Float, Trickle, Boost Charging Difference and Examples

There are different types of charging procedures are available for batteries. Those charging procedures are used according to voltage level, types of battery, operation, and requirements. In this article, we are going to discuss about the concepts of Float Charging, Trickle Charging, and Boost Charging, differences between them, examples, advantages and disadvantages, and their applications. There are different types of charging methods are used to increase the reliability, efficiency, and smooth operation of the battery. An improper charging method may cause to reduce the battery life, battery overheating, battery overcharging, etc.

What is Float Charging?

Float Charging is the most commonly used charging method of the battery which works with the principle of maintaining Float Voltage. Float voltage is a minimum voltage which always applied to the battery even after it is fully charged. Obviously, this float voltage is lower than the maximum charging voltage of the battery to reduce the possibility of overcharging. In the float charging system, as always a voltage is applied to the battery, so the battery is always in a charged condition.

Float charging systems are mainly designed for backup power and emergency purposes. In the float charging method, the battery, load, and charger all are connected in parallel, so in normal conditions when power is available load will draw current from the charger, and at the same time battery also draw current from the charger to get the charge but when main power not available load will draw current from the battery. 

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Float Charging System Description

1. In the Float Charging system charger, battery, and load are connected in parallel.

2. In the float charging system battery is always in charged condition and there is no self-discharge possible.

3. It works on the reduced voltage procedure to eliminate the overcharging.

4. It works with low and constant current delivery.

5. In the float charging system, generally, voltage is maintained at approximately 2.25V per cell or 13.5V for a 12V battery.

Types of batteries used for Float Charging are Lead Acid Batteries(used in automotive), sealed lead acid batteries (used in emergency light), NiMH cells, NiCD cells, etc.

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Pros or Advantages of Float Charging

1. As the battery, charger, and load all are connected in parallel so it is best for backup and emergency purposes, there is no power interruption for the load.

2. As here reduced voltage, a low constant current is used so the battery has a high life span.

3. Almost no chances of overcharging, overheating, automatic self-discharge, or voltage drain.

4. Float Charger has a very simple circuit design(generally a rectifier circuit) and is a low-cost device.

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Cons or Disadvantages of Float Charging

1. The battery takes more time to charge as it works with low current.

2. It is most suitable for low power and low backup time applications, not suitable for high backup time applications.

Example and Applications of Float Charging

The main application of the float charging system is for emergency and backup power supply purposes. This charging system is used in emergency lights, automotive batteries, UPS, etc.

What is Boost Charging?

Boost charging is the charging method of the battery where a boost voltage(more than float voltage) is applied temporarily to the battery to accept more current as it gets charged fully in a very short time. Of course, the voltage must be reduced to float voltage once the battery is fully charged to avoid overcharging. The boost charger is mainly designed for fast charging purposes.

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Boost Charging System Description

1. High voltage and current applied to the battery for a short time.

2. It shortens the recharge time and provides fast charging.

3. The boost charging method forces the battery to draw maximum current to get a full charge quickly.

4. In the boost charging system, the battery is disconnected from the charger after it is fully charged. But the float cum boost charger does not disconnect the battery when it is fully charged, it just reduces the voltage from boost to float level.

Types of batteries used for Boost Charging are Lithium-Ion batteries and Lithium Polymer Battery.

Pros or Advantages of Boost Charging

1. It provides very fast or quick charging.

2. It is most suitable for low to high-power applications.

3. Battery can drive a heavy load such as high torque motors, actuators, etc.

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Cons or Disadvantages of Boost Charging

1. In this method high voltage and current are applied to the battery, so battery life span may be reduced.

2. It is not suitable for Lead Acid batteries, it is most suitable for Li-Ion batteries.

3. Boost Charger has complex design than other chargers because here timer circuit is also required to reduce the boost voltage to float voltage when the battery is fully charged.

Examples and Applications of Boost Charging

In modern smartphones, the boost charging method is used for fast charging. In generator set batteries also sometimes the float cum boost charging method is used although they use lead-acid batteries.

In a High Voltage Switchgear system, the float cum boost charger is used.

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What is Trickle Charging?

The trickle Charging method is almost the same as the float charging method, only the difference is, that in the float charging method battery is always connected to the load whereas in the trickle charging method battery is not connected to the load during charging. Another difference between Trickle Charger and Float Charger is Float Charger disconnects the battery from the source when it gets charged fully but the trickle charger has not this facility. The main aim of designing the trickle charger is to charge the battery continuously to keep it fully charged for all time.

The Trickle Charger charges the battery at the self-discharging rates of the battery. Like a float charger, a trickle charger also provides very low voltage and current to the battery to avoid overcharging. 

Types of batteries used for Trickle Charging are Lead Acid Batteries, SLI Batteries, etc.

Examples and Applications of Trickle Charging

The trickle charging method is used in automotive batteries, portable electronic tools, flashlights, battery-powered screwdrivers, and other electro-mechanical tools.

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Difference between Float, Trickle, and Boost Charger

Here some differences between Float, Trickle, and Boost Charger are given below.

Float Charger	Trickle Charger	Boost Charger
Does not provide a constant voltage	Provide constant voltage and current	Does not provide constant voltage and current
Provide low voltage and current to the battery	Provide low voltage and current to the battery	Provide high voltage and current to the battery
Provide voltage and current for a long time	Provide continuous voltage and current	Provide voltage and current for a short time
Provide a Slow charging rate	Provide a Slow charging rate	Provide a fast-charging rate
No harm in reducing battery life	Chances of reducing battery life	Chances of reducing battery life
Disconnect the battery after fully charged.	Do not disconnect the battery after fully charged.	Disconnect the battery after fully charged.
Best for Lead Acid battery	Best for Lead Acid battery	Best for Lithium-Ion Battery
Used for emergency and backup purposes	Used for light loads	Used for heavy loads

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