Fortress Power FlexTower DuraRack User manual

Table of Contents
About Fortress Power....................................................................................................................................2
About FlexTower All-In-One Cabinet.............................................................................................................2
General Safety Precautions and Safety Instructions .....................................................................................3
Transportation and Handling.........................................................................................................................4
Response To Emergency Situations...............................................................................................................4
Required Tools & Materials ...........................................................................................................................5
Included with FlexTower................................................................................................................................6
FlexRack Installation Steps ............................................................................................................................7
Multiple FlexTowers / Spacing Requirements.............................................................................................14
Torque Specifications ..................................................................................................................................15
Inverter Programming .................................................................................................................................15
Grounding and Stability...........................................................................................................................16
External Views..............................................................................................................................................18
Wire Sizing ...................................................................................................................................................18
Heating for Flextower..................................................................................................................................20
Fan Maintenance .........................................................................................................................................21
Operating Temperatures .............................................................................................................................22
Storage and Self-Discharge..........................................................................................................................22
SolArk 15kW Wire Diagram Example...........................................................................................................23

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: [email protected]m
Phone: [phone]
About FlexTower All-In-One Cabinet
The FlexTower All-In-One cabinet is designed to
hold up to a 15kW inverter in the upper cabinet with up
to four eFlex 5.4 KWH lithium batteries in the lower
cabinet, in an indoor or outdoor setting. The cabinet is
NEMA3R rated and the battery compartment was made
part of the eFlex UL9540 large-scale fire testing.
The cabinet includes a combining busbar, battery cables
to the busbar, inverter cabinet cooling fan control
powered from the batteries directly. It also includes
multiple side knockouts for flexible expansion, including
paralleling two FlexTower cabinets, or adding in
multiple sources of power (grid, generator, EV charger,
communication lines etc). The cabinet should stand
level on a stable foundation. It includes anchor bolt to
optionally secure the DuraRack to a concrete pad.
At this time, only battery conductors and a combiner are included. Specifically, power
cables between the combining busbar and inverter. Additionally, battery heaters are not
included, but can be added to the lower battery cabinet through included din-rail mounting
discussed later within this manual.

General 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 FlexTower must always be installed
and commissioned with settings to protect the batteries from open PV voltage and other high voltage charging
sources. The 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 batteries. 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.

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;
•Do not transport battery upside down.
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.
• 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.

Required Tools & Materials
The following tools and materials are required:
•Positive battery-combiner-to-inverter cable –22.5” flexible 2/0 AWG
•Negative battery-combiner-to-inverter cable –24” flexible 2/0 AWG
•2/0 Crimp Terminal lugs for above cables with ring size of 3/8ths or larger
•Screwdriver (not included)
•M3, M5, M6 Hey Keys
•snap in knockout bushing for inverter knockouts (various sizes –depends on
application)
•three ¾” washers with ¼” holes
•utility knife
•outdoor rated sealant
•conduit connectors
•Guardian monitoring hub (optional)
•Din-rail 120V AC thermostat heater (optional)
•OHSA approved personal protective equipment such as the following (not
included)

Included with FlexTower
FlexTower Upper Inverter Cabinet
fasteners for upper and lower inverter mounting rails
FlexTower Lower Inverter Cabinet (DuraRack)
4 x red and black battery cables
2 x battery combiner blocks with 3 mounting ring terminal + bolts and 2 x low amperage connections
(for DC fan + fan controls)
2 x din rails + bolts for din rail mounting
4 x floor mount expansion bolts

FlexRack Installation Steps
1. Open boxes and confirm all components are included and in
working order.
Contact Fortress power if the box is damaged prior to opening. Open box,
Tilt Box on edge with top side up then slide out of box. The rack boxes are
heavy [lower cabinet (DuraRack) 150 pounds, upper cabinet (FlexTower)
134 pounds].
Turn on eFlex batteries and confirm battery voltage using a voltmeter or
Guardian monitoring hub. Individually pre-charge each eFlex to within 1/2V
of the other batteries.
Record the serial number of the upper
and lower battery cabinet units, inside
the door at the lower hinge.

2. Install at desired location.
The FlexTower is designed to be pad or floor mounted. There are 4 mounting holes provided, along with
M10 masonry sleave anchor bolts and nuts. Note the location of external grounding tabs on both sides
of the lower battery cabinet.
A 3” concrete pad or greater is recommended but strength of
pad is dependent on sub-base / location. The M10 expansion
bolts have a 12mm sheathing so a ½” masonry drill is
necessary. Drill approximately ½” deeper than the intended
depth of the sleave anchor bolt, at least 1.5” deep, and use a
hammer drill to drive the anchors into place, positioning the
nut on the bolt as to protect the threads when driving into
place.

