Testing Dual Battery Setup with Voltmagic
05-22-2010, 08:55 PM
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Testing Dual Battery Setup with Voltmagic
I'm not sure I am interpreting the data from my Voltmagic correctly so I wanted to run this by you guys for some input. I am finished with my 50cc Aeroworks 260 and I am using dual 2300 A123 packs into separate switches to supply power for everything....including ignition. Hitec 7955TG's on everything except throttle where I have the metal gear version. Two servos on elevator, two on wing total and one on rudder. The IBE isn't factored into this test because I am not running the engine.
Anyway, I configured my voltmagic for an averge voltage (AV) range of 6.92 to 6.22 and a peak low voltage (PLV) range of 5.6 to 4.8. When I turn on both switches (both batteries fully charged) I get a nice solid voltage reading of 6.82 and no matter what I do with the sticks I don't get any PLV readings in the range of 4.8 to 5.6. In other words, when I swash the sticks around to simulate flight loads all is good.
However, when I turn one of the switches off (intending to simulate a failure) I get interesting results. Moving any one stick input back and forth quickly is ok and I don't get any PLV reading. But when I go corner to corner with aileron and elevator I immediately get a PLV reading of 5.1 volts and if I do it fast enough and/or add a rudder input at the same time I immediately get a 4.8 volt reading. The test results are the same when I use either battery individually.
Based on my understanding of things Iwould interpret this to mean that something is wrong with my set-ups ability to deliver the right amount of amps through one switch and battery. But I am not sure what to do next to isolate what the problem is. I have heavy duty switches, heavy duty extensions etc. I'm hoiping this is not normal because the results seem to defeat the purpose of the redundancy in the first place.
Also of interest to me is why the 4.8 voltage reading didn't seem to throw the receiver into failsafe...but I have to look at that a little more closely.
I'll take suggestions about what process I should use from here and of course, I'll provide additional information if I left out something that is relevant.
Thanks guys,
Tom
05-24-2010, 07:33 PM
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RE: Testing Dual Battery Setup with Voltmagic
Any thoughts guys and/or any Voltmagic users have any insights? I'm grounded until I resolve this....
Appreciate it!
Tom
Appreciate it!
Tom
05-25-2010, 07:18 AM
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RE: Testing Dual Battery Setup with Voltmagic
If I understand what you are saying, it sounds normal to me. A battery's voltage drops when it is delivering current with the drop depending on the amount of current delivered. When two batteries are in parallel, they each deliver half the current needed by the receiver and servos. If you run only one battery, then it must deliver all of the current and its voltage will drop more than when it is in parallel with another. That is why you get a lower voltage reading when you remove one battery.
Bruce
Bruce
05-25-2010, 01:35 PM
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RE: Testing Dual Battery Setup with Voltmagic
Thank you for your reply...
I agree and understand what you are saying...so probably what is messing me up thenis my expectation of the dual battery set-up. While control can be maintained on one battery in the event of failure on the other side...I'm still not protected against a voltage drop that could send the receiver into failsafe. Even on a fully charged set of batteries the voltage dipped.
Which begs a different inquiry then because I understood that some guys choose not to run a dual battery set-up. All things remaining equal, that would mean a single battery set-upwould alwayshave potential to dipinto 4.8 volt territory with some reasonably aggressive flying. Even on a full charge and even with dual powerfeed leads from the same battery etc.
Since I am not hearing (from my reading) about constant failsafe issues with a one battery set-up I wonder if the Voltmagic is more sensitive than the receiver. The instructions say it samples voltage 1000 times per second.So even though the dip shows up on Voltmagic it may not be a long enough duration for the receiver to brown out / failsafe. I wonder how long a JR receiver has to see sub 4.8 voltage before it runs into a problem.
So for you Voltmagic users out there it looks like the dreaded red light isn't so dreaded afterall as built into thatlight is a good amount of safety threshold. It would be nice to hear from some of these users if you had a moment to comment.
Thanks again,
Tom
05-25-2010, 03:30 PM
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RE: Testing Dual Battery Setup with Voltmagic
Tom, four things:
1. Fail-safe does not kick in on power failures because the receiver needs power to move to fail-safe settings. Fail-safe only works on loss or interference of the radio signal.
