4S 5A Active Balancer: Precision Cell Equalisation for LiFePO4 and Li-ion Battery Packs

Maintain Peak Battery Performance with Capacitive Energy Transfer Balancing

The 4S 5A Active Balancer is a high-efficiency battery equaliser designed to keep your LiFePO4 or Li-ion cells in perfect balance. By actively transferring energy from higher-voltage cells to lower-voltage cells, it maximises usable capacity, extends cycle life, and prevents premature failure caused by cell imbalance. This module is an essential component for anyone managing 3S or 4S lithium battery banks in caravans, RVs, marine systems, solar storage, or off-grid power setups.

Unlike passive balancing boards that waste excess energy as heat, this active balancer uses a capacitive energy transfer method to redistribute charge efficiently across the entire pack simultaneously. The result is faster balancing, less energy loss, and cooler operation, even under continuous use.

Why Active Balancing Matters for Lithium Batteries

In series-connected lithium battery packs, slight differences in cell capacity, internal resistance, or temperature can cause voltage drift over time. Without balancing, the weakest cell limits the entire pack's performance, leading to reduced runtime, premature low-voltage cutoffs, and accelerated degradation. An active cell balancer like this unit continuously corrects these imbalances, ensuring every cell reaches full charge and discharges evenly. This is particularly critical for lithium iron phosphate (LiFePO4) batteries, which have a very flat voltage curve and require precise balancing to maintain state-of-charge accuracy.

Key Features

• 5.5A peak balancing current dynamically adjusts based on voltage difference, delivering rapid equalisation for large capacity packs (60-300Ah recommended)
• Capacitive energy transfer technology shifts charge between all cells simultaneously, minimising energy loss and heat generation
• Ultra-precise balancing with voltage accuracy within 5mV, ensuring optimal cell matching and maximum pack capacity
• Wide compatibility with ternary lithium (NMC), lithium iron phosphate (LiFePO4), and lithium titanate (LTO) chemistries across a 2.7V-4.2V working range
• Under-voltage sleep protection automatically puts the balancer into a low-power state (<0.1mA) when cell voltage drops below 2.7V, preventing over-discharge
• Robust construction with ultra-low resistance MOSFETs and a 2oz copper PCB for reliable, high-current operation and long service life
• Compact and lightweight at just 66 x 46 x 16mm, easily integrated into existing battery enclosures or DIY power walls

Engineered for Australian Conditions

Whether you're building a 12V lithium battery balancer for your caravan, a 48V LiFePO4 battery balancer for an off-grid solar system, or maintaining a marine house bank, this module is built to perform. It requires no external power supply, drawing only about 13mA during operation and entering a deep sleep mode when cells are low. The wide operating temperature range (-10°C to 60°C) suits the diverse Australian climate, from cold highland mornings to hot outback afternoons.

Installation is straightforward: simply connect the balance leads to each cell in the correct order, and the board begins equalising automatically. The adaptive balancing current means it works efficiently with both small voltage differences (0.5A at 0.01V delta) and larger imbalances (up to 5.5A), making it suitable for both maintenance and initial top-balancing of new packs.

Applications

• Caravan and RV lithium battery banks – keep your 12V LiFePO4 cells balanced for reliable off-grid power
• Marine and boat electrical systems – maintain house battery health in saltwater environments
• Solar energy storage – balance 24V or 48V battery stacks for maximum energy harvest and longevity
• DIY power walls and e-bike/e-scooter packs – ensure safe, even charging and discharging of series-connected cells
• Backup and UPS systems – prevent cell drift that can cause unexpected shutdowns

Protect Your Battery Investment

Don't let cell imbalance silently reduce your battery's capacity and lifespan. Add the 4S 5A Active Balancer to your lithium battery system today and experience the benefits of precise, efficient equalisation. Whether you're upgrading an existing setup or building a new pack, this balancer delivers the performance and reliability needed for demanding Australian applications.