MOTOR & BATTERY MAINTENANCE & CHARGING
IMPORTANT! THIS SECTION CONTAINS MATERI-
AL ESSENTIAL TO YOUR SAFETY AND THE MAX-
IMUM PERFORMANCE OF YOUR ELECTRA!
Please take the time to read this section very careful-
ly. If you don’t understand, read again or get help from
an experienced electric pilot.
The Turbo 550 is a special motor designed for electric
plane use on 6-cell 1200 MAH nicad battery packs.
This battery is commonly used with 1/10 scale “off
road” electric cars and is therefore readily available. 7-
cell batteries also may be used and give a better climb
rate, but this will produce a shorter engine run and the
motor will run hotter. See figure A below.
MOTOR
The motor is ready-to-use;just install as shown and be
sure there is enough ventilation around the motor for
adequate cooling. After a few flights, you should notice
a small increase in power, as the motor “breaks in.”
You may also wish to experiment with other propellers,
but we recommend you stay in the 8-4 size range.
BATTERY
This section is particularly important!
One way to
think of a battery charging is to imagine the battery as
a bucket and electricity as water. What you are trying
to do is to fill up the bucket (battery), but not overfill it.
At the very quick charge rate that is common with
today’s field chargers, there is little room for error.
When you over-charge a battery, the temperature rises
quickly and there is
potential for EXPLOSION
, or at
least battery damage (Figure B). There are numerous
ways to prevent this.
How
you charge depends on the
type
of charger you use.
IMPORTANT! ALWAYS ALLOW THE BATTERY TO
COOL BEFORE CHARGING.
TYPES OF CHARGERS
Basic Charger with a Timer.
To prevent an over-
charge, you must know how full the battery is. A new
or nearly empty battery should receive a full charge,
per the instructions that come with the battery. This is
usually about 15-minute charge (at 4.5 AMPS, if you
have an ammeter.)
During the last 5 minutes, lightly and carefully touch
the battery several times (ever minute or so). If it is
slightly warm, that is OK. If it is hot to the touch, that
signals that it is overcharged. STOP CHARGING
IMMEDIATELY! Allow the battery to cool to room tem-
perature (usually 15-20 minutes) before using.
If you don’t know how full your battery is, set your timer
for no more than 5 minutes and monitor the tempera-
ture by lightly touching the battery every 1-2 minutes.
When the temperature starts to rise, the battery is fully
charged. Stop immediately (Figure C).
If you have a digital volt meter, it can be very useful in
detecting when the battery reaches a full charge. As
the battery fills, the voltage goes up. When it’s fully
charged, the voltage will stop rising and in a minute or
two, as the battery temperature rises, the voltage will
drop slightly. As soon as it drops, stop charging. This
is an excellent way to get maximum batter perform-
ance. (Figure D.)
FIG. A
FIG. B
FIG. C
FIG. D
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