2.4 Receiver Batteries
12-30-2010, 11:29 AM
#51
Banned
RE: 2.4 Receiver Batteries
Hello fizzwater,
Trying to please as many as possible I will switch to green. LOL .
I still believe that inserting within the original text is the best method to avoid the reader from having to keep scrolling to find "what was the original text saying?"
Red is still easier to read I think.
End
Zor
Trying to please as many as possible I will switch to green. LOL .
I still believe that inserting within the original text is the best method to avoid the reader from having to keep scrolling to find "what was the original text saying?"
Red is still easier to read I think.
ORIGINAL: fizzwater2
Zor - the contact wiper in the pot does NOT have to touch only that small of an amount in order to resolve position.
Agreed and I am sure it does not. I have opened many potentometers in my long career. These pots cannot be that much different.
Imagine a sharp blade 0.001 inch (from some previous posting) contacting the resistive surface. It would ruin it in no time at all.
However what is happening is that the rotating cursor actually touch a small length of the resistor and effectively short circuit (cannot find a better description) the length of the resistive surface equal to its own width. thus a voltage output from the cursor being the voltage existing across it own width.
Let us note that the cursor is reading an analog DC potential (not a digital one) .
The effective position of the wiper is more like the average of the contact area - not the whole thing. If it was truly limited to the width of the wiper contact area, then you would expect by your expectations that you get a stepped response out of a pot.
Readers ___please read my previous lines above. Any portion of the resistive surface where the cursor is touching is, I believe, effectively shorted so there is a single voltage. It is impossible to have an average voltage in such a small piece of conductor. No doubt the cursor is made of metal.
If it was wirewound, you do get steps - for each turn in the winding. For a conductive plastic (most of the pots probably are, or cermet) there are no "steps" in the output of a potentiometer.
Ah Ah ___let me joke ___if there are steps they would be at the size of the granular formulation of the resistive material which is as fine a powder as can be imagined.
Noise, yes - steps, no. Many years ago Bourns made a pot that was a hybrid - wirewound with a conductive plastic coating over that, to get the linearity of the wirewound and the stepless response of a conductive plastic. We used them in military resolvers for gimbal positioning of some fancy optics that had better resolution than RC servo positioning - had to, in order to meet the optical resolution required by the system.
This makes lots of good sense. It establishes known potential levelat known spacing and it interpolattes between these points.
We also used split spring loaded gears to take gear backlash out of the picture, too.
The ability of the pot to resolve position is more limited by the absolute linearity of the resistive material and the surface roughness of the material, not the size of the contact wiper.
Right ON ___The consideration remains that any manufacturing has tolerances and some dissimilarity (lack of similarity) may account and / or explain the event of bringing up little problems such as buzzing servos.
I have proven to myself that one specific DS821 servo had the ability of returning to neutral within 0.001 inch measured at 1/2 inch radius from its rotation axis. Now how much differnceis necessary for another servo to "cry" ___Hey Iam not yet where I am told to go. Can you not hear my innerds complaining ? That differential amplifier in here is still giving me a voltage to move a little bit more (in either direction). You are jammng me while I still have lots of torque (and elctrical current) trying to finish my motion. I am sweating and soon I will overheat. and my fuel supplier is mad at me (current from the battery pack).
Zor - the contact wiper in the pot does NOT have to touch only that small of an amount in order to resolve position.
Agreed and I am sure it does not. I have opened many potentometers in my long career. These pots cannot be that much different.
Imagine a sharp blade 0.001 inch (from some previous posting) contacting the resistive surface. It would ruin it in no time at all.
However what is happening is that the rotating cursor actually touch a small length of the resistor and effectively short circuit (cannot find a better description) the length of the resistive surface equal to its own width. thus a voltage output from the cursor being the voltage existing across it own width.
Let us note that the cursor is reading an analog DC potential (not a digital one) .
The effective position of the wiper is more like the average of the contact area - not the whole thing. If it was truly limited to the width of the wiper contact area, then you would expect by your expectations that you get a stepped response out of a pot.
Readers ___please read my previous lines above. Any portion of the resistive surface where the cursor is touching is, I believe, effectively shorted so there is a single voltage. It is impossible to have an average voltage in such a small piece of conductor. No doubt the cursor is made of metal.
If it was wirewound, you do get steps - for each turn in the winding. For a conductive plastic (most of the pots probably are, or cermet) there are no "steps" in the output of a potentiometer.
Ah Ah ___let me joke ___if there are steps they would be at the size of the granular formulation of the resistive material which is as fine a powder as can be imagined.
Noise, yes - steps, no. Many years ago Bourns made a pot that was a hybrid - wirewound with a conductive plastic coating over that, to get the linearity of the wirewound and the stepless response of a conductive plastic. We used them in military resolvers for gimbal positioning of some fancy optics that had better resolution than RC servo positioning - had to, in order to meet the optical resolution required by the system.
This makes lots of good sense. It establishes known potential levelat known spacing and it interpolattes between these points.