2. I fly with Futaba Fasst systems and the reciver does not quit at 4.8 volts, rather at, IIRC, 3.4 volts. At that voltage the servos are no long working. For JR/Spectum systems it is higher but still far below 4.8 volts. Also a battery does not quite the instant the power drops to the critical level in that there is still current available from capacitors, etc. in the receiver. This may be enough to bridge a drop of only a few milliseconds.
3. I use VoltWatch on all of my systems. Even with a good but not full charge on the batteries, if I move all of the contols at once I do get very short flashes of the caution lights but it does not effect the receiver. Once in a while I will even get a red flash without effect. I quit flying when moving the servos puts me in the caution area most of the time.
4. The purpose of dual battery packs and switches is to save a plane when a power system (battery + switch) completely fails. Note that switches are more likely to fail than batteries. That is why it is a good pratice to test each power system seperately with an ESV before flying to make sure each is working correctly. A VoltWatch type device will not tell this on dual power systems because it takes only one of the power systems to be working to give a good reading at the receiver.
Bruce
1. Fail-safe does not kick in on power failures because the receiver needs power to move to fail-safe settings. Fail-safe only works on loss or interference of the radio signal.
2. I fly with Futaba Fasst systems and the reciver does not quit at 4.8 volts, rather at, IIRC, 3.4 volts. At that voltage the servos are no long working. For JR/Spectum systems it is higher but still far below 4.8 volts. Also a battery does not quite the instant the power drops to the critical level in that there is still current available from capacitors, etc. in the receiver. This may be enough to bridge a drop of only a few milliseconds.
3. I use VoltWatch on all of my systems. Even with a good but not full charge on the batteries, if I move all of the contols at once I do get very short flashes of the caution lights but it does not effect the receiver. Once in a while I will even get a red flash without effect. I quit flying when moving the servos puts me in the caution area most of the time.
4. The purpose of dual battery packs and switches is to save a plane when a power system (battery + switch) completely fails. Note that switches are more likely to fail than batteries. That is why it is a good pratice to test each power system seperately with an ESV before flying to make sure each is working correctly. A VoltWatch type device will not tell this on dual power systems because it takes only one of the power systems to be working to give a good reading at the receiver.
Bruce
05-25-2010, 08:57 PM
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RE: Testing Dual Battery Setup with Voltmagic
Tom your seeing the same thing I see on my setup. The only thing I would suggest is make sure the servo's are not running into stall with extreme travels. People tend to just go for everything they can (deflection) when everything is not always the best.
05-26-2010, 11:33 AM
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RE: Testing Dual Battery Setup with Voltmagic
Alright...I get it now and now I like the Voltmagic even more! This gives great on-board and real-time information...great. Please see bold below:
Tom, four things:
1. Fail-safe does not kick in on power failures because the receiver needs power to move to fail-safe settings. Fail-safe only works on loss or interference of the radio signal. Yes, I was mixing these up. I went back and re-read this section of my transmitter manual.The receiver re-boot from the momentary power loss is what I should have been concerned about.
2. I fly with Futaba Fasst systems and the reciver does not quit at 4.8 volts, rather at, IIRC, 3.4 volts. At that voltage the servos are no long working. For JR/Spectum systems it is higher but still far below 4.8 volts. Also a battery does not quite the instant the power drops to the critical level in that there is still current available from capacitors, etc. in the receiver. This may be enough to bridge a drop of only a few milliseconds. Yes again. According to my manual, they encourage a minimum of 4.8 volts (which is what I was fixated on) but that is just to allow enough headroom for the 3.6 volt no-go range that would cause the re-boot. Momentary dip into 4.8 range or not...doesn't matter because it is way higher than the re-boot range.
3. I use VoltWatch on all of my systems. Even with a good but not full charge on the batteries, if I move all of the contols at once I do get very short flashes of the caution lights but it does not effect the receiver. Once in a while I will even get a red flash without effect. I quit flying when moving the servos puts me in the caution area most of the time. Pretty much the same thing but I think the Voltmagic works a little different. Rather than the short flashes you describe the Voltmagic just lights up solid for whatever your Average Voltage is and then blinks constantly at the Peak Low Voltage even if it hits it just once for a very short duration.Same data though basically.
