Voltage drop and the dreaded "Brownout" , What's really at fault ?
09-30-2015, 01:17 PM
#126
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Yes I know, thank you 
... if you buy the un-assembled kit, you can use the heavy duty servo extension wires and cut them to length from where you placed your receiver and servos to the power board and solder them into the board... that way they lay in nicely, and can be dressed in tidy.
Right now I'm using a 5 cub "C" cell 3000 mAh NiMh pack for the servo buss... but I'm going to swap that out for another 2500mAh 2S A123 pack... as it turns out, the 0.6 volt difference isn't going to hurt anything... and have found out that the surface charge on a NiMh battery pack takes longer to normalize than the surface charge of the A123 batteries, so in actual fact the 5 cell 6 volt NiMh batteries are harder on 6 volt rated devices, than the 6.6 volt A123 batteries are... so out goes the two 3000 mAh NiMh packs (servo buss & ignition) and in goes two more 2S A123 packs.
They wouldn't state the speed and torque values for 6 volts, if the servos were not designed to handle 6 volts.
+1
John M,
... if you buy the un-assembled kit, you can use the heavy duty servo extension wires and cut them to length from where you placed your receiver and servos to the power board and solder them into the board... that way they lay in nicely, and can be dressed in tidy.Right now I'm using a 5 cub "C" cell 3000 mAh NiMh pack for the servo buss... but I'm going to swap that out for another 2500mAh 2S A123 pack... as it turns out, the 0.6 volt difference isn't going to hurt anything... and have found out that the surface charge on a NiMh battery pack takes longer to normalize than the surface charge of the A123 batteries, so in actual fact the 5 cell 6 volt NiMh batteries are harder on 6 volt rated devices, than the 6.6 volt A123 batteries are... so out goes the two 3000 mAh NiMh packs (servo buss & ignition) and in goes two more 2S A123 packs.
They wouldn't state the speed and torque values for 6 volts, if the servos were not designed to handle 6 volts.
+1
John M,
That is true if you are using FUTABA...Not true for all manufacturers I am afraid. I was misled by seeing torque and speed for both 4.8V and 6V when the servos were only factory rated for 4.8v. Maybe we should carry our Voltmeters with us at all times. LOL
09-30-2015, 01:19 PM
#127
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Current is what destroys a servo,not voltage. A servo rated for 4.8 volts can be used on 8.4v if it is not in a heavy use situation. The higher voltage will draw higher current if it is worked hard and that is what burns it out. The tail rotor servo in a helicopter is working hard all the time and is subject to hard use. The same servo can be used on say the ailerons of a foamy and not be bothered.
In any case I would never exceed its specified rating.
.If you use a stabilizer in your aircraft,keep in mind the control servos will likely be working all of the time like a hellie tail servo does
In any case I would never exceed its specified rating.
.If you use a stabilizer in your aircraft,keep in mind the control servos will likely be working all of the time like a hellie tail servo does
As usual, you are correct...Gyros can cause Brown outs as you already know. They work constantly as you pointed out.
09-30-2015, 03:22 PM
#129
They wouldn't state the speed and torque values for 6 volts, if the servos were not designed to handle 6 volts.
That is true if you are using FUTABA...Not true for all manufacturers I am afraid. I was misled by seeing torque and speed for both 4.8V and 6V when the servos were only factory rated for 4.8v. Maybe we should carry our Voltmeters with us at all times. LOL
That is true if you are using FUTABA...Not true for all manufacturers I am afraid. I was misled by seeing torque and speed for both 4.8V and 6V when the servos were only factory rated for 4.8v. Maybe we should carry our Voltmeters with us at all times. LOL
That's more than likely a sales typo error on some of these web stores... I always browse the mfg's web site, be it futaba or hitec, and look at the servo spec's... I usually run futaba servos, but hitec has some nice servos as well, HS-645MG or HS-5645MG for example.
John M,
Last edited by John_M_; 10-01-2015 at 07:38 AM.
09-30-2015, 05:15 PM
#130
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If someone has had a servo burn up within those parameters it appears to be very, very rare. I haven't ever seen servo windings or brushes burn when loads have exceeded the servo's capability. That is not to say that you couldn't do it on a bench top or on purpose.