We also used split spring loaded gears to take gear backlash out of the picture, too.
The ability of the pot to resolve position is more limited by the absolute linearity of the resistive material and the surface roughness of the material, not the size of the contact wiper.
Right ON ___The consideration remains that any manufacturing has tolerances and some dissimilarity (lack of similarity) may account and / or explain the event of bringing up little problems such as buzzing servos.
I have proven to myself that one specific DS821 servo had the ability of returning to neutral within 0.001 inch measured at 1/2 inch radius from its rotation axis. Now how much differnceis necessary for another servo to "cry" ___Hey Iam not yet where I am told to go. Can you not hear my innerds complaining ? That differential amplifier in here is still giving me a voltage to move a little bit more (in either direction). You are jammng me while I still have lots of torque (and elctrical current) trying to finish my motion. I am sweating and soon I will overheat. and my fuel supplier is mad at me (current from the battery pack).
Zor
12-30-2010, 01:56 PM
#52
Senior Member
RE: 2.4 Receiver Batteries
I for one, enjoy Zor's post. While I might disagree at times, he constantly encourages a little deeper thought into the problems/solutions and often has some very good points. At the very least, he stimulates further thought from us all.
12-30-2010, 04:51 PM
#54
Banned
RE: 2.4 Receiver Batteries
All readers,
I just wish to make sure the following is clear in everybody's mind.
I related a case of split ailerons in whih the long aileron in effet was two ailrons end to end and each part had its own servo working independently and thus avoiding any difficulty of potential servo to servo interference.
It brought some reaction that sounded like it was ridiculous.
Imagine now that it is done on purpose and the separation of the two ailrons on the same wing barely has any gap. The near trailing edge of two ribs are more or less rubbing each other slightly.and the servo linkages are adjusted so the trailing edges are vey well aligned in neutral.
I am now making an analogy with a twin engine airplane.
The old jokes is that when you have two engines you have twice as much chance of loosing one.
But we all know that 2 minus 1 is 1 and half the total available power can take us to an airport instead of having an undesired drink down there in the water or cutting the tooth pics in that full grown forest. You get the point.
Now if we have a single powerful servo on that enormous aileron and it fails and it is not statically balanced or the servo refuses to return to neutral and is holding the aileron in the airstream or any situation you can think of like disconnected linkage and the airstream supporting the aileron weight and resulting rolling force that has to be counter-reacted by the opposite wing aileron . . . . . .
I see you doing some of your own thinking.
I did lots of IFR flying but always with a two engine airplane. In case someone is unacquainted IFR meanis Instrument Flight Rules and is flying in the clouds or between clouds without any ground or horizon reference. You are flying solely on your panel instruments and navigating by radio.
Yes I know that some single engine airplanes are licensed and approved to fly IFR but I would make sure there is plenty of altitude below the lowest clouds and not crossing an extensive water area like the great lakes in case of an engine failure.
Back to our ailerons . . . i kind of like the idea of redundant servos on large ailerons which of course are on large models of much higher $$$$ value. I dislike the idea that if one servo gets jammed the remaining good one would have to try to move the dead servo. I imagine you all know how difficult it may be to force a servo to turn by grabbing the horn and forcing it to turn with your fingers which is what the good servo would have to do.
Like in the engine analogy; I would prefer to have half an aileron than no aileron.
But _ _ _ as per the thinking perhaps of someone _ _ _ I never built a large model and never used two servos on one aileron (or other surface) so of course I do not know what the hell I am talking about. Hee Hee !
.Have a great day on New Year's eve.
Zor
12-30-2010, 09:19 PM
#55
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RE: 2.4 Receiver Batteries
re 2.4 batteries
yard-[dart
I just purchased the new 2.4 Futaba 8FG.system.The instruction manual is very specific regarding batteries. The transitter comes equipped with a Ni-MH battery andf the receiver calls for a Ni-Cd battery which is not syupplied with the system. This is my first computer radio and II'm trying to digest 133 pages of info about the radio and its uses.
I hope this is of some help.
Ed Emmons
yard-[dart
I just purchased the new 2.4 Futaba 8FG.system.The instruction manual is very specific regarding batteries. The transitter comes equipped with a Ni-MH battery andf the receiver calls for a Ni-Cd battery which is not syupplied with the system. This is my first computer radio and II'm trying to digest 133 pages of info about the radio and its uses.
I hope this is of some help.
Ed Emmons
12-31-2010, 05:59 AM
#56
Banned
RE: 2.4 Receiver Batteries
Good morning on New Year's eve ___2010 > 2011 .
Going back to the original topic of this thread.
If anyone knows why NiCd cells (batteries) develop memory please post the reason. What is going on inside these batteries ? My research keep referring to this behavior but I cannot find any explanation of the process (of the reason).
First let me say that manufacturer's engineering departments are staffed by human beings 
.
What they do and recommend is based on their own knowledge and experience.
We do not really know how much personal experimentation a certain group may have done and how much is based on the existing general knowledge (what others have published).
