Charging Batteries in Series with a Multi-Bank Charger
Dual Pro multi-bank chargers are engineered with fully independent, electrically isolated charging banks. This design allows each bank to function as its own dedicated 12V smart charger, enabling safe and effective charging of batteries connected in series while using separate 12V leads to each individual battery.
How It Works
Batteries remain connected in series for normal operation:
- A jumper cable connects the negative terminal of the first battery to the positive terminal of the second battery (and so on for additional batteries), creating a 24V, 36V, or higher voltage system for loads such as trolling motors.
Each charging bank connects directly across one 12V battery:
- Bank 1 charges the first battery using its dedicated positive and negative leads.
- Bank 2 charges the second battery using its own separate positive and negative leads.
- Additional banks follow the same principle for 36V and higher systems.
Because the charging banks are fully isolated from one another, each bank only “sees” its own 12V battery. The series jumper between batteries remains in place during charging and does not interfere with the process.
Key Benefits
- Each battery receives its own independent smart charging profile (bulk, absorption, and float stages).
- Batteries stay better balanced over time compared to charging the entire series string with a single higher-voltage charger.
- No need to disconnect the series jumper wires when charging.
- Simultaneous charging of all batteries in the bank.
- Compatible with flooded, AGM, and lithium batteries (when the charger is set to the correct profile).
Common Applications
- Two 12V batteries in series (24V trolling motor systems) – Use a 2-bank charger
- Three 12V batteries in series (36V systems) – Use a 3-bank charger
- Larger series strings using additional isolated banks
Important Notes
- Only use multi-bank chargers with fully isolated outputs. Chargers with shared negatives or non-isolated banks can cause damage or unsafe operation.
- Always match the charger’s output profile to your battery type (flooded lead-acid, AGM, or lithium).
- For best results, disconnect or turn off loads during charging when possible.
- Proper wire gauge, fusing, and installation practices should always be followed per the charger’s manual.
This configuration provides efficient, balanced charging while maintaining the integrity of your series-connected battery system for high-voltage loads.