And, technically speaking, if they publish a voltage and rotational speed and a torque at that voltage that is a rating, by definition. However, I do not recall seeing published voltage ranges or recommendations for "ordinary" servos (I'm not talking about the HV.
Heck, I have a friend that used to fly top level IMAC with Futaba S3004 servos on a bird powered by a G62, something we would never consider today; that same bird is still flying with only one servo replaced since then.
Ultimately, we are back where we started. Builders need to build their models with components that are suitable for their intended use, whether that is batteries, wiring, switches, connectors, motors, etc..
Every ARF includes servo spec recommendations. If you build from plans or short-kits then there is plenty of information available. If you build your own from scratch you either have the experience to know what you need or the wisdom to get some advice.
If anyone fails at that it is their own fault.
09-30-2015, 07:15 PM
#131
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Watt rating, not volts, is the real limiting factor. However, that isn't very practical based upon the actual duty cycle of the servos. But you have to start somewhere, and since the manufacturers provide torque ratings at 6 volts, we ought to be able to count outputting those torques at that voltage on intermittent basis.
If someone has had a servo burn up within those parameters it appears to be very, very rare. I haven't ever seen servo windings or brushes burn when loads have exceeded the servo's capability. That is not to say that you couldn't do it on a bench top or on purpose.
.
If someone has had a servo burn up within those parameters it appears to be very, very rare. I haven't ever seen servo windings or brushes burn when loads have exceeded the servo's capability. That is not to say that you couldn't do it on a bench top or on purpose.
.
The JR 8411 actually reached the torque it was specified to produce. But at maximum torque it would burn out in 3 seconds. Users not need to worry though as it took an error displacement of about 45degrees to get it to produce maximum torque.
Hitec servos would produce only about 75% of the torque they claimed to produce. It would produce its torque at a much lower error displacement. It took about 30 sec to burn out at max torque. It was a 5955 I tested
10-01-2015, 07:47 AM
#133
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Several years ago I tested several servos.
The JR 8411 actually reached the torque it was specified to produce. But at maximum torque it would burn out in 3 seconds. Users not need to worry though as it took an error displacement of about 45degrees to get it to produce maximum torque.
Hitec servos would produce only about 75% of the torque they claimed to produce. It would produce its torque at a much lower error displacement. It took about 30 sec to burn out at max torque. It was a 5955 I tested
The JR 8411 actually reached the torque it was specified to produce. But at maximum torque it would burn out in 3 seconds. Users not need to worry though as it took an error displacement of about 45degrees to get it to produce maximum torque.
Hitec servos would produce only about 75% of the torque they claimed to produce. It would produce its torque at a much lower error displacement. It took about 30 sec to burn out at max torque. It was a 5955 I tested
You took two servos, a JR 8411 and a Hitec 5944, mounted them, and I'm guessing used a weight/tension gauge to pull against the servo arm at a right angle.
Note: You didn't mention if you kept the load at a right angle to the servo arm as it deflected under the load. If the direction of the load is not kept perpendicular to servo arm you will get erroneously high measurements (Approx. 40% too high at 45 degrees)
JR 8411
- Produced its rated torque, but with 45 deg. of deflection from the starting point (I assume you started from the centered position)
- Catastrophically failed very quickly holding that torque (about 3 seconds)
Hitec 5944
- Only produced a maximum of 75% of its rated torque
- The peak torque was produced at much lower deflection from the commanded position than the JR
- It held this position for about 30 seconds before before catastrophically failing
Two questions:
Was the load kept perpendicular to the servo arm when the measurements were made?
Do you have a guess as to how much the Hitec deflect before it hit peak output?
Thanks,
Paul
10-01-2015, 08:14 AM
#134
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The arm was kept perpendicular for all tests.
I tested several more servos. I have plots of all of the results.
They are on my old XP computer. I hope they are still there.
The plots are torque vs error signal.
I also have some current vs torque plots.
I did this for an article for RCU. They paid me but never published it.
I made a stupid mistake in the presentation and had to correct it. They lost interest.