4. The purpose of dual battery packs and switches is to save a plane when a power system (battery + switch) completely fails. Note that switches are more likely to fail than batteries. That is why it is a good pratice to test each power system seperately with an ESV before flying to make sure each is working correctly. A VoltWatch type device will not tell this on dual power systems because it takes only one of the power systems to be working to give a good reading at the receiver. I see this better now on the power system failure part. As to the ESV though I am thinking I can turn on each battery separately before my flight and note the voltage at the receiver by looking at the Voltmagic reading. I can put a small load on the battery by moving one stick around and then repeat for the other battery. I remember from my reading that checking loaded voltage before flight is good...but we know the context of that with the A123 chemistries and the rest of the battery management regimen.
Mikecam...thanks again for chiming in...I was thinking about you so I am glad you are still hovering around in RCU helping guys like me out. By the way, are you using the NORM PLV or LOW PLV?
Tom
Tom, four things:
1. Fail-safe does not kick in on power failures because the receiver needs power to move to fail-safe settings. Fail-safe only works on loss or interference of the radio signal. Yes, I was mixing these up. I went back and re-read this section of my transmitter manual.The receiver re-boot from the momentary power loss is what I should have been concerned about.
2. I fly with Futaba Fasst systems and the reciver does not quit at 4.8 volts, rather at, IIRC, 3.4 volts. At that voltage the servos are no long working. For JR/Spectum systems it is higher but still far below 4.8 volts. Also a battery does not quite the instant the power drops to the critical level in that there is still current available from capacitors, etc. in the receiver. This may be enough to bridge a drop of only a few milliseconds. Yes again. According to my manual, they encourage a minimum of 4.8 volts (which is what I was fixated on) but that is just to allow enough headroom for the 3.6 volt no-go range that would cause the re-boot. Momentary dip into 4.8 range or not...doesn't matter because it is way higher than the re-boot range.
3. I use VoltWatch on all of my systems. Even with a good but not full charge on the batteries, if I move all of the contols at once I do get very short flashes of the caution lights but it does not effect the receiver. Once in a while I will even get a red flash without effect. I quit flying when moving the servos puts me in the caution area most of the time. Pretty much the same thing but I think the Voltmagic works a little different. Rather than the short flashes you describe the Voltmagic just lights up solid for whatever your Average Voltage is and then blinks constantly at the Peak Low Voltage even if it hits it just once for a very short duration.Same data though basically.
4. The purpose of dual battery packs and switches is to save a plane when a power system (battery + switch) completely fails. Note that switches are more likely to fail than batteries. That is why it is a good pratice to test each power system seperately with an ESV before flying to make sure each is working correctly. A VoltWatch type device will not tell this on dual power systems because it takes only one of the power systems to be working to give a good reading at the receiver. I see this better now on the power system failure part. As to the ESV though I am thinking I can turn on each battery separately before my flight and note the voltage at the receiver by looking at the Voltmagic reading. I can put a small load on the battery by moving one stick around and then repeat for the other battery. I remember from my reading that checking loaded voltage before flight is good...but we know the context of that with the A123 chemistries and the rest of the battery management regimen.
Mikecam...thanks again for chiming in...I was thinking about you so I am glad you are still hovering around in RCU helping guys like me out. By the way, are you using the NORM PLV or LOW PLV?
Tom
Good luck with your flying and may your batteries never fail.
05-31-2011, 12:29 PM
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RE: Testing Dual Battery Setup with Voltmagic
OK this is an older thread; but I'm still messed up on this so I want to revisit things.
My Voltmagic is plugged into the receiver...measuring voltage at the receiver. I originally passed off the low voltages sensed by the Voltmagic to be too sensitive or the samplerate too quickfor the receiver to notice. But I don't think that is true because I amplugged intothe receiver.
Now, ONE flight and I get solid green on green LED #4 which means average voltage of 6.66; I also get one flash on red LED #7 which means peak low voltage (PLV)of 4.6. This is voltage seen at the receiver! That's too low for just one flight and I can't help but think something isn't right.
Each flight I average about 200mah used per battery.
Switches, wires etc. are all heavy duty but I would like to do something proactive to figure this out. And remember I struggle with this part of the hobby...
Can someone walk me through how to test each switch to see if I have a problem with one of them sucking up amps?
Can anyone speak to the demands of a DA50 ignition (I am using the IBE)? For example, I notice right after startup I get a yellow LED on PLV. Does the ignition draw amps proportional to throttle and/or more abruptly at start-up?
I have the same results on a full flight at low rates...so I know I am not overthrowing and binding a servo. But what else can I test on the servo?
Any thougths would be appreciated.
