Key takeaways
- 12V models: maximum 4S4P (four series, four parallel, 16 batteries).
- 24V models: maximum 1S4P — parallel only, never series.
- Series adds voltage, capacity stays the same; parallel adds capacity, voltage stays the same.
- Use the same model, similar age and similar state of charge; equal cable lengths.
1. What series and parallel actually do
| Connection | Voltage | Capacity | Example |
|---|---|---|---|
| Series | Adds up | Same as one battery | 2 × 12V 100Ah → 25.6V 100Ah (2.56 kWh) |
| Parallel | Same as one battery | Adds up | 2 × 24V 200Ah → 24V 400Ah (10.24 kWh) |
| Series + parallel | Series count × 12.8V | Parallel count × 100Ah | 12V 100Ah 4S4P → 51.2V 400Ah (20.5 kWh) |
2. The limits for the four models
| Model | Series | Parallel | Maximum bank |
|---|---|---|---|
| 12V 100Ah | 4S | 4P | 51.2V 400Ah (20.5 kWh) |
| 12V 314Ah | 4S | 4P | 51.2V 1,256Ah (64.3 kWh) |
| 24V 100Ah | 1S | 4P | 25.6V 400Ah (10.24 kWh) |
| 24V 200Ah | 1S | 4P | 25.6V 800Ah (20.48 kWh) |
The 24V models are parallel-only. Connecting two 24V packs in series to make 48V is outside the spec and can damage the BMS. For 48V, use four 12V models in series or a native 48V product.
3. Rules for a bank that stays balanced
- Same model, same age, similar state of charge. Do not mix 100Ah and 314Ah in one bank.
- Charge each battery fully before connecting, then let them rest and check the voltage.
- Use equal cable lengths and the same lug/torque on every battery.
- Fuse the bank positive close to the battery; size the cable for the inverter surge.
- Do not rely on one BMS to protect the whole string — each battery protects itself.
- Re-check torque and balance after the first week, then once a season.
4. Worked examples
24V from two 12V 314Ah: 2S → 25.6V 314Ah, 8,038 Wh. This is a common way to get 24V with the higher-capacity 12V pack; both batteries must be the same model and age.
48V from four 12V 100Ah: 4S → 51.2V 100Ah, 5,120 Wh. Four in series is the maximum for the 12V models; do not add a fifth.
Larger 24V bank: four 24V 200Ah in parallel → 25.6V 800Ah, 20.48 kWh. This is the maximum 1S4P configuration; a fifth pack is outside the limit.
5. Before you connect
Turn off all loads and chargers. Check polarity twice. Use insulated tools and remove metal jewellery. If you are not comfortable working with high-current DC, use a qualified installer — the bank can deliver enough current to weld a wrench.
Common questions
Can I connect two 12V batteries to make 24V?
Yes, 2S is within the 4S limit for the 12V models. Use the same model and age, charge both fully, and check the series voltage before connecting the load.
Can I connect two 24V batteries to make 48V?
No. The 24V models are limited to 1S4P — parallel only. For 48V, use four 12V models in series or a native 48V product.