airbusdrvr

Would like to know if anyone is using the Jomar Products Ultimate Battery Backer( http://www.emsjomar.com/SearchResult.aspx?CategoryID=4 ) with the JR/Spektrum 2.4Ghz receivers. We all know that "momentary" voltage drop to about 3.8V causes a lockout. Was wondering if the UBB switches from one battery to the other would there be a "momentary" voltage drop that would cause the receiver to lockout. I wrote to Jomar and received the following reply:

"The systems senses a one volt difference between main and backup and then switches instanteously to the backup. The 2.4 GHz shouldn't see the changeover as it takes place extremely quickly. I haven't had any reports of the systems going into lockout and we have customers using the UBB with 2.4 GHz systems.

Mark Schwing"

Sounds like it might be a system to consider and wanted user input. Thanks,

sodbuster 1

am planning on doing the same. hope we can!

alan0899

G'day Mate,
Why bother buying something extra to add more weight, the same objective is achieved by plugging both batteries into the RX, with 2 separate switches.
After all you would have to have two batteries for this change over dohicky, I don't see the point of adding more cost & complexity, & chance of failure, when 2 decent capacity packs plugged into the RX & switched on will give the same result, without the chance of an electronic failure.

sodbuster 1

ok. what happens if one pack shorts out? read the following. it's from Aero-Accessories.com



"August 5th 2006 was a sunny, hot, humid Kentucky day. I was attending my local Warbird event held annually. I was enjoying the day flying my Ziroli Beech 18, my Mig 21 and my newly finish Meister Scale P-47. The wind had picked up towards the end of the morning and I elected to fly the P-47. The p-47 really doesn’t care much either way if it is windy or not. There was no flying and I was asked to do a little demonstration with the big beast. I love putting on a show, so I fueled her up, cranked the big Quadra 100 and taxied out.



I really enjoy the feeling I get watching that big hunk of metal (okay, balsa wood and glass, but it looks like metal) screaming down the runway with that deafening Q-100 turning a 26-10 prop. As it growled by us, I gently lifted back on the stick and we were air born! I could hear the awe of the crowd (many seeing model airplanes for the first time) as I rolled, low fly bys, and other maneuvers in my routine. I felt good and really enjoyed the moment until out of my crosswind turn, turning upwind, the plane jerked to the right. I gave full left aileron and the plan immediately snapped to the left. I knew that I was going to loose the plane and retarded the throttle to idle. Nothing! The plane dove into the ground spinning to the left at full throttle. It took about 1.5 seconds to spin in from approximately 600 feet.



I only knew that I had lost all radio communication with the receiver. I immediately asked if anyone was on my frequency. Of course no one stepped up. I went to the CD and asked if anyone was registered on my frequency. He said I was the only one. Walking out to the crash site, I asked the “gents� helping me not to touch anything. I wanted to give a good look to see if I could find the culprit. The crash site consisted of about 100sq feet of balsa, wiring, servo remains, etc. However, I noticed my two batteries. Battery 1, a 2700 NiMh pack bought new for this plane showed what looked like the remnants of a slow burn. Battery 2, a 1500 NiMh bought new for this plane showed no sign of wear. Not even a scratch. I almost dismissed this as an impact explosion, when I noticed the foam packing about 7 feet opposite the batteries. The foam told the story! You can clearly see that point of concentration on the slow burn as the burn marks get lighter. Battery number 1 started a slow burn and locked out my system in doing so. I had battery 1 in the batt plug on the receiver and battery 2 on channel 7 in the receiver. Two separate high end JR switches, and two battery monitors. I bought a battery backup system from Dino but couldn’t find the time to put it in. Playing Monday morning Quarterback, I should have put it in.



If you are flying large aircraft, please consider a battery backup. This would have saved me countless grief and hours lost on building this plane. You can get these from Aero-Accessories from the mid 50s to the mid 80s depending on how many bells you want. Seeing that an extra 70 bucks would have saved my plane, I think it would have more than been a well worth insurance investment.



Plans are underway to re-build another Meister P-47. I will keep you all informed of my progress. Please learn from my mistakes and seriously consider (if you haven’t) looking at two batteries, two switches, a battery back up for your large aircraft. For the relatively small extra investment, you can rest assured that in case of a battery problem, you have a much better chance to fly your plane safely to the ground.



Keep ‘em flyin! "

Have a change of mind now? A Jomar backup is around $50. Certainly worth saving your plane that cost over $1,000 , no?

airbusdrvr

sodbuster, what does a slow burn do to the output of the battery? How did the slow burn keep the other battery from powering the receiver/servos? I'm curious how this scenario would play out with a battery backer in place.

ishangupta77

i have a spektrum 5 channel radio which igot with my blade cx2.is that compatible with an rc airplane.if so please tell me how

sodbuster 1

I would imagine a "slow burn" would probably mean a short or open of some kind or a cell that overheated and burned. I would think either way it would probably mean a voltage drop or a total lack of which the battery backer would read then switch to the other battery.


HOPEFULLY!

sodbuster 1

as far as why the receiver didn't take power from the other battery, if it was a short I imagine it caused all kinds of havoc for the receiver.

rorrock

A short more than likely would drain the second battery completly as there is no way to isolate the faulty batter when they are both connected directly to the reciever.
It is in this situaion a backup unit would have saved the aircraft..

jerdavis

My Feedback: (3)

I tried a battery backer (not the Jomar unit) for the same reason: to avoid a 2.4 brown out.
I disovered that the battery backer itself causes a voltage drop of about .5 volts, making the operating voltage even lower, especially under a load.

I,ve decided, in my case, that running two parrallel batteries is a lower risk than a brown out with a backer.

JD

jerdavis

My Feedback: (3)

.

flynut007

My Feedback: (31)

Found this, and it seems to fit my problem....I have been flying a plane set up with dual nicd batteried 6V and dual switches with a 945 72 mhz receiver with the Jomar battery backer between the switches and receiver for some time with no problems.... I have switched to the ar9000 2.4 receiver and had some issues.
After installing the new receiver and satellite receiver....I could not bind the new receiver with the binding plug with the switches that were installed in the plane with the jomar installed as well.....I had to use a spare switch and plug it direct the receiver, and now after binding when I turn my main switch on and move the controls and turn the second swith on it will lock out a channel like rudder..... but when I remove the jomar battery backer and plug battery #1 into battery port, and battery #2 in an open plug.....everything works properly.....
maybe I have other problems, but in the process of doing a good battery test right now with my batteries

Bill