Can we charge inverter battery with car alternator?

A power inverter, or inverter, is a power electronic device or circuitry that changes direct current (DC) to alternating current (AC). The resulting AC frequency obtained depends on the particular device employed. Inverters do the opposite of “converters” which were originally large electromechanical devices converting AC to DC. The input voltage, output voltage and frequency, and overall power handling depend on the design of the specific device or circuitry. The inverter does not produce any power; the power is provided by the DC source. A power inverter can be entirely electronic or may be a combination of mechanical effects and electronic circuitry. Power inverters are primarily used in electrical power applications where high currents and voltages are present; circuits that perform the same function for electronic signals, which usually have very low currents and voltages, are called oscillators. Circuits that perform the opposite function, converting AC to DC, are called rectifiers. Back to the question, can inverters charge battery? Yes an inverter is meant to charge batteries which is a storage medium for power.

A car battery is a rechargeable battery that is used to start a motor vehicle. Its main purpose is to provide an electric current to the electricity-powered starting motor, which in turn starts the chemically-powered internal combustion engine that actually propels the vehicle. Once the engine is running, power for the car's electrical systems is still supplied by the battery, with the alternator charging the battery as demands increase or decrease.

Types of Car batteries

The car batteries in a vehicle should not be judged on its size. Though small, it plays many major roles in running the vehicle smoothly. Functions like starting your car, providing power to the infotainment system, headlights, etc. The running engine charges the battery in the car. Over the year after numerous cycles, the battery will eventually die and needs to be replaced. The various types of car batteries include:

1. Starting, Lighting, and Ignition Batteries (SLI):

Most of the vehicles on the road comes with starting, lighting, and ignition batteries or for short SLI batteries. Like the name suggests, apart from starting the car, it powers all the electronics like the interior and exterior lights, infotainment system, etc. An SLI battery has a very short charge cycle. That is the time for the battery to charge and then discharge is fairly less. This type of battery can deliver power in short bursts of time like the starter motor of the car. The SLI batteries are made up of 6 galvanic cells oriented in a series format which forms a system and provides 12-volts. Each cell provides 2.1 volts to give a total output of about 12.6 volts at full charge.

2. Lithium-Ion (Li-ion) Batteries:

This is a very incompatible battery of the lot. A Lithium-ion Battery has become famous for the last few years. The recent hybrid vehicles and electric cars use a Li-ion battery. As compared to the other batteries the Li-ion battery significantly stores more charges. Another plus positive is that these batteries weigh less than conventional car batteries of the same power. Regardless of the use, the life span of the Li-ion batteries is short which is about 3-4 years.

3. Lead-Acid Batteries: 

These are the batteries with the lowest maintenance. Unlike the other batteries Lead-Acid batteries are sealed hence they cannot be serviced. These batteries can only be replaced. Lead-Acid Batteries also work in short bursts to provide power to the starter motor.

Understanding Car Batteries

Batteries are typically made of six galvanic cells in a series circuit. Each cell provides 2.1 volts for a total of 12.6 volts at full charge. During discharge, at the negative terminal a chemical reaction releases electrons to the external circuit, and at the positive terminal, another chemical reaction absorbs electrons from the external circuit. This drives the electrons through the external circuit wire (an electrical conductor) to produce an electric current. As the battery discharges, the acid of the electrolyte reacts with the materials of the plates, changing their surface to lead sulfate. When the battery is recharged, the chemical reaction is reversed. With the plates restored to their original condition, the process may be repeated.

Can you Charge a Car Battery Using an Inverter?

You can charge a car battery with an Inverter. Most home Inverters are rated for 12 Volt batteries and have a charging circuit to recharge batteries at 13–14 Volts. Same is the case with Car batteries, they are rated at 12 Volts and recharged with Car Alternators providing 13–14 Volts. The difference between an Inverter battery & car battery is one of capacity among other things. A car battery has a capacity of 50Ah on an average whereas an Inverter battery is rated as 120 Ah.

How to Charge Car Battery Using an Inverter

Using an inverter to charge the car battery will take less time than the charger method. You shouldn’t use this method frequently, but it’s a simple and easy method to apply once in a while. It’s an easy method for fast charging. If you don’t have enough time to wait overnight for a ride, the inverter method would be a great option.

1. Setting up the connection:

The connection setup is the same as the car charger. The inverter shouldn’t be connected to the power supply before you set up all the connections. Connect the negative port of the battery to the black wire of the output port of the inverter. The positive wire has to go to the red port of the output’s positive port.

2. Supplying power:

Home inverters use the direct power from the power outlets of your house. Check the connections again before you turn the power supply on. If the connections are alright, plug the inverter into the power outlet. Connecting the wires in the wrong manner may make the battery explode.

3. Finishing up: Home inverters have a high-power supply. It might take as low as 1.5 hours for an inverter to charge the battery completely. Some might take up to 3 hours.

Things to keep in mind while charging car battery using an Inverter:

1.Keep the mains supply ON but the Inverter OFF, since you do not wish to provide power backup using a car battery that you are charging.

2.Inverters are notorious in recognizing extension cables for battery terminals. Try not to add an extension cable, instead bring the polarity matched Inverter lead and clip it tightly on the battery using a Connector.

3.Take voltage reading of dead batteries using a multimeter. If your SLI battery is 6 cells it should be approx. 11 volt and for 5 cells it should be 10. Below these voltages your battery needs special care.

4.You need to check voltage and current rating of your battery as well as the Inverter output terminal. Most of the SLI batteries need voltage between 12 to 13 volts to charge it. Note: If the Inverter has a high current rating but similar voltage rating than your battery, it will charge fast.

Is Charging A Car Battery with An Inverter Safe?

It is safe to change a battery with an Inverter, but before using the car battery, you should consider some of the factors for safety:

I.  Car batteries are heavy and large in size.

II.  Lead-acid car batteries are not usually sealed so there is a danger of acid spill or escape.

III. Car batteries can source lots of currents and if there is accidental shorting without the use of adequate protection  devices the massive current can do a lot of damage.

IV. Charging lead-acid car batteries lead to hydrogen gas production which can be dangerous if done indoors and/or in a confined space.

V.  Connection of low current load wires to a car battery can be somewhat of a pain as regular battery terminals do not normally accommodate small wires.

VI. You will have to evaluate the discharge rate versus the available charging rate to determine if the downtime duty cycle of the battery is too large for your application.

VII. If usage of the battery capacity is done over a long time period there may be self-discharge loss of overall capacity to consider.

In summary, you can charge a car battery with an Inverter. As stated earlier, home Inverters are rated for 12V batteries and have a charging circuit to recharge batteries at 13–14 Volts. Same is the case with Car batteries, they are rated at 12 Volts and recharged with Car Alternators providing 13–14 Volts.

Hopefully, this article has been helpful. Kindly contact us for more information. If you are in the market to make a choice on the brand to buy read our article on the best inverter battery in Nigeria 2021 reviews

Jan 14, 2021

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