How Big an Inverter Can One 100 Ah LiFePO4 Battery Run? Amps at Full Load Against the Battery's Limit
Summary
About 1,000 W continuously, on most 100 Ah lithium batteries. At 12.8 V and 90% inverter efficiency, a 1,000 W load pulls about 87 A from the battery, a 2,000 W load about 174 A and a 3,000 W load about 260 A. Victron's Lithium NG 100 Ah allows 100 A continuous; its Lithium Smart 100 Ah allows 200 A but recommends 100 A or less. Renogy's 12 V inverters are sold at 700, 1,000, 2,000 and 3,000 W, with surge ratings of double and no-load draws of 0.8 to 2.5 A, and the datasheet shuts the inverter down at 10.5 V.
Current at full load
| Inverter rating | Battery current at 12.8 V, 90% efficiency | Renogy surge rating | Renogy no-load draw |
|---|---|---|---|
| 700 W | about 61 A | 1,400 W | 0.8 A |
| 1,000 W | about 87 A | 2,000 W | 1.0 A |
| 2,000 W | about 174 A | 4,000 W | 2.0 A |
| 3,000 W | about 260 A | 6,000 W | 2.5 A |
The current column is our arithmetic. Renogy's datasheet gives the surge and no-load figures and does not state efficiency per model; its 2,000 W product page says "over 90%," which is the figure we used.
Against the battery's data sheet
| Battery | Max continuous discharge | Largest inverter at full load |
|---|---|---|
| Victron Lithium NG 12.8 V/100 Ah | 100 A (1C) | 1,000 W (about 87 A) |
| Victron Lithium Smart 12.8 V/100 Ah | 200 A, 100 A recommended | 2,000 W at the maximum; 1,000 W within the recommendation |
| Victron Lithium NG 12.8 V/300 Ah | 300 A (1C) | 3,000 W (about 260 A) |
| Victron Lithium Smart 12.8 V/330 Ah | 400 A, 300 A recommended | 3,000 W |
Surge is the second check. A 2,000 W inverter's 4,000 W surge would ask about 350 A for a moment; the NG 100 Ah lists a 200 A ten-second peak, so even the brief start of a large motor is outside it. Two batteries in parallel double both limits, which is the usual answer when the inverter is bigger than the battery.
The voltage cut-off is the other way to lose power
Renogy's inverters sound a low-battery alarm at 11 V ±0.3 and shut down at 10.5 V ±0.3. A lithium battery holds voltage until it is nearly empty, so the shutdown arrives late and suddenly; heavy loads also pull the terminal voltage down, which can trip the alarm with charge still in the cells.
Idle draw is paid every hour
The no-load currents above become 0.8 to 2.5 A around the clock if the inverter stays on: about 290 Wh a day for the 1,000 W unit and about 580 Wh for the 2,000 W, a quarter to nearly half of a 100 Ah battery's 1,280 Wh. Switch the inverter off, or use the remote switch Renogy includes, when nothing needs AC. The 3,000 W unit ships without battery cables.
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Sources
- Victron Energy — Lithium NG 12,8 V manual, Technical data
- Victron Energy — Lithium Smart Battery Manual, 7. Technical data
- Renogy — 12V Pure Sine Wave Inverter datasheet (700/1000/2000/3000 W)
- Renogy — 2000W 12V Pure Sine Wave Inverter
We have not tested these products. Specs, prices, stock and terms are as published on these pages on the date above and can change; check the manufacturer or retailer before you buy.