Thanks guys,
Tom
My Voltmagic is plugged into the receiver...measuring voltage at the receiver. I originally passed off the low voltages sensed by the Voltmagic to be too sensitive or the samplerate too quickfor the receiver to notice. But I don't think that is true because I amplugged intothe receiver.
Now, ONE flight and I get solid green on green LED #4 which means average voltage of 6.66; I also get one flash on red LED #7 which means peak low voltage (PLV)of 4.6. This is voltage seen at the receiver! That's too low for just one flight and I can't help but think something isn't right.
Each flight I average about 200mah used per battery.
Switches, wires etc. are all heavy duty but I would like to do something proactive to figure this out. And remember I struggle with this part of the hobby...
Can someone walk me through how to test each switch to see if I have a problem with one of them sucking up amps?
Can anyone speak to the demands of a DA50 ignition (I am using the IBE)? For example, I notice right after startup I get a yellow LED on PLV. Does the ignition draw amps proportional to throttle and/or more abruptly at start-up?
I have the same results on a full flight at low rates...so I know I am not overthrowing and binding a servo. But what else can I test on the servo?
Any thougths would be appreciated.
Thanks guys,
Tom
05-31-2011, 07:16 PM
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RE: Testing Dual Battery Setup with Voltmagic
A DA-50 will draw about 800-900 mAmps at full throttle. Much less at idle. You didn't state how long of flights you do. I know on my 35% Extra330SC, I use about 250mA per 8 minute flight (combination 3D and IMAC). 400mA on a 50cc airplane seems very high to me, unless you are doing 25 minute flights.
I don't use a voltwatch and no-one I fly with does either so I can't speak to that. For me, I load test each of my A123 with 1 amp load prior to each flight. The 1 amp load only drops the voltage by a small amount (typical reading is 6.36V). If everything was good in your system, there is no way you will drag down the voltage of an 2300mA A123 to 4.6 volts just by moving the sticks. These batteries can take a tremendous load without dragging down the voltage. On a fresh 2300 A123, I can put a 3 amp load on it and still hold over 6 volts.
My airplane has 2 each HS-7955, 4 each HS-5955, 1 HS-7980 and 1 each HS-985.
I don't use a voltwatch and no-one I fly with does either so I can't speak to that. For me, I load test each of my A123 with 1 amp load prior to each flight. The 1 amp load only drops the voltage by a small amount (typical reading is 6.36V). If everything was good in your system, there is no way you will drag down the voltage of an 2300mA A123 to 4.6 volts just by moving the sticks. These batteries can take a tremendous load without dragging down the voltage. On a fresh 2300 A123, I can put a 3 amp load on it and still hold over 6 volts.
My airplane has 2 each HS-7955, 4 each HS-5955, 1 HS-7980 and 1 each HS-985.
06-01-2011, 02:19 AM
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RE: Testing Dual Battery Setup with Voltmagic
Rcairflr...thank you for your post; please see bold below:
ORIGINAL: rcairflr
A DA-50 will draw about 800-900 mAmps at full throttle. Much less at idle. You didn't state how long of flights you do. I know on my 35% Extra330SC, I use about 250mA per 8 minute flight (combination 3D and IMAC). 400mA on a 50cc airplane seems very high to me, unless you are doing 25 minute flights. My transmitter timer is set for 10 minutes and that timer starts automatically when the throttle stick is advanced. Since I always do a quick engine run-up in the pits, my 10 minute flight begins in the pits. Also, just to be clear, my set-up has 5 HS-7955TG's and 1 HS-7955MG for 6 servos total. I have dual 2300mah A123's that power all airframe control surfaces AND the DA50 ignition through an IBE. So correct, I use about 200mah per battery per flight. If you are using a separate ignition battery we may not be that different in terms of total mah usage. I'm wondering if you, or anyone else, has some mah usage data for a DA50 ignition on a 8 to 10 minute flight for comparison. That would help me break this down.
