Fortress eFlex User Manual

Table of Contents   

5. About Fortress Power    3
6. Safety Precautions and Instructions    4
7. Data Sheet    6
8. Warranty and Support    8
9. Quickstart Guide    9

7. Unboxing Check List    11
8. System Sizing    14
9. Storage and Self-Discharge    15
10. Temperature Considerations    16
11. Transportation and Handling    17
12. UL9540 / UL9540a Fire Test Report    18
13. Response To Emergency Situations    19

8. Tools & Materials    20
9. Outdoor Installations    21
10. Pre-Installation Checklist    23
11. Mechanical Installation    24
12. Cabinet Options    26
13. Wall Mount    28
14. Electrical Installation    32
15. Battery Communication Circuits    33

6. LED Display    35
7. Inverter Guides    37
8. Voltage and Amperage Settings    38
9. Commissioning    41
10. Decommissioning    43
11. Key Points Summary    44

4. Updating Firmware    45
5. BMS Recovery    46
6. Deep Discharge Recovery    48
7. Removing the eFlex Lid    50

Removing the eFlex Lid    50

7. Fuse Replacement    54
8. BMS Replacement    55
9. Cell Inspection    57

Collecting BMS Data    59

2. Tools Required    59
3. Instructions    59

1. About Fortress Power

Our mission is to provide compact, user-friendly, and affordable energy storage solutions using the latest technology for all homes and businesses. Fortress solar energy storage batteries can easily integrate with new and existing PV systems and work with a wide range of existing inverter and charge controller manufacturers for ease in system design.

Contact Information

Address:

Corporate Headquarters 505 Keystone Rd, Suite D

Southampton, PA 18966 USA

Website: www.fortresspower.com Email: techsupport@fortresspower.com Phone: (877) 497-6937

2. Safety Precautions and Instructions

All types of damage to the product may lead to a leakage of electrolyte or flammable gas. During installation of the battery, the utility grid, solar input must be disconnected from the Battery Pack wiring. Wiring must be carried out by qualified personnel. The battery pack contains no user serviceable parts. High voltage or current is present in the device. The electronics inside the Battery Pack are vulnerable to electrostatic discharge. Observe the following precautions:

• Risks of explosion

• Do not subject the battery pack to strong impacts.
• Do not crush or puncture the battery pack.
• Do not dispose of the battery pack in a fire.

• Risks of fire

• Do not expose the battery pack to temperatures in excess of 122°F (50°C).
• Do not place the battery pack near a heat source such as a fireplace.
• Do not expose the battery pack to direct sunlight.
• Do not allow the battery connectors to touch conductive objects such as wires.

• Risks of electric shock

• Do not disassemble the battery pack
• Do not touch the battery pack with wet hands
• Do not expose the battery pack to moisture or liquids
• Keep the battery pack away from children and animals.

• Risks of damage to the battery pack
• Do not allow the battery pack to come in contact with liquids.
• Do not subject the battery pack to high pressures.
• Do not place any objects on top of the battery pack.

IMPORTANT NOTE: Circuit Breakers, Disconnects and Fuses should be employed throughout the energy storage and generation installation to isolate effectively and protect all components of the system against faults, short circuits, polarity reversals or a failure of any component in the overall system.

Fuses, breakers, wiring ratings and values should be determined by established standards and evaluated by certified electricians, licensed installers, and regional code authorities. The eVault Max must always be installed and commissioned with settings to protect the batteries from open PV voltage and other high voltage charging sources. The eFlex Battery Management System (BMS) alone will not protect the batteries from these extreme electrical events. Failure to adhere to installation protocol will void the warranty.

CAUTION! Verify polarity at all connections with a digital voltmeter before energizing the system. Reverse polarity at the battery terminals will void the warranty and destroy the batteries. Do not short circuit the batteries.

Most batteries pose some risk of shock or sparking during the installation and initial wiring and connection process. Wearing insulated gloves, clothing and footwear and using electrically insulated tools are required when working with eFlex. Cover or remove jewelry or conductive objects (metal bracelets, rings, belt buckles, metal snaps, zippers, etc.) when working with any electrical or mechanical device. Cover or restrain long hair and loose clothing when working with any electrical or mechanical device. CAUTION! Do not disassemble or modify the battery. If the battery housing is damaged, do not touch exposed contents.

