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rx battery

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Old 05-21-2011, 01:22 PM
  #1
Dano
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Default rx battery

I recently ordered a couple of rx batteries for my planes. I recieved two 6.0 volt 5 cell packs. I use 4.8 volt 4 cell packs. Can I use these rx batteries (6 volt 5 cell packs)in my planes?
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Old 05-21-2011, 02:13 PM
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Steve Percifield
 
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Default RE: rx battery

yes
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Old 05-21-2011, 03:25 PM
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Default RE: rx battery

Yup, should't be any problems. As long as the servos you're using are rated for 6v (most of them are) you will be fine.
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Old 05-21-2011, 03:29 PM
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Default RE: rx battery

Most servos today are good for both 4.8 and 6 volt. It's easy to check, if your servo has the rated power listed for 4.8 only then 4.8 volts it is. If it shows the power for both 4.8 and 6 volts your good to go and better off with the trade up.
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Old 05-21-2011, 04:56 PM
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Dano
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Default RE: rx battery

Thanks
much appreciated. Dano
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Old 06-10-2011, 12:10 AM
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Default RE: rx battery

Dano

A lot of the very experienced pilots and vendors suggest you put a couple of 1N3007 diodes on the positive battery lead to step down the voltage a bit on a 6.0v battery pack. A fully charged battery pack will be up near 7.0 volts, and this is known to have caused problems with receivers and ignition systems on gas engines. I have done this and checked it out under load with a expanded volt meter. The manufactures also state use only 4.8v -6.0v and they don't mean 6.9 volts. You might get away with it, but best to be safe. Solder the diodes end to end with the black bar code facing the device to be charged. Put them between the battery and the receiver on the (red) positive lead. I used a short servo extension so that I could just plug it in as needed.

I will try to upload a diagram I got off this RCU site. Good luck.
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Old 06-10-2011, 12:25 AM
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Default RE: rx battery

Dano

Sorry, use 1N4007 diodes. When I looked at the diagram I uploaded I realized that I made a mistake and called them 1N3007 diodes. Hay, it's late, what do expect from an old guy...
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Old 06-10-2011, 04:55 AM
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Default RE: rx battery

Their is absolutely no reason to regulate a 6V battery if you are using newer equipment. Even unregulated A123s that come off the charger @ 7.2V are supported with most if not all of the current components.
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Old 06-10-2011, 05:10 AM
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Default RE: rx battery


Quote:
ORIGINAL: Jonde

Dano

A lot of the very experienced pilots and vendors suggest you put a couple of 1N3007 diodes on the positive battery lead to step down the voltage a bit on a 6.0v battery pack. A fully charged battery pack will be up near 7.0 volts, and this is known to have caused problems with receivers and ignition systems on gas engines. I have done this and checked it out under load with a expanded volt meter. The manufactures also state use only 4.8v -6.0v and they don't mean 6.9 volts. You might get away with it, but best to be safe. Solder the diodes end to end with the black bar code facing the device to be charged. Put them between the battery and the receiver on the (red) positive lead. I used a short servo extension so that I could just plug it in as needed.

I will try to upload a diagram I got off this RCU site. Good luck.
Ummm....

Really?

Wow...

NO need for anything like this.. What RX has problem?????
Which Pilots and Which Vendors???


To the OP, the 5 cell pack is fine.. assuming you are using an appropriate mAh size pack...
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Old 06-10-2011, 05:17 AM
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Default RE: rx battery

The only manufacturer I've seen that is nervous about putting 7 volts through their receiver is Futaba who recommends not to use A123 packs, and there are plenty of guys who have done it anyway with no problems. The manufacturers know how much voltage our packs actually put out. A 4.8v pack is rarely actually 4.8 volts in actual use; it's usually a bit higher because that's how NiCd/Nimh batteries work. The manufacturers know we will put 6v packs on our planes that will be at 7 volts hot off the charger, so they design their systems to work with the actual voltages the packs will put out in normal use.
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Old 06-10-2011, 10:07 AM
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Default RE: rx battery


Quote:
ORIGINAL: Jonde

Dano

Sorry, use 1N4007 diodes. When I looked at the diagram I uploaded I realized that I made a mistake and called them 1N3007 diodes. Hay, it's late, what do expect from an old guy...
This is a first for me?? Some of my electronic ignitions do state you should only run 4.8 volt Nicad but Nim work just fine for me. As far as the flight pack of a plane goes even the charged voltage of the A123 doesn't have any effect on the RX, the servos are what doesn't like the added voltage. Now they are making high voltage servos for those that like to feed them the higher juice.
The diodes look like a cool idea but isn't that just a do it yourself voltage regulator??? If so I like the idea as a money saver plus I like making my own gear.
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Old 06-10-2011, 10:13 AM
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Default RE: rx battery

