24VDC Li Expander Pak 1300 Operator Manual
June 2020
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Solar Stik® Inc.
24
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ADDENDUM – Understanding Li Expander Paks
LiFePO
4
Batteries and the Battery Management System (BMS)
This section provides information about the individual battery cells that are integrated into Solar Stik
Li Expander Paks and the multi-functional BMS that maintains them. Additionally, safeguards to
prevent failure are discussed.
LiFePO
4
Battery Chemistry
The Solar Stik 24VDC Li Expander Pak 1300 contains a custom LiFePO
4
battery module that was
designed, tested, and UN certified for use in the Solar Stik System.
There are significant advantages to using LiFePO
4
batteries in that they offer good electrochemical
performance with low internal resistance. Key benefits include high current rating and long cycle life,
good thermal stability, enhanced safety and good tolerance for stressful operating conditions:
• High cycle life; up to 3000 cycles*
• Rapid and deep discharges (can go to near 0% without hurting the cells*)
• Rapid recharge
• High energy density—twice that of lead-acid (double the energy for its weight)
• Safety: LiFePO
4
battery chemistry is as safe as lead-acid
• Other than passenger aircraft, transport regulations are the same as for lead-acid
*
The cycle life of LiFePO
4
is generally advertised as 3000 cycles, but it may be affected by adverse
operating temperature conditions (extreme heat and cold) and high C-rates (rate of current charge
and discharge)
*Batteries must not be stored in a discharged state or they may become permanently
damaged
The primary factors that determine the life-expectancy of a battery are:
• Cycles and Application
• Abuse and Improper Cycling
Either one of these forms of abuse alone could cause damage while the battery is not in service. A
combination of these abuses will (most likely) cause damage while the battery is not in service. The
duration of exposure to high heat will be directly correlated to the amount of damage done. These
phenomena are not unique to LiFePO
4
batteries.
Storing Li Expander Paks in a hot container is unavoidable at times; however, the damage can be
mitigated in two ways:
1. ALWAYS charge the Expander Paks fully before storage.
2. Perform a maintenance charge on the system at three (3) months. The maximum time between
services (FULL recharging) for a system stored in a climate-controlled environment is six (6)
months. If it is stored in a high-heat environment, then more frequent inspection/charging is
absolutely necessary.