My new Spektrum system included both Tx and Rx battery packs.
The receiver pack is branded Spektrum 4.8 V 1100 mAh NiCd
The transmitter pack is branded Spektrum 9.6 V 1500 mAh Ni-MH
I have no way to know who took the decision of marketing the system with this choice of battery packs.
Personally I think the receiver pack is NiCd because NiCd batteries can deliver higher current instantaneous loads with less voltage drops compared to Ni-MH and such a requirement exist in the airplane with the servos demand.
In the case of the transmitter the current demand is not varying much and the Ni-MH battery pack can store more capacity in a given physical size and since 8 cells are needed to give the 9.6 volts then a smaller package can be made to store 1500 mAh .
When you write
quote
I'm going completely off of hear-say. Is there any truth to this that you know of?
unquote
you are asking a question and our answer can only be "more hearsay"
.
My hearsay" answer is that it is not true.
The only differnce betwen the lower frequency operation and the 2.4 operation is the radio frequency band being used. The servos do not even see that and they operate the same with the same current demands. The 2.4 receiver may draw a few miliamps different than the low freq. receiver but that difference is negligeable
Similar difference with the transmitter. The 2.4 module or PCB may draw slightly different miliamps but again the difference is not much Transmitters do not have wide differences in current demand while in action so the Ni-MH is quite well suited and the space available in the Tx case can then have more capacity stored.
I did not read the whole thread again so if this is repeating others postings then please absolve the old man
.
Best to you in the New Year.
Zor
.
Going back to the original topic of this thread.
ORIGINAL: yard-dart
Over the past several years, I've gone copletely to Nimh batteries in all of my planes. I used to be copletely Nicd but it got to where I was constantly having to cycle batteries simply because I may go weeks not flying certain planes and I didn't want the batteries to develop "memory".
Over the past several years, I've gone copletely to Nimh batteries in all of my planes. I used to be copletely Nicd but it got to where I was constantly having to cycle batteries simply because I may go weeks not flying certain planes and I didn't want the batteries to develop "memory".
ORIGINAL: yard-dart
Anyway, that was before I went to 2.4 Ghz. I"ve heard that it's better to use Nicd packs with the new 2.4 sytems rather than Nimh. Something about 2.4 has more constant draw and the Nimh's want stand up to it. I'm going completely off of hear-say. Is there any truth to this that you know of?
Anyway, that was before I went to 2.4 Ghz. I"ve heard that it's better to use Nicd packs with the new 2.4 sytems rather than Nimh. Something about 2.4 has more constant draw and the Nimh's want stand up to it. I'm going completely off of hear-say. Is there any truth to this that you know of?
.What they do and recommend is based on their own knowledge and experience.
We do not really know how much personal experimentation a certain group may have done and how much is based on the existing general knowledge (what others have published).
My new Spektrum system included both Tx and Rx battery packs.
The receiver pack is branded Spektrum 4.8 V 1100 mAh NiCd
The transmitter pack is branded Spektrum 9.6 V 1500 mAh Ni-MH
I have no way to know who took the decision of marketing the system with this choice of battery packs.
Personally I think the receiver pack is NiCd because NiCd batteries can deliver higher current instantaneous loads with less voltage drops compared to Ni-MH and such a requirement exist in the airplane with the servos demand.
In the case of the transmitter the current demand is not varying much and the Ni-MH battery pack can store more capacity in a given physical size and since 8 cells are needed to give the 9.6 volts then a smaller package can be made to store 1500 mAh .
When you write
quote
I'm going completely off of hear-say. Is there any truth to this that you know of?
unquote
you are asking a question and our answer can only be "more hearsay"
.My hearsay" answer is that it is not true.
The only differnce betwen the lower frequency operation and the 2.4 operation is the radio frequency band being used. The servos do not even see that and they operate the same with the same current demands. The 2.4 receiver may draw a few miliamps different than the low freq. receiver but that difference is negligeable
Similar difference with the transmitter. The 2.4 module or PCB may draw slightly different miliamps but again the difference is not much Transmitters do not have wide differences in current demand while in action so the Ni-MH is quite well suited and the space available in the Tx case can then have more capacity stored.
I did not read the whole thread again so if this is repeating others postings then please absolve the old man
.Best to you in the New Year.
Zor
.
12-31-2010, 06:39 AM
#57
Banned
RE: 2.4 Receiver Batteries
ORIGINAL: Ed Emmons
re 2.4 batteries
yard-[dart
I just purchased the new 2.4 Futaba 8FG.system.The instruction manual is very specific regarding batteries. The transittercomes equipped with aNi-MH battery andf the receiver callsfor aNi-Cd battery which is not syupplied with the system. This is my first computer radio and II'm trying to digest 133 pages of info about the radio and its uses.
I hope this is of some help.
