Power Expander or not -that's the question
12-07-2008, 10:31 AM
#101
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RE: Power Expander or not -that's the question
I'm going to actually agree with Tired Old Man on something now.
I agree that there's no need to argue this any further. I think all the points have been made, and people have enough info to make up their own minds now, as to whether they want to use a Power Expander or not.
I'll also agree with those on this thread that said a Power Expander is not necessary, because there are other ways to set up a plane and still have good current flow. I do however, think that a Power Expander is the best and simplest way to do so on a giant scale plane.
I've got one last bit of info, and that pertains to the issue of equipment failures. I have never heard of a Power Expander failure during flight. There have been 2 or 3 that didn't work correctly (when new) on initial set up, but if they work right when new, I've never heard of them failing after that. I don't think any other component we use is as reliable as a Power Expander is.
Jim
I agree that there's no need to argue this any further. I think all the points have been made, and people have enough info to make up their own minds now, as to whether they want to use a Power Expander or not.
I'll also agree with those on this thread that said a Power Expander is not necessary, because there are other ways to set up a plane and still have good current flow. I do however, think that a Power Expander is the best and simplest way to do so on a giant scale plane.
I've got one last bit of info, and that pertains to the issue of equipment failures. I have never heard of a Power Expander failure during flight. There have been 2 or 3 that didn't work correctly (when new) on initial set up, but if they work right when new, I've never heard of them failing after that. I don't think any other component we use is as reliable as a Power Expander is.
Jim
12-07-2008, 07:50 PM
#102
Thread Starter
RE: Power Expander or not -that's the question
ORIGINAL: cap10b
Virginian,
You can see you did open a can o worms.
Virginian,
You can see you did open a can o worms.
12-07-2008, 08:24 PM
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RE: Power Expander or not -that's the question
I believe this was a great thread! Doesn't matter which way you decided to go, expander or not, there was some good info here! Just shows there is more than one way to set up a plane, which IMO is a great thing!
12-08-2008, 10:56 AM
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RE: Power Expander or not -that's the question
For me theres 1 "unknown" and another "misleading" numbers that make it difficult to know exactly what is safe & what is not. The power expander does make me "feel" comfortable knowing that it provides a current path directly to the servos & not thru the rcv. Specially the receivers I have used-Futaba 607 FASST, only have 8 amps continuous rating.(from Futaba tech) Hitec rates the 5955 & 7955 TG's 1-2 amps under flight loads, 4.2 amps stalled. If my 30%'s used 1-2 amps per/servo continuously, they would have burnt up my receiver by now, over 1 year flying.(no power expander-no nothing for redundancy). That 1-2 amps draw must be a momentary load, if it was continuous it would be burning something up or my batteries wouldnt last as long as they do. Has anyone used a telemetry unit & can they give readings on each channel? That is the unknown I'm referring to, I really dont know what is going on in my receiver system other than a rough idea on power in vs. power used.
12-08-2008, 11:59 AM
#105
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RE: Power Expander or not -that's the question
It might be worth the time to investigate those Futaba numbers in a little more depth. It seems odd that Futaba would so significantly derate their power buss in their recevers over what they used to be. It woul be interesting to find out why, or if that 8 amp number was truly factual.
BTW, the numbers I came up with for a stalled 5955 was in the area of 2.9-3.5 amps. The JR 8611 would initially peak a bit higher than the Hitecs. So there's room for discussion in the servo current values.
BTW, the numbers I came up with for a stalled 5955 was in the area of 2.9-3.5 amps. The JR 8611 would initially peak a bit higher than the Hitecs. So there's room for discussion in the servo current values.
12-08-2008, 12:27 PM
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RE: Power Expander or not -that's the question
This is why I set up my systems to provide a minimum of 3 amps per servo, and then go fly. I now know my servos will get all the current flow they ask for, no matter what. I'm not trying to provide "just enough" current. I provide more current flow than is needed on purpose.
Doing so adds no, or very little weight; and doing so adds no or very little cost; so why not do so?
Jim
Doing so adds no, or very little weight; and doing so adds no or very little cost; so why not do so?