I don't use a voltwatch and no-one I fly with does either so I can't speak to that. For me, I load test each of my A123 with 1 amp load prior to each flight. The 1 amp load only drops the voltage by a small amount (typical reading is 6.36V). If everything was good in your system, there is no way you will drag down the voltage of an 2300mA A123 to 4.6 volts just by moving the sticks. These batteries can take a tremendous load without dragging down the voltage. On a fresh 2300 A123, I can put a 3 amp load on it and still hold over 6 volts. Yea...and its the "If everything was good in your system" comment that has got me questioning the readings on my Voltmagic in the first place. Just so you know, the instructions on the Voltmagic assert that by swashing the sticks (rapidly moving both gimbals in a circular fashion) you can simulate actual flight loads. The theory being that the sudden stop and change in direction of digital servos creates a momentary increase in current draw similar to flying. Also, the Voltmagicsamples voltage 1,000 times per second and reports the Peak Low Voltage (PLV) at whatever it's plugged into (regulator, receiver etc.). This is the value that comes back between 4.6 and 4.8 volts on my set-up. At the same time, it averages all its readings and filters out voltage spikes to report Average Voltage (AV). That value is always much higher and Idon't think I have evergone lower than 6.6 volts.
You are correct on load testing the A123 with a voltmeter and not getting much voltage sag. But from what I am reading, the Voltmagic's sample rate is so fast at 1,000 times per second that it "sees" voltage dips that the ESV is blind to, and since my Voltmagic is plugged into my receiver I think my receiver "sees" the voltage dip too.
The Voltmagic instructions tell you to test your switches by plugging directly into the receiver and swashing the sticks. But that is not apples to apples for me as I use the IBE. So I have an idea to test my switches by plugging my batteries directly into my receiver on a full charge, flying a 10 minute flight,and then comparing thereadings on the Voltmagic.I'll pick up the demands of the DA 50 that way.
Not sure how to run a test on the servos yet...
Anyway...what say ye now!
Thanks.
My airplane has 2 each HS-7955, 4 each HS-5955, 1 HS-7980 and 1 each HS-985.
A DA-50 will draw about 800-900 mAmps at full throttle. Much less at idle. You didn't state how long of flights you do. I know on my 35% Extra330SC, I use about 250mA per 8 minute flight (combination 3D and IMAC). 400mA on a 50cc airplane seems very high to me, unless you are doing 25 minute flights. My transmitter timer is set for 10 minutes and that timer starts automatically when the throttle stick is advanced. Since I always do a quick engine run-up in the pits, my 10 minute flight begins in the pits. Also, just to be clear, my set-up has 5 HS-7955TG's and 1 HS-7955MG for 6 servos total. I have dual 2300mah A123's that power all airframe control surfaces AND the DA50 ignition through an IBE. So correct, I use about 200mah per battery per flight. If you are using a separate ignition battery we may not be that different in terms of total mah usage. I'm wondering if you, or anyone else, has some mah usage data for a DA50 ignition on a 8 to 10 minute flight for comparison. That would help me break this down.
I don't use a voltwatch and no-one I fly with does either so I can't speak to that. For me, I load test each of my A123 with 1 amp load prior to each flight. The 1 amp load only drops the voltage by a small amount (typical reading is 6.36V). If everything was good in your system, there is no way you will drag down the voltage of an 2300mA A123 to 4.6 volts just by moving the sticks. These batteries can take a tremendous load without dragging down the voltage. On a fresh 2300 A123, I can put a 3 amp load on it and still hold over 6 volts. Yea...and its the "If everything was good in your system" comment that has got me questioning the readings on my Voltmagic in the first place. Just so you know, the instructions on the Voltmagic assert that by swashing the sticks (rapidly moving both gimbals in a circular fashion) you can simulate actual flight loads. The theory being that the sudden stop and change in direction of digital servos creates a momentary increase in current draw similar to flying. Also, the Voltmagicsamples voltage 1,000 times per second and reports the Peak Low Voltage (PLV) at whatever it's plugged into (regulator, receiver etc.). This is the value that comes back between 4.6 and 4.8 volts on my set-up. At the same time, it averages all its readings and filters out voltage spikes to report Average Voltage (AV). That value is always much higher and Idon't think I have evergone lower than 6.6 volts.
You are correct on load testing the A123 with a voltmeter and not getting much voltage sag. But from what I am reading, the Voltmagic's sample rate is so fast at 1,000 times per second that it "sees" voltage dips that the ESV is blind to, and since my Voltmagic is plugged into my receiver I think my receiver "sees" the voltage dip too.
The Voltmagic instructions tell you to test your switches by plugging directly into the receiver and swashing the sticks. But that is not apples to apples for me as I use the IBE. So I have an idea to test my switches by plugging my batteries directly into my receiver on a full charge, flying a 10 minute flight,and then comparing thereadings on the Voltmagic.I'll pick up the demands of the DA 50 that way.