Ed Emmons
re 2.4 batteries
yard-[dart
I just purchased the new 2.4 Futaba 8FG.system.The instruction manual is very specific regarding batteries. The transittercomes equipped with aNi-MH battery andf the receiver callsfor aNi-Cd battery which is not syupplied with the system. This is my first computer radio and II'm trying to digest 133 pages of info about the radio and its uses.
I hope this is of some help.
Ed Emmons
Your post #1 confirms that Futaba are using Ni-MH in their transmitter and recomment NiCd for the airplane.
That is the same as Spektrum / JR and it shows that what I just wrote earlier this morning might make sense.
.I am a bit surprised that a receiver battery was not supplied.
I hope that it did not go home in someone's pocket when he looked at the package.
You will have so much enjoyment with your new acquisition. You can spend hours playing wih it and trying things.
Do you have a model airplane in which you can install the receiver, plug in the servos and have "table top flying"
.Was there servos in the packaging ? so that you have the possibility of experimenting some programming ? (some function selection and activation of already programmed software)
.If you need any help, I am sure some young fellows here with an 8FG will be glad to assist.
Have a great New Year 2011.
Zor
12-31-2010, 07:01 AM
#58
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RE: 2.4 Receiver Batteries
the 8FG is not supplied with a Rx pack nor servo's.I use 6.6V LiFePO4 packs in all my planes. These batteries remain at 6.6V for around 85% of their capacity. There are reliable and cost effective voltage and capacity checkers for these batteries. All read voltage down to 0.001V. the voltage is measured under load.
12-31-2010, 12:39 PM
#59
Banned
RE: 2.4 Receiver Batteries
ORIGINAL: TimBle
the 8FG is not supplied with a Rx pack nor servo's.I use 6.6V LiFePO4 packs in all my planes. These batteries remain at 6.6V for around 85% of their capacity. There are reliable and cost effective voltage and capacity checkers for these batteries. All read voltage down to 0.001V. the voltage is measured under load.
the 8FG is not supplied with a Rx pack nor servo's.I use 6.6V LiFePO4 packs in all my planes. These batteries remain at 6.6V for around 85% of their capacity. There are reliable and cost effective voltage and capacity checkers for these batteries. All read voltage down to 0.001V. the voltage is measured under load.
I read Ed's posting ____
12-31-2010, 02:02 PM
#60
Banned
RE: 2.4 Receiver Batteries
ORIGINAL: BuschBarber
Zor - I am by no means an expert on anything. I have been posting on RCU for many years, with three purposes in mind.
1) Help someone if I can
2) Learn something I did not know
3) Get help with a problem I am having
I do not have anything against you personally.
Do you realize that you have generated more Red Ink than my Government has. You are the one of the only posters I know that does this. It is somewhat annoying to people as it just goes On and On.
I am sure that you are very experienced in your line of work. That does not necessarily make you an expert on everything RC, yet you constantly argue with many people about things we have learned from practical experience and know to be true.
There is no reason why you can't continue to contribute to any discussions on any of these threads, but try to be a little less argumentative.
Zor - I am by no means an expert on anything. I have been posting on RCU for many years, with three purposes in mind.
1) Help someone if I can
2) Learn something I did not know
3) Get help with a problem I am having
I do not have anything against you personally.
Do you realize that you have generated more Red Ink than my Government has. You are the one of the only posters I know that does this. It is somewhat annoying to people as it just goes On and On.
I am sure that you are very experienced in your line of work. That does not necessarily make you an expert on everything RC, yet you constantly argue with many people about things we have learned from practical experience and know to be true.
There is no reason why you can't continue to contribute to any discussions on any of these threads, but try to be a little less argumentative.
I am thinking about my New Year resolutions.
I think the above post is well worth recalling for all to read again.
I am not responding here as I already did in post #41.
I know a very good way of complying with the underlined remarks above (the undelining was by me Zor)
I will include that good way in my New Year resolutions.
Regards to "all readers". I never forget you Gals and Guys.
Zor
12-31-2010, 03:26 PM
#61
Banned
RE: 2.4 Receiver Batteries
I know this is out of topic but I cannot resist showing a type of airplane I have flown for many years.
This video is a Srike Aero Commander with piston engines.
I was flying a Grand Commander (extended fuselage) with Airresearch turbo-prop engines.
Very similar in overall appearance.
As you get the link, scroll down to the video and enjoy.
http://www.radiocontrolledairplane.info/aero-commander/
If you scroll down further (below the video) you can see pictures of the Grand with turbo engines.
Zor
This video is a Srike Aero Commander with piston engines.
I was flying a Grand Commander (extended fuselage) with Airresearch turbo-prop engines.
Very similar in overall appearance.
As you get the link, scroll down to the video and enjoy.
http://www.radiocontrolledairplane.info/aero-commander/
If you scroll down further (below the video) you can see pictures of the Grand with turbo engines.
Zor
01-03-2011, 10:36 PM
#62
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RE: 2.4 Receiver Batteries
ORIGINAL: Zor
I was flying a Grand Commander (extended fuselage) with Airresearch turbo-prop engines.
Very similar in overall appearance.
