A 100Ah LiFePO4 battery may power a 2000W inverter, but that does not mean it can supply a continuous 2000W AC load. The answer depends on battery voltage, the battery's discharge-current limit, the inverter's requirements and the equipment you actually run.
For example, a single 12.8V, 100Ah battery limited to 100A continuous discharge cannot support a sustained 2000W AC load. Using an assumed 90% inverter efficiency, that load would require about 174A at 12.8V. A lighter load on the same inverter is a different question.
Before buying, check two separate things: whether the battery can deliver enough current now, and whether it stores enough energy for the time you need.
100Ah tells you capacity, not the maximum appliance size
Amp-hours describe battery capacity. Amps describe current. A 100Ah label is not a promise that the battery can deliver any chosen number of amps, and it does not specify the battery's maximum continuous output.
For energy planning, a 12.8V, 100Ah battery has approximately 12.8 × 100 = 1280Wh of nominal energy. Usable energy and runtime still depend on the allowed discharge, operating conditions and system losses. A 25.6V battery with the same 100Ah label has twice that nominal energy; voltage must therefore be part of the comparison.
For power delivery, find the battery manufacturer's maximum continuous discharge current and any separate peak-current rating. The battery's BMS may disconnect the load when its protection limits are reached. Battle Born's BMS guide explains this distinction using ratings for its own batteries; those ratings do not apply to every LiFePO4 battery.
How much battery current does a 2000W load need?
For a steady load, a useful planning estimate is:
DC current (A) ≈ AC load power (W) ÷ [voltage at the inverter's DC input (V) × overall inverter efficiency]
The table below assumes 12.8V at the inverter input and 90% overall efficiency for every row. These are illustrative assumptions, not WZRELB specifications or measured performance. Actual efficiency changes with the operating point.
| Actual AC load | Estimated DC current | Compared with a 100A continuous limit |
|---|---|---|
| 100W | 8.7A | Below the limit in this calculation |
| 500W | 43.4A | Below the limit in this calculation |
| 1000W | 86.8A | Closer to the limit; check other loads and operating conditions |
| 2000W | 173.6A | Exceeds the limit |
As DC voltage falls, the current needed for the same AC load rises. At 12.0V and the same assumed efficiency, 2000W requires approximately 185.2A. Include other loads sharing the battery when checking its total current demand.
Working the calculation backwards, 12.8V × 100A × 0.90 gives 1152W. This is an illustrative current-based ceiling, not a recommended continuous operating target. It leaves no allowance for additional battery loads or changing conditions.
Can I use the 2000W inverter for a 500W appliance?
Potentially, yes. A 2000W rating describes the inverter's output capability; it does not mean that the inverter draws 2000W whenever it is on. With the assumptions above, a steady 500W AC load requires about 43.4A from the battery.
The complete setup still needs compatible DC voltage, sufficient discharge capability and a suitable installation. Check the appliance's startup demand as well as its running watts. An appliance that runs comfortably once started can still cause a shutdown during startup.
For broader load selection, see how to size your inverter. For runtime, use the separate battery capacity and runtime guide.
Why might it shut down even when the battery is charged?
A high state of charge does not remove a current limit. Compare the battery's peak-current allowance and permitted duration with the inverter and appliance requirements. Do not treat a short peak rating as continuous capacity.
Also identify when the shutdown occurs: when the inverter is first connected or enabled, when an appliance starts, or after it has been running. These observations help separate input inrush, appliance startup and sustained-load problems. They are clues, not a diagnosis by themselves.
Record the inverter alarm, the BMS event if available and the connected load. Follow the manufacturers' recovery instructions instead of repeatedly resetting protection. If low voltage appears despite a charged battery, our low-voltage troubleshooting guide explains the next checks.
Five checks before pairing the battery and inverter
- Match the voltage range. Compare the inverter's permitted DC input range with the battery's operating range, including charging conditions. A 12V inverter must not be connected to a 24V bank.
- Check continuous and peak current separately. Read the complete battery discharge specification, including duration and temperature conditions. Add the demands of other battery-powered equipment.
- Check low-voltage behavior. Where settings are adjustable, use the battery manufacturer's guidance. For fixed settings, confirm suitability before purchase. Victron's configuration guidance likewise ties shutdown settings to battery requirements.
- Specify the whole DC circuit. Cables, connections, isolators and DC-rated fuses must suit the installation. A BMS does not replace appropriate circuit protection. See the battery installation guidance; have a qualified installer select the actual components.
- Check charging separately. An inverter-only unit converts battery DC to AC; it does not become a lithium charger because a LiFePO4 battery is connected. Any charger used in the system needs its own compatibility check.
Common questions
Will two 100Ah batteries solve the problem?
Possibly, but first confirm that the battery manufacturer permits the proposed arrangement. Parallel wiring keeps the bank voltage the same and can increase available capacity and current capability. Series wiring raises voltage and requires an inverter matched to the resulting bank. Do not assume two batteries will always share current equally or connect batteries in series simply to run an existing 12V inverter.
Is a 200Ah battery automatically suitable?
No. A larger Ah number increases nominal capacity at the same voltage, but you still need the battery's actual discharge-current specification. Compare the battery model, not just its capacity label.
How long would a 500W load run?
As a separate hypothetical energy example, assume a 12.8V, 100Ah battery, an 80% usable fraction and 90% overall conversion efficiency. Estimated runtime is 1280Wh × 0.80 × 0.90 ÷ 500W = 1.84 hours. This estimate assumes current and startup requirements are already satisfied, no other loads and no charging input. It is not a runtime guarantee.
Choose the battery and inverter as a pair
For help selecting a WZRELB inverter, send your battery model or datasheet, battery voltage, continuous and peak discharge ratings, appliance running and startup requirements, and required AC voltage, frequency and socket type. Include the runtime you want.
Use the website chat or email Sales@powerreliable.com. Those details make it possible to assess the configuration instead of choosing from “100Ah” and “2000W” labels alone.