Voltage drop and the dreaded "Brownout" , What's really at fault ?
09-27-2015, 06:51 AM
#76
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I PREFER 6V (5 CELL) IF USING NICD OR NIMH BATTERIES. BOTH HAVE DIFFERENT ADVANTAGES.
From everything I have been told, you should pay attention to the mAh ratings. I use 2300 minimum up to 2700 because of price.
The 2700 gives you 2.7Amps max and the 2300 gives you 2.3 Amps max.
I suggest you see how many Amps your servos require and purchase your battery accordingly. I have A-123 (LIFE) which are 6.6 Volts for my receiver. However, they are 4500mAh which gives me 4.5 Amps max.
Sometimes I run two of those. Depends on the servos draw.
Remember the guy in the CIRCUS that took a million volts and his hair stood on end? He made sure there were no Amps to Electrocute him...great show.
Hope this helps.
From everything I have been told, you should pay attention to the mAh ratings. I use 2300 minimum up to 2700 because of price.
The 2700 gives you 2.7Amps max and the 2300 gives you 2.3 Amps max.
I suggest you see how many Amps your servos require and purchase your battery accordingly. I have A-123 (LIFE) which are 6.6 Volts for my receiver. However, they are 4500mAh which gives me 4.5 Amps max.
Sometimes I run two of those. Depends on the servos draw.
Remember the guy in the CIRCUS that took a million volts and his hair stood on end? He made sure there were no Amps to Electrocute him...great show.
Hope this helps.
09-27-2015, 06:54 AM
#77
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I PREFER 6V (5 CELL) IF USING NICD OR NIMH BATTERIES. BOTH HAVE DIFFERENT ADVANTAGES.
From everything I have been told, you should pay attention to the mAh ratings. I use 2300 minimum up to 2700 because of price.
The 2700 gives you 2.7Amps max and the 2300 gives you 2.3 Amps max.
I suggest you see how many Amps your servos require and purchase your battery accordingly. I have A-123 (LIFE) which are 6.6 Volts for my receiver. However, they are 4500mAh which gives me 4.5 Amps max.
Sometimes I run two of those. Depends on the servos draw.
Remember the guy in the CIRCUS that took a million volts and his hair stood on end? He made sure there were no Amps to Electrocute him...great show.
Hope this helps.
From everything I have been told, you should pay attention to the mAh ratings. I use 2300 minimum up to 2700 because of price.
The 2700 gives you 2.7Amps max and the 2300 gives you 2.3 Amps max.
I suggest you see how many Amps your servos require and purchase your battery accordingly. I have A-123 (LIFE) which are 6.6 Volts for my receiver. However, they are 4500mAh which gives me 4.5 Amps max.
Sometimes I run two of those. Depends on the servos draw.
Remember the guy in the CIRCUS that took a million volts and his hair stood on end? He made sure there were no Amps to Electrocute him...great show.
Hope this helps.
I use A123 batteries to fly an airplane I have. They are 2300mah. My aircraft draws about 30 normally and the flight lasts about 5 min.
09-27-2015, 07:02 AM
#78
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The specification 1600mah does not mean the battery is limited to 1.6 amps max. It means it will put out 1.6 amps for 1 hour.
Depending on its internal resistance it will put out many more amps for a shorter period. The C rating tells you how much current the battery can source. NIMH batteries are not C rated.
A decent digital can draw many more amps than 1.6 depending on the load.
Depending on its internal resistance it will put out many more amps for a shorter period. The C rating tells you how much current the battery can source. NIMH batteries are not C rated.
A decent digital can draw many more amps than 1.6 depending on the load.
absolutely 100% correct Dirtybird...I f you know how to pm send me one.
09-27-2015, 03:07 PM
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I forgot to mention that if whatever receiver you are using has a circuit board with the etched "traces" made too small they can not carry the Amps , You may have a problem. All circuit boards and not created equal. We have taken most of them apart and looked for ourselves....You might be surprised at the differences.
If you take a close look at the typical receiver, you will see the + and - leads for servos are on a husky buss and not on those flimsy traces.
The traces carry only the internal signals usually in micro amps. They never carry amps
If you take a close look at the typical receiver, you will see the + and - leads for servos are on a husky buss and not on those flimsy traces.
