Fortress Power eFlex 5.4
The Fortress Power eFlex 5.4 is a battery pack with a nominal voltage of 51.2V, a nominal capacity of 105Ah, dimensions of 18x23x7.3 inches 446x546x183 mm, a continuous discharge of 60 A, a peak of 100 A (5 KW 60 Min), a weight of 49kg and an ingress rating of IP65.
Last updated: 28 October 2026
Battery and charging
- Energy (kilowatt-hours)
- 5.374 kWh
- Voltage
- 51.2V
- Rated charge cycles
- 8,000 (@ 80% DoD)
- Nominal capacity
- 105Ah
- Maximum continuous discharge
- 60A (3KW DC)
- Peak discharge
- 100A (5 KW 60 Min)
- Recommended charging
- <55A
- Highest charge current it will take
- 100A
- Efficiency
- >98%
- Charging voltage
- 54.4V
- Depth of discharge it is rated at
- Up to 100%
Row from the maker’s page: “Rated Capacity @ 0.5C (50A):” | “5.374 kWh”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Nominal Voltage:” | “51.2V”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Cycle Life” | “8,000 (@ 80% DoD)”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Nominal Capacity:” | “105AH”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Recommended Continuous Discharge Rate:” | “60A (3KW DC)”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Peak Continuous Discharge Rate:” | “100A (5 KW 60 Min)”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Recommended Charge Current:” | “<55A”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Maximum Charge Current:” | “100A”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Efficiency (at 0.5C):” | “>98%”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Recommended Charge Voltage:” | “54.4V”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Depth of Discharge:” | “Up to 100%”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Battery care and safety
- Ingress protection
- IP65
- Temperatures it may be charged in
- 32°F ~ 114°F (0°C ~ 45°C)
- Temperatures it may be run in
- -4°F~131°F (-20°C ~ 55°C)
- Temperatures it may be stored in
- 20°F ~ 95°F (-6°C ~ 35°C)
Row from the maker’s page: “Enclosure Protection:” | “IP65”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Charge Temperature:” | “32°F ~ 114°F (0°C ~ 45°C)”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Discharge Temperature:” | “-4°F~131°F (-20°C ~ 55°C)”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Storage Temperature:” | “20°F ~ 95°F (-6°C ~ 35°C)”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Size and fit
- Weight
- 49kg
- Overall dimensions
- 18x23x7.3 inches 446x546x183 mm
- Series and parallel connection
- 30
Row from the maker’s page: “Weight:” | “108 lbs (49kg)”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Dimensions: (L*W*H)” | “18x23x7.3 inches 446x546x183 mm”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Row from the maker’s page: “Maximum Allowed Modules in Parallel:” | “30 (162kWh)”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Certification claims
- Standard certified to
- UL9540, UL9540A. UL1973, UL1642, CEC, SGIP
Row from the maker’s page: “Certifications:” | “UL9540, UL9540A. UL1973, UL1642, CEC, SGIP”
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Sources
- Archived document
Source: fortresspower.com/download/947/legacy-data-sheets/47959/fortress-power-eflex-datasheet-english.pdf
Retrieved October 28, 2026