Macon Aero Modelers Safety News September 14, 2008
From the Safety Coordinator
Dear MAM Members,
It has come to my attention that we might have a problem with the loss of radio link or binding of the Spectrum 2.4 receivers at the field. Preliminary discussion with some of the affected owners seem to believe it is a result of low battery voltage. Kenyon lost a Patty Wagstaff Extra today and had just recharged the flight pack one flight earlier. After the crash on the second flight he checked the battery and it was dead or very low on voltage. Paul and Erwin have had very similar issues with their spectrum systems. It seems to be the 1100 Mah 4.8 Volt battery that is causing the problem. I have researched this on RC universe and provide you the following links to read the discussion. I am in no way trying to bash JR or spectrum systems but I, as the clubs Safety Coordinator do feel that this is a safety concern and you need to address it and take extra precautions until a solution is achieved. Regularly check your battery between flight with a load tester volt meter. They are several different makes of these and should be another piece of your field gear. Consider replacing the spectrum packs with another type or brand, or contact JR via Horizon Hobbies and see if they have any suggestions.
Here are the links to the discussion forums, They are sometime very biased but read all the way thru them. You can usually pick out the truth... One guy even suggests going to 6 volt packs.... they are calling it a receiver Brown Out.
Spectrum update thread:
Low Voltage Cut Off thread with Solution
Again, I only want to bring this to your attention. Please check your gear in between flights. If you are flying electric aircraft then make sure your BEC cut off voltage is below the minimum required voltage for the receiver (3.5 volts) to prevent a brown out. Or fly very, very high so it will have time to relink before the crash... at the least I would make some calls and ask some questions to feel safe.
There has actually been an update to correct the problem:
Here is a copy of their post with a good description of the problem:
“Quick Connect” Voltage Recovery System for DSM2 AIR receivers
Performance modelers have known for some time that care must be taken to assure adequate power supplies for their airborne system. It’s true for all radios systems, but it’s doubly important when using high performance servos, flying harder maneuvers, and trying to save weight with inadequate batteries and/or regulators. For more in-depth information on the topic, go to www.spektrumrc.com.
Spektrum systems are designed with an operating threshold of 3.5 volts, and lower voltages cause the system to shut down. When adequate power is regained (usually the drop is momentary), earlier Spektrum systems re-boot and rescan for two previous channels before control is restored – a process usually requiring two-five seconds.
The new “Quick Connect” feature, however, eliminates the scanning delay and restores control almost instantly. We have been integrating this upgrade into receivers in a running change. Here’s how to identify if your receiver has “Quick Connect”:
With the system operating normally, simply switch the airborne power off, then on. If your system shows virtually no delay in regaining control, your receiver includes the Quick Connect feature.
Flashing LED’s indicate low voltage alert
Quick Connect allows most flyers to fly through common low voltage situations caused by insufficient battery “headroom” – in many cases, without knowing a problem ever occurred. As a result, Spektrum engineers decided to program the system so that the receiver LED’s would flash, should the Quick Connect feature be triggered in flight. This can also be demonstrated on the bench, by toggling the airborne power.
If your receiver is missing one or both of these features, first off, it’s important to recognize that the vast majority of flyers using “normal” servos with “normal” properly charged batteries will be unaffected by low voltage issues.
However, if you’re using numerous high-performance servos and wish to have your receiver system modified, simply return it to Horizon for free upgrading. Please return your receiver and all remotes, as all components must have the upgraded software for the new features to function. The best fix, however, remains assuring adequate power supply to the airborne system with sufficient voltage “headroom”.
Your flying success is of paramount importance to Spektrum and JR, and as the leaders in spread spectrum technology, we’re constantly moving the bar upward. Also, whenever you have questions regarding your Spektrum or JR equipment, please feel free to contact our Product Support Team at 877 504-0233.
Edit: no distinguishing mark I'm aware of. Just plug in the system (even at the LHS) bind and when the set is operating with one or more servos turn the Rx off and then immediately back on. You will be able to ID instantly____just like the QC feature reboots.
As your safety Officer I will further my investigation into this and keep you posted as I find out more details.....
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