3. Data Sheet

Fortress eFlex 5.4 kwh Data Sheet

4. Warranty and Support

Unless otherwise submitting a Fortress warranty through the Guardian hub, please submit your eFlex warranty here:

https://fortresspower.com/warranty

Beyond this product manual, you may also find our inverter guides useful to system installation and commissioning:

https://www.fortresspower.com/inverter-guides

Beyond that, please find additional resources within our Support Portal https://support.fortresspower.com/portal/en/kb

• Create a support ticket
• Inverter Guides
• Product Manuals
• Firmware Updates
• Warranty Submittal
• System Design
• Application Notes
• Scheduled Meetings
• Accessories
• And More!

Note: Sign into the Support Portal to access all features

5. Quickstart Guide

Pre Check List

• System is De-energized
• eFlex is Turned off

1. After unboxing, turn on unit by press-and-releasing the push button and wait for the light show to complete.

• Verify battery voltage of EACH battery 49V with a volt meter
• If the batteries are not within 0.5V of each other, a special process must be followed before commissioning
• Take pictures of the battery serial numbers for warranty submittal.

2. Wire up the batteries. Torque battery cable connections to 7-7.7 Nm or 5.1-5.7 ft-lbs.
3. Install communication circuits.

• Batteries without inverter communication should have CANBus terminators on both ends of the battery-battery communication chain. Hand-tighten but do not over tighten.
• Batteries with inverter communication should substitute one CANBus terminator with the female-female RJ45 pinout connector
• Batteries with the Guardian hub and battery-inverter communication do not use the CANBus terminators.
• See inverter guides for additional programming details.

4. Make any disconnects between inverter and batteries.
5. Turn on the batteries.

• Any battery may be turned on so long as it is within 0.5V of the DC bus voltage.

1. If batteries are not just outside of the 0.5V range, use this procedure to bring the highest and lowest voltage batteries closer together:

1. Turn on the lowest and middle voltage battery and let them settle.
2. Turn on the highest and middle voltage battery and left them settle.
3. If now within 0.5V, proceed to turn on all the batteries. lower group and middle group are within 0.5V, turn them on.

2. Alternately, use an external trickle charger to raise the battery voltage.
3. If charging the batteries individually using solar charging equipment, limit the charge to 60A. Do not use this technique on batteries <49V.

• If installing multiple inverters or charge controllers and they fail to power up, turn the breakers to any secondary inverter or charge controls OFF and repeat step 5 with only the master inverter and charge controller breakers in the ON position. Turn the remaining inverter charger equipment ON after starting up the primary inverter / charger.

6. Use Fortress inverter guides to program inverter settings at https://fotresspower.com/inverter-guides
7. Take a "far away" photo of the completed installation and submit your warranty at https://fortresspower.com/warranty
8. Visit https://support.fortresspower.com to submit technical support requests.

1. Unboxing Check List

Please confirm and do not discard the following items:

CAN Bus Terminator + Cap.

Installed on the last available communication port of the eFlex when paralleling multiple batteries. The terminator is installed backwards into the cap.

RJ45 adapter.

Installed between the eFlex communication port and the battery inverter during closed loop communication on compatible inverter systems.

Alternately, this can be used along with a RS485 cable as a CAN bus terminator if the Can Bus terminator + cap is lost.

RS485 cable + RJ45 Cable + Cable glands

The included RS485 cables are waterproof and moisture proof. Please match environmental ratings of additional RS485 cables if appropriate.

Battery Terminal Caps

The eFlex battery terminal caps have been upgraded to provide additional weather protection and physical contact prevention. Place these caps over battery terminals to protect against accidental contact.

Note: terminal caps have been upgraded and are now screw-on hard plastic.

eFlex Wall Mount Bracket (does not include wall fasteners):

2. System Sizing

Please refer to our sizing guide and warranty letter for appropriate sizes between various inverter models and the eFlex.

https://support.fortresspower.com/portal/en/kb/articles/minimum-battery-sizing

Instead of memorizing the above chart, a good rule of thumb is a maximum of 3.3kW of power output per eFlex without battery-inverter communication. Alternately, you may design with 5kW of power output per eFlex with battery-inverter communication, but it may limit the inverter burst capacity.

