Smart battery chargers: How chargers from MEAN WELL charge lithium and lead-acid batteries

As energy storage devices, batteries are used not only in consumer electronics, cars and uninterruptible power supply (UPS) systems, but also in e-mobility and renewable energy storage. The varying characteristics of the different kinds of batteries, however, means it isn’t always easy to choose the right batteries or chargers.

Lead-acid batteries offer higher charging voltage tolerance, high surge current capability, a broad operating temperature range, and low price. They are often used in drive applications – such as in cars or forklifts – or in emergency power systems. Their disadvantages, however, include high self-discharge and a relatively low number of charge/discharge cycles, which makes them unsuitable for energy storage applications.

Lithium-ion batteries, with their high charge/discharge rate, low self-discharge, and high energy density, are better designed for longer-term energy storage. Depending on the cathode material, they deliver varying performance. Lithium cobalt oxide (LCO) is popular in consumer electronics thanks to its high energy density. Lithium iron phosphate (LiFePO4), with a longer lifespan and good thermal stability, works well for energy storage solutions. The disadvantage of Li-ion batteries is that they can catch fire due to thermal runaway and must be charged and discharged in a more specific way

• Lead-acid batteries: Because of their high self-discharge, the 3-stage charging method is frequently recommended. A typical charging cycle begins with the constant-current stage – the charger limits its output current to the maximum rated current and slowly increases the output voltage. If the battery voltage has reached the maximum charging voltage, the charger switches over to the constant voltage stage. It then constantly outputs its maximum rated voltage and monitors its output current. Finally, when the charging current falls below about 10% of the rated current, the charger switches to the trickle-charge stage. In this stage, the charger reduces its output voltage to avoid overcharging the battery

• Li-ion batteries, by contrast, cannot tolerate a high charging voltage and don’t require trickle charging to maintain their state of charge. As a result, they are often charged using a two-stage charging process with no trickle-charge stage.
With large lithium modules, a possible imbalance in the cells caused by assembly tolerances presents a problem, with cells in the same module possibly being charged with different voltage or current strength. Because cells with low ESR (Equivalent Series Resistance) are always fully charged and discharged first, this not only shortens battery life, but can also lead to thermal runaway and present a safety risk. To prevent this, the Li-ion battery should be equipped with a battery management system (BMS).

To ensure the reliability, long service life, and safety of batteries, it is recommended to optimise the charging curve – in fact, this is mandatory for lithium batteries. MEAN WELL's programmable chargers with PMBus or optional CANBus interface, or the SBP-001 intelligent programmer, which includes free configuration software, all offer flexibility and a user-friendly interface for adjusting the charging curve. They are suitable for use with both lead-acid batteries and Li-ion batteries.

• Standard setting: constant voltage 48V and max. 1008W (HEP-1000-48)
• Connectable with the SBP-001 smart programmer
• 3-stage charging mode: standard charge curve for typical sealed lead-acid batteries, with boost charge voltage of 57.6V and float charge voltage of 55.2V

• Charging voltage and charging current for other kinds of lead-acid batteries adjustable to 36 to 60V and 3.5 to 17.5A respectively.
• 2-stage charging mode: for charging Li-ion batteries with the same range of settings. Fastest charging using the CV and CC options to 56V and 17.5A for 20Ah LiFePO4 batteries with max. charging voltage of 56V.

• Charging current can be reduced to prevent temperature increase, and voltage can be lowered to prevent possible overcharging.

At Schukat electronic, we offer the smart battery chargers in MEAN WELL’s HEP-1000 series direct from stock.

In addition, our technical sales team will advise you on any battery or power supply questions you may have.