I tested several more servos. I have plots of all of the results.
They are on my old XP computer. I hope they are still there.
The plots are torque vs error signal.
I also have some current vs torque plots.
I did this for an article for RCU. They paid me but never published it.
I made a stupid mistake in the presentation and had to correct it. They lost interest.
Last edited by dirtybird; 10-01-2015 at 08:19 AM.
10-01-2015, 11:41 AM
#135
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Sounds like an interesting article. I wish they would resurrect it.
Paul
Paul
The arm was kept perpendicular for all tests.
I tested several more servos. I have plots of all of the results.
They are on my old XP computer. I hope they are still there.
The plots are torque vs error signal.
I also have some current vs torque plots.
I did this for an article for RCU. They paid me but never published it.
I made a stupid mistake in the presentation and had to correct it. They lost interest.
I tested several more servos. I have plots of all of the results.
They are on my old XP computer. I hope they are still there.
The plots are torque vs error signal.
I also have some current vs torque plots.
I did this for an article for RCU. They paid me but never published it.
I made a stupid mistake in the presentation and had to correct it. They lost interest.
10-01-2015, 12:35 PM
#136
The arm was kept perpendicular for all tests.
I tested several more servos. I have plots of all of the results.
They are on my old XP computer. I hope they are still there.
The plots are torque vs error signal.
I also have some current vs torque plots.
I did this for an article for RCU. They paid me but never published it.
I made a stupid mistake in the presentation and had to correct it. They lost interest.
I tested several more servos. I have plots of all of the results.
They are on my old XP computer. I hope they are still there.
The plots are torque vs error signal.
I also have some current vs torque plots.
I did this for an article for RCU. They paid me but never published it.
I made a stupid mistake in the presentation and had to correct it. They lost interest.
John M,
10-01-2015, 02:55 PM
#137
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The servo was set in place with the arm extended to one side and tied to a strain gauge.A servoXciter pulse generator was used to produce the control pulse. This unit provides the pulsewidth in usec. The servo power was provided by a power supply with current and voltage readout.
The procedure was to increase the pulse width in 5usec steps and read the strain gauge and current.The servo arm was held in place by the strain gauge. Tests were made at 4.8 and 6.0V. The results were recorded in a spreadsheet that automatically calculated the torque in consideration of the different arm lengths.
The results were then loaded into a program I got off the internet that plotted and provided a smooth curve that best fit the data points.
The major problem was the servo would heat up and reduce its output. I had to set a point then swiftly read the data and let the servo cool before I took the next point.
I will see if I can dig up some of the plots and post them
The procedure was to increase the pulse width in 5usec steps and read the strain gauge and current.The servo arm was held in place by the strain gauge. Tests were made at 4.8 and 6.0V. The results were recorded in a spreadsheet that automatically calculated the torque in consideration of the different arm lengths.
The results were then loaded into a program I got off the internet that plotted and provided a smooth curve that best fit the data points.
The major problem was the servo would heat up and reduce its output. I had to set a point then swiftly read the data and let the servo cool before I took the next point.
I will see if I can dig up some of the plots and post them
10-01-2015, 11:34 PM
#139
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John Mac (another John M 
)
The idea of using two separate batteries, one for the servos, and one for the receiver is not for redundancy protection... its to get the current hungry hi-voltage, digital / coreless servos off the receiver's pin connector buss... putting the servos on their own high current buss, and powering the receiver with its own battery, done properly is just as reliable as a single battery arrangement... actually its more reliable in the terms of protecting the receiver from a brown-out... and with the batteries we have today that were designed for repeated hi-discharge / re-charge cycles, used to power these minimally current hungry devices in retrospect, the batteries will never see their maximum designed thermal / discharge rates in these two particular locations (receiver and servo power), which further reduces the chance of a battery failure.