The DuraRack cabinet contains a floor plate that allows for ground mounting using M10 bolts.
3. Set the cabinets on top of each other.
When installing the upper battery cabinet on top of the lower battery cabinet, remove the two
top watertight feedthrough covers on the lower cabinet, using a razor knife on cabinet gromet.
Set the upper inverter cabinet on top of the lower cabinet and then affix the two cabinets
together using provided 8 attachment screws. Do not perform this step with the batteries or
inverters inside the cabinet.
Use the waterproofing tape around the interior edges of the upper inverter cabinet before
setting on top of the lower battery cabinet:
4. Mounting and wiring Combiner Block

Connect the included battery-to-combiner power cables to the busbar, if not pre-wired. Use red
for positive and black for negative, taking care not to reverse these cables. If the battery-to-
busbar power cables are pre-wired, remove any cables which will not be used. Only install the
correct number of battery cables, equal to the number of eFlex batteries. Torque the
connections to 7-9 ft lbs / 10-12 Nm.
The combiner blocks are mounted on the upper bay din rail. The dinrail should be in the lowest position,
if not mounted already. You may make up the combiner blocks before
installing the dinrail, or install the din rail and then make up the combiner
block wiring.
Make and connect the combiner-to-inverter power cables (not
included). Space is provided on the combiner to accommodate single
or parallel cable runs. Use fine stranded
cable, with a manufacturer required
minimum wire size of 2/0 on single
conductor runs 10’ or less, or up to 4/0 maximum. Note: if using 4/0
cable, check terminal lug width to ensure compatibility with inverter
port. UL battery cable is recommended. DLO cable can be used, but is
difficult to bend in the space provided. If using parallel conductor runs
to an inverter (Ex. Envy 12k, Sol-Ark 15k configurations), use 1/0 cable
minimum when running parallel power conductors to the inverter. Do
not use larger than 2/0 cable for parallel runs.
The combiner block provides 3 positions for connecting 2/0 using 5/16 lugs. The combiner block also
provide 2 positions for low current connections supporting Flex Tower Fan and Guardian Power. You
may double lug on either of these lower power connections, or single lug. MAKE ALL OF THESE
CONNECTIONS TO THE COMBINER BEFORE INSTALLING EFLEX INTO THE LOWER BATTERY CABINET.

The DC fan power cables are also powered by the battery. The entire system has a 48V DC power
lead which is to be routed through the FlexTower to land on the busbar terminals inside the lower
battery cabinet.

5. Install, wire, and secure the eFlex batteries.
Up to four batteries can be installed using the supplied mounting
brackets. The batteries each weigh over 100 pounds and the Dura
Rack has limited space. Wire each eFlex at an angle, as it is being
placed into the cabinet. Load the eFlex batteries from back to front,
landing the battery-to-combiner conductors onto the combiner
block as you go. Additionally, use the security straps to secure the
eFlex batteries to the cabinet as you go.
Attach the metal strap to the back of the eFlex, using the lower T-
slot channel. The strap hugs the bottom of the eFlex and is secured
by a bolt in the front.
The front of the metal strap is secured to a mounting hole at the
front of the shelf of the FlexTower.
6. Install the battery-to-battery and battery-inverter communication circuit.
See Fortress inverter guides in our online knowledge base for inverter-specific instructions at
https://support.fortresspower.com. You may also find useful information in the Guardian
installation manual.
Do not forget the RJ45 pinout connector between the eFlex and the inverter (which contains a
canbus terminator), as well as the canbus terminator on the final communication port at the
end of the eFlex communication circuit. If installing a Guardian monitoring hub, this final
canbus terminator will be replaced by the canbus terminator contained within the Guardian
hub.

