Model Forum / Radio Controlled / Air Models / November 2003

If the low voltage alarm goes off at 9.8 volts I can tell you that is to high.

Cycle the battery a few times using an automatic cycler and find out what your
capacity in minutes and mAhs is.  On a useable battery you should come up with
greater than 80% of capacity and more than 90 minutes of safe flying time.  The
time is an estimate depending on how you stir the sticks, and I hesitated
before giving you a number because others I'm sure will disagree.  You could
plot voltage vs. time in fifteen minute increments using an ESV to put a load
on your battery and draw a profile curve to see how your battery is
discharging.  Your reading of 10.6 volts after a full charge seems kind of low.
My experience taking readings immediately after a good overnight charge has
been greater than 11 volts.  This is however a surface charge and will
dissipate quickly to ~10.5 volts within several minutes under a typical load.
Joe L.

There have been three iterations of the 9Z; the 9Z, 9Z WC, and the 9Z WC2.
The first two came stock with a 700 ma battery pack, and the latest, the WC2
comes with a 1100 ma pack. So, if you really have a 1200 ma pack, it is a
replacement from somewhere and not original Futaba.

On all three of my 9Z's the LCD voltage reading with NiCad packs right after
removing the charger is 10.8 - 10.9; they never have shown 11+ as most other
radios seem to. On all three of my 9Z's the low voltage alarm sounds at
about 8.6v. I would think something is wrong with your system if you are
getting a low voltage alarm at voltages above the nominal rating of a eight
cell battery pack (9.6v).

If you are going to do some real battery cycling and testing, you need to
remove the battery case from the transmitter. While holding the case in
front of you, looking at the back of the case (i.e. the face that has the
female plug), with the connector to your right, you need to short the top
two connector holes to bypass the diode. This can be done by modifying an
old Futaba "G" connector pigtail, or Futaba sells a pre made jumper for this
purpose (appx $5). There are schemes around for bending pins in the xmtr,
modifying circuit boards, etc to accomplish this same end, but I do not
recommend going that far. A simple shorting jumper works just fine and
requires no hardware mods.

BTW, the 9Z is a energy hog. Do not expect the same power duration that most
lesser capable transmitters have.  I have recently attempted to solve this
problem by installing NiMH packs. If you make this switch, then you will
need charging systems that recognize NiMH cells vice NiCad cells. The jury
is still out on this being a significant improvement. In any case, all my
9Z's will hold a charge for months

I am just wondering that if you are getting an alarm after just one week of
sitting idle, and the voltage is still reading over 9.0v, that your problem
may be the lithium battery that is in there to retain all your programming
data. In any case I doubt that the system is less than a year old. It may
have been sitting on a shelf somewhere for a very long time. The WC2 has
been out for over two years.  An easy way to tell which version you have is
the programming buttons around the LCD. The original 9Z had the bottom strip
was gold in color, with the side strips are black. On the 9Z WC, all three
are black in color, and on the  9ZWC2 all three are blue in color. I you
have one of the earlier versions it could actually be ten or more years old.
In that case, you could have easily used up the rated five year lifespan of
the lithium battery.

Good luck,
Tom