A properly assembled battery pack (one each for the receiver & servo buss), with a high quality soft switch, or even mechanical switch; properly isolated from vibration, has proven to be extremely reliable... in over the 50 years I've been in this hobby, since I was a young kid, and especially in the last 25 years, I have never seen a battery pack, short out internally or go open from a bad cell... all the failures I seen related to batteries, are caused by the operator; poor installation, poor assembly of the battery pack / cold solder joints... broken battery or servo wires from allowing them to dangle and not properly restrained.. using damage batteries recovered from crashes, etc.... granted mechanical switches can fail under vibration, but this is preventable with proper installation and maintenance... and as previously mentioned, the use of good quality components.
John M,
)The idea of using two separate batteries, one for the servos, and one for the receiver is not for redundancy protection... its to get the current hungry hi-voltage, digital / coreless servos off the receiver's pin connector buss... putting the servos on their own high current buss, and powering the receiver with its own battery, done properly is just as reliable as a single battery arrangement... actually its more reliable in the terms of protecting the receiver from a brown-out... and with the batteries we have today that were designed for repeated hi-discharge / re-charge cycles, used to power these minimally current hungry devices in retrospect, the batteries will never see their maximum designed thermal / discharge rates in these two particular locations (receiver and servo power), which further reduces the chance of a battery failure.
A properly assembled battery pack (one each for the receiver & servo buss), with a high quality soft switch, or even mechanical switch; properly isolated from vibration, has proven to be extremely reliable... in over the 50 years I've been in this hobby, since I was a young kid, and especially in the last 25 years, I have never seen a battery pack, short out internally or go open from a bad cell... all the failures I seen related to batteries, are caused by the operator; poor installation, poor assembly of the battery pack / cold solder joints... broken battery or servo wires from allowing them to dangle and not properly restrained.. using damage batteries recovered from crashes, etc.... granted mechanical switches can fail under vibration, but this is preventable with proper installation and maintenance... and as previously mentioned, the use of good quality components.
John M,
I Take your point in what you are trying to achieve. I was merely making the point that you have introduced one extra critical entity and therefore increased the statistical chances of failure. I also agree with your observation that most failures are due to inadequate quality of component or poor installation. But not all. I have been unlucky enough to have a singe cell in a brand new, and top quality battery go open circuit. Not only did I loose a brand new all moulded scale glider of 4. metres span, but the model crashed in open moor land, but within 30 paces of a member of the public. Scary stuff! Since then all my models have two battery systems installed.
As well as large scale gliders that have many servos and are quite power hungry, I have been flying jets for about 15 years, which are even more power hungry. Only now as I am building much larger jets with HV servos, have I felt the need to go beyond the basic set up I have used all these years, of twin batteries and diodes. So now I am relying on power distribution systems from Powerbox, Emcotec and Jeti. All utilise twin batteries arranged in parallel, to provide the current capacity and voltage overhead that is required to ensure that servos are driven fully, receivers are provided with stabilised supply to ensure they never get close to the brownout stage, and the current for servos is handled by a separate and capable bus.
Like many other contributors here I have settled on the A123 battery as the go to type, for many years. I have never had a failure. Then again I do treat them with respect and with care. I am just trying out the new generation of Li Ion Cell from Jeti, as this has a high voltage rating and allows me to get the most from my HV servos.
I gave up using NiMh more than a decade ago, do to the inability of these cells to provide the current that I required. I avoid Lipos only because of the installation difficulties (they must be removed for charging). However, if the installation difficulties are not proesent then Lipo's are also a good choice.
John
Last edited by JohnMac; 10-01-2015 at 11:37 PM.
10-02-2015, 05:04 AM
#140
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Hi John,
I Take your point in what you are trying to achieve. I was merely making the point that you have introduced one extra critical entity and therefore increased the statistical chances of failure. I also agree with your observation that most failures are due to inadequate quality of component or poor installation. But not all. I have been unlucky enough to have a singe cell in a brand new, and top quality battery go open circuit. Not only did I loose a brand new all moulded scale glider of 4. metres span, but the model crashed in open moor land, but within 30 paces of a member of the public. Scary stuff! Since then all my models have two battery systems installed.