Jim
12-08-2008, 03:39 PM
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RE: Power Expander or not -that's the question
I got the same number from 2 different Futaba "team" sources, 8 amps does sound weak, maybe the weak point is the "etched" part of the circuit board,who knows? I will either go with 2 receivers or a power expander, maybe even the Servocity cheapy. A flying buddy of mine had a 40% w/2 rcv/batts/switches. He landed the plane safely with one "side" completely dead due to a battery dump. That answers the question whether that method is truely redundant or not. The only thing he noticed was sluggish response.
12-08-2008, 05:22 PM
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RE: Power Expander or not -that's the question
ORIGINAL: MIXMASTER
I got the same number from 2 different Futaba "team" sources, 8 amps does sound weak, maybe the weak point is the "etched" part of the circuit board,who knows? I will either go with 2 receivers or a power expander, maybe even the Servocity cheapy. A flying buddy of mine had a 40% w/2 rcv/batts/switches. He landed the plane safely with one "side" completely dead due to a battery dump. That answers the question whether that method is truely redundant or not. The only thing he noticed was sluggish response.
I got the same number from 2 different Futaba "team" sources, 8 amps does sound weak, maybe the weak point is the "etched" part of the circuit board,who knows? I will either go with 2 receivers or a power expander, maybe even the Servocity cheapy. A flying buddy of mine had a 40% w/2 rcv/batts/switches. He landed the plane safely with one "side" completely dead due to a battery dump. That answers the question whether that method is truely redundant or not. The only thing he noticed was sluggish response.
Just noticed Hitec is offering 7950 next year, 403 in-ozs of torque at 6 volts, same speed as the 5955.
[link]http://www.hitecrcd.com/servos/show?name=HS-7950TG[/link]
12-08-2008, 08:39 PM
#111
Thread Starter
RE: Power Expander or not -that's the question
ORIGINAL: MIXMASTER
I will either go with 2 receivers or a power expander, maybe even the Servocity cheapy. A flying buddy of mine had a 40% w/2 rcv/batts/switches. He landed the plane safely with one "side" completely dead due to a battery dump. That answers the question whether that method is truely redundant or not. The only thing he noticed was sluggish response.
I will either go with 2 receivers or a power expander, maybe even the Servocity cheapy. A flying buddy of mine had a 40% w/2 rcv/batts/switches. He landed the plane safely with one "side" completely dead due to a battery dump. That answers the question whether that method is truely redundant or not. The only thing he noticed was sluggish response.
12-08-2008, 10:40 PM
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RE: Power Expander or not -that's the question
If he never had the redundant setup there would have been the failure either. Adding more parts ads more failure points. Smart fly EQ6 turbo two batteries, one switch one reciever. Done. A total of 5 components. Switches fail on, one battery is redundant. That leaves 2 components that COULD fail. I am sure that the chance of me getting into a crach on my way to work tommorrow is far greater that either of the two components failing. Ever.
This horse has been beat around the block, but I know what works for me.
This horse has been beat around the block, but I know what works for me.
12-09-2008, 06:30 PM
#115
RE: Power Expander or not -that's the question
Here's a test that Tom from Wildhare did. Pretty interesting in that it shows how much power is used when using good servos.
OK for all you folks who are interested in the A123 batteries, I have some real world data for you.
This data was collected today, 11/23/2007 flying my 106†100cc Giles G202. The plane weighs about 27 lbs., has a DA-100, 6 5955s and 1 8711 on the rudder. No matchbox, the ailerons are on a Y cable on 2 channels, 2 servos per channel. The linkages are as close as I could get them mechanically and there seems to be no real binding although there is probably a small amount of mismatch at extreme throws, it’s hard to get it perfect.
In the plane I have a single A123 2300mah pack that goes to two switches through a Y and then into the receiver using two standard JR servo connectors. It’s a JR 921 2.4 GHz. Receiver and I use a JR X9303 transmitter, not that it really matters.
I made two flights of about 10 minutes each, with (apparently) 3-4 minutes of recorded data from the startup period. I did a range check, taxied around a bit, the usual.