Under no circumstance should you install an inverter with charging capacity greater than 100A per eFlex, even if you intend to limit the charge or discharge capacity of the inverter either manually or digitally.

Design questions can be submitted as support tickets at: https://support.fortresspower.com

3. Storage and Self-Discharge

Fortress Lithium Batteries should be stored out of direct sunlight under the following temperature conditions:

Do not expose the battery to high temperatures.

Relative Humidity (Min./Max.): 5%~75% RH Storage Temperature (Min./Max.):

Every 1-3 months:

Systems should be put into storage at 60% SOC and checked to ensure the system SOC does not fall below 20%.

Power the battery off while in long term storage.

The self-discharge rate of the battery is 1% when powered off and SoC is above 20%.

Every 6 months:

Charge the battery to ~60% SoC every 6 months.

Note for leaving energized systems unattended for long periods of time:

If leaving the battery unsupervised for long durations, consider a high battery cutoff voltage. If the site electricity is critical and the solar charging source may become covered by snow or dust, install a backup generator with an autostart. The inverter and battery management system components put a small load on the battery even while other loads are turned off, which can drain the battery if no charging sources are unavailable for long periods of time.

4. Temperature Considerations

CAUTION! Do not attempt to charge the battery below 32 degrees F (0 degrees C). Attempts to charge at subfreezing temperatures can adversely affect State of Health (SOH) and cycle life and will void the warranty; never charge battery if it is frozen; never charge a visibly damaged battery. Charging the battery near freezing should only be done with a low amperage external charger or closed-loop communication inverter, unless the battery bank is heated. There is no need to heat the batteries above 50F.

• Do not charge the battery when ambient temperature is at freezing or below. Discharge current at sub-freezing temperatures should also be significantly reduced. Consider the Fortress DuraRack cabinet for din-rail friendly heater installation.

CAUTION! Do Not Operate Fortress Lithium Batteries where average internal battery temperature exceeds 30 °C / 86 °F over the life of the battery.

Recommended operating parameters of charger/Inverters For 3,000 Cycles:

• Internal battery temperature range: 32 F to 120 F (0 °C to 49°C) without close-loop communication.
• Bulk voltage and absorb voltage should be set to 54.4V if no battery-inverter communication is available.

Recommended operating parameters of charger/Inverters For 8,000+ Cycles:

• Operating temperature range: 50 F to 110 F (10°C to 43°C) with closed-loop communication

5. Transportation and Handling

• Do not knock, drop, puncture, or crush the battery;
• Do not expose battery to flames, incinerate or direct sunlight;
• Do not open battery case or disassemble the battery;
• Do not lift battery by the terminal cables;
• Do not vibrate battery;
• Do not expose battery to water or other fluids;
• Do not expose battery to open flame;
• Do not place the product nearby highly flammable materials, it may lead to fire or explosion in case of accident; Store at cool and dry place.
• Do not store in greenhouses and storage areas for hay, straw, chaff, animal feed, fertilizers, vegetables or fruit products;
• Store the product on a flat surface; A ventilated area is strongly recommended for handling the product;
• Store the product out of reach of children and animals;
• Store the product where it should be minimal dust and dirt in the area; do not transport battery upside down or with the terminals towards the ground.
• Batteries should be discharged to 30% state of charge or 52.0V resting voltage before transporting.

6. UL9540 / UL9540a Fire Test Report

The eFlex has been listed to UL9540 standards as a DC ESS, without any dependency upon an external inverter or power conditioning system. It has passed the UL9540a large scale fire testing. Here is a sample directly from the report:

Find more information on the Fortress eFlex product page in the Downloads section: https://www.fortresspower.com/products/eflex-5-4kwh-lifepo-battery/

7. Response To Emergency Situations

The battery pack consists of multiple batteries and a sophisticated Battery Management System that are designed to prevent hazards resulting from failures.However, Fortress Power cannot guarantee their absolute safety.

