Overcharging of car batteries | Is it good or bad for the battery?
When car batteries are charged beyond the manufacturer recommended voltage typically 13.5V, overcharging is said to occur.
Overcharged car batteries get extremely hot – you may literally boil out the battery solution, have a battery explosion causing irreparable damage to the battery.
How do I know if my car battery is overcharging?
The following signs though not conclusive may be a sign that your battery is being overcharged:
- High battery temperatures during charging batteries
- Battery case covered with battery solution in the case of flooded lead acid batteries
- Bulging of battery sides
- Depending on external charger or car model, overcharge indicator light displaying on your external charger or car’s dashboard
- Battery voltages as high as 17V measured across the battery terminals with the car engine running
Possible causes of battery overcharging
Car alternators can overcharge and may kill the battery if they are:
- faulty with the inbuilt regulator exposing the battery to higher than recommended voltages for a long time
- replaced with non recommended manufacturer alternator that produces higher than recommended charging currents that are bad for
External battery chargers too can overcharge batteries. They are usually designed to charge different battery types. Always make sure the charger setting are set according to the manufacturer recommended settings to ensure optimum charging and prevent overcharging. Typically this will require you to set the battery type to AGM, Lithium or other depending on the chemistry of the battery you need charged.
Can a bad battery cause overcharging?
Note: A bad battery is unlikely to result in the battery being overcharged provided that the alternator is working well.
How to prevent your battery from overcharging
To avoid damage to your car battery as a result of overcharging, use good quality chargers that have an automatic shut-off feature when the battery is fully charged or one recommended by the manufacturer.
This way, you can leave your battery connected indefinitely to the charger – you need not worry about forgetting to turn off your battery charger when the car battery is fully charged!
Check that the charger settings are set for the battery type you are charging – AGM or Flooded Lead Acid.
When replacing car alternators, replace with the car manufacturer recommended alternator to avoid the danger from overcharging.
How do you fix an overcharged battery?
If your battery has not been subjected to excessive voltages (17V) for a long time, it is possibly fine. If however, it has, then your battery will likely suffer permanent damage and needs to be replaced (check out section on signs of a bad battery).