When flying I flew a lot of typical IMAC type maneuvers, loops, hammerheads, humpties, lots of rolls and point rolls, and a lot of snaps. I flew several multiple snap sequences of 3 or 4 rolls in an effort to put as much stress on the electrical system as possible.
I used my Eagletree systems elogger V3 and the included software that downloaded it to my PC and analyzed it.
Before doing my flight test I tested the logger itself by running my battery tester through the logger and then recharging. The Eflight power meter said I used about 1430 mah, the elogger said I used almost exactly the same and the Cellpro charger recharged to pack and said it put in 1431 mah. Close enough; all 3 readings agree within a fraction of a percent, I think we can trust the logger’s data.
I collected data samples 10 times per second, or every 100 milliseconds. Any event lasting less than 100 milliseconds could theoretically have been missed. Any voltage spike or current surge lasting greater than 100ms will certainly have been recorded, and a shorter duration event would have had to be positioned exactly between the sample periods to be missed, making hidden events even more unlikely. I think that what we see here is a good representation of exactly what happened.
My only disappointment was the fact that I was unable to save the graphs off as a jpeg file which would have been useful in making this report. The best I could do was to take a photo of the computer screen which is not real clear. In the photos the pink traces indicate current draw, the blue line shows voltage.
So, on to the data. What did I learn?
The freshly charged pack started out at 7.05 volts. It took about 5 minutes of usage/flying to come down to 6.6v, and another 3 or 4 of flying for it to settle in at the 6.5 volts that it stayed at for the rest of the test. Average voltage throughout the test was 6.58 volts, and the lowest voltage recorded was 6.12v. According to the graph voltage dipped below 6.2 volts about 6 times, probably during the extended multiple snaps. The voltage dips coincided with spikes in current usage as one might expect. This A123 pack is not going to allow reboots, you’d need to melt the wires to pull it down to 3.5 volts.
What about current demand? The maximum current drawn in both flights was 11.56 amps. There were about a dozen times when current draw went over 6 amps, and a half dozen times when it exceeded 8 amps. Again, the voltage drops coincide with the current spikes.
The average current demand throughout most of the 2 flights was in the 2 to 3 amps range. It never fell much below 2 amps and rarely exceeded 3 amps. Based on my recollection of the flight, the big current draws were in long snaps and long knife-edges. The rest of the time power usage was fairly modest.
Total power used was 479 mah; this is pretty consistent at around 25mah per minute of flight time. A single 2300 mah A123 pack will support at least 60 minutes of flight time plus all the messing around that goes with it with probably a 25% cushion at the minimum.
So, what do we know? On a plane of this size, especially if it uses multiple rudder servos, you should probably have 15 amps available in bursts, and that burst should not pull the voltage down much if you want your flight performance to be consistent. But you can probably fly IMAC basic with no more than a 1200mah Nimh pack since that type of flying rarely draws more than 3 amps.
I would speculate that a 40% plane with 14 servos could easily require double this amount of power, needing burst current of 30 amps but living between the bursts easily on 5 or 6 amps. I’d use dual 2300 packs on a 40%, if not for the added current then for the redundancy, but I have no problem with using one A123 2300 on a 40% plane since one pack will easily burst over 30 amps.
Tom Fawcett
Wild Hare R/C
OK for all you folks who are interested in the A123 batteries, I have some real world data for you.
This data was collected today, 11/23/2007 flying my 106†100cc Giles G202. The plane weighs about 27 lbs., has a DA-100, 6 5955s and 1 8711 on the rudder. No matchbox, the ailerons are on a Y cable on 2 channels, 2 servos per channel. The linkages are as close as I could get them mechanically and there seems to be no real binding although there is probably a small amount of mismatch at extreme throws, it’s hard to get it perfect.
In the plane I have a single A123 2300mah pack that goes to two switches through a Y and then into the receiver using two standard JR servo connectors. It’s a JR 921 2.4 GHz. Receiver and I use a JR X9303 transmitter, not that it really matters.
I made two flights of about 10 minutes each, with (apparently) 3-4 minutes of recorded data from the startup period. I did a range check, taxied around a bit, the usual.