• Leaking Batteries
• If the battery pack leaks electrolyte, avoid contact with the leaking liquid or gas. If a person is exposed to the leaked substance, immediately perform the actions described below.
• Inhalation: Evacuate the contaminated area and seek medical attention.
• Contact with eyes: Rinse eyes with flowing water for 15 minutes and seek medical attention.
• Contact with skin: Wash the affected area thoroughly with soap and water, and seek medical attention
• Ingestion: Induce vomiting, and seek medical attention
• Fire
• In case of fire, make sure that an extinguisher is available near the battery pack. If possible, move the battery pack to a safe area before it catches fire.

Note: Fire extinguisher

• Water, carbon dioxide, dry chemical powder and foam are the most effective means to extinguish a Lithium Ferrous Phosphate (LFP) battery fire
• Use ABC Fire extinguisher, if the fire is not from battery and has not spread to it yet.

1. Tools & Materials

The following tools and materials are required:

• Positive and negative battery cables, we recommend copper cable starting at 1/0 AWG for runs of less than 10ft. Please refer to your adopted version of the National Electric Code or Local Authority Having Jurisdiction for more guidance (not included)
• Positive and Negative Terminal lug recommendation: M8 (diameter: 8mm or 5/16in). Note that the ring terminal size for the terminal lug is 3/8ths or larger.
• Screwdriver (not included) • Battery parallel communications cable (included)
• Inverter to Battery CAT5/5e communications cable (not included)
• Communication Bus Terminator: to Match Impedance during parallel setup
• RS 485 cable
• Wall Mount Stabilizers (included)
• OHSA approved personal protective equipment such as the following (not included)

2. Outdoor Installations

The Fortress eFlex is an IP65 battery with a 1/4" thick aluminum case.

It is suitable for indoor and outdoor use, both residential and commercial.

It does not emit any gas during operation and has passed UL9540a large-scale fire unit tests.

The eFlex should not be installed in direct exposure to the sun.

Likewise, its terminal caps should be protected against rain. Heated

battery cabinets are also recommended where operating temperatures are below 40F, even if staying above freezing.

Consider the DuraRack battery cabinet in cold, very hot, or very humid Outdoor environments.

When wall mounting outdoors, only one configuration is allowed:

Mounting in any other orientation may void the warranty.

When wall mounting indoors, the eFlex may be mounted in any orientation except with the lid facing right, with the text logo upside down:

3. Pre-Installation Checklist

• Check the battery package, type, quantity, appearance and other components for damage and completeness
• Check the battery terminals and connections to make sure they are clean, free of dirt, fluids or corrosion
• All battery cables and their connections should be tight, intact, and NOT broken or frayed
• Check torque on terminal bolts
• Replace any damaged batteries and cables.
• Check the Open Circuit Voltage.
• Set the battery on a clean working space.
• Make sure the + and - terminals are not contacting anything.
• Locate the eFlex Power Button and press it momentarily. Wait for ~10 seconds for the LED self - diagnostic to complete before continuing to the next eFlex.
• Confirm that the LED lights are green and that the BMS light does not remain on. The operator should see the LED lights indicating the battery state of charge.
• Using a Voltage Meter check that the voltage across the terminals is between 50V- 55V.

1. If Voltage is <50V, charge the battery using an approved battery charger.
2. If the Voltage is >55V, contact Fortress Power.

IMPORTANT NOTE: Please inform us of any problems with the battery within 7 days of receipt of goods. Otherwise, we will deem the product delivered in good condition

The battery pack must be installed indoors. In addition, make sure that the installation location meets the following conditions:

• At minimum, the eFlex should be protected from inclement weather with a cover/enclosure. The IP65 rating of the eFlex prevents ingress of direct water spray and dust. However, the eFlex cannot be immersed in water, nor are its exposed terminals waterproof.
• The area is completely waterproof.
• The floor is flat and level (Inclination < 15°).
• There are no flammable or explosive materials nearby.
• The optimal ambient temperature is within the range from 59° to 95°.
• The temperature and humidity are maintained at a constant level.
• There is minimal dust and dirt in the area. IMPORTANT NOTE: If the ambient temperature is outside the operating range, the battery pack may stop operating to protect itself. Frequent exposure to harsh temperatures may deteriorate the performance and life of the battery pack.

