Battery Chargers. Design Note 32


IMAGEPresenting here three circuits to make efficient Battery chargers. The 12 volt Lead Acid Car battery requires high current for fast charging. If we provide high current, the battery will charge within 1-2 hours fully. Usually a Lead Acid battery takes high current initially, which drops to 500 mA or less after 10-20 minutes. As a rule, it is advisable to charge the battery with a current that is 10 times lesser than the battery capacity. The Car battery is 32 Amps or 45 Amps so it requires 3.2 Ampere and 4.5 Ampere current respectively. So the charger should provide 14 volts with a current of 5 Amperes.

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How to Protect Solar Inverter Battery .Design Note 28


Hybrid-Solar-Charger-Circui
One of the main problems in Solar Inverter system is poor charging of Battery during rainy seasons and in cloudy days. The high current Tubular battery requires more than 1 Ampere current for proper charging. To solve this problem, I have designed a” Hybrid Solar charger” and the circuit was published in Electronics for You magazine September 2013 issue. So the charger has two sides. One side gets power from Solar panel and the other side from a Step-down transformer. If the voltage from Solar panel reduces below 9 volts, the charger shifts to AC mode and battery charges via the current from transformer.
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Solar Power for Lighting. Design Note 27


Solar panelYou can use a Solar panel to power electrical appliances directly during day time if the Sunlight is very good, direct and continuous. So you have to install a Solar panel in a well lit area over the roof top in the East- West direction with a slight angle facing the Solar panel to the sky. So when the solar panel gets sunlight, it generates voltage and current which flows through the cables connected to it. You can have two options. The current can be stored in a battery to power the appliances at night through an Inverter or you can directly use the solar power using an Inverter without battery. Solar power is DC voltage and the Inverter converts this DC into AC to power the AC appliances. So let us see the requirements.
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Lead Acid Battery


A lead acid battery is composed of series of plates immersed in a solution of Sulphuric acid. Each plate has a Grid on which the active material is attached. In the negative plate, lead oxide is attached as the active material while on the positive plate, pure lead is attached. All the negative plates are connected together. Similarly all the positive plates are also connected together.

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Car Battery Monitor. Beginner’s Trial 14


Monitor your Car battery or Inverter battery with this simple circuit. It always follows the terminal voltage of the battery and gives corresponding LED indications. A 12 volt Lead-Acid battery attains 13.85 volts in full charged condition and Inverter Tubular battery 14.85 volts. So it is necessary to have an idea about the charge status of the battery. If the battery discharges below 10 volts, it needs immediate charging to prevent the deep discharge. The circuit gives three LED indications. If the terminal voltage of the battery rises above 13.5 volts, Red LED lights. If the voltage drops below 10 volts, Green LED lights. If the voltage is normal around 12 volts, both the LEDs remain off.

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High Current Battery Charger. Design Trick 10


Lead Acid and Tubular battery sometimes require boost charging with high current to remove the memory effect. In Inverter battery, the charger delivers low current since the charger is always on to charge the battery. If the line voltage is low, the charging will not be complete and battery gets only partial charge. This leads to memory effect and the battery remembers this partial charge as full charge in the subsequent charging. The best method to remove the memory effect is boost charging with high current for a short period. It is better to boost charge the inverter battery once in a month using an external charger after removing the battery connection from the inverter. This charger will do a quick charging and is ideal for Automobile battery and Inverter battery.
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Why water topping is essential in Car battery? Fact File 31


12 Volt battery used in vehicles is the Lead Acid (LA) type battery which can deliver more than 45 Ampere current to ignite the engine. It is the type of Starting battery or SLI battery (Starting Light Ignition) designed to give a heavy current to start the engine. The lead acid battery is composed of series of plates immersed in a solution of Sulphuric acid. Each plate has a Grid on which the active material is attached. In the negative plate, lead oxide is attached as the active material while on the positive plate, pure lead is attached. All the negative plates are connected together and connected to the external negative terminal. Similarly all the positive plates are connected together and with the positive terminal.

The electrolyte in the battery is sulphuric acid- water mixture which has specific gravity. The specific gravity is the weight of the sulphuric acid- water mixture compared to equal volume of water. Pure water has a specific gravity of 1.

During the battery discharge, the sulphuric acid in the electrolyte combines with the active material of the plates. This releases energy and the plate material becomes Lead sulphate both in the positive and negative plates. When this happens, hydrogen atoms of the sulphuric acid combines with oxygen to form water. As a result, positive plates release electrons and the negative plates accept equal number of electrons. This creates a potential difference between the positive and negative plates and current passes through the load.
During the charging and discharging process, heavy chemical reaction takes place which changes the specific gravity of sulphuric acid .This can damage the plates and may reduce the charging holding capacity. To prevent plate drying, topping with desired quantity of distilled water is necessary.
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