I was flying a Grand Commander (extended fuselage) with Airresearch turbo-prop engines.
Very similar in overall appearance.
01-03-2011, 11:59 PM
#63
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RE: 2.4 Receiver Batteries
Zor, Hyperion markets a capacity checker under the EOS sentry name. Hangtimes, markets a unit called volt magic. Not sure why you are sceptical about voltage readers being sensitive to 0.001V, these have been around for a long time. However with scientific instruments you pay for calibration and servicing upfront. In the hobby we don't a unit that is super accurate, just super consistent. If its out by 0.005V then it should remain at that deviation. I find mine reads capacity remaining very conservatively. It will show 70% remaining while I only replace 80mA after one 12min flight on a 1600 mA.hr LiFe battery. and that conservatism is consistent.
01-04-2011, 06:15 AM
#64
Banned
RE: 2.4 Receiver Batteries
ORIGINAL: EJWash1
300 or 400 series?
ORIGINAL: Zor
I was flying a Grand Commander (extended fuselage) with Airresearch turbo-prop engines.
Very similar in overall appearance.
I was flying a Grand Commander (extended fuselage) with Airresearch turbo-prop engines.
Very similar in overall appearance.
Picture from the manual.
01-04-2011, 07:20 AM
#65
Banned
RE: 2.4 Receiver Batteries
ORIGINAL: TimBle
Zor, Hyperion markets a capacity checker under the EOS sentry name. Hangtimes, markets a unit called volt magic. Not sure why you are sceptical about voltage readers being sensitive to 0.001V, these have been around for a long time. However with scientific instruments you pay for calibration and servicing upfront. In the hobby we don't a unit that is super accurate, just super consistent. If its out by 0.005V then it should remain at that deviation. I find mine reads capacity remaining very conservatively. It will show 70% remaining while I only replace 80mA after one 12min flight on a 1600 mA.hr LiFe battery. and that conservatism is consistent.
Zor, Hyperion markets a capacity checker under the EOS sentry name. Hangtimes, markets a unit called volt magic. Not sure why you are sceptical about voltage readers being sensitive to 0.001V, these have been around for a long time. However with scientific instruments you pay for calibration and servicing upfront. In the hobby we don't a unit that is super accurate, just super consistent. If its out by 0.005V then it should remain at that deviation. I find mine reads capacity remaining very conservatively. It will show 70% remaining while I only replace 80mA after one 12min flight on a 1600 mA.hr LiFe battery. and that conservatism is consistent.
In the RCA engineering department I was for a while the test equipment specialist.
I am not scepticle (variant of skeptical) about voltage readers (voltmeters) being sensitive to 0.001V.
Even the cheapest and lowest quality voltmeter witl be exposed to any voltage they are connected to.
If we connecta voltmeter to a voltage source __imagine 10 vols which happens to be 10.000,000,000 volts where the fact happens to be that it is 10 volts and really has only zeros after the decimal point.
The cheap voltmeter is exposed to the same voltage as a highly accurate voltmeter.
It is not a matter of sensitivity. It is a matter of accuracy of the reading and display.
We cannot confuse the two. Sensitivity and accuracy are entirely different.
What I am saying is that a digital display showing 3 decimals DOESNOT mean the device is accurate to 1/1000 of a volt
Assume for a moment that the voltage source is really 10 V and has 9 or more zeros after the decimal point (it is dead on 10 volts) then a voltmeter may read 10.000 if accurate but may read 9.827 or 10.344 or any value close by but not the dead on 10.000
If the voltmeter is known to be accurate within 1% then it would not read less than 9.900 and no more than 10.100
If accurate within 0.25% (one quarter of one percent) than it would not read less than 9.975 and no more than 10.025 volts.
Now a cheap voltmeter that would read let us say 9.800 (it is 2% off) might very well detect and show a voltagevariation that is very small (like along the dischare voltage of a battey pack) and we migh see a variation of 0.005 V , may be even 0.002 V , but if that voltmeter is not sufficiently accurate and read 9.800 instead of 10.000 we then do not know where the battery pack real voltage is on its discharge.
I am using a round figure of 10 volts for explanation. We can see the same conditions within the voltage range of any battery power pack.
Imagine now that the power pack has 10.500 volts after loosing 10% of its full charge and reads 9.600 when only 10% of its capacity remains (near dead) Now our cheap voltmeter may read 10.050 V and we think we still have half charge. But the real volage actually is 9.800 and we read 10.500 because the voltmeter is only 2.5 % out and reads on the high side.
Now there is something we can do to make the cheap voltmeter useful if it is "consistent" although far from accurate.
That will be the subject of a following posting in order to keep this one not too long.
Zor
.
01-04-2011, 08:28 AM
#66
RE: 2.4 Receiver Batteries
If you would like to get up to speed on really good rx batteries - buy some genuine A123 cells and examine their characteristics.
The use of even extremely good v meters to try and measure remaining capacity is frankly a poor approach.
The reason being the chemistry produces a plateau of voltage which has a severe ramp at both ends.
