How Many Batteries for a 5kW Inverter?
The rule most buyers miss: size the battery bank to the inverter's continuous current limit, not just the watts. A 5kW inverter pulls roughly 104A at 48V — your battery must deliver that without exceeding its 1C rating.
🎯 The basic relationship
Required Ah (at 48V) ≈ Inverter Watts ÷ 48V ÷ 1C
5,000W ÷ 48V = 104A. A 100Ah LiFePO4 at 1C delivers 100A — just under. Step up to 120-150Ah for headroom.
5kW inverter — the math
| Inverter | Current @48V | Minimum bank | Recommended |
|---|---|---|---|
| 5kW | 104A | 48V 100Ah (5kWh) | 48V 120-150Ah (6-7.5kWh) |
| 10kW | 208A | 48V 200Ah (10kWh) | 2 × 48V 120Ah parallel |
Why 1C matters
LiFePO4 is rated for continuous 1C discharge. A 100Ah pack safely gives 100A all day. Push it to 2C (200A) and it heats, the BMS trips, and cycle life drops. Matching the bank to the inverter's 1C draw keeps the pack cool and within warranty.
Parallel packs for bigger inverters
A single 48V 200Ah rack is one option; two 48V 100Ah wall-mounted packs in parallel is another. Both give 200Ah. Parallel needs:
- Identical Ah, same firmware/BMS version on both packs
- A busbar sized for total current (≥ 208A for 10kW → 70mm² copper)
- Equal cable lengths so current splits evenly
Don't forget surge
Motor loads (pumps, compressors) spike 3-5× at startup. If your 5kW inverter must start a 1.5kW pump, the bank must briefly deliver ~300A. A 48V 200Ah bank handles that fine; a 100Ah bank may sag and trip the inverter. Size the bank to the largest surge, then confirm the 1C continuous check.
Need a bank matched to your inverter?
Tell us the inverter model and your loads — we'll size the 48V LiFePO4 bank and confirm the parallel setup.
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