Not sure how to run a test on the servos yet...
Anyway...what say ye now!
Thanks.
My airplane has 2 each HS-7955, 4 each HS-5955, 1 HS-7980 and 1 each HS-985.
06-01-2011, 11:08 AM
#12
RE: Testing Dual Battery Setup with Voltmagic
It will be interesting to see your results without the switches in the circuit. I suspect that the voltage drop you are seeing is because of the (relatively) small gauge wire and connectors that are being used. Even heavy duty switches and extensions use the same small connectors, and the wire is usually only about 22 gauge. That stuff is really only rated to about 3-4 amps. When you use both switches and batteries, the load is distributed across two sets of wires and connectors so the resistance is less and the volt drop is less. Eliminating one of your battery/switches places all the load on one set of wires and connectors and you get more voltage drop. You are probably still safe with only one battery/switch powering the RX and servos, but you can clearly see the benefit of having a parallel setup.
To improve your results and lower your voltage drop, I'd suggest getting the wires between your battery and RX as short as possible...and eliminate any extensions if possible. You might also consider shortening the leads on your switch and extending the wires on your battery with larger gauge wire. Try to eliminate any extra connectors as well.
The best solution would be to use one of JR/Spektrum's powersafe receivers. These units use large gauge wire and high current connectors to DIRECTLY connect the battery to the receiver. They also use a soft switch to turn on and off the RX...it's not a part of the actual power circuit so no current flows through it and it does not add failure points in the power path. With one of these powersafe receivers, and your A123 batteries, you will have the best possible power/RX setup available today in my opinion.
KennyMac
To improve your results and lower your voltage drop, I'd suggest getting the wires between your battery and RX as short as possible...and eliminate any extensions if possible. You might also consider shortening the leads on your switch and extending the wires on your battery with larger gauge wire. Try to eliminate any extra connectors as well.
The best solution would be to use one of JR/Spektrum's powersafe receivers. These units use large gauge wire and high current connectors to DIRECTLY connect the battery to the receiver. They also use a soft switch to turn on and off the RX...it's not a part of the actual power circuit so no current flows through it and it does not add failure points in the power path. With one of these powersafe receivers, and your A123 batteries, you will have the best possible power/RX setup available today in my opinion.
KennyMac
06-07-2011, 09:01 AM
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RE: Testing Dual Battery Setup with Voltmagic
Well....my mystery is solved! I bypassed both switches by plugging directly into the receiver, screwing on the canopy and flying. The reading on my voltwatch isn't even picking up a PLV reading and only reports back an Average Voltage. Somewhere between 4 and 5 flights, my Average Voltage drops from 6.68 to 6.58 volts but still never a peak low voltage reading. Based on my mah used per flight that is somewhere between 800 and 1000 mah used on a 2300 mah pack. All of that makes sense and lines up to what is expected.
Now what to do about it. Couple things:
1. There must be hundreds of guys using the exact same set-up because there just can't be that much variation on a 50cc Aeroworks Extra. Twoheavy duty switches (I'm using MPI), Hitec digitals, dual batteries etc. The point being, either several guys have this same low voltage problem and don't know it because they have elected not to use a Voltmagic or similar on-board voltage monitoring device or I have two bad switches (not likely). But I suppose its possiblethat I need new switches... No?
2. To GR7Racer's point,I could have my A123's wired for a powersafe receiver and use my existing switches as a charge port only. I probably should have done that originally anyway...
Anyone have any comments?
Tom
Now what to do about it. Couple things:
1. There must be hundreds of guys using the exact same set-up because there just can't be that much variation on a 50cc Aeroworks Extra. Twoheavy duty switches (I'm using MPI), Hitec digitals, dual batteries etc. The point being, either several guys have this same low voltage problem and don't know it because they have elected not to use a Voltmagic or similar on-board voltage monitoring device or I have two bad switches (not likely). But I suppose its possiblethat I need new switches... No?
2. To GR7Racer's point,I could have my A123's wired for a powersafe receiver and use my existing switches as a charge port only. I probably should have done that originally anyway...
Anyone have any comments?