The traces carry only the internal signals usually in micro amps. They never carry amps
09-27-2015, 03:46 PM
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09-27-2015, 04:15 PM
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This thread is very good with excellent information. I went back today and traded the 1600mah 6v NiMh battery for a little larger 2200mah 6v NiMh size. Probably didn't need to but got it for the same price. This will only be used to power 4 standard size analog servos in a .40 size plane so I think I should have plenty of power to spare.I haven't got one yet, but I will end up buying one of the servo load testers. Sure seems like a handy tool to have on hand.
09-27-2015, 04:26 PM
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This thread is very good with excellent information. I went back today and traded the 1600mah 6v NiMh battery for a little larger 2200mah 6v NiMh size. Probably didn't need to but got it for the same price. This will only be used to power 4 standard size analog servos in a .40 size plane so I think I should have plenty of power to spare.I haven't got one yet, but I will end up buying one of the servo load testers. Sure seems like a handy tool to have on hand.
09-27-2015, 05:00 PM
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Here is a useful tool. Measure your servo current without breaking into the wiring.It says you can even capture the startup inrush current.
I couldn't find the price though.
http://www.amprobe.com/Amprobe/usen/...FciIfgodnzMDdA
I couldn't find the price though.
http://www.amprobe.com/Amprobe/usen/...FciIfgodnzMDdA
09-27-2015, 08:11 PM
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"I forgot to mention that if whatever receiver you are using has a circuit board with the etched "traces" made too small they can not carry the Amps , You may have a problem. All circuit boards and not created equal. We have taken most of them apart and looked for ourselves....You might be surprised at the differences.
If you take a close look at the typical receiver, you will see the + and - leads for servos are on a husky buss and not on those flimsy traces. The traces carry only the internal signals usually in micro amps. They never carry amps
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
It's amateur hour on this thread (again). Having dealt with "traces" and circuit boards for 40+ years, HANDS ON "dealt with", not "my company built 26 layer boards... so I must be important " crap...I can say that without a doubt two of the posters on this thread are complete b.s. artists. Nothing more. Nothing less. Power bus traces are intended to be more robust based on current requirements. Logic traces are not intended to handle high current and are intentionally smaller as they carry signals, analog or digital. The copper required to carry the signal is not as wide as power traces, intentionally, and typically restrained by layout limitations, be it digital or RF. There may be impedance matching considerations, routing, blind vias, buried vias, proper ground, power, Vcc/Vbb layers, isolation, cross talk and a host of other "things" that some posting "experts" claim....for SOME reason, TOTALLY undefined, MIGHT be a problem. Or not. "We have examined..."...really, what did you find? ahhhhhh.... no specifics. Yea, right. Once again, some posters are shooting in the dark with no concept of the real world. Their key agenda is to spread fear for a personal agenda with no real substance to back up the claim. If you have intelligent, reasoned and carefully examined data to support your premise, REGARDLESS of the product manufacturer, present it. If not, please feel free to take up another hobby or at least stop your internet connection. Pure amateur hour.... Sorry for the rant but when something smells like b.s., reads like b.s., conveys like b.s.... it's typically.... b.s.
If you take a close look at the typical receiver, you will see the + and - leads for servos are on a husky buss and not on those flimsy traces. The traces carry only the internal signals usually in micro amps. They never carry amps
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
It's amateur hour on this thread (again). Having dealt with "traces" and circuit boards for 40+ years, HANDS ON "dealt with", not "my company built 26 layer boards... so I must be important " crap...I can say that without a doubt two of the posters on this thread are complete b.s. artists. Nothing more. Nothing less. Power bus traces are intended to be more robust based on current requirements. Logic traces are not intended to handle high current and are intentionally smaller as they carry signals, analog or digital. The copper required to carry the signal is not as wide as power traces, intentionally, and typically restrained by layout limitations, be it digital or RF. There may be impedance matching considerations, routing, blind vias, buried vias, proper ground, power, Vcc/Vbb layers, isolation, cross talk and a host of other "things" that some posting "experts" claim....for SOME reason, TOTALLY undefined, MIGHT be a problem. Or not. "We have examined..."...really, what did you find? ahhhhhh.... no specifics. Yea, right. Once again, some posters are shooting in the dark with no concept of the real world. Their key agenda is to spread fear for a personal agenda with no real substance to back up the claim. If you have intelligent, reasoned and carefully examined data to support your premise, REGARDLESS of the product manufacturer, present it. If not, please feel free to take up another hobby or at least stop your internet connection. Pure amateur hour.... Sorry for the rant but when something smells like b.s., reads like b.s., conveys like b.s.... it's typically.... b.s.