4. Mechanical Installation

Mounting the battery pack to a wall

The eFlex 5.4 can be easily wall-mounted using the included wall mount bracket. The wall- mounting brackets are sold separately. Please ensure the wall and mounting hardware can handle the weight of the batteries. Please note that wall mounting the eFlex is not an acceptable UL9540a fire tested installation configuration. However, Fortress Power allows the eFlex to be wall mounted.

Before getting started, please see Site Selection for section of this manual for allowable orientation of wall mounted eFlex.

1. Line up the top bracket on the wall.

1. Mark the desired placement using a level to ensure the bracket is horizontal
2. Affix the larger mounting bracket into the wall

2. Using the T-slot screws, fix the smaller brackets onto the eFlex.
3. Carefully lift the battery with the help of a second person and gently drop it into the wall mounted brackets.
4. Screw in the security screw into the center mounting location using the included hex key. It may be necessary for a second person to position the battery while performing this task. Floor mount installation

The eFlex 5.4 can be floor-mounted in several orientations. The orientation depicted to the right, with the terminals towards the ground, is the only orientation NOT allowed. All other orientations are allowed, but regardless of orientation, the included floor mounting bracket must be used to prevent the battery from tipping over. Therefore, it is common to put the back of the eFlex battery against the wall.

1. Place the eFlex in the preferred orientation.
2. Attach the mounting bracket using the T-slot fastener and T-slot groove on the back of the eFlex.
3. Screw the mounting bracket into the wall.
4. Connect the battery terminals to the corresponding bus bar and inverter.

Other installation methods

The eFlex is designed for multiple installation methods. The T-slot at the back of the enclosure provides the flexibility to use a standard size 8 - M6 or M8 hammer screw to secure the battery to a variety of racks, including 19” server racks. In all cases, a clearance of 1” around the eFlex battery is required. Please visit https://www.fortresspower.com/fortress-power-video-library- 2/ for videos on installing the eFlex.

5. Cabinet Options

Note: Fortress Power allows wall mounting, cabinet mounting with Fortress- approved cabinets, and floor-mounting as valid cabinet mounting options.

Installers are also welcome to fashion their own racking, utilizing the T- channel slots on the back of the eFlex.

Use of Fortress DuraRack or Flextower cabinets are recommended for additional environmental production, security, and appearance but are not required by Fortress Power. The DuraRack is included with the FlexTower. Battery-combiner cables are included with either cabinet option (battery- inverter cables not included).

The Fortress eFlex is UL9540 listed regardless of what mounting methodology is selected. Use of the DuraRack may be required by your local jurisdiction for UL9540a compliance. Please see product pages for additional UL9540 information.

Please visit the eFlex section of our support center for DuraRack or FlexRack manuals. https://support.fortresspower.com/portal/en/kb/product-manuals/eflex

DuraRack

FlexTower

6. Wall Mount

The eFlex should not be installed in direct exposure to the sun.

When wall mounting outdoors, only one configuration is allowed.

Do not wall mount the eFlex in any other orientation.

1. Attach the smaller wall mount bracket (wall mount hook) to the eFlex.

The Fortress logo will be upright when mounted. The eFlex lid will be on the right side of the battery in the correct orientation.

Use the provided T-bolts to connect to one of the eFlex T-slot channels on the back of the

case. Torque strongly.

2. Attach the larger wall mount bracket (wall mount plate) to the wall.

Mark the desired placement using a level to ensure the bracket is horizontal Affix the larger mounting bracket into the wall using appropriate mounting screws or bolts in the Eight, ¼ x 1 ¾ inch slots. The fasteners cannot project more then ¼ inch from the plate or they will interfere with

the alignment of the eFlex.

Install the security bolt into the wall mounting plate threading as the bolt hole location. Only install a few turns.

Note: Early eFlex wall hooks do not have a key hole slot. For these installations, Installers should line up center holes on the wall mount hook and plate, and install the bolt from the top down.

3. Attach the eFlex to the wall mount plate and insert bolt.

Using two or three persons, lift the eFlex over the wall mount plate. Lift the eFlex and align the security bolt so the head passes through the key slot.

Position the eFlex so the bolt goes through the keyhole as shown. The slide the eFlex to the narrow part of the keyhole before tightening the bolt.

