Are there any special requirements for charging lead-acid batteries?
Charging lead-acid batteries with a power supply
Lead-acid batteries can be charged manually with a commercial power supply featuring voltage regulation and current limiting. Calculate the charge voltage according to the number of cells and desired voltage limit. Charging a 12-volt battery (6 cells) at a cell voltage limit of 2.40V, for example, would require a voltage setting of 14.40V.
The charge current for small lead-acid batteries should be set between 10% and 30% of the rated capacity (30% of a 2Ah battery would be 600mA). Larger batteries, such as those used in the automotive industry, are generally charged at lower current ratings. Cells constructed of a non-antimonial lead grid material allow higher charge currents but have a lower capacity. The cylindrical Cyclone is sealed and can sustain a pressure of up to 3.5 Bar (50 psi). A pressurized cell assists in the recombination of gases.
Observe the battery temperature, voltage and current during charge. Charge only at ambient temperatures and in a ventilated room. Once the battery is fully charged and the current has dropped to 3% of the rated current, the charge is completed. A good car battery will drop to about 40mA when fully charged; a bad battery may not fall below 100mA.
After full charge, remove the battery from the charger. If float charge is needed for operational readiness, lower the charge voltage to about 13.50V (2.25V/cell). Most chargers perform this function automatically. The float charge can be applied for an unlimited time.
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Don't boil it dry! If it's a sealed unit it should have a maximum charging rate, usually printed on its side or available on the manufacturer's website. If it's a "car type" then just don't let the electrolyte boil off. Dry plates mean disaster for the life span of the battery.
Lead Acid battery is a heavy current device and it contains sulphuric acid. It is necessary to take precautions during battery charging to avoid hazards due to sparking, acid spilling, explosion etc.
Following are some tips to be followed while charging Lead Acid Battery:
Always keep the battery in a well ventilated space.
Do not keep any inflammable liquid like Petrol near the battery.
The charger should be plugged in to the AC socket only after it is connected to the battery.
Observe the battery while charging. If the water boils ( bubbles may appear in normal charging) and battery heat up, stop the charging immediately.
Use a good quality transformer based charger. For Automobile and Inverter battery, use a 14 volt 5-10 Amps transformer.
Do not wear any metal bangle or metal wear in the hand while handling battery. This prevents shorting and burning.