When flying I flew a lot of typical IMAC type maneuvers, loops, hammerheads, humpties, lots of rolls and point rolls, and a lot of snaps. I flew several multiple snap sequences of 3 or 4 rolls in an effort to put as much stress on the electrical system as possible.
I used my Eagletree systems elogger V3 and the included software that downloaded it to my PC and analyzed it.
Before doing my flight test I tested the logger itself by running my battery tester through the logger and then recharging. The Eflight power meter said I used about 1430 mah, the elogger said I used almost exactly the same and the Cellpro charger recharged to pack and said it put in 1431 mah. Close enough; all 3 readings agree within a fraction of a percent, I think we can trust the logger’s data.
I collected data samples 10 times per second, or every 100 milliseconds. Any event lasting less than 100 milliseconds could theoretically have been missed. Any voltage spike or current surge lasting greater than 100ms will certainly have been recorded, and a shorter duration event would have had to be positioned exactly between the sample periods to be missed, making hidden events even more unlikely. I think that what we see here is a good representation of exactly what happened.
My only disappointment was the fact that I was unable to save the graphs off as a jpeg file which would have been useful in making this report. The best I could do was to take a photo of the computer screen which is not real clear. In the photos the pink traces indicate current draw, the blue line shows voltage.
So, on to the data. What did I learn?
The freshly charged pack started out at 7.05 volts. It took about 5 minutes of usage/flying to come down to 6.6v, and another 3 or 4 of flying for it to settle in at the 6.5 volts that it stayed at for the rest of the test. Average voltage throughout the test was 6.58 volts, and the lowest voltage recorded was 6.12v. According to the graph voltage dipped below 6.2 volts about 6 times, probably during the extended multiple snaps. The voltage dips coincided with spikes in current usage as one might expect. This A123 pack is not going to allow reboots, you’d need to melt the wires to pull it down to 3.5 volts.
What about current demand? The maximum current drawn in both flights was 11.56 amps. There were about a dozen times when current draw went over 6 amps, and a half dozen times when it exceeded 8 amps. Again, the voltage drops coincide with the current spikes.
The average current demand throughout most of the 2 flights was in the 2 to 3 amps range. It never fell much below 2 amps and rarely exceeded 3 amps. Based on my recollection of the flight, the big current draws were in long snaps and long knife-edges. The rest of the time power usage was fairly modest.
Total power used was 479 mah; this is pretty consistent at around 25mah per minute of flight time. A single 2300 mah A123 pack will support at least 60 minutes of flight time plus all the messing around that goes with it with probably a 25% cushion at the minimum.
So, what do we know? On a plane of this size, especially if it uses multiple rudder servos, you should probably have 15 amps available in bursts, and that burst should not pull the voltage down much if you want your flight performance to be consistent. But you can probably fly IMAC basic with no more than a 1200mah Nimh pack since that type of flying rarely draws more than 3 amps.
I would speculate that a 40% plane with 14 servos could easily require double this amount of power, needing burst current of 30 amps but living between the bursts easily on 5 or 6 amps. I’d use dual 2300 packs on a 40%, if not for the added current then for the redundancy, but I have no problem with using one A123 2300 on a 40% plane since one pack will easily burst over 30 amps.
Tom Fawcett
Wild Hare R/C
12-09-2008, 06:56 PM
#116
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RE: Power Expander or not -that's the question
"In the plane I have a single A123 2300mah pack that goes to two switches through a Y and then into the receiver using two standard JR servo connectors"
He's using switches rated at 5 amps each, and only 2 standard plugs going into the rx rated at 3 amps each. I believe his current flow is low because of this. Like I've said before, others have reported amp readings of as much as 22 amps on a 35%er.
If you guys want to go by that data though, go right ahead. It's your plane......................
Jim
He's using switches rated at 5 amps each, and only 2 standard plugs going into the rx rated at 3 amps each. I believe his current flow is low because of this. Like I've said before, others have reported amp readings of as much as 22 amps on a 35%er.
If you guys want to go by that data though, go right ahead. It's your plane......................
Jim
12-09-2008, 08:51 PM
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RE: Power Expander or not -that's the question
We can't let this thread die, it's too much fun! 