As well as large scale gliders that have many servos and are quite power hungry, I have been flying jets for about 15 years, which are even more power hungry. Only now as I am building much larger jets with HV servos, have I felt the need to go beyond the basic set up I have used all these years, of twin batteries and diodes. So now I am relying on power distribution systems from Powerbox, Emcotec and Jeti. All utilise twin batteries arranged in parallel, to provide the current capacity and voltage overhead that is required to ensure that servos are driven fully, receivers are provided with stabilised supply to ensure they never get close to the brownout stage, and the current for servos is handled by a separate and capable bus.
Like many other contributors here I have settled on the A123 battery as the go to type, for many years. I have never had a failure. Then again I do treat them with respect and with care. I am just trying out the new generation of Li Ion Cell from Jeti, as this has a high voltage rating and allows me to get the most from my HV servos.
I gave up using NiMh more than a decade ago, do to the inability of these cells to provide the current that I required. I avoid Lipos only because of the installation difficulties (they must be removed for charging). However, if the installation difficulties are not proesent then Lipo's are also a good choice.
John
I Take your point in what you are trying to achieve. I was merely making the point that you have introduced one extra critical entity and therefore increased the statistical chances of failure. I also agree with your observation that most failures are due to inadequate quality of component or poor installation. But not all. I have been unlucky enough to have a singe cell in a brand new, and top quality battery go open circuit. Not only did I loose a brand new all moulded scale glider of 4. metres span, but the model crashed in open moor land, but within 30 paces of a member of the public. Scary stuff! Since then all my models have two battery systems installed.
As well as large scale gliders that have many servos and are quite power hungry, I have been flying jets for about 15 years, which are even more power hungry. Only now as I am building much larger jets with HV servos, have I felt the need to go beyond the basic set up I have used all these years, of twin batteries and diodes. So now I am relying on power distribution systems from Powerbox, Emcotec and Jeti. All utilise twin batteries arranged in parallel, to provide the current capacity and voltage overhead that is required to ensure that servos are driven fully, receivers are provided with stabilised supply to ensure they never get close to the brownout stage, and the current for servos is handled by a separate and capable bus.
Like many other contributors here I have settled on the A123 battery as the go to type, for many years. I have never had a failure. Then again I do treat them with respect and with care. I am just trying out the new generation of Li Ion Cell from Jeti, as this has a high voltage rating and allows me to get the most from my HV servos.
I gave up using NiMh more than a decade ago, do to the inability of these cells to provide the current that I required. I avoid Lipos only because of the installation difficulties (they must be removed for charging). However, if the installation difficulties are not proesent then Lipo's are also a good choice.
John
I think if you were to do a failure mode and effects analysis(FMEA) you will find a simple A123 battery will be more reliable.Just check it prior to each flight and plug it in without the use of a switch
10-02-2015, 05:25 AM
#141
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I have to wonder about the complexity of all of the equipment you have in there.
I think if you were to do a failure mode and effects analysis(FMEA) you will find a simple A123 battery will be more reliable.Just check it prior to each flight and plug it in without the use of a switch
I think if you were to do a failure mode and effects analysis(FMEA) you will find a simple A123 battery will be more reliable.Just check it prior to each flight and plug it in without the use of a switch
What you suggest is not legal here in the UK on these larger models. Redundancy is a requirement laid down by the CAA (Equivalent of your FAA). They have some degree of experience in FMEA I suspect. I would not like to fly on an airliner without it having redundant systems, and of course airliners do have many redundant systems.
I have the same. two completely duplicated, end to end power chains and receivers.
But I think we are straying from the original context of this ppost so I will leave it here.
John
10-02-2015, 08:26 AM
#142
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I think your CAA is short sighted. If they require that, they need to follow it up with the requirement that the equipment should be installed and checked by a certified technician.
Flying in an airliner is a completely different situation. The equipment is required to operate for hours without rechecking. It is also required to be installed and checked by a certified technician that knows how to check everything. Our flights are usually 15 minutes or less. The probability of failure is low in that time span
My point is all the equipment you require is getting beyond the ability to determine proper operation by the average modeler.
I think this is within the purview of this thread. A lot of "brownout" problems are cause by improper installation
Flying in an airliner is a completely different situation. The equipment is required to operate for hours without rechecking. It is also required to be installed and checked by a certified technician that knows how to check everything. Our flights are usually 15 minutes or less. The probability of failure is low in that time span
My point is all the equipment you require is getting beyond the ability to determine proper operation by the average modeler.
