When you invest in a high-quality multi-stage battery charger, you’re giving your battery more than a straightforward plug-in charge. Smart chargers move through a sequence of stages to maximise battery health, efficiency and lifespan. A perfect example is the KickAss 12 V 22 Amp ACDC 9 Stage Smart Battery Charger, which features a full nine-stage process. Here’s a breakdown of each stage – what it does, why it’s included, and what it means for you and your battery.
Stage 1: Primary evaluation (diagnostic)
In this first phase the charger checks the battery’s condition: voltage, internal resistance, state of charge, and whether the battery can safely accept a charge.
Why it matters: it ensures the charger adapts its strategy to the battery’s actual state. If the battery is deeply discharged, damaged or sulphated, the next stages may be altered or triggered to help recovery.
Tip: if the battery is very flat or has been unused for a long time, this evaluation step is especially important before full charging occurs.
Stage 2: Recovery (or rejuvenation)
If the battery has been deeply discharged or neglected, this stage applies a low current or special pulses to “wake up” the battery and make it receptive to the bulk charge. This phase is sometimes referred to as “Battery Reconditioning Mode”.
What to expect: charging may progress slowly as the charger gently brings the battery back to a state where full charging is safe.
Benefit: this stage helps prevent damage that might occur if you applied full current to a weak battery.
Stage 3: Soft-start charging
Once the battery is deemed receptive, the charger begins with a gentle current to ensure that the battery is accepting charge and is safe to proceed at higher rates. The “Soft Start” stage reduces stress and risk of overheating or over-voltage early on.
Why it’s included: it protects the battery from shock and allows the charger to fine-tune its parameters.
Stage 4: Pulse / desulphation (optional in some units)
In many nine-stage systems this refers to a pulse or desulphation cycle where short high-frequency pulses are applied to break down sulphate build-up on lead-acid battery plates. If the battery has been sitting unused or has undergone heavy use, this stage can help restore battery performance – though it won’t make a badly damaged battery brand new.
Stage 5: Reconditioning or equalisation
This stage further conditions the battery, especially for lead-acid/AGM types, by equalising cells (ensuring all plates/cells are at similar state) and prepping for full charge. This is sometimes called an “Equalisation Charging”. Its purpose is to improve capacity, balance cells, and help maintain longevity.
Note: When charging Lithium types, this change might not apply (or may be bypassed) because of different chemistry.
Stage 6: Bulk charging
Here the charger applies the maximum safe current to quickly raise the battery’s state of charge, typically up to around 80-90%. It’s the heavy-lifting part of the charge cycle.
What you’ll notice: the battery voltage rises steadily, current remains high, and the charger’s fan (if fitted) may be active.
Best practice: make sure the battery is properly ventilated and the charger is suitable for the battery chemistry (lead-acid, AGM or Lithium) before this stage.
Stage 7: Absorption charging
Once the battery is nearing full charge, the charger switches to a constant voltage with a gradually decreasing current to avoid overcharging and to finish the charge safely.
Why this matters: high currents at this stage can cause gassing, overheating or shorten battery life. The absorption stage ensures the final fraction of the charge is done gently.
Stage 8: Evaluation/analysis
After the battery is fully charged, the charger assesses how well the battery holds the voltage under no-load conditions, assesses internal resistance and determines if it is healthy. Outcome: if the battery fails this stage (for example if voltage drops too quickly), the charger may flag a fault or keep the battery in maintenance mode rather than assume full capacity.
Stage 9: Maintenance/float (and long-term pulse)
Finally the charger drops to a float/maintenance mode where minimal current is applied just to keep the battery at 100 % and compensate for self-discharge. Some chargers also include periodic pulse maintenance to prevent sulphation or cell imbalance over long idle periods.
How this applies to the KickAss 9-Stage Charger
The KickAss 12 V 22 Amp ACDC 9 Stage Smart Battery Charger supports multiple battery chemistries (lead-acid, AGM, lithium) and incorporates the nine-stage process to maximise charge efficiency and battery health.
This means: when you connect a battery, the charger will assess its state, condition it if necessary, charge it fast and safely through bulk and absorption, evaluate its health, and then maintain it for the long term.
Why this matters for you
- Older or deeply discharged batteries benefit from the recovery and re-conditioning stages, rather than being exposed to full current too soon.
- High-quality charging means less stress on your batteries, improving their lifespan and reliability.
- Smart maintenance means you can leave the battery on charge safely when stored or unused, especially important for 4WDs, caravans, marine applications or off-grid setups.
- Multi-chemistry compatibility (lead-acid / AGM / lithium) ensures you’re not limited when upgrading or mixing battery types.
Things to keep in mind
- Always select the correct battery type setting (lead-acid vs lithium) if the charger requires manual selection.
- Ensure proper ventilation and correct connection polarity before starting.
- For lithium batteries, check if the BMS (battery management system) requires a wake-up signal. If it does, your 22A charger does include a lithium activation mode.
- Although the charger can be left plugged in for long-term maintenance, periodic checks of battery health, corrosion, and electrolyte (if applicable) are still good practice.
Final thoughts
Understanding the nine stages of smart charging gives you real insight into what a smart charger is doing and why it costs a little more. With the KickAss 12 V 22 Amp ACDC 9 Stage Smart Battery Charger you’re not just dumping current into a battery; you’re letting a thoughtful, automated sequence look after everything from diagnosis to maintenance. By matching the charger’s capability to your battery chemistry and use scenario, you’ll help your battery last longer, perform better and stay ready when you need it most.
If you’re looking for more detail on installation, wiring or how to select the right mode for your battery, we’re happy to help you through that too. Drop into one of our retail stores, or give us a call on 07 3123 4715. Our team of 12V experts will be more than happy to help.