I've got to throw my .02 worth in here.......
I've always been rather "thrifty" I guess in my RC purchases. Never buying into the power expander scheme or such. My latest plane, 36% Edge/DA100 started out with a single A123 2300 mAh pack with two leads/two switches going to a Spektrum AR7000 receiver. I also had a third line coming off the battery and powering the ignition as well. How's that for pushing it. The plane flew great, no reboots...... I flew it like this for 100 flights or so. I started getting nervous [X(] so I added a second 2300 battery. It has one lead going to the receiver, and one going to the ignition. So let me summarize that. I now have one 2300 with two leads going to the receiver, and the other 2300 has one to receiver and one to ignition. So that's three std plugs powering the receiver. I'm charging with a Cellpro 4S, so I know my total current usage per 15 minute flight. I use the timer on my transmitter as well. I've got 280 flights combined with this system. The plane has always felt sluggish on the rudder with 2-5955 pull-pull on it, and snaps seem kind of weak as well compared to some other 35% planes I fly with. Ailerons,elevators, and rudder servos are all on HD Y's. Leads coming out of A123's are 20 GA. I know enough about electricity to know, that if you limit current anywhere, you can't get the amps out of your servos. Yes the plane will fly, but at a reduced capacity. This I think is one of the most important things that Hammbone has pointed out in several of his threads.
So........... Winter is here, I've got a little extra cash, and my curiosity is killing me! I'm pulling my batteries, and installing a Smart Fly Power Expander Pro. I'll be using the ONE failsafe switch instead of the current three that I have. I've ordered new 2300- A123's from Radical that will come with 16 Ga leads/Deans Ultra plugs. The two batteries will plug directly into the power expander. One 2300 will also power my ignition, so that will all stay the same. The extensions will be redone, and NO Y's will be used. Each servo will have it's own lead plugged directly into the power expander. The way I see it is if my old system was delivering all the power that my servos needed, then my mAh's use per flight will stay the same. If the old system was falling short, then with the power expander the plane should fly more crisp, and the mAh's used per flight should increase. The results will be interesting.........
Forgot to add that it has eight 5955's and one std. analog 545 (I think) on throttle.
I've got to throw my .02 worth in here.......I've always been rather "thrifty" I guess in my RC purchases. Never buying into the power expander scheme or such. My latest plane, 36% Edge/DA100 started out with a single A123 2300 mAh pack with two leads/two switches going to a Spektrum AR7000 receiver. I also had a third line coming off the battery and powering the ignition as well. How's that for pushing it. The plane flew great, no reboots...... I flew it like this for 100 flights or so. I started getting nervous [X(] so I added a second 2300 battery. It has one lead going to the receiver, and one going to the ignition. So let me summarize that. I now have one 2300 with two leads going to the receiver, and the other 2300 has one to receiver and one to ignition. So that's three std plugs powering the receiver. I'm charging with a Cellpro 4S, so I know my total current usage per 15 minute flight. I use the timer on my transmitter as well. I've got 280 flights combined with this system. The plane has always felt sluggish on the rudder with 2-5955 pull-pull on it, and snaps seem kind of weak as well compared to some other 35% planes I fly with. Ailerons,elevators, and rudder servos are all on HD Y's. Leads coming out of A123's are 20 GA. I know enough about electricity to know, that if you limit current anywhere, you can't get the amps out of your servos. Yes the plane will fly, but at a reduced capacity. This I think is one of the most important things that Hammbone has pointed out in several of his threads.
So........... Winter is here, I've got a little extra cash, and my curiosity is killing me! I'm pulling my batteries, and installing a Smart Fly Power Expander Pro. I'll be using the ONE failsafe switch instead of the current three that I have. I've ordered new 2300- A123's from Radical that will come with 16 Ga leads/Deans Ultra plugs. The two batteries will plug directly into the power expander. One 2300 will also power my ignition, so that will all stay the same. The extensions will be redone, and NO Y's will be used. Each servo will have it's own lead plugged directly into the power expander. The way I see it is if my old system was delivering all the power that my servos needed, then my mAh's use per flight will stay the same. If the old system was falling short, then with the power expander the plane should fly more crisp, and the mAh's used per flight should increase. The results will be interesting.........