Do not use the eFlex wall mount without the security bolt.

Note: The security bolt is M4 0.7 pitch x 30mm stainless cap bolt. You may want to substitute a M4 0.7 pitch x 100mm or longer which makes setting the eFlex easier, but requires more turns to tighten the bolt.

eFlex Wall mount bracket (wall hook - attach to eFlex)

Wall Mount Bracket (Wall Plate - attach to wall):

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7. Electrical Installation

Connecting the battery to the Charge Controller and/or Hybrid Inverter

1. Ensure the battery is turned off by verifying the LED lights are is off and there is no voltage across the terminals.
2. Install the positive cable first and the negative cable second. Do not cross the positive and negative terminals; also, ensure the terminals are not connected to any metal mounting, fixture, or body part. Ensure the terminals are tightened to the recommended terminal torque of 7.0 – 7.7 Nm (5.1 – 5.7 ft-lb)

The Fortress Lithium Batteries are equipped with two M8 threaded terminals with a lock washer and nut. 8mm ring terminals or 3/8ths inch ring terminals, along with proper size wiring cables, are required to connect the battery to the inverter/charger. Do not reverse polarity-- doing so will void warranty. Use a voltmeter to check polarity before connecting terminals.

8. Battery Communication Circuits

Using RS485 modbus and CAN communication

The eFlex 5.4 has two universal ports on the lid of the battery, which handle both the battery-battery and battery-inverter communication.

Battery-inverter communication is not required for the eFlex 5.4 to safely operate with most programmable 48V inverters.

At a minimum, the inverters need to be digitally programmed to comply with correct amperage and voltage stated elsewhere in this guide. Special communication cables may need to be field made. If using battery-inverter communication, please consult our inverter guides: https://www.fortresspower.com/inverter-guides

Fortress eFlex batteries also contain battery-battery communication circuits. This communication circuit is required to be installed unless otherwise directed by Fortress technical support. Battery-battery communication requires a canbus terminator be installed at one end of the battery communication circuit. The other end of the circuit either requires another canbus terminator, or the RJ45 pinout converter to terminate the battery-battery communication while passing through the battery-inverter communication. Do not forget to install the RJ45 pinout converter when using battery- inverter communication!

Battery-battery communication is installed as pictured:

If making a communication cable, please refer to the pin out diagram for an RJ45 cable below.

Type A format ethernet cable may also be used.

1. LED Display

The eFlex has six LEDs on the front face allowing the user to decode the state of the battery as well as any important messages from the BMS. When the eFlex is turned on, each LED will also turn on and display a LED mode.

The red “BMS” light will turn on during start-up diagnostic as well as when there is a communication error between batteries. If the problem persists, please fill out a support ticket at https://support.fortresspower.com .

In normal operation, the “RUN” LED light will be on or flashing.

The number of charging lights (LED1-4) that are on depends on the battery state of charge.

If the BMS requires calibration, perform the following steps:

If the batteries are showing four green State-of-Charge LEDs, but the battery resting voltage is below 54V, manually charge the battery to 54.4V. If the batteries are showing less than four green SoC LEDs, charge the battery manually to 56V or until the SoC lights all show solid green. Then restore original inverter settings.

See chart below:

2. Inverter Guides

Fortress inverter guides are for programming popular 3rd party inverters. They also serve as a "quick start" guide for powering up the entire system.

They are found in our online knowledge base: https://support.fortresspower.com/portal/en/kb

Please differ to our product documentation when programming the inverter with Fortress batteries.

For example, if the inverter manufacturer says charge the battery at 56.7V, and our inverter guide indicates a charge rate of 56V, please use the voltage listed in our inverter guide.

Charge rates listed in Fortress inverter guides are based on lab testing and field feedback.

We have inverter guides for:

• Sol-Ark
• Schneider
• SMA
• Victron
• Outback
• Magnum
• LuxPower
• Studer
• Morningstar
• Phocos

For additional inverter sizing and compability information, pleae visit: https://www.fortresspower.com/dealers/inverter-compatibility/

When using an inverter or charge controller that is not on the above list, the charge conditions listed in this product manual are sufficient. Fortress Inverter guides can expand system charge/discharge voltages and amperage beyond values stated in this guide while maintaining Fortress warranty. In most cases, these expanded settings require successful communication between the battery and inverter.