7. Install the inverter.
Two adjustable height mounting rails are
included to attach to any inverter using the
inverter-supplied wall mounting brackets.
The rail locations are flexible to
accommodate different inverter mounting
plates.
Most 8kW inverters have plenty of room to
fit inside the Flextower, starting with the
2nd mounting location from the top of the
rail supports. Note: The Outback Mohave
inverter does not fit inside the FlexTower
If installing a 12k or 15k inverter, position the upmost rail in the top mounting slot. The FlexTower
is designed to exhaust heat from the cabinet through 48V DC fans mounted to the side of the
inverter, sized for inverters of this class.
If in doubt on rail placement, start with the tallest mounting location –especially if using a 12k or
15k inverter. Some inverter mounting plates may require custom attachment to the back inverter
support rails.
8. Commissioning the System
Fortress Power maintains documentation on its batteries and inverters within its Product
Manuals, which can be found at https://support.fortresspower.com
When using a 3rd party inverter, please refer to our Inverter Guides, also found on the Fortress
Power support page linked above.

Multiple FlexTowers / Spacing Requirements
The Flextower is a NEMA3R cabinet which be stacked adjacent to other FlexTower units
including just the lower battery cabinet (i.e. the DuraRack).
The internal battery combiner block is rated for 500A and intended for direct paralleling of up
to two battery cabinets.
When installing more than two cabinets, external battery combiners (even if mounted within
the DuraRack) are be necessary, particularly where battery inverter power sources exceed 500A
DC.
It may be necessary to provide battery-battery CAT6 communication cables when paralleling
multiple battery cabinets together for battery-battery communication.
Maintain at least 6” clearance to the right of the FlexTower upper cabinet to maintain airflow from the
internal fan. Maintain at least 3’ clearance in front of the FlexTower. Maintain at least 1” clearance
otherwise (additional clearance is recommended for installation ease). The minimum required spacing
between FlexTower units to remain compliant with UL9540 large-scale fire testing is 1”. When installing
within an air-conditioned space where use of internal fans is not necessary, only a 1” clearance is
needed.
If installing outdoors, use raintight conduit connectors.

Torque Specifications
**Please note: Battery to inverter cables are for 3/8 ring crimp lug
Please use the following Torque Values for the above steps:
Bolting Specification
Torque Value (Nm)
M4*8 Hexagon socket screw
1.0~1.8
M6*15 Ground Bolt
3.6~4.8
M8*20 Combining Screw
9.8~12
M10 Expansion Bolt
19.6~32.2
Inverter Programming
See Fortress eFlex Guide for programming and commissioning the eFlex Batteries.

Grounding and Stability
Grounding Method
Grounding tabs are located both inside and outside the lower battery cabinet.
The green bonding cables are placed on cabinet doors to bond the doors to the rest of the
cabinet. The FlexTower upper cabinet is bonded to the DuraRack via an included bonding
jumper.

External Views
Wire Sizing
The FlexTower includes a 500A busbar as well as #4 AWG Flexible Cable sized for each eFlex
battery. Installers should use flexible cable if installing their own battery cable. The combiner-
to-inverter run should be a minimum of 2/0 flexible cable, or 1/0 when a single inverter
requires parallel conductors (4/0)
Refer to the Inverter Guide and Product Manual eFlex 5.4 for the battery operation and
maintenance information.
Please see the following for the required cabling between the inverter and battery:

Heating for Flextower
Heating must be added to the lower cabinet should if installed in environments which fall below
sustained temperatures of 40F during the year to avoid throttling back or disconnection of battery
power.
The colder environments, the larger and more important the need for external heating.
AC-din rail heating options
An easy heating option is to route 120V AC power circuit to the lower battery cabinet
Example:
https://www.stego-usa.com/products/heating/heaters/csf-060-50w-150w-w-thermostat/
Part number 06001.0-00 is 50W and suitable for mild climates where winter temperatures get down
below 40F each year. Part number 06011.0-00 is 100W and suitable for moderate climates where
winter temperatures reach 20F each year. Part number 06021.0-00 is 150W and suitable for cold
climates where winter tempertures fall below 20F each year.
DC-din rail heating options
Another option is to install a DC-powered heating system, avoiding the need to run 120V AC power.
Fortress has not found any readily-available, off the shelf heating solutions for 48V DC power. Installers
may need to find separate heating elements, thermostats, and switch controls and wire these devices
together to form a complete heating system.
Example (note: items may be difficult to source):
Heater: Stego 04640.2-00 –is a din-rail mounted heater.
https://docs.rs-online.com/e1bf/A700000006486356.pdf
Thermostat with integrated Switch: Stego 01011.0-31 or 01011.0-32 can be wired directly to the DC
busbar inside the DuraRack. https://www.stego-
usa.com/products/regulating/regulators/dct-010-electronic-thermostat-dc-20-v-to-
56-v/
Other approaches may involve relays or switches that are separate from the thermostat, silicon heating
mats, etc.