Have you ever wondered if it is right to store batteries in the refrigerator to prolong their life? We can answer that question.
In fact, the recommended storage temperature for most batteries is 15 degrees Celsius (hence the refrigerator). The lowest temperature at which they should be stored is between minus 40 and minus 50 degrees Celsius. Lead-acid batteries should be fully charged during storage, but nickel and lithium dry batteries should be stored at about 40% of charge (SoC) to minimize aging capacity while allowing the battery to self-discharge and remain operational.
Voltage as an indicator
It is difficult to determine the magic 40% SoC because the open-circuit voltage (OCV) of batteries is difficult to estimate. It is best to use voltage as a rough indicator of energy. The SoC of lithium-ion batteries is about 50% at 3.80V/cell and 40% at 3/75V/cell. The lithium-ion battery must rest for 90 minutes after charging or discharging before the voltage can be checked.
Nickel-based batteries are the most difficult SoC to determine. This is due to the flat discharge curve, mixing after charging and discharging, and temperature-dependent voltage change. There is no practical assessment tool for nickel-based batteries. Since the battery’s state of charge is not critical, simply add some charge when the battery is discharged (if not, add nothing) and then store it in a cool, dry place.
higher temperatures effects
Storage always ages batteries. On the other hand, higher temperatures accelerate the permanent loss of battery capacity. Lithium-ion batteries in particular are often exposed to high temperatures. Just think of how many people leave their cell phones or laptops in hot places, such as the front seat of a car on a sunny day. Conversely, low temperatures and incomplete SoC slow down the aging process, but cannot stop it.
Another factor that shortens battery life is overcharging or keeping the battery at maximum charge voltage for extended periods of time. Batteries are like people: they need to be able to rest after charging, even if they are only left in float or trickle charge.
A sealed lead-acid battery can be stored for up to two years. However, it is important to monitor the voltage or gravity and charge the battery when it drops to 70% SoC or below. A low charge will cause an oxidation layer to form on the negative plate, preventing current flow; this is called sulfation and can cause small sealed lead-acid cells to fail to charge.
The following are some basic recommendations for battery storage:
– Remove batteries from equipment and store them in a cool, dry place.
– Lead-acid batteries should be charged before storage; monitor voltage or gravity frequently and recharge when voltage drops below 2.10 V/cell or gravity drops below 1/225.
– Avoid freezing and remember that batteries freeze more easily when discharged than when uncharged.
– Alkaline and lithium primary batteries can be stored for up to ten years with moderate capacity loss.
– Nickel batteries can be stored for five years or longer, even at zero voltage; they should be recharged before use.
– Lithium-ion batteries should be stored in a charged state; ideally 40%. This ensures that the battery voltage does not drop below 2.50 V per cell as it self-discharges and that the battery does not go into a dormant state. Dispose of it if the voltage drops below 2.00 V/cell for more than seven days.
Charging the batteries
- Make sure the polarity is correct and connect the charger.
- The battery should be charged at a normal charging rate. The battery is fully charged when the charge voltage and electrolyte level have not risen for at least 2 hours. The minimum charging time is 4 hours. The charging time should be increased proportionally if the only available current is lower than specified.
- The temperature of the acid must not exceed 50°C during charging. Interrupt or reduce the charging current if necessary.
- Ensure that the specific gravity of all cells is 1.280 (0.010 at full charge).
- Now install a vent plug and check the electrolyte level in all cells after two hours of charging. If necessary, bring the electrolyte level to 15 mm above the plates or to the “MAX” line with distilled water.
Look for any powder build-up around the poles or bottom of the batteries, as well as leaks. This can lead to corrosion. Look for any damage or impact to the batteries.
- The tops and terminals of the batteries must be kept clean.
- Use petroleum jelly or similar products sparingly to lubricate terminals and connections.
- NEVER over-tighten the terminals, but keep them tight.
- The electrolyte should be 1/8″ (3 mm) to 1/4″ (6 mm) above the top of the plates. Check periodically. Use only distilled or chemically pure water when refilling is required.
- Make sure the alternator/generator belt is tensioned according to the manufacturer’s recommendations. Check it periodically. Also, check it regularly for signs of wear.
Checking the batteries
Always perform a visual inspection before checking the batteries with instruments.
- corroded terminals – a white powdery substance around the stud terminals that may prevent the battery from charging.
- Check to see if all cells contain electrolytes. A dry cell indicates a crack in the case.
- Check for loose terminals and other external damage.
Check with hydrometer
Use a hydrometer to determine the specific gravity of the sulfuric acid in the battery and the state of charge.
- do not add distilled water. 2. hold the vessel vertically.
- Hold the vessel vertically and remove enough electrolyte from each cell, in turn, to allow the float to move freely. If necessary, tilt the battery to obtain a sufficient amount of electrolyte. Read at eye level.
1.270 – 1.280 S G Full charge
1.220 – 1.230 S G Half charge
1.150 – 1.220 S G Discharge
All cell readings should be within 0.030 points. If the difference is greater, the battery probably needs to be replaced.
If all cell readings are consistently low, the battery may still be usable, but we recommend replacing it as soon as possible.
Batteries for diesel generators
When people mention power systems and batteries, they rarely think of diesel generators, but the battery is a key component of any emergency generator. A battery is essential to start a generator as soon as grid power fails, and without it, the generator would be useless.
Like UPS batteries, generator batteries should checked and replaced as needed. By following these simple guidelines, you can extend the life of your batteries and get more out of them.
For details, please visit: https://www.multilinkeng.com