The other LIFE cells are very similar in this respect.
Apprears you are enjoying learning the nuances of the new technologies
Have fun
The use of even extremely good v meters to try and measure remaining capacity is frankly a poor approach.
The reason being the chemistry produces a plateau of voltage which has a severe ramp at both ends.
The other LIFE cells are very similar in this respect.
Apprears you are enjoying learning the nuances of the new technologies
Have fun
01-04-2011, 08:34 AM
#67
Banned
RE: 2.4 Receiver Batteries
Addressed to everyone,
We are discussing 2.4 receiver batteries.
Really we are discussing batteries since they do no know what they are supplying.
I will try to find answers to the following questions myself but in case someone knows.
QUESTIONS ___that are illustrating what goes on in my mind.
Why is the voltage so high at full charge ?
Why does it drop so fast at the beginning of discharege ?
Why does it flatten out and drops very little during most of the discharge ?
Why is a lipo damaged if it goes below a certain voltage ?
What kind of damage takes place ?
What happens that NiCd develop "memory" (and apparently NiMH do not)
Note : I do not need answers such as "they are different composition".
I am looking for what really happens in those cells.
What really is taking place in those cells ? ; it may answer many questions.
That info is not easy to find.
Is the internal resistance increasing as more dischage is taking place ?
Why ?
If so it would mean that the voltage drop of the battery is higher at the same curent rate as less remaining capacity exist.
Yes ___I am so ignorant ___it is not funny.
Zor
We are discussing 2.4 receiver batteries.
Really we are discussing batteries since they do no know what they are supplying.
I will try to find answers to the following questions myself but in case someone knows.
QUESTIONS ___that are illustrating what goes on in my mind.
Why is the voltage so high at full charge ?
Why does it drop so fast at the beginning of discharege ?
Why does it flatten out and drops very little during most of the discharge ?
Why is a lipo damaged if it goes below a certain voltage ?
What kind of damage takes place ?
What happens that NiCd develop "memory" (and apparently NiMH do not)
Note : I do not need answers such as "they are different composition".
I am looking for what really happens in those cells.
What really is taking place in those cells ? ; it may answer many questions.
That info is not easy to find.
Is the internal resistance increasing as more dischage is taking place ?
Why ?
If so it would mean that the voltage drop of the battery is higher at the same curent rate as less remaining capacity exist.
Yes ___I am so ignorant ___it is not funny.
Zor
01-04-2011, 09:06 AM
#68
Banned
RE: 2.4 Receiver Batteries
Oh ___I love that Libby watching me. A beautiful animal.
Did you examine their characteristics ?
Can you help ? (no pont in re-inventing the wheel)
Sure is a poor approasch
I have discussed some of that topic in this thead.
We know that and I am trying to find the reason(s) as you may have read in close by postings from me.
I am having lots of fun mixed with a bit of frustration due to the difficulty of finding information.
I am not the type of fellow that sits in front of a "boob tube" (TV).
How many here remember the days of carbon-zinc cells and lead-acid batteries and that was the end of the world ?
.
The teacher had said we can take a penny (copper) and a dime (90% silver in those days) and put in between a facial tissue wetted with saliva and we had a cell. We went home and built a pile about an inch high trying to make a flashlight bulb light up.
Oh "The Good Old Times".
Zor
ORIGINAL: rmh
If you would like to get up to speed on really good rx batteries - buy some genuine A123 cells and examine their characteristics.
If you would like to get up to speed on really good rx batteries - buy some genuine A123 cells and examine their characteristics.
Can you help ? (no pont in re-inventing the wheel
)
The use of even extremely good v meters to try and measure remaining capacity is frankly a poor approach.
I have discussed some of that topic in this thead.
The reason being the chemistry produces a plateau of voltage which has a severe ramp at both ends.
The other LIFE cells are very similar in this respect.
Apprears you are enjoying learning the nuances of the new technologies
Have un
Apprears you are enjoying learning the nuances of the new technologies
Have un
I am not the type of fellow that sits in front of a "boob tube" (TV).
How many here remember the days of carbon-zinc cells and lead-acid batteries and that was the end of the world ?
.The teacher had said we can take a penny (copper) and a dime (90% silver in those days) and put in between a facial tissue wetted with saliva and we had a cell. We went home and built a pile about an inch high trying to make a flashlight bulb light up.
Oh "The Good Old Times".
Zor
01-04-2011, 10:40 AM
#69
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RE: 2.4 Receiver Batteries
Zor, thanks for the explanation. The checker is sensitive to 0.001V and accurate to that voltage when checked against my calibrated Fluke voltmeter. Where the checker is conservative is on capacity interpolation. I am assuming it interpolates remaining capacity against ideal curve for a given chemistry but real batteries seldom follow that curve exactly.In the english language we spell sceptic with a "c". north americans may spell it differently but we are rather good sports so we include the incorrect spelling in the Oxford dictionary so people from that continent can claim they speak english too 
01-05-2011, 01:11 AM
#70
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RE: 2.4 Receiver Batteries
i tried reading this thread... oye the back n forth gave me a head ache. You guys are silly. What happened to iron sharpens iron? Intellectual debates are what brings progress, if you can get over "measuring contests". Anyways.. you cant argue against physics, unless the laws of physics are different in your region of time and space. .