I think this is within the purview of this thread. A lot of "brownout" problems are cause by improper installation
10-02-2015, 09:40 AM
#143
Hi John,
I Take your point in what you are trying to achieve. I was merely making the point that you have introduced one extra critical entity and therefore increased the statistical chances of failure. I also agree with your observation that most failures are due to inadequate quality of component or poor installation. But not all. I have been unlucky enough to have a singe cell in a brand new, and top quality battery go open circuit. Not only did I loose a brand new all moulded scale glider of 4. metres span, but the model crashed in open moor land, but within 30 paces of a member of the public. Scary stuff! Since then all my models have two battery systems installed.
As well as large scale gliders that have many servos and are quite power hungry, I have been flying jets for about 15 years, which are even more power hungry. Only now as I am building much larger jets with HV servos, have I felt the need to go beyond the basic set up I have used all these years, of twin batteries and diodes. So now I am relying on power distribution systems from Powerbox, Emcotec and Jeti. All utilise twin batteries arranged in parallel, to provide the current capacity and voltage overhead that is required to ensure that servos are driven fully, receivers are provided with stabilised supply to ensure they never get close to the brownout stage, and the current for servos is handled by a separate and capable bus.
Like many other contributors here I have settled on the A123 battery as the go to type, for many years. I have never had a failure. Then again I do treat them with respect and with care. I am just trying out the new generation of Li Ion Cell from Jeti, as this has a high voltage rating and allows me to get the most from my HV servos.
I gave up using NiMh more than a decade ago, do to the inability of these cells to provide the current that I required. I avoid Lipos only because of the installation difficulties (they must be removed for charging). However, if the installation difficulties are not proesent then Lipo's are also a good choice.
John
I Take your point in what you are trying to achieve. I was merely making the point that you have introduced one extra critical entity and therefore increased the statistical chances of failure. I also agree with your observation that most failures are due to inadequate quality of component or poor installation. But not all. I have been unlucky enough to have a singe cell in a brand new, and top quality battery go open circuit. Not only did I loose a brand new all moulded scale glider of 4. metres span, but the model crashed in open moor land, but within 30 paces of a member of the public. Scary stuff! Since then all my models have two battery systems installed.
As well as large scale gliders that have many servos and are quite power hungry, I have been flying jets for about 15 years, which are even more power hungry. Only now as I am building much larger jets with HV servos, have I felt the need to go beyond the basic set up I have used all these years, of twin batteries and diodes. So now I am relying on power distribution systems from Powerbox, Emcotec and Jeti. All utilise twin batteries arranged in parallel, to provide the current capacity and voltage overhead that is required to ensure that servos are driven fully, receivers are provided with stabilised supply to ensure they never get close to the brownout stage, and the current for servos is handled by a separate and capable bus.
Like many other contributors here I have settled on the A123 battery as the go to type, for many years. I have never had a failure. Then again I do treat them with respect and with care. I am just trying out the new generation of Li Ion Cell from Jeti, as this has a high voltage rating and allows me to get the most from my HV servos.
I gave up using NiMh more than a decade ago, do to the inability of these cells to provide the current that I required. I avoid Lipos only because of the installation difficulties (they must be removed for charging). However, if the installation difficulties are not proesent then Lipo's are also a good choice.
John
I make up my own battery packs; I just don't like those solder tabs, because they can pop off if they're not spot welded correctly... with the A123 cells; I de-solder and remove the button cap over the fill / vent... those have been known to come loose if they were not solder properly, if one happens to get past QC.
I've been using NiMh for many years, my choice over NiCad... I use the hi discharge sub "C" NiMh cells; same cells they use in the electric 1/10th scale cars... I don't know what power requirements you are looking to get out of your NiMh's, but those sub C's will produce 25 amps or more, just look how hard they run them in those cars.
