Battery chargers

Battery chargers are essential for recharging vehicle batteries from the mains. They may come with the following functions: restoring battery capacity, testing the battery state, desulfation of the lead plates, and starting the engine. The amperage is adjusted manually or automatically.

Operating principle

Transformers operate based on electromagnetic induction. They contain a magnetic core around which a coil is tightly wound. They reduce the output voltage from 220 V to the optimal 14 – 15 V. A rectifier connected to the secondary winding converts the alternating current from the mains to direct current. The amperage set on the transformer battery charger should be 10% of the battery capacity.

Pulse devices are more advanced. They apply high-frequency currents to the battery — recharging is accomplished via short pulses. There are no cores and windings, and the devices are lightweight. Their operation does not depend on the amperage or voltage, and charging can be done in various modes.

Types of battery chargers available on the market

By battery type:

• Lead-acid (flooded) batteries filled with liquid electrolyte.
• AGM/GEL batteries containing an aqueous sulfuric acid solution retained in a non-liquid state by a separator/in a gel-like state by a thickener.

By battery operating voltage:

• 6 V. For two-wheeled motor vehicles.
• 12 V. For cars and small commercial vehicles.
• 24 V. Designed for large vehicles with a 24 V electrical system. They also allow simultaneous charging of two 12 V batteries.
• Universal. These chargers are suitable for all types of vehicles.

By purpose:

• Starter chargers. These charge the discharged battery and start the engine. They are used when it is impossible to dismantle the battery and time for charging is limited.
• Restoring chargers. Due to the rapid alternation of charge and discharge pulses, the properties of the battery are partially restored.
• Equalising chargers. To provide 24 V of onboard voltage, two batteries connected in series are often used, which are discharged unevenly. When charging, one battery may be overcharged, and the other undercharged. Equalising chargers transfer the current from the battery with greater capacity to the other one, thus equalising their capacities.

Recommendations for using battery chargers

1. Take off all metal jewelry in advance, as it can provoke an electric shock if it accidentally comes into contact with the terminals.
2. Make sure that the room’s ventilation system is working properly. The vapours of electrolyte solutions are hazardous to human health.
3. Place the battery on a firm, level surface to avoid tipping over.
4. Before and after the procedure, clean the battery container body and remove oxidation from the terminals.
5. Make sure to unscrew the inlet valves of the batteries, since overpressure may cause an explosion.
6. Remember that AGM or GEL batteries are sensitive to overvoltage during charging. Make sure the device used is intended for your battery type.
7. Always observe correct polarity when connecting the device.
8. Only use the device in an emergency or when you are short on time. Regular accelerated charging reduces the service life of your battery.
9. Do not smoke in front of a charged battery — the emitted chemicals are flammable and explosive.

AUTODOC: easy online shopping

Buy battery chargers in our online store at advantageous prices. Our support specialists will advise you if you have any questions regarding the product. Pay for your order online and get it in no time.

Useful information on functions, causes of malfunction, diagnosis and replacement intervals

• The 5 Best Car Battery Charger Brands