Quote:
The diodes look like a cool idea but isn't that just a do it yourself voltage regulator??? If so I like the idea as a money saver plus I like making my own gear
Eh sorta. A diode doesn't actually regulate anything it just drops the voltage down. The higher the input voltage the higher the output voltage. A regulator attempts to regulate down and maintain a set output voltage no matter the input (within reason)
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Old 06-10-2011, 10:44 AM
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Default RE: rx battery

6V 5 cell packs on all my smaller planes.
4.8 4s or 3.6 3s on ign.
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Old 06-10-2011, 12:05 PM
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Default RE: rx battery

i use 6v no worrys on spektrum gear 3003 futaba servos never had an issue, its like having free speed and torque by using a 6v
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Old 06-10-2011, 08:10 PM
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Default RE: rx battery

K-Bob
exeter_acres
jester_s1
Gray Beard
scooterinvegas
shayne1983

Wow!  Apparently, my comments to a question on batteries by Dano garnered quite a response.  I too like 6.0v battery packs and have used them for many years.   Certainly the added servo speed and  torque are a bonus.  About 1-2 years ago I switched to the 6.0v NiMH 2000mah packs as I liked the greater capacity.   No agruement there with most of your comments.  

I decided to venture in my first gas engine recently and so I have been reading and participating in the thread,"New DLE 20cc gasser!".  Somewhat to my surprise, I found that a number of the experienced rc guys on this thread were very much for keeping the battery voltage down close to 6.0 volts.  In large part due to concerns about gas engine igintion problems. You all can speed-read some of this thread if you want to read some of the specific comments.  A few of the most recent start with Post #3768, but there is a lot of discussion going back to about page 35 or so of this thread.
One of the key vendors in this discussion is Valley View RC, whom sell the DLE gas engines. 

I guess, bottom line, I just decided to start putting the diodes on my battery packs to keep the max voltage nearer to 6.0 volts just to be safe.  I still get the extra speed and torque.  For a buck and a few minutes soldering, how can you lose.  I use a little electrial shrink wrap over the soldered diodes to protect the bare wire.  BarracudaHockey's definition of a diode was correct.  It only allows current to flow one way and simply steps down the voltage a bit. 

Use what ever voltage you are comfortable with.   I'm just picking out the essence of a lot comments on this subject.  I'm not so worried about the receiver as the servo's and ignition system.  The servo is a added heat thing and the gas electronic iginition systems apparently are more sensitive to higher voltages according to the guys with a lot more experience with them then me. 

Enjoy your building and flying.
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Old 06-11-2011, 07:40 AM
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Default RE: rx battery

Thanks to everyone that responded all replies were much appreciated. Will use the packs, if anything out of the ordinary happens (That isn't PILOT ERROR) I will post. Thanks again, Danny
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Old 06-12-2011, 02:16 PM
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Default RE: rx battery

I wasn't arguing with you Jonde, just pointing out that that actual voltage that the receiver sees with an A123 isn't much different than with a 6v NiCd. A recurring error is to think that the nominal volt rating of the pack is what it actually puts out, when it actually puts out a good bit more when fully charged. So I have trouble understanding why a given voltage is fine from one battery chemistry, but potentially harmful from another one.
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Old 06-12-2011, 02:55 PM
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Default RE: rx battery

Barracuda

In fact a different kind of diode called a Zenner is used in voltage regulators. It is connected accross the outputs, not in series. A 5.6v zenner would be used for ignitions that require 6v or less. See this explanation

http://en.wikipedia.org/wiki/Zener_diode
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Old 06-12-2011, 07:41 PM
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Default RE: rx battery

jester_s1

I did not mean to imply that, I tookyour comments as arguing, but thanks for your response. You are correct that the nominal voltage of a A123 battery is basically the same as from a 6.0 volt NiCd or NiMH battery pack. Only the chemistry is different. And, A123 battery packs are highly recommended for Rx packs in RC airplanes. I guess,I'm personally, just abit moreconcerned about going too much over 6.0 volts then most. So, ifsoldering in acouple of cheap diodes can keep the peak voltage nearer to 6.0 volts, I like the idea.A Zenner type diode like huck1199 mentioned or a 1805 fixed voltage diode for $1.79 at Radio Shack can be considered as while. Even though standard 6.0 volt battery packs have been used extensively there are a number of people on various RCU threads that have reported problems or preceived problelmswhen they went to fully charged 6.0v packs. No, I don't remember the specific names or post numbers, but the guys reporting this seemed serious enough tofindvariouswaysofreducing the peak voltage. I will admit that most of what was reported was not or could not necessarily be directly attributed to the higher voltage. One credible source from Valley Vier RC does rather strongly recommend not to use over 6.0 volts when using 6.0v batteries to power the iginition for DLE gas engines. I think theconcern was shortening the life of the iginition module. To my understanding, the Chinese manufacture concers.

