Charging Batteries While They are Connected in Series

History Debunked fan

I have an electrically powered boom lift (also called cherry picker). It is powered by lead acid batteries connected in series. Is it possible to charge all the batteries at the same time using smart chargers (CTEK-type chargers) while the batteries are still connected in series?

Thanks in advance.

VatrerPower

Yes, you can charge lead acid batteries connected in series using smart chargers, as long as the charger is compatible with the total voltage of the battery bank. Connect the charger’s positive terminal to the first battery’s positive terminal and the negative terminal to the last battery’s negative terminal. Ensure the charger has balancing features to prevent uneven charging. Monitor the charging process to avoid overcharging or overheating.

olelon david

Hi! Great question.

Yes, you can charge lead-acid batteries connected in series using smart chargers, but there are some important details and limitations to keep in mind:

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🔌 Option 1: Single Charger for the Entire Bank

If your batteries are connected in series (e.g., four 12V batteries to make 48V), the ideal way is to use a single charger that matches the total voltage — in this example, a 48V charger designed for lead-acid batteries.

✅ Pros: Balanced charging across all batteries.
⚠️ Cons: Needs to be a proper charger for the total system voltage.

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🔌 Option 2: Multiple Smart Chargers (e.g., CTEK) Charging Each Battery Individually

Yes, you can use multiple 12V smart chargers (like CTEKs), one per battery, while the batteries remain connected in series — but with caution.

✅ When this works:

The smart chargers are electrically isolated (most modern CTEK chargers are).
Each charger is connected directly to a single battery’s + and - terminals.

⚠️ Be careful of:

Charger ground referencing: If the chargers are not isolated, you might cause a short or damage them when connecting across different voltage potentials in the series.
Make sure each charger’s negative is only connected to the battery it’s charging, and not to a shared chassis ground or earth ground.
All chargers need to be powered from the same power source, ideally without grounding issues.

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✅ Best Practices:

Disconnect the batteries from the boom lift circuit while charging to avoid interference.
Label each charger to avoid cross-wiring.
Regularly check for imbalance between batteries, especially with lead-acid types — unequal aging or sulfation can cause undercharging or overcharging.

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🔋 Alternative / Better Long-Term Option:

If you’re using this equipment regularly, a proper multi-bank or high-voltage charger (e.g., a 48V charger for 4× 12V batteries) is safer, simpler, and more efficient than using multiple smart chargers.

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Would you like help choosing a charger based on your boom lift’s battery setup (how many batteries, total voltage, etc.)?