, which will make the battery leak acid. A friend of mine discovered this the hard way when he decided to recharge the battery in his kitchen. Ate through the formica on the countertop.
If you’ll be doing this again, either put the battery on a trickle charger or disconnect it while you’re gone.
Most battery chargers today are “smart” and have built in indicators and will switch off when the battery is fully charged and go back to trickle when the charge goes low again. The cost of these battery chargers are less than the cost of a new battery. Mine has paid for itself many times over. If you want to avoid the risk of frying your alternator/battery/electrial, it may be worth your while to pick up a newer “smart” battery charger.
charge the battery outdoors, not in an enclosed location. Check your car for electrial vampires, little leds that stay on when the car is turned off. defeat them if you can and the battery will keep its charge longer. These little drains are a kind of trickle discharge system and there should be a way to make sure they are all off.