The effect of the Temperature on the Battery capacity

On the occasion of winter, let’s talk briefly about an important parameter in solar energy batteries:
Which are the temperature and its effect on the battery capacity.


As the temperature is lower than 25 degrees, the battery capacity decreases, and vice versa.
For example, as shown in the diagram, at 25 degrees, the battery capacity and the service give you the same value recorded on it by 100%, And when the temperature drops, for example, to 5 degrees, its capacity decreases, giving you only about 78%.


On the same scale, if the temperature rises to 50 degrees, for example, this increases the battery capacity, giving approximately 117% of its capacity, due to the increase in internal reactions.
On the other hand, in general, whenever the temperature increases to 25 degrees, this reduces battery life.
It is worth noting that these values ​​change up and down according to the type of battery and according to the manufacturer. For example, lithium batteries have a greater tolerance for temperature changes than AGM and Gel batteries.
Designers should focus on this simple and important point when designing any system that contains batteries.
Read also: 10 best solar batteries

The battery charge voltage changes as the temperature changes. Figure (1) shows an example of a change in Battery voltage 12 volts and another 27 volts with temperature, as well as a voltage change
The cell (making up the battery) with the temperature.

Other Factors Affecting battery life

  • Overcharging: It increases the speed of plate wear
  • Deep discharging: Lead to non-work of chemical analysis inside the battery
  • Exposure to high temperature :It works on the speed of the occurrence of corrosion
  • low electrolyte level : Reduced capacity due to exposure to the atmosphere

Requirements for using batteries

  • Batteries are better connected in series than parallel because it is easier to specify Failures and operating currents are less.
  • Never use batteries of different types or capacities together in one chain.
  • Do not use new batteries with old batteries.
  • Batteries should be placed in a well-ventilated and cool place.
  • The typical maximum design depth of discharge should not be less than 50%

General operating requirements for batteries

  1. Battery Self-Service Duration (Self-Time)
    • Design the batteries to obtain rated power for an actual typical period of time of 1 -15 days with or without solar radiation.
  2. Currents of charging and discharging.
    • According to the type of batteries and standard specifications.
  3. The daily cycle.
    • The batteries are exposed to a daily cycle as follows:
      *Charging during daylight hours
      *Emptying during the night hours

Usually, the discharge is between 2% to 22% of the batteries capacity per day.

4.The seasonal cycle

It means that the battery is exposed to a seasonal cycle of the charging state as follows:

  • During winter the periods of solar radiation are low, and thus the production occurs Low power than the battery charge status (available capacity) drops to me 22% or less of the rated capacity.
  • During summer the periods of solar radiation are high, and thus up to The battery has reached a fully charged state, with the possibility that the battery will reach a state of Overcharging.

5.The period of the overcharge condition

The period of the high charge case 80% 100%: During summer the batteries operate at a typical high charge between 32% Of rated capacity.

6.Periods of continuous low charge status

Solar cells are exposed to low solar radiation in some geographical locations
During winter periods, heavy clouds, rain, and dust accumulation. Then there is energy
Produced by solar cells is insufficient to fully recharge the battery, at this condition decreases the charge status and cycles (charge/discharge) occur at the charge state Low.

7.Increased deposition of the lower electrolyte layers as a result of non-stirring

In lead-acid batteries the electrolyte liquid may decrease :

  • In self-venting lead-acid batteries, deficiency can be avoided the solution is by stirring the electrolyte or preventing periodic overcharging during operation.
  • In lead batteries with a regulated valve, precipitation can be avoided Layered electrolyte with good design or operation according to the manufacturer’s instructions.

8.Charge control

Charging is controlled using appropriate controls.

9.Natural protection.
Batteries should be provided with natural protection in normal conditions such as:

  • Exposure to direct sunlight (ultraviolet rays)
  • Excessive and uneven thermal distribution.
  • Air loaded with dust and sand.
  • Shock and vibration (during transportation)
  • Water vapor condensation, water splash.

10.Storage:
Observe the manufacturer’s directions for storing batteries, if needed Lead-acid or nickel-cadmium batteries are filled with electrolytes It should be stored when fully charged. Capacity loss may occur Batteries due to exposure to high temperatures or saturated atmosphere Moisture during storage.

11. Operating temperatures

The temperature limits for batteries during on-site operation are Important factors in choosing batteries and their expected service life. Important notes:

  • Battery life decreases with a higher operating temperature.
  • Low battery temperature leads to reduced battery performance Battery during discharging as well as capacity.
  • Observe the manufacturer’s recommendations regarding  temperatures Operating and operating humidity

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