Regards,
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Old 06-13-2011, 06:28 AM
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Default RE: rx battery

The uninitiated might make a bad assumption on the above discussion of Zenner Diodes. You must use a dropping resistor or load in front of the zenner which can cause a lot of excess heating if the difference between the source voltage and regulated load is large; in short, you can not just put a zenner diode in parallel with the load to drop the voltage. This becomes even more complicated if there is a large variance in the load current during normal operation.
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Old 06-13-2011, 06:53 PM
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Default RE: rx battery

Rodney

You are technically correct, although I admit I am not expert in electronics. I did, however, read up on the Zenner diodes. It's why I decided to go with a couple of simple diodes to step the voltage down a bit. You know the old KISS approach- keep it simple stupid! When huck1199 mentioned the Zenner diode as a consideration, I acknoledged that it is an option, particullary since the current being regulated is fairly constant. I would hope each individual would either get some specific advice or do a little research before making any modifications to their battery packs. But, point taken.

I got the idea for using a coupleof specific diodes and a installation diagramto bootfrom a RCU post.

Thanks,
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Old 06-13-2011, 09:50 PM
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Default RE: rx battery

Quote:
ORIGINAL: Jonde

jester_s1

I did not mean to imply that, I took your comments as arguing, but thanks for your response. You are correct that the nominal voltage of a A123 battery is basically the same as from a 6.0 volt NiCd or NiMH battery pack. Only the chemistry is different. And, A123 battery packs are highly recommended for Rx packs in RC airplanes. I guess, I'm personally, just a bit more concerned about going too much over 6.0 volts then most. So, if soldering in a couple of cheap diodes can keep the peak voltage nearer to 6.0 volts, I like the idea. A Zenner type diode like huck1199 mentioned or a 1805 fixed voltage diode for $1.79 at Radio Shack can be considered as while. Even though standard 6.0 volt battery packs have been used extensively there are a number of people on various RCU threads that have reported problems or preceived problelms when they went to fully charged 6.0v packs. No, I don't remember the specific names or post numbers, but the guys reporting this seemed serious enough to find various ways of reducing the peak voltage. I will admit that most of what was reported was not or could not necessarily be directly attributed to the higher voltage. One credible source from Valley Vier RC does rather strongly recommend not to use over 6.0 volts when using 6.0v batteries to power the iginition for DLE gas engines. I think the concern was shortening the life of the iginition module. To my understanding, the Chinese manufacture concers.

Regards,

ok on the dle ignition i remember reading that that issue was fixed, now their is no benifit to useing 6v packs on the ignition anyways so why not just use a 4 cell pack to begin with? its cheaper and lighter
as for the servos and reciever, early on that was more of an issue. today its doesnt exist, (except for the servos not rated to 6v)
now if your just tinkering and having fun theirs nothing wrong with that, just understand that it is no safer and possible more dangerous if your diodes cant handle the current (im no expert but arnt diodes rated by voltage and mah they allow to pass through?) for example http://www.radioshack.com/product/in...ductId=2036269 (your diode) is only rated to 1 amp.....so what happens when your servos draw more than one amp? 1 single servo at stall draws about an amp, 600 mah ish in normal opperation.........just pointing that out, again im no electronics guy....just saying
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Old 06-14-2011, 12:59 AM
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Default RE: rx battery

jimmyjames213

Some of the guys seem to like a 6.0 volt pack, (receiver and/or ignition), because they are concerned about losing one cell in a 4 cell pack and having the resulting voltage drop below minimum operating requirments. If you lose one cell in 5 cell pack you still have ~ 4.8 volts. Smart? I don't know. I did lose a nice .60 size plane some years ago on it's second flight. It just quit responding to imputs. After the crash the only thing wrong other than one broken servo gear was I found one dead cell in my 4.8v NiCd battery pack. I'm assuming it was the battery failure as the servo was clearly due to impact damage. The battery was wrapped in heavy dense foam and still in it's compartment. ???

As for the 1 amp limit on the 1N4007 diode, you are correct that a major surge in current, (amps) could exceed the 1 amp. However, under normal operations we are talking current loads well under that to my understanding.A very complicated area of current measurement from what I have read on the subject. I guess the real answer to your caution is that if any servo or combination of servo's is pulling much over 1 amp for more that a very short periodit's going to result in an on-board electronics failure somewhere, diodes or no diodes!

Frankly speaking, it's hard to find real measured servo stall values. The manufactures tend to use "Peak stall torque values", which is when the shaft is prevented from turning. These values are reported to be 5-10 times higher than "Maximium continuous stall torque values". The latter being where the servo is at or near it's maximum torque due to high resistance, but still allowed to move a little at a very slow speed. Just what I've read, like you I'm not electronics expert.

Thanks for your comments. Good food for thought.
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