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How Long Does It Take to Charge a Car Battery

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To charge a car battery it must be done on the same as it was discharged. Before attempting to recharge the car battery always make sure that the battery is at room temperature (60 °F to 80°F). Also, when it is extremely cold remove the battery from the car and bring it indoors to allow the battery to become warm before begin the charging.

If the battery has been used for a rather long time, it may not maintain charging efficiency when it is completely new. If the vehicle is used too infrequently, or the vehicle makes too many short starts, or runs in a cold environment, then its battery needs to be charged regularly. Before charging, be sure to check the state of the battery.

While being charged, the battery will generate corrosive acidic volatile gases and a current that can cause serious damage. When charging a battery, always pay attention to the following precautions.

How to charge a car battery

Before charging, disconnect the battery terminals from the vehicle and remove the battery. Charging a battery whose wires have been connected will damage the electrical system of the vehicle.

Before turning on the charger switch, confirm that the wires of the battery charger are safely clipped to the terminals of the battery. Once the charger is turned on, no wires can be moved.

While charging the battery, be careful to protect your eyes. Make sure the top and vicinity of the battery is properly ventilated, and avoid strong light near the battery (before and after the battery is charged, it will generate flammable hydrogen). When the color display in the battery monitoring indicator window is green, stop charging. Otherwise, this will lead to excessive battery charging.

When charging ends, you need to turn off the battery charger before disconnecting the wires from the battery terminals. After the engine is turned off, if the ignition remains in ON mode for a long time or the rear side lights or the parking signal light is still in ON mode after the vehicle has parked, the battery may discharge quickly, resulting in power deficiency.

In a cold environment, it may take a long time to charge the battery. Before mounting the battery onto the vehicle after charging, it is necessary to put the battery to one side for one hour so as to dispel inflammable gases and minimize the danger of fire or explosion.

How long does it take to charge a car battery

Slow charging is done if the battery was discharged slowly over a long period of time such as standing loss while in storage, lights of the car were left on, the voltage regulator setting was too low, and small short slowly draining the battery. In this case, recharge the battery slowly at 6 to 10 amps for up to 8 to 10 hours.

A good rule of the thumb slow charging rate – charge at a rate equal to one-half the number of plates per each cell.

Example:
A 13 plate cell should charge at 7 amps.
A 7 plate cell should charge at 4 amps.

How long does it take to charge a car battery by fast charging

Fast charging is done on the battery if it was discharging rapidly such as during a starting failure you cranked the engine until the battery went dead. In this case, the battery must be charged using a fast charger at a rate of up to 40 amps for a 12-volt battery or 70 amps for a six-volt battery for a maximum of 1 to 2 hours.

Safety precautions when doing a fast charging

Keep a careful watch on the battery that is being fast-charged. When the battery temperature reaches 125 °F or when the gasses are seen coming out of the battery then reduce the rate of charge to a slow charge rate.

Battery damage that can result from fast charging

Warp and buckle plates can cause by overheating, this could damage the separator and could cause a short circuit within the cell. Reduce battery capacity caused by violent bubbling and gassing action of the electrolyte, this could wash the active material from the plates and could cause an internal short.

Exploding batteries

Batteries can and will also explode, and sometimes with considerable force. A few simple precautions will prevent battery explosions.

A battery by itself will not explode unless a spark or flames has ignited the hydrogen and oxygen gas. Keep sparks, flames away from batteries while charging. Keep your charging area well ventilated. Turn off the battery charger before disconnecting charger clamps and keep electrolytes up to the proper level. This means a less volume of gas can collect in a full cell.

Batteries generate gas in in-vehicle as well, since the alternator has been recharging the battery. Again, keep sparks, flames, and cigarettes away when working on a battery in a customer automobile.

How to disconnect a car battery to avoid sparks depends on what to disconnect first. Before you start disconnecting the battery cable turn off all lights and accessories then disconnect the ground cable first.

How to Disconnect a Car Battery
Do you know how to disconnect a car battery? as simple as it is, not doing it correctly increases the possibility of damaging your car's electricals. Read more » How to Disconnect a Car Battery


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