Airtronics (what i use) said their RX will go down to about 3.3v before you get reboots. I run 6v nimh packs and I would have to pull a lot of amperes to get a fresh pack to dip that far. If I did,, I could run a capacitor in there to smooth out the bumps. I also use 2100mah packs.. ill fly for about an hr then charge up while i take a break... never have to worry. I wouldnt recommend hybrid nimh (name brand enerloop) as they have high internal resistance and dont take well to high amperes. Supposidly they have a higher voltage drop than normal nimh.... I don't have any metrics on this, its just what ive read on various websites. I did use a custom hybrid pack on a RDS8000 i had... would run all day without any voltage drops.
. Airtronics (what i use) said their RX will go down to about 3.3v before you get reboots. I run 6v nimh packs and I would have to pull a lot of amperes to get a fresh pack to dip that far. If I did,, I could run a capacitor in there to smooth out the bumps. I also use 2100mah packs.. ill fly for about an hr then charge up while i take a break... never have to worry. I wouldnt recommend hybrid nimh (name brand enerloop) as they have high internal resistance and dont take well to high amperes. Supposidly they have a higher voltage drop than normal nimh.... I don't have any metrics on this, its just what ive read on various websites. I did use a custom hybrid pack on a RDS8000 i had... would run all day without any voltage drops.
01-05-2011, 04:38 AM
#71
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RE: 2.4 Receiver Batteries
Interesting thread!
Because I'm short on planes and in-process of assembling some I'm rethinking my battery utilization. Have decided my TX packs will be eneloop only because I'll set one aside for a couple of weeks at a time and want it to retain its charge until I decide to use it again.
But on my receivers I've been using NIMH 4 cell packs and am now moving towards 5 cell packs. Have to wonder if the 2 cell (2S ?) A123 would be wiser? One of my chargers will handle up to 6 cell LiPO, LiPion, or LiFe packs and has the balance connections on it. But I have never used it nor seen it. Are all balance plug connections the same? (I ask because my charger manual doesn't specify what the connections are called.)
How do you balance charge the A123 packs while inside the fuselage? From everything I've been able to read it appears that if you don't balance charge A123 packs everytime you charge you risk cell failure even though it is possible to charge without balancing and necessary to "fast charge" without balancing. Both ways cannot be "Best".
Do you use any voltage regulation between the A123 packs and the receiver...the ignition where applicable? Do you use tradtional charge/switch jacks?
I'm all ears (eyes)
,
Clay
Because I'm short on planes and in-process of assembling some I'm rethinking my battery utilization. Have decided my TX packs will be eneloop only because I'll set one aside for a couple of weeks at a time and want it to retain its charge until I decide to use it again.
But on my receivers I've been using NIMH 4 cell packs and am now moving towards 5 cell packs. Have to wonder if the 2 cell (2S ?) A123 would be wiser? One of my chargers will handle up to 6 cell LiPO, LiPion, or LiFe packs and has the balance connections on it. But I have never used it nor seen it. Are all balance plug connections the same? (I ask because my charger manual doesn't specify what the connections are called.)
How do you balance charge the A123 packs while inside the fuselage? From everything I've been able to read it appears that if you don't balance charge A123 packs everytime you charge you risk cell failure even though it is possible to charge without balancing and necessary to "fast charge" without balancing. Both ways cannot be "Best".
Do you use any voltage regulation between the A123 packs and the receiver...the ignition where applicable? Do you use tradtional charge/switch jacks?
I'm all ears (eyes)
,Clay
01-05-2011, 04:57 AM
#72
RE: 2.4 Receiver Batteries
A123 for rx and eneloop (where applicable) for tx
NO REGULATORS!
This issue is well explored and the A123 is the preferred rx battery for all except those sponsered to use LiPo and regs- A setup I wouldn't have as a gift
NO REGULATORS!
This issue is well explored and the A123 is the preferred rx battery for all except those sponsered to use LiPo and regs- A setup I wouldn't have as a gift
01-05-2011, 07:08 AM
#73
My Feedback: (2)
RE: 2.4 Receiver Batteries
I haven't used Enyloop batteries, yet, but they are a form of NiMh that hold their charge more like LiPos. Guys in our RC club use them in their Transmitters since Transmitters do not draw more than 200mah or so.
Balance Plugs vary with different battery manufacturers and obviously with the number of cells in a pack. Chargers like the FMA 4S, 10S, and Pro Lab 8 offer addapters that contain connectors for multiple types of Balance Taps. I have sets of Great Planes adapters and Thunderpower/Polyquest adapters for my 10S chargers. I have seen other charger manufacturers with even more elaborate charge adapters.