09-28-2015, 04:19 AM
#87
My Feedback: (27)
I forgot to mention that if whatever receiver you are using has a circuit board with the etched "traces" made too small they can not carry the Amps , You may have a problem. All circuit boards and not created equal. We have taken most of them apart and looked for ourselves....You might be surprised at the differences.
If you take a close look at the typical receiver, you will see the + and - leads for servos are on a husky buss and not on those flimsy traces....
The traces carry only the internal signals usually in micro amps. They never carry amps
If you take a close look at the typical receiver, you will see the + and - leads for servos are on a husky buss and not on those flimsy traces....
The traces carry only the internal signals usually in micro amps. They never carry amps
And your point is...??? I apologize, I should have said " If you know what you are looking at, you might be surprised at the differences"
What brand is your "typical Receiver" we would like to compare it with others.
The Micro amps you speak of are for the components...Running the power through the receiver to the servos requires heavy duty servo operating system. That is what we are talking about. Trace the Servo "OUTPUT" back to the power "INPUT" and look for the weakest link.
The Firmware in all Receivers are not equal.
Thank you in advance.
09-28-2015, 05:58 AM
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Here is a useful tool. Measure your servo current without breaking into the wiring.It says you can even capture the startup inrush current.
I couldn't find the price though.
http://www.amprobe.com/Amprobe/usen/...FciIfgodnzMDdA
I couldn't find the price though.
http://www.amprobe.com/Amprobe/usen/...FciIfgodnzMDdA
09-28-2015, 08:31 AM
#91
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Here is a link to A123's own website that rates the 2500mAh batteries as 70amp max discharge and perfectly happy at 20c continuous discharge rates - 50 amps!
I'm guessing that you are applying a NiMH and NiCad rule of thumb to A123 cells.
A123 ANR26650 cell datasheet: http://www.a123systems.com/Collatera...ta%20Sheet.pdf
I believe that your 4500mAh A123 cells are good for 80A continuous discharge - not "4.5 Amps max."
Keep in mind that all LiFe-type batteries are not created equal. Hobbico and Hobby King brand LiFe batteries can put out plenty of power, but not as much as the A123 brand cells.
Paul
09-28-2015, 08:36 AM
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I am with dirtybird on this.
Here is a link to A123's own website that rates the 2500mAh batteries as 70amp max discharge and perfectly happy at 20c continuous discharge rates - 50 amps!
I'm guessing that you are applying a NiMH and NiCad rule of thumb to A123 cells.
A123 ANR26650 cell datasheet: http://www.a123systems.com/Collatera...ta%20Sheet.pdf
I believe that your 4500mAh A123 cells are good for 80A continuous discharge - not "4.5 Amps max."
Keep in mind that all LiFe-type batteries are not created equal. Hobbico and Hobby King brand LiFe batteries can put out plenty of power, but not as much as the A123 brand cells.
Paul
Here is a link to A123's own website that rates the 2500mAh batteries as 70amp max discharge and perfectly happy at 20c continuous discharge rates - 50 amps!
I'm guessing that you are applying a NiMH and NiCad rule of thumb to A123 cells.
A123 ANR26650 cell datasheet: http://www.a123systems.com/Collatera...ta%20Sheet.pdf
I believe that your 4500mAh A123 cells are good for 80A continuous discharge - not "4.5 Amps max."
Keep in mind that all LiFe-type batteries are not created equal. Hobbico and Hobby King brand LiFe batteries can put out plenty of power, but not as much as the A123 brand cells.
Paul
09-28-2015, 09:01 AM
#93
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Futaba seems to think this discussion applies to their receivers. They don't have magic circuitry or wizard firmware. It is a matter of physics.
All receivers have a voltage where the receiver will reset. If your battery, wiring, connectors, etc. are insufficient for the power required, and the receiver is not on a separate power bus, EVERY receiver will take a nap - at similar voltages, particularly when you consider that it is probably happening on the steep end of the battery's voltage-current discharge curve.
http://www.futabarc.com/faq/faq-receivers.html#q878
Paul
All receivers have a voltage where the receiver will reset. If your battery, wiring, connectors, etc. are insufficient for the power required, and the receiver is not on a separate power bus, EVERY receiver will take a nap - at similar voltages, particularly when you consider that it is probably happening on the steep end of the battery's voltage-current discharge curve.
