Rev. 1.8
505 Keystone Rd, Southampton, PA 18966, USA
.
(877) 497 6937
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www.fortresspower.com
12
2.6 System sizing
Proper system sizing is vital to the health and proper
operation of your battery. Using an inverter with a charging
rate too close to the maximum recommended charge rate of
the battery can cause the battery to malfunction due to safety
mechanisms. Therefore, it is important to size the number of
batteries correctly, depending on the power of the inverter.
The table below lists some common inverters and the
minimum number of eFlex batteries necessary to avoid
malfunction.
Furthermore, it is necessary to remember the contribution of
MPPT solar charge controllers to charging current when
designing a system. The max charge current of the batteries
must be greater than or equal to the sum of max charge
output of the inverter and the MPPT charge controller. Or,
An example is proposed to illustrate the matter. Consider a
Schneider XW+ 6848, which has a max charge rating of
120A and one MPPT charge controller capable of charging at
60A. In addition, assume 3 x eFlex batteries connected in
parallel, which are recommended to be charged at 55A or
less. If we follow the equation above and sum the values we
have, we get
55𝐴 + 55𝐴 + 55𝐴 ≥ 120𝐴 + 60𝐴
or
165𝐴 ≥ 180𝐴
Therefore, the potential charging current exceeds the
maximum charge current of the 3 parallel batteries. In this scenario the
3 x eFlex batteries are not sufficient
to handle the full charging power of the inverter and the charge controller at the same time. To remedy this
situation it is necessary to either add a fourth eFlex battery in parallel. If four batteries is not an option, please
contact Fortress Power tech support for help sizing the system.
eFlex 5.4
51.2Vnom
MS 4448
2
MS 4048
2
Radian 8048A
4
Radian 4048A
2
SkyBox SBX
5048
2
VFXR 3648A
2
FXR 3048A
2
Sunny Island
6048
3
Sunny Island
4548
2
XW Pro 6848
3
XW+ 6848
3
XW+ 5548
3
SW 4048
2
SP PRO SPMC
481- AU
2
SP PRO SPMC
482- AU
4
8K
4
12K
4
Quattro
48/3000/35
2
Quattro
48/5000/70
2
Quattro
48/10000/140
4
Quattro
48/15000/200
6
Selectronic
Sol-Ark
Victron
Energy
Magnum /
Sensata
OutBack
Power
SMA
Schneider
Electric
Inverter