Forgot to add that it has eight 5955's and one std. analog 545 (I think) on throttle.
12-09-2008, 09:36 PM
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RE: Power Expander or not -that's the question
ORIGINAL: mrbigg
Too bad you can't just swap in the Power Expander without changing the Y's and everything else. That way you'd have a true comparo.
Too bad you can't just swap in the Power Expander without changing the Y's and everything else. That way you'd have a true comparo.
Think of it like water going through pipes. If you have 4" diameter pipe running 30', but have one small section that is reduced down to 1/2" diameter, you are only going to get as much water as will flow through the 1/2" pipe out the other end. If you had 4" pipe the whole way, you'd get much more water through the pipes. Putting in a section of 6" pipe will not improve your flow if you still have the section of 1/2" pipe inline somewhere.
If he just put in the Power Expander without changing out the other potential current flow bottlenecks in his system, it wouldn't tell us anything. The way he is doing it will tell us something. He should feel a difference in performance with the new set up. His servos should be stronger with the new set up.
When I started using the A123's / Power Expander set up, I noticed a definite improvenment in both the speed and power of my servos, but I can't say for sure that it was due completely to better current flow, it's probably due to the higher voltage (6.6v) of the A123 batteries without a reg. I used to use Li Ion batteries with a 6v reg.
Jim
12-09-2008, 09:51 PM
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RE: Power Expander or not -that's the question
ORIGINAL: Nogyro
We can't let this thread die, it's too much fun! I've got to throw my .02 worth in here.......
I've always been rather "thrifty" I guess in my RC purchases. Never buying into the power expander scheme or such. My latest plane, 36% Edge/DA100 started out with a single A123 2300 mAh pack with two leads/two switches going to a Spektrum AR7000 receiver. I also had a third line coming off the battery and powering the ignition as well. How's that for pushing it. The plane flew great, no reboots...... I flew it like this for 100 flights or so. I started getting nervous [X(] so I added a second 2300 battery. It has one lead going to the receiver, and one going to the ignition. So let me summarize that. I now have one 2300 with two leads going to the receiver, and the other 2300 has one to receiver and one to ignition. So that's three std plugs powering the receiver. I'm charging with a Cellpro 4S, so I know my total current usage per 15 minute flight. I use the timer on my transmitter as well. I've got 280 flights combined with this system. The plane has always felt sluggish on the rudder with 2-5955 pull-pull on it, and snaps seem kind of weak as well compared to some other 35% planes I fly with. Ailerons,elevators, and rudder servos are all on HD Y's. Leads coming out of A123's are 20 GA. I know enough about electricity to know, that if you limit current anywhere, you can't get the amps out of your servos. Yes the plane will fly, but at a reduced capacity. This I think is one of the most important things that Hammbone has pointed out in several of his threads.
So........... Winter is here, I've got a little extra cash, and my curiosity is killing me! I'm pulling my batteries, and installing a Smart Fly Power Expander Pro. I'll be using the ONE failsafe switch instead of the current three that I have. I've ordered new 2300- A123's from Radical that will come with 16 Ga leads/Deans Ultra plugs. The two batteries will plug directly into the power expander. One 2300 will also power my ignition, so that will all stay the same. The extensions will be redone, and NO Y's will be used. Each servo will have it's own lead plugged directly into the power expander. The way I see it is if my old system was delivering all the power that my servos needed, then my mAh's use per flight will stay the same. If the old system was falling short, then with the power expander the plane should fly more crisp, and the mAh's used per flight should increase. The results will be interesting.........
Forgot to add that it has eight 5955's and one std. analog 545 (I think) on throttle.
We can't let this thread die, it's too much fun!