Hi Dirtybird,
What you suggest is not legal here in the UK on these larger models. Redundancy is a requirement laid down by the CAA (Equivalent of your FAA). They have some degree of experience in FMEA I suspect. I would not like to fly on an airliner without it having redundant systems, and of course airliners do have many redundant systems.
I have the same. two completely duplicated, end to end power chains and receivers.
But I think we are straying from the original context of this ppost so I will leave it here.
John
What you suggest is not legal here in the UK on these larger models. Redundancy is a requirement laid down by the CAA (Equivalent of your FAA). They have some degree of experience in FMEA I suspect. I would not like to fly on an airliner without it having redundant systems, and of course airliners do have many redundant systems.
I have the same. two completely duplicated, end to end power chains and receivers.
But I think we are straying from the original context of this ppost so I will leave it here.
John
I think you'll find here in the states the AMA requires redundancy in the large models especially the jets... it wasn't a requirement with my 1/4 scale super cub.
John M,
10-02-2015, 12:12 PM
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I am sorry John but that is the typical mistake modelers make.The case of an A123 is not easy to solder to. You must use a considerable amount of heat. The manufacturers of A123 do not recommend soldering to it. That is why they will supply soldering tabs. If you damage the cell internally you will have to take it apart to inspect it.
A welded tab is easy to inspect. Just pull on it.
You may think you have improved reliability, but instead you have reduced it.
A welded tab is easy to inspect. Just pull on it.
You may think you have improved reliability, but instead you have reduced it.
10-02-2015, 01:43 PM
#145
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Are we still going with this issue.I got rid of my earlier spectrum after 2 brown outs destroyed 2 beautiful 3d planes,got back to futaba and never ever had an issue since.I guess new spectrum have resolved this but I am a happy futaba ownwer.bye
10-02-2015, 03:07 PM
#146
I am sorry John but that is the typical mistake modelers make.The case of an A123 is not easy to solder to. You must use a considerable amount of heat. The manufacturers of A123 do not recommend soldering to it. That is why they will supply soldering tabs. If you damage the cell internally you will have to take it apart to inspect it.
A welded tab is easy to inspect. Just pull on it.
You may think you have improved reliability, but instead you have reduced it.
A welded tab is easy to inspect. Just pull on it.
You may think you have improved reliability, but instead you have reduced it.
See pdf attachment below
https://www.youtube.com/watch?v=vkDgoXikI_8
https://www.youtube.com/watch?v=UTDctiyUa9E
John M,
Last edited by John_M_; 10-02-2015 at 08:34 PM.
10-02-2015, 06:02 PM
#147
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I've followed this thread with great interest as I fly Jets, using Spectrum Equipment and (2) 123 batteries exclusively in all my Jets. I read a lot of subjective opinions and some with expert analysis. I've never experienced a brown out i.e. losing control, but my curiosity drove me to the following experiment.
A friend and I hooked up a Spectrum power save receiver to 4 Hitec 5955 servo's one charged 123 battery and a volt meter in line with the receiver. The voltage was 6.62 volts and momentarily dropped .10 volts when power applied. We held the 4 servos to a full stalled position and the voltage dropped 6.10 volts. We did the same using a ni-cad and got similar results. I appreciate this may not have been very scientific but my opinion is this.
My style of flying is average meaning I don't always fly at full throttle and pull hard on the controls. But even if I used full aileron ( 2 servo's) and full elevator (2 servo's) deflection the voltage drop would not approach the brown out thresh hold of 3.5 volts on the receiver.
In conclusion have battery redundancy and keeping them charged would go a long way to eliminating problems. I'm not sure what the score is between Spectrum and Futaba but perhaps it is possible Spectrum could be more sensitive to a voltage drop when approaching the threshold.
K.O.
A friend and I hooked up a Spectrum power save receiver to 4 Hitec 5955 servo's one charged 123 battery and a volt meter in line with the receiver. The voltage was 6.62 volts and momentarily dropped .10 volts when power applied. We held the 4 servos to a full stalled position and the voltage dropped 6.10 volts. We did the same using a ni-cad and got similar results. I appreciate this may not have been very scientific but my opinion is this.
