Most 12V sockets can supply up to ten amps, while most chargers use one to three amps.
When you charge your devices via your car's power socket, you're likely to be using a 12V power socket, which can supply more than enough voltage to support a typical car charger with 2.1A to 4.8A.
Some faster chargers can use up to 20 W, but the majority of standard chargers are more around the 5 W range. Phone chargers usually use one to two amps, and connect to a 120-volt outlet .
A 12v car battery charger typically uses between 10 and 20 watts of power. The specific wattage will depend on the make and model of the charger, as well as the voltage of the battery being charged. For example, a charger for a lead-acid battery will use more power than one for a lithium-ion battery.
The higher power (2.4amps or 2.4A, 12watts or 12W) chargers are often required by modern phones and tablets in order to charge the device. Lesser powered USB chargers (1A or 5W) have been the standard for many years but they are only sufficient for charging smaller mobile devices.
For example, a 1-amp charger will take twice as long (technically) to charge your device as a 2-amp charger. So, when shopping for a charger, go for one with higher amps. But then again, remember that your phone won't draw more amps than it's designed to.
Either will work. That spec is for the maximum current the power adapter can put out. 2.1A may work faster. 2.1A could never be harmful as the charging circuit in your phone is what actually decides how much current to use.
Battery chargers often have different amperage depending on their purpose. Common charging rates include 2-amp, 10-amp, 12-amp, or 15-amp charge rates. Higher amp ratings will lead to faster charging, but exceeding the recommended rate for your battery could lead to dangerous situations.
An average car battery has a capacity of around 48 amp hours which means that, fully charged, it delivers 1 amp for 48 hours, 2 amps for 24 hours, 8 amps for 6 hours and so on.
Power consumption can be obtained from the data plate on the device. If you do not know the power rating of a device, multiply the maximum current (in Amps) by 12v to obtain Watts (e.g. 4A x 12V = 48W).
Apple 20W USB-C power adapter
Line Voltage: 100 to 240 VAC. Output Voltage/Current: 9 VDC/2.2 A.
Examples: 1 amp is equal to 220 watts at 220V voltage.
The Qi 1.2 standard supports charging speeds of up to 15 watts (9 volts, 1.67 amps), but 7.5 W and 10 W chargers are more common right now.
How Much Power Does an Idle USB Socket Draw? A USB charger draws about 0.05W when nothing is plugged in. By comparison, a 60W light bulb will use 60W of electricity, so a USB outlet uses very little power.
Avoid Car Battery Drainage
Even when it is not charging anything, leaving the phone charger plugged in may drain the car battery and may deplete its power if the engine is not running, which could leave you stranded or make for an inconvenient morning.
A: If you leave the charger connected continuously, even at a mere 2 amps, the battery eventually will die. Overcharging a battery causes excessive gassing — the electrolyte gets hot and both hydrogen and oxygen gas are generated.
How long does it take to charge a car battery with a 12 volt charger? Car batteries usually hold 48 amps, so it will take about 12 hours to reach a full charge using a 12 volt charger.
One of the biggest dangers of leaving your phone charger plugged in is the risk of fire. If your charger overheats, it could potentially catch something on fire. This is especially dangerous if you leave your charger plugged in overnight, as you may not be around to notice if there is a fire.
As we know that charging current should be 10% of the Ah rating of battery. Therefore, Charging current for 120Ah Battery = 120 Ah x (10 ÷ 100) = 12 Amperes.
A higher amp charger will charge the batteries quicker, but may shorten their life somewhat, if much above the 50% level (a 50 amp charger in this case).
How long to charge a battery at 2 amps? It takes 24 hours to fully charge a 48 amp battery at 2 amps.
Most phones and other devices are capable of handling 5V/2.4A. For fast charging, manufacturers bump the voltage up from 5V to 9V or 12V and beyond, or increase amperage to 3A and above.
According to the Energy Saving Trust, any switched on charger that is plugged in will still use electricity, regardless of whether the device is attached or not. The amount of electricity produced from this only costs a few pence, but it will shorten the shelf life of the charger.
The safest amp to charge car batteries is from 4 to 7.5 amps. Charging within this range ensures the vehicle battery won't overcharge, overheat, or be damaged in the process.