Two amps are the standard amount of power increase that the average car battery charger provides. A car battery is rated by how many amp hours it can provide before it is depleted. 48 is the most typical number of amp hours a car battery can provide, but there are larger batteries, and some of the marine batteries can provide as many as 100 amp hours.
The amps required by a car depending on how many accessories you are running while the car is running. Each component in your car requires your battery to produce more amps per hour.
Things that increase the number of amps your car battery must provide in an hour include:
- The radio
- Heated seats
- Heated rear windows
- Electric windows
- Heater and air conditioner blowers and fans
- Electric powered seats
- Automatic defrosters
- DVD equipment
- Interior dome lights
You know that if you do not close your car door completely then the interior dome light will stay on and this dome light can cause your car battery to be drained and dead when you go to use the car the next morning. That is because the battery had to provide amps for the dome light to work, and the car was not started so the alternator was not recharging the battery.
When a battery charger is said to provide 2 amps it means that it will increase the amount of power the battery has by approximately 2 amps for each hour it is connected. So in order to determine how many hours it will take a charger at the rate of 2 amps per hour to restore a complete charge to your battery, you must take the number of amp hours your battery is capable of providing and divide that number by 2. So a battery that provides 48 amp hours will need 24 hours to be recharged at the rate of 2 amps per hour. A marine battery that is capable of providing 100 amp hours would need approximately 50 hours to be restored to a full charge at the rate of 2 amps per hour.
You will likely be tempted to find a battery charger that charges at a much higher number of amps per hour so that it will take less time to charge your battery. The fact of the matter is that the slower charges are more effective and are less likely to do any damage to your battery. Often quick charges can cause the plates of the battery to buckle and bend so that the battery life is reduced and the battery is permanently damaged.
The best car battery charger is one that provides a fairly fast number of amps per hour for the initial portion of the charging, and then switches over to a slower number of amps per hour for the finishing of the charging, and then lowers the amps provided even more so that it can maintain the charge of the battery without causing damage to the battery. You can buy chargers that do this without you having to time the battery, or make any changes. With these fully automated chargers, all you have to do is connect them to the battery that is depleted and then let them do their work.
The temperature that the outside air is will play a part in how long it will take your battery charger to complete a full charge on your battery. You should progressively reduce the number of amps per hour that your charger is providing as the outside temperature rises.