E T X S E R I E S L I T H I U M B A T T E R I E S
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Overview
EarthX Lithium batteries are designed as a maintenance free replacement for the 24-volt
lead-acid or lithium starter batteries. The Starting Battery (Function) is considered Primary
in the electrical system for Category I and II part 23 Aircraft. The alternator charging system
is considered secondary. Per 14 CFR 23.1309-1E and TSO-C179b, the Failure Condition
Classification (FCC) for this TSO Battery is “Major” - unless other installations deem the
analysis lessor or greater, dependent on the function in the particular installation Aircraft.
This manual covers the TSO Article (Part) installation aspects for the ETX900-TSO Battery
to be installed on 14 CFR part 23 Aircraft. Refer to AC 20-184 for full Aircraft installation
guidance and requirements not the subject of this manual.
Failure to follow all application use, installation, charging, and storage instructions may result
in battery damage and or fire!
Technology Inside
Battery Cells
The batteries use cells made of Lithium Iron Phosphate (LiFePO
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). This chemistry is one of
the highest performance and safest on the market today.
Lithium batteries are fundamentally different than lead-acid batteries. A lithium battery
voltage remains relatively constant while discharging, while voltage for a lead-acid battery
decreases. As such, 16Ah lithium battery has the equivalent “useable” capacity. What do you
mean here? Also, a lithium battery’s cranking power is stronger, for the voltage while
cranking is generally higher.
LiFePO
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cells by the nature of their chemistry are 3.3 volt. 12V/24V lithium batteries are
created by using 4 cells/8 cells in series (technically it is a 13.2V / 26.4 V battery). The
typical full charge resting voltage is >13.3V for a 12V replacement battery and 26.6V for a
24V replacement battery. Another difference is that lithium cells are a dry cell technology,
where the cells are packaged individually. As such, the individual cell’s charge level will
diverge with repeated charge/discharge cycles and age. This condition reduces the
performance of the battery (reduces capacity), for the battery charge level is only as good as
the charge level of the weakest cell.
BMS
EarthX’s integrated Battery Management System (BMS) monitors each cell’s voltage. If the
voltage (charge) of a cell exceeds the others, the BMS circuits will work to reduce that cell’s
charge level. This ensures that the charge level of all the cells remains equal, even with the
high discharge (> 100Amps) and charge current (>10Amps) of your aircraft.