My style of flying is average meaning I don't always fly at full throttle and pull hard on the controls. But even if I used full aileron ( 2 servo's) and full elevator (2 servo's) deflection the voltage drop would not approach the brown out thresh hold of 3.5 volts on the receiver.
In conclusion have battery redundancy and keeping them charged would go a long way to eliminating problems. I'm not sure what the score is between Spectrum and Futaba but perhaps it is possible Spectrum could be more sensitive to a voltage drop when approaching the threshold.
K.O.
10-02-2015, 06:04 PM
#148
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Interesting.
The manufacturer says not to do this.
In the beginning of the video is a disclaimer absolving of their responsibility if you do this.
And you go ahead and do it
The manufacturer says not to do this.
In the beginning of the video is a disclaimer absolving of their responsibility if you do this.
And you go ahead and do it
10-02-2015, 08:22 PM
#149
That's just a general disclaimer so no one will blame the author of the video if the individual screws something up... typical disclaimer legalities.
I use silver solder, and use the acid flux on a Q-tip, the silver solder flows better than the rosin core 60/40 solder does... when I say silver solder, I mean the low temp solder... I clean the cell ends well with some mild soap and water afterwards to get any flux residue off.
Now, I have not yet tried soldering the next gen ANR26650M1-B A123 cells... but Harris makes an aluminum solder and flux paste that works on aluminum as well as regular 60/40 solder does on brass... but my understanding is the next gen A123 cell metal casings have a coating on the aluminum, and the special solder and flux is not needed... I've solder several of the ANR26650M1A cells using the 60/40 or the silver solder with no problems... in my opinion the silver solder flows much nicer with the same heat, or less applied.
I will also add this... the solder tabs are induction spot welded to the cell ends after the cells are manufactured... when you solder on your own tabs, and you do it quickly as you see in the videos, I personally don't think any more heat goes into the cells than when you induction spot weld the solder tabs on... and don't forget, the MFG'er (A123) solders the end button caps over the fill / vent after the cell is manufactured.... but having said that, if you don't know how to solder well, then you could put too much heat, but with my experience, they solder extremely well.
John M,
I use silver solder, and use the acid flux on a Q-tip, the silver solder flows better than the rosin core 60/40 solder does... when I say silver solder, I mean the low temp solder... I clean the cell ends well with some mild soap and water afterwards to get any flux residue off.
Now, I have not yet tried soldering the next gen ANR26650M1-B A123 cells... but Harris makes an aluminum solder and flux paste that works on aluminum as well as regular 60/40 solder does on brass... but my understanding is the next gen A123 cell metal casings have a coating on the aluminum, and the special solder and flux is not needed... I've solder several of the ANR26650M1A cells using the 60/40 or the silver solder with no problems... in my opinion the silver solder flows much nicer with the same heat, or less applied.
I will also add this... the solder tabs are induction spot welded to the cell ends after the cells are manufactured... when you solder on your own tabs, and you do it quickly as you see in the videos, I personally don't think any more heat goes into the cells than when you induction spot weld the solder tabs on... and don't forget, the MFG'er (A123) solders the end button caps over the fill / vent after the cell is manufactured.... but having said that, if you don't know how to solder well, then you could put too much heat, but with my experience, they solder extremely well.
John M,
Last edited by John_M_; 10-02-2015 at 08:56 PM.
10-03-2015, 06:33 AM
#150
DirtyBird;
You had reeds ? I could not afford reeds. I had an escapement.
I solder A123. 100W iron, 3/8 screwdriver tip, rosin flux. You don't need to put a huge blob of solder on the cell to secure a maybe 14 AWG wire. Let the pack sit for a week and then cycle it 10 times. I use the Deans 4 pin connectors - two pins per lead. Good enough for RX packs.
You had reeds ? I could not afford reeds. I had an escapement.
I solder A123. 100W iron, 3/8 screwdriver tip, rosin flux. You don't need to put a huge blob of solder on the cell to secure a maybe 14 AWG wire. Let the pack sit for a week and then cycle it 10 times. I use the Deans 4 pin connectors - two pins per lead. Good enough for RX packs.
Last edited by Four Stroker; 10-03-2015 at 06:42 AM.