Tom
06-07-2011, 01:19 PM
#15
RE: Testing Dual Battery Setup with Voltmagic
Well if you don't want to go to the powersafe receiver, I would suggest making the leads on your switches as short as possible. You could also substitute a higher current rated connector such as an Ultra Deans or EC3 between your battery and switch. If you need to add more length to the battery lead, use a heavier gauge wire in the 18-16 gauge range. Larger wire, a better connector, and less of that small gauge servo wire will result in a lower resistance path between your battery and receiver.... that means less voltage drop under load. I'm not familiar with mpi switches, but they might be adding resistance as well.
You'll also want to make sure you still have the capability of balance charging your a123 packs..(always balance chage these packs!). The best way to do this is have separate pigtails coming from the battery...one set to power the RX and the other for balance charging. Check out no bs batteries/hangtime hobbies or electrodynamics website for more info on charging connections and cables for these systems. They also have some very good heavy duty switches with high current connectors that will work better for your application. You'll also find some valuable info on parallel systems and a123 batteries there as well.
You'll probably end up spending nearly the same amount of money fixing this system as you would if you had purchased a powersafe RX initially, so that might be something to consider on your next model.
Ken
You'll also want to make sure you still have the capability of balance charging your a123 packs..(always balance chage these packs!). The best way to do this is have separate pigtails coming from the battery...one set to power the RX and the other for balance charging. Check out no bs batteries/hangtime hobbies or electrodynamics website for more info on charging connections and cables for these systems. They also have some very good heavy duty switches with high current connectors that will work better for your application. You'll also find some valuable info on parallel systems and a123 batteries there as well.
You'll probably end up spending nearly the same amount of money fixing this system as you would if you had purchased a powersafe RX initially, so that might be something to consider on your next model.
Ken
06-07-2011, 01:38 PM
#16
06-16-2011, 10:44 AM
#17
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RE: Testing Dual Battery Setup with Voltmagic
GR7Racer,
Thanks again for your input on this. Just so you know, I purchased my A123's from NoBs and went with the single power feed and modified DSC switch set-up for balance charging through the switchport. I always balance charge with my Multi; very good advice you are giving thereand not everyone does that!
Anyway, the easiest thing for me to do would change out the MPI switches to the ones that NoBs sells. But I'm not convinced I would solve the problem that easily. Could it be that the differences in HD switches is that great such that one will work adequately and the other wont? I don't want to start a switch war (I am really, really not interested in that), but I have seen many, many threads where members reference heavy duty MPI switches. If you don't have a voltmagic device...how would you ever,ever know that you had a problem cooking! I don't know....
The other option, which I am leaning toward, is just ordering a Powersafe receiver and a new set of batteries from NoBs. I'llorder the batteries with the EC3 powerfeed and the universal 3-wire JR connector as my balance tap and use only the soft switch that comes with the receiver for on/off. Since they are installed, I can use the MPI switch for balance charging purposes onlythrough the switchport and just disconnect the lines from the switch to the receiver. It's either that or remove the MPI altogetherand install a separate chargeport. Frankly, I don't even mind pulling off the canopy to charge it's not that big ofa deal on the extra 260 because everything is accessible. I mean, four flights...charge...fly some more and then go home! Besides, there is value to checking connections etc. inside the fuse half-way through your flying session.
No problems with charging dual batteries one at a time that are hooked up to a Powersafe receiver right? Not from a common ground perspective but from a cell count standpoint....right?
Tom
Thanks again for your input on this. Just so you know, I purchased my A123's from NoBs and went with the single power feed and modified DSC switch set-up for balance charging through the switchport. I always balance charge with my Multi; very good advice you are giving thereand not everyone does that!
Anyway, the easiest thing for me to do would change out the MPI switches to the ones that NoBs sells. But I'm not convinced I would solve the problem that easily. Could it be that the differences in HD switches is that great such that one will work adequately and the other wont? I don't want to start a switch war (I am really, really not interested in that), but I have seen many, many threads where members reference heavy duty MPI switches. If you don't have a voltmagic device...how would you ever,ever know that you had a problem cooking! I don't know....
The other option, which I am leaning toward, is just ordering a Powersafe receiver and a new set of batteries from NoBs. I'llorder the batteries with the EC3 powerfeed and the universal 3-wire JR connector as my balance tap and use only the soft switch that comes with the receiver for on/off. Since they are installed, I can use the MPI switch for balance charging purposes onlythrough the switchport and just disconnect the lines from the switch to the receiver. It's either that or remove the MPI altogetherand install a separate chargeport. Frankly, I don't even mind pulling off the canopy to charge it's not that big ofa deal on the extra 260 because everything is accessible. I mean, four flights...charge...fly some more and then go home! Besides, there is value to checking connections etc. inside the fuse half-way through your flying session.
