How long does a 2 amp charger take to charge a car battery?
About 18.0 h for a typical 60Ah car battery at half charge, and 34.2 h from nearly flat, using amp-hours to replace x 1.2 / 2 amps. A 2 amp unit works as a maintainer.
2-Pack 1.75A Car Battery Charger 6V &12V Battery Maintainer Trickle Charger
1.75A
A charger rated at 1.75 amps by its listing, the class this page is about.
How long for each battery size?
Hours at 2 amps from three starting points: 75 percent (about 12.4V resting), 50 percent (12.2V) and nearly flat (11.8V). The 1.2 factor covers charging losses and the slow absorption stage near full.
| Battery | From 75% | From 50% | From nearly flat |
|---|---|---|---|
| 40Ah | 6.0 h | 12.0 h | 22.8 h |
| 50Ah | 7.5 h | 15.0 h | 28.5 h |
| 60Ah | 9.0 h | 18.0 h | 34.2 h |
| 70Ah | 10.5 h | 21.0 h | 39.9 h |
| 80Ah | 12.0 h | 24.0 h | 45.6 h |
| 100Ah | 15.0 h | 30.0 h | 2.4 days |
Other charger sizes
Chargers near 2 amps
Amp ratings as stated in each listing. Prices change often.
Frequently asked questions
Is a 2 amp charger good for a car battery?
A 2 amp unit is best as a maintainer: it keeps a charged battery full through storage. Recovering a flat 60Ah battery at 2A takes 34.2 h, so for a dead battery a 6 to 10 amp charger is far more practical.
Can I leave a 2 amp charger on overnight?
A modern smart charger switches to float or maintenance mode when the battery is full, so leaving it connected is safe. An old manual charger without automatic shutoff will overcharge if left on; unplug it when the battery reaches 12.6 to 12.7 volts at rest. Charge in a ventilated space either way.
How do I know my battery size in amp-hours?
Many labels list Ah or reserve capacity (RC) in minutes. Roughly, Ah is about half the RC figure: a 120-minute RC battery is close to 60Ah. Most cars use 45 to 70Ah; full-size trucks and diesels 70 to 100Ah, often in pairs.