Every thing you want to konw about lithium ion battery voltage
What is “battery voltage”?
It takes energy to move something. This applies to our cars too. Imagine a car rolling down a steep road with the engines off. You may wonder where it gets the energy to gain speed. It is from the pull of gravity. When the car was at the top of the road, it had the “potential” to gain speed. Thanks to gravity.
When your car is not rolling down slopes, it gets the energy needed for movement from its battery. The battery gives the “potential” needed to gain speed. Thanks to the electrical energy stored within the battery. This energy stored in the battery is called “electrical potential energy.” Battery voltage is one measure of this energy. The other measure is the charge stored within the battery.
Batteries are made up of one or more cells. The energy stored within these cells depends on the chemical reactions that take place inside them. For example, Lithium ion battery voltage depends on the reaction between Lithium ions and other chemicals that are in the cell.
What is “normal”battery voltage?
The voltage of a battery is a measure of the energy that the battery can generate in a unit of time. In other words, voltage determines the power of a battery. As the energy is generated by chemical reactions, the battery voltage varies a little. This variation is determined by the factors that influence the rate of the chemical reaction. However, the battery voltage stays within a small range in most cases and at most times. Unless the batteries have gone bad!
The voltage of battery pack is the sum of the voltages of the cells. The chemicals and materials used in the making of a cell decide its voltage.
Conveniently, the unit of voltage is “volts(v).”
The terminal voltage of a battery cell depends on the chemicals and materials used in its construction, and not on its physical size. For example, primary alkaline batteries which are used in household items like flashlights have a voltage of 1.5V. The button-shaped lithium batteries used in watches have a voltage of 3V. The cells that make up the ternary lithium ion battery, have a voltage of 3.7V.
What’s the range of lithium ion battery voltage?
Lithium ion batteries are used in portable electronic devices and electric vehicles. Lithium ion cells can make up a lithium ion battery. The active chemicals that are used in these cells include the materials of anode and cathode, both of which are compounds containing lithium atoms. Some common cells are, ones having lithium iron phosphate anode with graphite cathode(3.2V), or Lithium nickel manganese cobalt (NMC) oxide anode with graphite cathode (3.7V).
The voltage of these cells can be above or below these values when they are being charged or discharged, respectively. These cells should be within a safe voltage range for optimal function and lifespan. The range of the most commonly used cell is 3V to 4.2V.
Lithium ion battery voltage will be the sum of the voltage of the cells connected in series inside them. If two common Lithium ion cells are used, the voltage range will be from 6V to 8.4V (Twice the range of the cell). Using batteries outside of the safe lithium ion battery voltage range harms the battery and may even harm the user. When below the range, the lithium ion cells will develop a larger resistance, lower capacity, and short circuits. When above the range, the cell life span and capacity will reduce.
What is the actual voltage of a 12V lithium ion battery?
By now you know that the voltage of batteries takes a range. The voltage varies according to the charge percentage in the battery. The 12V Lithium ion battery is no exception to this. Especially since these are deep-cycle batteries. Meaning, they are discharged almost completely while being used.
Lithium ion battery voltage range for a 12V battery depends on the internal chemistry of the battery, its age, its temperature, and continuity of use. Lithium ion battery voltage of 12V is seen in Lithium Iron Phosphate (LFP or LiFePo) batteries. The voltage of LFP batteries ranges from 10V to 14.6V, depending on the charge status of the battery. However, for best life expectancy the battery should be used at a voltage above 12.9V. This translates to, charge status of above 30%.
My battery voltage is shown as 14V at times. Is it good for the car?
The voltage marked in a battery is its nominal voltage. Whether it be your good Lithium Iron Phosphate (LFP) battery, or a Lead Acid battery, or an Absorbent Glass Mat (AGM) battery, the voltage ranges about 2-4 voltages above or below the nominal voltage. If your car battery is fully charged, the voltage will be above its nominal voltage. An 12v LFP battery with a 100% charge will have a voltage of 14.6V. When the charge drops to 90%, the lithium ion battery voltage will drop to 13.6V. So yes, a voltage of 14V is safe in a car battery.
How to choose the right voltage for charging a lithium ion battery?
Chargers must be selected considering the full charge voltage and the capacity (C Ah) of the battery. It is healthy to charge using a voltage of 4.2 volts per cell. Meaning, you can charge a battery with three cells connected in series with a charging voltage of 12.6V. A lithium ion battery of capacity C Ah can be charged at C Amperes. If the capacity is 20 Ah, it is charged by a 20 A current.
What voltage should I replace my car battery voltage with?
You can find out if your battery needs replacing by measuring its standing unloaded voltage. This should be close to the nominal voltage. The typical 12V lithium ion battery voltage (nominal) is 12V. Therefore, you can be reassured if your battery measures a voltage close to 12.6V after a night of rest. Otherwise, you can get your battery checked by a professional.