Cell and battery voltages

Batteries for electric vehicles got specification as 6V and 12 V. To produce this voltage cells inside batteries are connected in series so the voltage required to propel the vehicle is produced. Electric cells got their nominal voltage which represent approximate voltage when cell is in working condition (electrical power delivering). When power is given out, voltage will decrease and in charging conditions voltage will be rising. Electric charge is crucial parameter of a battery. To take SI units, SI unit is Coulomb. It represents a charge one Amp flowing per one second. This unit is practically small so in practice unit in use is Amp hour, meaning one Amp flowing per one hour. If we take battery with capacity of let’s say 20 Amp hours, it means that this battery can give 1 Amp for 20 hours or 2 Amp for 10 hours, or in practice 20 Amp for 1 hour. This is just theoretical point of view. Things are not that simple in practice, no matter what kind of battery is taking place.

It is very significant to understand that if one battery can provide 1 Amp for 20 hours and in case of 20 Amp drawn, it will be empty in less than one hour. Usual capacity of electric vehicles in use nowadays is given in 5 hour use or discharge. Capacity of the battery is greatly affected if stored energy (charge) is going more slowly or more quickly. There are lot unneeded inside reactions into cells. This reductive effect is most viewable at lead acid based batteries, but it is present in all types of batteries. Medium discharge will provide most effective using time for all batteries. That’s easy to say, but as we all know there is no ideal need for discharge. So theoretical and effective ”life” of battery is not the same. The better the battery is, the closer these values are.