E T X T S O L I T H I U M B A T T E R I E S
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10
Normal Operation
Under normal operating conditions the battery performs as any lead acid battery, storing
energy from the charging system and suppling it when the charging system is off.
Abnormal Operation
i.
If the battery fault indicator LED turns on and remains on solid, it is an indication
that the BMS electronics has failed. In this case, the battery should continue to
provide power as normal, but it is recommended that the pilot shall pay more
attention to the aircraft bus voltage or current. As long as the bus voltage or current
remains normal, this is not an emergency. The battery shall be replaced prior to any
future flights.
ii.
If the battery fault indicator LED slowly cycles 5 seconds on \5 seconds off, and the
aircraft bus voltage is within its normal range, it is an indication that one or more
cells in the battery is failing to charge up equal to others (cell charge level imbalance).
The slow flashing fault may come on briefly (less than 60 minutes) during or
following periods of high current charging (greater than 50 amps). In this case the
battery should continue to provide power as normal, but the pilot shall pay more
attention to abnormal aircraft bus voltage or current. However, the battery shall be
maintained or replaced prior to any future flights.
iii.
If the battery fault indicator cycles 2 second on\2 second off is an indication of high
temperature; temperature exceeding the normal operating or storage limits of the
battery. As long as the bus voltage \current remains normal, this is not an
emergency.
Emergency Operation
Emergencies with Aircraft Charging System as Root Cause
i.
If the battery fault indicator LED slowly cycles 5 second on \5 second off, and the
aircraft bus voltage is greater than 15 volts, or the high voltage warning light is on, it
is an indication that the aircraft’s charging system voltage regulator has failed. If the
aircraft charging system voltage exceeds 16 volts, then the charging system’s
automatic over voltage protection device (OVPD) has failed to operate. In these
cases, the battery is functioning normally, but the pilot shall turn off or isolate the
charging system to eliminate the bus over-voltage event. Additionally, the pilot
should make preparations to land prior to the battery’s reserve capacity being
depleted.
ii.
If the battery fault indicator LED slowly cycles 5 second on\5 seconds off and the
aircraft bus voltage is less than 12.8 volt or the low voltage warning light is on, or the
amp meter is indicating no current from the alternator; it is an indication that the
aircraft’s charging system has failed. In this case, the battery is functioning
normally, but the pilot shall make preparations to land prior to the battery’s reserve
capacity being depleted. Note, below 12.8 volt the battery is already deeply drained
(as much as 80%).
Emergencies with Battery as Root Cause
i.
If the battery fault indicator LED comes on “solid” it is an indication of a Battery
Management System (BMS) electronics failure. If the fault indicator remains on and
the aircraft charging system exhibits abnormal behavior (i.e. current or voltage