I've got to throw my .02 worth in here.......I've always been rather "thrifty" I guess in my RC purchases. Never buying into the power expander scheme or such. My latest plane, 36% Edge/DA100 started out with a single A123 2300 mAh pack with two leads/two switches going to a Spektrum AR7000 receiver. I also had a third line coming off the battery and powering the ignition as well. How's that for pushing it. The plane flew great, no reboots...... I flew it like this for 100 flights or so. I started getting nervous [X(] so I added a second 2300 battery. It has one lead going to the receiver, and one going to the ignition. So let me summarize that. I now have one 2300 with two leads going to the receiver, and the other 2300 has one to receiver and one to ignition. So that's three std plugs powering the receiver. I'm charging with a Cellpro 4S, so I know my total current usage per 15 minute flight. I use the timer on my transmitter as well. I've got 280 flights combined with this system. The plane has always felt sluggish on the rudder with 2-5955 pull-pull on it, and snaps seem kind of weak as well compared to some other 35% planes I fly with. Ailerons,elevators, and rudder servos are all on HD Y's. Leads coming out of A123's are 20 GA. I know enough about electricity to know, that if you limit current anywhere, you can't get the amps out of your servos. Yes the plane will fly, but at a reduced capacity. This I think is one of the most important things that Hammbone has pointed out in several of his threads.
So........... Winter is here, I've got a little extra cash, and my curiosity is killing me! I'm pulling my batteries, and installing a Smart Fly Power Expander Pro. I'll be using the ONE failsafe switch instead of the current three that I have. I've ordered new 2300- A123's from Radical that will come with 16 Ga leads/Deans Ultra plugs. The two batteries will plug directly into the power expander. One 2300 will also power my ignition, so that will all stay the same. The extensions will be redone, and NO Y's will be used. Each servo will have it's own lead plugged directly into the power expander. The way I see it is if my old system was delivering all the power that my servos needed, then my mAh's use per flight will stay the same. If the old system was falling short, then with the power expander the plane should fly more crisp, and the mAh's used per flight should increase. The results will be interesting.........
Forgot to add that it has eight 5955's and one std. analog 545 (I think) on throttle.
Jim
12-09-2008, 10:09 PM
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RE: Power Expander or not -that's the question
Hammbone, I'll agree with you 100% about taking Mr. biggs data. It would be quite unwise to compare his data with any individuals system. Unless it is exactly the same, or damn near close.
HOWEVER, Mr. bigg has done EXACTLY what we all should be doing. He has aquired data of HIS system and now knows hes good to go! Good hard evidence!!
I will also agree with you his system is most likley "choking" some of his usable amperage.....BUT He seems to be quite comfortable with how his servos (flight) performs and he has proven to himself hes well within the saftey net.
We all should be testing our own systems or getting help to do so. Guessing is so very very bad. Anyone think the engineer who designed the first pacemaker said "AAhh this battery aught' ta work lets try it"
I highly dought it. I understand a human life is more important than our planes(in most cases) but the idea is If your not willing to give a 100% pride in your work than why do it at all.
You could pretty much build your system any way you wanted, but you must match supply to demand... period.
HOWEVER, Mr. bigg has done EXACTLY what we all should be doing. He has aquired data of HIS system and now knows hes good to go! Good hard evidence!!
I will also agree with you his system is most likley "choking" some of his usable amperage.....BUT He seems to be quite comfortable with how his servos (flight) performs and he has proven to himself hes well within the saftey net.
We all should be testing our own systems or getting help to do so. Guessing is so very very bad. Anyone think the engineer who designed the first pacemaker said "AAhh this battery aught' ta work lets try it"
I highly dought it. I understand a human life is more important than our planes(in most cases) but the idea is If your not willing to give a 100% pride in your work than why do it at all.
You could pretty much build your system any way you wanted, but you must match supply to demand... period.