3. Voltage and Amperage Settings

The battery must be transported, stored, and used according to the instructions in this manual. If any of the following improper operations occur, this product will cancel the warranty.

• Do not use unqualified equipment for charging and discharging, please follow the correct instructions for use
• Do not discharge the battery when the battery is depleted
• Do not charge or discharge batteries that are hot, deformed, or leaking.
• The output cable length of the battery should be less than 10 meters long
• Do not connect a power and load that exceed the power level to the two ends of the battery
• Do not mix different batteries
• Different manufacturers, chemistry, models, and lifespans cannot be paralleled.

Charging Voltage:

Without battery-inverter communication, eFlex batteries should be charged at 54.4V

With battery-inverter communication, eFlex batteries this voltage may be increased according to the published inverter guides:

https://www.fortresspower.com/inverter-guides

Low battery cut-off voltage:

The eFlex battery is below a 20% state-of-charge when its resting voltage is below 51.4V In order to keep the inverter and battery system powered up while waiting for a charge, this is the recommended low battery cut-off voltage. It is appropriate to lower this to 51V if using a generator or grid charge to automatically maintain or charge the battery at 51.4V or above. Many older battery inverters cannot program a low battery cut-out voltage above 48V. The eFlex has a safety feature that will cut around this voltage level if necessary. If regularly deep discharging the eFlex down to 48V, please increase your battery size or upgrade your inverter to maintain warranty compliance.

Charging and Discharging Amperage

The eFlex can safely operate at 100A, but its maximum rating is not intended for long duration use. Unless otherwise specified through our inverter guides, set the charge and discharge rates of the eFlex at 60A to comply with the 10 year warranty. Any grid sellback or demand management function should also be limited to 60A per eFlex. Limiting the charge rate of the eFlex to 60A will result in longest battery life.

Precaution should be taken when adding charging sources which are not controlled by a single inverter or control system (Ex. using different manufacturer's DC charge controllers and inverters, solar + wind inverters, EV chargers etc) to ensure the total system charges or discharges the battery within its specification. controllers do not charge the battery concurrently, when and if their combined charge current totals are greater than the charge current of the combined battery bank. Take additional extra precautions when using wind power to charge the battery, or if the inverter and charge controllers are not the same manufacturer.

Charging Notes

If the following scenarios occur, the battery must be charged before use, otherwise the battery damage caused is not covered by the warranty:

• The battery has not been powered on or otherwise discharged without any charging sources available.
• The battery has been turned off for a long period during transportation or storage.
• The battery has been deeply discharged and reached under-voltage protection status.
• The battery has been aggressively recharged during deep discharge conditions through bypassing the BMS
• The battery has been recharged during freezing condition through bypassing the BMS.
• Bypassing the BMS is not allowed without logging a support ticket with Fotress Technical Support at https://support.fortresspower.com

Discharging Notes

• Do not regularly discharge battery below 51V, 20% SoC. This capacity should be reserved for power outages and idleing the load until a charging source can be applied.
• Do not discharge battery at rates greater than maximum continuous current.

Parameter set up guide for Charger/Inverter

Unless explicitly stated in Fortress inverter guides or contrary to the above charging amperages and voltages, charge controller and inverter settings must be programmed per the manufacturer’s recommendations. Consult the manufacturer’s manuals and/or access technical support. In order to achieve extended life cycles and to comply with the Warranty, the following guidelines should be followed:

Understanding Charge Stage

1. Bulk Charge: Charge at Constant Current (CC) to Bulk/Absorb Voltage.
2. Absorption Charge: Maintain Constant Bulk/Absorb Voltage (CV). Note - if the battery is not reaching 100% capacity, it is allowable to adjust this voltage from 54.4V to 55V. Any higher charging voltage must be explicitly stated a Fortress inverter guide specific to that brand of inverter.
3. Unless otherwise stated in a Fortress inverter guide, keep float voltages at 54.4V or less to maintain warranty compliance. While most end users will want to enable a float mode of operation if available to keep batteries at 100%, it is healthier for the battery only to use the bulk/absorb cycle - which allows the batteries to exercise daily.