I have just been reading that some people use 2cell (6.6v) A123 Rx packs and they say their servos have not shown any issues. There are others who feel the servos will eventually fail.
I used NiCad and NiMh for many years. Now I use LiPos, LithIons, or A123. They are faster to charge and hold their charge for months. Presently, I use 3cell LiPos in all my Tx's and 2cell LiPos in all my Rx packs. I have been doing this for years and I have never had a problem. I use 5v or 6v regulators on my Rx packs. My JR 791 Retract servos will not work properly at 6v so I use 5v regulators in that aircraft. I do not use regulators in my Tx's, however, some threads talk about using Diodes, in the Tx, to drop the voltage for Unregulated LiPos. I might do that.
2cell LiPos have a Nominal Voltage of 3.7v per cell and charge to 4.2v per cell. A 2cell Rx pack would be 8.4v fully charged. I recharge at about 7.1v.
Balance Plugs vary with different battery manufacturers and obviously with the number of cells in a pack. Chargers like the FMA 4S, 10S, and Pro Lab 8 offer addapters that contain connectors for multiple types of Balance Taps. I have sets of Great Planes adapters and Thunderpower/Polyquest adapters for my 10S chargers. I have seen other charger manufacturers with even more elaborate charge adapters.
I have just been reading that some people use 2cell (6.6v) A123 Rx packs and they say their servos have not shown any issues. There are others who feel the servos will eventually fail.
I used NiCad and NiMh for many years. Now I use LiPos, LithIons, or A123. They are faster to charge and hold their charge for months. Presently, I use 3cell LiPos in all my Tx's and 2cell LiPos in all my Rx packs. I have been doing this for years and I have never had a problem. I use 5v or 6v regulators on my Rx packs. My JR 791 Retract servos will not work properly at 6v so I use 5v regulators in that aircraft. I do not use regulators in my Tx's, however, some threads talk about using Diodes, in the Tx, to drop the voltage for Unregulated LiPos. I might do that.
2cell LiPos have a Nominal Voltage of 3.7v per cell and charge to 4.2v per cell. A 2cell Rx pack would be 8.4v fully charged. I recharge at about 7.1v.
01-05-2011, 07:15 AM
#74
My Feedback: (2)
RE: 2.4 Receiver Batteries
I prefer not to use the cheap Switch Harnesses that come with the radios. I like the Heavy Duty DSC compatible switch harnesses with the molded in charging jack. Some are made more vibration resistant.
The DSC compatibility refers to the previously used Direct Servo Controller technology we used to use to plug the Tx directly into the Rx so you did not have to turn on the Tx while you were testing the radio in your aircraft. Now, the DSC compatible Switch Harness allows you to Bind through the Charging Jack without having to connect the Bind Plug to the Rx, directly. Beware, you must have a DSC compatible Switch Harness to do this and if you are using a Voltage Regulator between the Switch Harness and the Rx, you cannot Bind through the Switch Harness.
The DSC compatibility refers to the previously used Direct Servo Controller technology we used to use to plug the Tx directly into the Rx so you did not have to turn on the Tx while you were testing the radio in your aircraft. Now, the DSC compatible Switch Harness allows you to Bind through the Charging Jack without having to connect the Bind Plug to the Rx, directly. Beware, you must have a DSC compatible Switch Harness to do this and if you are using a Voltage Regulator between the Switch Harness and the Rx, you cannot Bind through the Switch Harness.
01-05-2011, 07:48 AM
#75
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RE: 2.4 Receiver Batteries
Thanks Rich,
I'm going to have to find out what balance connectors fit the ports on my charger. For some reason the manual is silent on this and only tells me it will accept 1S-6S packs. My only interest presently is the 2S A123 and the settings available on the charger indicate its LiFe mode will be appropriate. Reckon I'd have to install the battery in such a way as to make it easily removable so I can charge outside the plane? Seems very inconvenient to me but perhaps it won't be as bad as it seems.
Truly I have zero interest in doing a search and beating myself up trying to figure the lingo out. While I do like to understand how things work I don't need to understand the chemical processes and I'm not "into" batteries and chargers beyond what I need to get flying with a clean setup.
You fellas seem to know what you're talking about and I suspect you can translate this to a dumbo like me.
Assistance much appreciated,
Clay
I'm going to have to find out what balance connectors fit the ports on my charger. For some reason the manual is silent on this and only tells me it will accept 1S-6S packs. My only interest presently is the 2S A123 and the settings available on the charger indicate its LiFe mode will be appropriate. Reckon I'd have to install the battery in such a way as to make it easily removable so I can charge outside the plane? Seems very inconvenient to me but perhaps it won't be as bad as it seems.
Truly I have zero interest in doing a search and beating myself up trying to figure the lingo out. While I do like to understand how things work I don't need to understand the chemical processes and I'm not "into" batteries and chargers beyond what I need to get flying with a clean setup.
You fellas seem to know what you're talking about and I suspect you can translate this to a dumbo like me.
Assistance much appreciated,
Clay