No problems with charging dual batteries one at a time that are hooked up to a Powersafe receiver right? Not from a common ground perspective but from a cell count standpoint....right?
Tom
06-17-2011, 09:35 AM
#18
RE: Testing Dual Battery Setup with Voltmagic
Tom....
I'm not that familiar with MPI switches, so I can't give you any valuable feedback on that. I do think that most of the Heavy Duty chargeswitches themselves are pretty similar in terms of the contacts that make up the switches. The differences are more likely to be in the quality and size of the wiring and the quality of the connectors. I think that you will get an improvement if you just shorten the switch leads as much as possible, and use larger gauge wire and heavy duty connectors to make everything reach and connect. To do that, you'd need to solder heavier gauge wire (16-14 awg) to the battery and use a better connector such as an EC3 or Ultra Deans. Then you'd want to shorten the leads on the switch and solder on the heavy duty connector of your choice (matching whatever you chose for the battery). You could preserve your balance charging option through the chargejack on the switch by keeping the node wire in the servo connector coming out of the battery as well as the switch and just plugging those two connectors together. To do this, you'd just plug the standard servo connector coming from the battery into the standard servo connector on the switch. The positive and negative wires on the lead coming from the switch would have been removed from that connector and soldered to a heavy duty connector (EC3, Ultra Deans).
On the receiver side, you'd want to pull the "signal" wire out of the connector that goes into the receiver (orange, yellow, or white depending on mfg). You'd also want to keep the lead from the switch to the RX as short as possible. These mods will lower your resistance as much as possible without purchasing new equipment. Whether that will be enough to make a difference in your voltage drop is hard for me to say.
That being said, it might be worth it to just go the powersafe RX route. You can probably get Steve at No BS/hangitmes to put the heavier gauge wire and connector on your existing packs for a small fee since you purchased them from him to begin with. The powersafe RX will set you back a few bucks, but it will be less work overall. For charging, I'd just put in a couple of charge jacks where your switches were. You'll want to either charge one at a time, or pop the canopy off and unplug one of the EC3 connectors so that you won't get a common ground problem with the chargers. Charging one at a time will work fine from a cell count standpoint. Make sure to balance charge though.
KMac
I'm not that familiar with MPI switches, so I can't give you any valuable feedback on that. I do think that most of the Heavy Duty chargeswitches themselves are pretty similar in terms of the contacts that make up the switches. The differences are more likely to be in the quality and size of the wiring and the quality of the connectors. I think that you will get an improvement if you just shorten the switch leads as much as possible, and use larger gauge wire and heavy duty connectors to make everything reach and connect. To do that, you'd need to solder heavier gauge wire (16-14 awg) to the battery and use a better connector such as an EC3 or Ultra Deans. Then you'd want to shorten the leads on the switch and solder on the heavy duty connector of your choice (matching whatever you chose for the battery). You could preserve your balance charging option through the chargejack on the switch by keeping the node wire in the servo connector coming out of the battery as well as the switch and just plugging those two connectors together. To do this, you'd just plug the standard servo connector coming from the battery into the standard servo connector on the switch. The positive and negative wires on the lead coming from the switch would have been removed from that connector and soldered to a heavy duty connector (EC3, Ultra Deans).
On the receiver side, you'd want to pull the "signal" wire out of the connector that goes into the receiver (orange, yellow, or white depending on mfg). You'd also want to keep the lead from the switch to the RX as short as possible. These mods will lower your resistance as much as possible without purchasing new equipment. Whether that will be enough to make a difference in your voltage drop is hard for me to say.
That being said, it might be worth it to just go the powersafe RX route. You can probably get Steve at No BS/hangitmes to put the heavier gauge wire and connector on your existing packs for a small fee since you purchased them from him to begin with. The powersafe RX will set you back a few bucks, but it will be less work overall. For charging, I'd just put in a couple of charge jacks where your switches were. You'll want to either charge one at a time, or pop the canopy off and unplug one of the EC3 connectors so that you won't get a common ground problem with the chargers. Charging one at a time will work fine from a cell count standpoint. Make sure to balance charge though.
KMac