Originally Posted by Futaba R6008HS Receiver Manual
OPERATING NOTES All robbe-Futaba receivers continue to work at full range down to a power supply voltage of 3 V. ...
Originally Posted by Futaba Receiver Technical Information FAQ
The receiver will not have a problem with the number or type of servos used. A large number of servos, such as the number that you are using, could cause the battery voltage to drop below what the receiver requires. You would want to make sure that your servo and battery wiring could handle the current needed from the servos without giving you much voltage drop. ...
Paul
Last edited by SkidMan; 09-28-2015 at 09:11 AM.
09-28-2015, 09:10 AM
#94
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Companies like Electrodynamics (great products) all use cells that they purchase elsewhere and assemble them into the packs they sell. This somewhat limits the quality they can add, compared to products they, themselves, design. That said, the quality of the welds, wiring and connectors are critical, and knowing Electrodynamics, but not owning any of their battery packs, I am certain theirs are high quality.
Whoever you get them from make sure they are genuine A123 cells, not knockoffs.
All that said, you cannot expect full performance from these packs if your connection to the receiver and servos is through a 3-pin servo type connector. Buy and use packs that have larger gauge discharge leads.
Paul
Last edited by SkidMan; 09-28-2015 at 09:13 AM.
09-28-2015, 09:11 AM
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Dirtybird: Your hypothesis that says if a company has been in business 10+ years and they have lots and lots of test equipment they could not possibly produce an inferior product does not hold water.
What about GM and their ignition switch problem... they should have found that with their test equipment right?
What about Volkswagen and their emissions problem they tried to cover up with a software tweak?
Those are examples that show any company can and will make mistakes.
Maybe Spektrum has a problem that their test equipment can't detect. The problem only seems to show up under actual use and no, it can't always be the batteries that are at fault or it would have been fixed by now.
The most obvious answer, to me, is that it is made in China. Spektrum needs to make them improve their quality control and the problem might just go away...
I like my DX7s but it makes me very nervous when I fly an expensive airplane with it.
Bob
What about GM and their ignition switch problem... they should have found that with their test equipment right?
What about Volkswagen and their emissions problem they tried to cover up with a software tweak?
Those are examples that show any company can and will make mistakes.
Maybe Spektrum has a problem that their test equipment can't detect. The problem only seems to show up under actual use and no, it can't always be the batteries that are at fault or it would have been fixed by now.
The most obvious answer, to me, is that it is made in China. Spektrum needs to make them improve their quality control and the problem might just go away...
I like my DX7s but it makes me very nervous when I fly an expensive airplane with it.
Bob
09-28-2015, 09:17 AM
#96
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On ebay I found this for $42.
http://www.ebay.com/itm/New-MASTECH-...-/180937984927.
Its shipped free from New Jersey.
I have two Mastech power supplies. They are well made
09-28-2015, 11:01 AM
#98
Paul, just curious what servos are you using, they must be using HV servos... I would run A123's on the servo buss, but the servos I'm running are rated for 6 volts and I wouldn't push them at 6.6 volts... I won't use a regulator, so I'm stuck with NiMh.
For the type of flying I do, running HV servos would be a waste because I don't do 3D, or any precision type flying... I have an eye condition that limits my abilities, so if I did anything remotely related to some of these aggressive 3D maneuvers I think everyone standing around would dive to the ground or hide behind something for shelter... LoL, when people see my glasses, I get stares, like they are questioning my ability if I can fly safely... I tell them not to worry, but if you see me drop everything and start running ,you know somethings wrong lol,
John M,
09-28-2015, 11:12 AM
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I checked Home Depot but could not find the Amprobe 25 listed. Amazon has them for $200.
On ebay I found this for $42.
http://www.ebay.com/itm/New-MASTECH-...-/180937984927.
Its shipped free from New Jersey.
I have two Mastech power supplies. They are well made
On ebay I found this for $42.
http://www.ebay.com/itm/New-MASTECH-...-/180937984927.
Its shipped free from New Jersey.
I have two Mastech power supplies. They are well made
