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A little lost in the world of batteries?

A short article to help you understand everything easily
Review of the most commonly used terms in the battery world; SOC, SOH, C-rate, Ah…

Current (A): flow of electrical charges passing through a conductor. For instance, a current of 1 ampere corresponds to the flow of 6 trillion electrons per second. The electric current can be seen as of the flow rate in a pipe. The rated current of a battery corresponds to the maximum current that it can provide continuously.

Voltage (V): measurement of the electrical potential difference between two points of a circuit, for instance, between the two terminals of a battery. The voltage is measured in volts and can be seen as the pressure head in a pipe: the higher it is, the more the electric current can flow. The rated voltage of a battery corresponds to the average voltage during a discharge.

Power (W): instantaneous energy flow, it’s the voltage times the current. A 12 volt battery on which a current of 3 amps is drawn provides a power of 36 watts. The rated power of a battery corresponds to the rated voltage times the rated current.

Capacity (Ah): indication of the electrical charge that a battery can store. It’s current times time. For instance, a 100 ampere-hour battery can provide 100 amps for one hour, which is the same as 50 amps for 2 hours, 25 amps for 4 hours, and so on. This same battery could also have a rated current limited to 60 amps, in this case, the battery wouldn’t handle a fast discharge at 100 amps.

Energy (Wh): it allows actions on the environment. Energy can modify the speed of objects, change a temperature, and so on. Energy can be converted into many different forms, but the total amount is conserved although it always ends up into heat. Energy is power times time. A 250 W device powered during 4 hours leads to an energy consumption of 1000 Wh, that can be written 1 kWh. Moreover, by multiplying the capacity of a battery by its rated voltage, we find the energy that can be stored expressed in Wh. For instance, a 12 volt battery with 100 Ah stores 1200 Wh or 1.2 kWh.

C-rate: ratio between the current and the capacity of a battery. It can be used to size charge and discharge currents. A 10 Ah battery that provides a current of 20 amps experiences a “2C” discharge (the current value is twice the capacity value). A 10 Ah battery charging with a current of 5 amps is charged at “0.5C”. The C-rate allows to compare charge and discharge rates between batteries with different capacities. Indeed, a charge or discharge at “1C” always lasts 1 hour, a charge or discharge at “0.2C” always lasts 5 hours, etc. The C-rate that a battery can tolerate is intrinsic to a technology and is therefore not directly linked to the capacity.

SoC (%): State of Charge. This is a percent indication of the energy remaining on a battery. A 100 Wh battery with a 70% SoC of can still provide 70 Wh of energy. The SoC is sometimes simplified to the ratio of the remaining capacity (and not the remaining energy), this increases the SoC a little bit because the voltage of a battery decreases slightly when the SoC decreases.

DoD (%): Depth of Discharge. This is a percent indication of the consumed energy on a battery. A 100 Wh battery with an 80% DoD can still provide 20 Wh of energy. The DoD is sometimes simplified to the ratio of the used capacity (and not the used energy), it lowers the DoD a little bit because the voltage of a battery decreases slightly when the DoD increases. This is the opposite of the SoC.

SoH (%): State of Health. This is a percent indication of the energy that a battery can store compared to what it could store when it was brand new. A given battery rated for 100 Wh with an 80% SoH can store more than 80 Wh. The SoH of a battery decreases with time.

BMS: Battery Management System. It is an electronic circuit board that allows to secure and enhance a battery. A BMS protects a battery against excessive charge and discharge currents, it also protects against overcharging and deep discharges. A BMS can also protect the battery from a thermal runaway and more generally during extreme weather conditions. A BMS can even balance the series of battery cells. Some BMS are real IoT devices and their applications are limitless.

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Victor, Batteries Engineer - Olenergies

It’s a cross-functional function where I have to brainstorm by all possible ways to design and industrialize the best batteries possible.

I was trained as an energy engineer, which allows me to take a step back on the sizing of a battery within any energy system.

Besides my professional activity, I am passionate about electronics and mechanics, I have realized self-taught projects related to these passions like electric vehicles. I have worked a lot with batteries, all morphologies and chemistries combined for more than 10 years. I finally do a lot of sports, especially Volleyball and Freerun.

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battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies
battery vocabulary, Battery vocabulary for beginners, Olenergies, Olenergies