RE: [CR 914 Class] Ranger II N Transmitter and Nickel Metal Hydride (NiMH) Rechargeable Batteries
- NiMH batteries work fine, Mike, and for our purposes are better than NiCads.
NiMHs' only drawback is that they undergo very slow spontaneous discharge
when they sit unused for a while. But an overnight trickle charge, of the
sort that is delivered by inexpensive chargers like the 55 mA Hitec CG-25A
that I use, boosts them back to a full charge (many 914ers simply keep their
Tx and boat NiMHs hooked up to a continuous trickle charge at home when they
The Ranger II when last tested by "the CR 914 Engineer," Chuck Winder,
showed a constant current drain of 265 mA (CR 914 NEWS, issue 5, March-April
1997, p 5). That is probably a good estimate of the maximum you will ever
experience. It means that a set of 2,650 mAH batteries, for example, would
provide ten hours of continuous current flow before the voltage fell enough
to make the Tx quit. Thus if you turn your Tx off between races (be sure to
turn your boat electronics off before you do, to avoid the potential for
damaging servos) modern NiMH batteries (2000 mAH+) should easily last
throughout a very long day of racing.
NiMHs are also the batteries of choice for use in the boat. I prefer to have
my battery store or local RC hobby shop solder and shrink-wrap a four- or
five-cell AA pack (which I then thoroughly waterproof with paint-on
electrical tape from the local hardware store) rather than using individual
cells in a battery case. The current draw of the boat (receiver and servos)
depends on the load on the servos, but a reasonable average current draw is
< 200 mA (my own tests several years ago showed a drain at rest of 66 mA,
with a maximum of 350 mA while deflecting the rudder and sheeting in against
a very heavy load). Again, a set of modern NiMHs should easily last for a
full day of racing, even in heavy weather, but it's always wise to carry
spares just in case.
It's good to see that you seem to have decided on a CR 914 rather than the
RC Laser you were considering back on March 22, Mike. I encourage you to
register your boat with the class, and subscribe to our quarterly class
newsletter, the name of which is now the CRonicle, which published its 50th
issue this week. In it you will find all sorts of useful tips about radios,
batteries, other electronic components, and virtually everything you could
ever want to know about our great little boats and the folks who sail them.
You will find a searchable archive of all back issues of the newsletter
dating back to issue #1 in 1996 on the class website at
CR 914 Class Secretary
1206 Castle Bay Pl
Columbia, MO 65203
Visit the CR 914 Class website at www.cr914class.org
From: email@example.com [mailto:firstname.lastname@example.org] On
Behalf Of Mike M.
Sent: Thursday, March 30, 2006 12:13 PM
Subject: [CR 914 Class] Ranger II N Transmitter and Nickel Metal Hydride
(NiMH) Rechargeable Batteries
Will Nickel Metal Hydride (NiMH) Rechargeable batteries work with the
Ranger II N Transmitter? The Ranger II N manual says to use Nickel
Cadmium (NiCd) or Alkaline.
Also what is the ma draw for the Ranger II N. The manual does not
provide this information.
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