Fortress Power eVault Max
Fortress states 18.43 kWh nominal energy (Fortress Power eVault Max 18.5, United States).
Fortress states 9.2 kW continuous power (Fortress Power eVault Max 18.5, United States, DC).
Warranty terms: 10 years (Fortress Power eVault Max 18.5, United States).
Brand: Fortress
Published figures
No figures have been collected for usable energy, motor-start current, end-of-warranty capacity, and warranty throughput.
| Figure | Value | Publisher | Source |
|---|---|---|---|
| Nominal energy, Fortress Power eVault Max 18.5 | 18.43 kWh | Manufacturer Not yet checked | Spec sheet, at p.1 / Electrical specifications, retrieved Sep 25, 2026 |
| Continuous power, Fortress Power eVault Max 18.5 (DC) | 9.2 kW | Manufacturer Not yet checked | Spec sheet, at p.1 / Discharge specifications, retrieved Sep 25, 2026 |
| Peak power, Fortress Power eVault Max 18.5 (power side and duration not stated) | 12 kW | Manufacturer Not yet checked | Spec sheet, at p.1 / Discharge specifications, retrieved Sep 25, 2026 |
| Surge power, Fortress Power eVault Max 18.5 | 12.8 kW | Manufacturer Not yet checked | Spec sheet, at p.1 / Discharge specifications, retrieved Sep 25, 2026 |
| Round-trip efficiency, United States, Fortress Power eVault Max 18.5 | 98% | Manufacturer Not yet checked | Spec sheet, at p.1 / Electrical specifications, retrieved Sep 25, 2026 |
| Units per system, Fortress Power eVault Max 18.5 | 20 units | Manufacturer Not yet checked | Spec sheet, at p.1 / Electrical specifications, retrieved Sep 25, 2026 |
| Largest stack, Fortress Power eVault Max 18.5 | 370 kWh | Manufacturer Not yet checked | Spec sheet, at p.1 / Electrical specifications, retrieved Sep 25, 2026 |
| Lowest operating temperature, Fortress Power eVault Max 18.5 (discharging) | −20°C | Manufacturer Not yet checked | Spec sheet, at p.1 / Temperature specifications, retrieved Sep 25, 2026 |
| Lowest operating temperature, Fortress Power eVault Max 18.5 (charging) | 0°C | Manufacturer Not yet checked | Spec sheet, at p.1 / Temperature specifications, retrieved Sep 25, 2026 |
| Highest operating temperature, Fortress Power eVault Max 18.5 (charging) | 49°C | Manufacturer Not yet checked | Spec sheet, at p.1 / Temperature specifications, retrieved Sep 25, 2026 |
| Highest operating temperature, Fortress Power eVault Max 18.5 (discharging) | 60°C | Manufacturer Not yet checked | Spec sheet, at p.1 / Temperature specifications, retrieved Sep 25, 2026 |
| Weight, Fortress Power eVault Max 18.5 | 235.87 kg | Manufacturer Not yet checked | Spec sheet, at p.1 / Mechanical specifications, retrieved Sep 25, 2026 |
See it on the home battery chart
Stated stack range
One unit: 18.43 kWh nominal. Largest stated stack: 370 kWh (energy basis not stated) (20 units).
Stated temperature limits
Stated charging range: 32°F (0°C) to 120.2°F (49°C), Fortress Power eVault Max 18.5.
Stated discharging range: −4°F (−20°C) to 140°F (60°C), Fortress Power eVault Max 18.5.
Warranty terms
| Term | Figure | Document |
|---|---|---|
| Warranty, United States | Fortress Power eVault Max 18.5: 10 years | Warranty, at p.1 / Limited Warranty, retrieved Sep 25, 2026, dated Feb 1, 2022 |
Features the manufacturer states
Configuration: Fortress Power eVault Max 18.5.
| Feature | Stated | Source |
|---|---|---|
| Chemistry | LFP Not yet checked | Spec sheet, at p.1 / Mechanical specifications, retrieved Sep 25, 2026 |
| Coupling | AC or DC Not yet checked | Spec sheet, at p.1 / intro, retrieved Sep 25, 2026 |
| Compatible inverters | Sol-Ark, Fortress Envy (per UL 9540 listing) Not yet checked | Web page, at Models, retrieved Sep 25, 2026, dated Apr 26, 2024 |
| Enclosure rating | IP55 Not yet checked | Spec sheet, at p.1 / Mechanical specifications, retrieved Sep 25, 2026 |
| Nominal battery voltage | 51.2 V Not yet checked | Spec sheet, at p.1 / Electrical specifications, retrieved Sep 25, 2026 |
| Dimensions | 515 x 515 x 1073 (L x W x H) mm Not yet checked | Spec sheet, at p.1 / Mechanical specifications, retrieved Sep 25, 2026 |
Government and program lists
This product is on none of the lists this site reads.
Installs
No install count this site publishes covers this product.
Recalls and safety notices
No notice in the recall sources this site reads is matched to this product. That is not a safety finding. See every recall notice.
- UL 9540 listed: Yes (Fortress Power eVault Max 18.5) as ESS with Sol-Ark 12K/15K or Fortress Envy
- UL 9540A tested: Yes (Fortress Power eVault Max 18.5)
The maker states the listing or test. The listing body's records have not been checked.
Backup hours from your load
This battery has no maker-stated usable energy on this site.