12-09-2008, 10:26 PM
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RE: Power Expander or not -that's the question
Yup what hammbone said...... maybe over thought but forgetting the simple idea that was established a long time ago
A simple relationship exists between voltage, current, and resistance in electrical circuits. Understanding this relationship is important for fast, accurate electrical problem diagnosis and repair. OHM'S LAW-Ohm's Law says: The current in a circuit is directly proportional to the applied voltage and inversely proportional to the amount of resistance. This means that if the voltage goes up, the current flow will go up, and vice versa. Also, as the resistance goes up, the current goes down, and vice versa. Ohm's Law can be put to good use in electrical troubleshooting. So that already being said why dont you find the resistance or do a VD voltage drop in your leads that power your servos ohhhhhhh here we go why dont you add them all up and if we want to argue the point at hand we can ohm every circuit out and figure the amp draw out Eureka,,,,,,......... But you cant teach old dogs new tricks and im as thrifty as they come too before i got an expander i flew on 10a battery eliminating circuits on lipos 2 actually tied to the same battery but guess what the circuitry was rated 10a but the bottle neck wires coming out of it was like ittty bitty haha well they may hold so what the hell lets fly it it flew and flew good but never had the power on the rudder and its a got a 5955tg on it elimintaed the bec wires i soldered good wires to it and it had a whole lot more rudder . So Point is anything can bottleneck the flow plan your build if you invest money in the best 100cc engine are you gonna run a 12x6 prop on it? ive tried both ways i feel safer with good equipment i can sometimes safe guard my plane with good equipment doesnt help the stupid moments likewrong rudder. Im not posting on this to say you need one or not if you feel confident in your setup Rock out fly it like you hate it. and as you said in your previous post TheVirginian there is more than one way to skin a cat just make sure your knife is sharp and the finger is out of the way because when it hits it cuts hard.... into your flying funds. oh and by the way the plane that had the becs on it got an expander and it will now do knife edge loops it used to not hold a high alpha....but hope this long overthought post may help someone i ohm out all my leads and ohm through connections when i put them way back in a fuse to make sure its all gonna work when i get them hooked up and put away nice and neat. If we all had one opinion then this world would be a boaring place!!!!
Fly em like you Hate them..
A simple relationship exists between voltage, current, and resistance in electrical circuits. Understanding this relationship is important for fast, accurate electrical problem diagnosis and repair. OHM'S LAW-Ohm's Law says: The current in a circuit is directly proportional to the applied voltage and inversely proportional to the amount of resistance. This means that if the voltage goes up, the current flow will go up, and vice versa. Also, as the resistance goes up, the current goes down, and vice versa. Ohm's Law can be put to good use in electrical troubleshooting. So that already being said why dont you find the resistance or do a VD voltage drop in your leads that power your servos ohhhhhhh here we go why dont you add them all up and if we want to argue the point at hand we can ohm every circuit out and figure the amp draw out Eureka,,,,,,......... But you cant teach old dogs new tricks and im as thrifty as they come too before i got an expander i flew on 10a battery eliminating circuits on lipos 2 actually tied to the same battery but guess what the circuitry was rated 10a but the bottle neck wires coming out of it was like ittty bitty haha well they may hold so what the hell lets fly it it flew and flew good but never had the power on the rudder and its a got a 5955tg on it elimintaed the bec wires i soldered good wires to it and it had a whole lot more rudder . So Point is anything can bottleneck the flow plan your build if you invest money in the best 100cc engine are you gonna run a 12x6 prop on it? ive tried both ways i feel safer with good equipment i can sometimes safe guard my plane with good equipment doesnt help the stupid moments likewrong rudder. Im not posting on this to say you need one or not if you feel confident in your setup Rock out fly it like you hate it. and as you said in your previous post TheVirginian there is more than one way to skin a cat just make sure your knife is sharp and the finger is out of the way because when it hits it cuts hard.... into your flying funds. oh and by the way the plane that had the becs on it got an expander and it will now do knife edge loops it used to not hold a high alpha....but hope this long overthought post may help someone i ohm out all my leads and ohm through connections when i put them way back in a fuse to make sure its all gonna work when i get them hooked up and put away nice and neat. If we all had one opinion then this world would be a boaring place!!!!
Fly em like you Hate them..
12-09-2008, 10:45 PM
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RE: Power Expander or not -that's the question
Ok guys, don't we still come back to our connecters being the weakest part of the system? It doesn't matter how we setup everything, the connecters only pass 3 to 5 amps
12-09-2008, 10:57 PM
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RE: Power Expander or not -that's the question
ORIGINAL: flatspinjim
Ok guys, don't we still come back to our connecters being the weakest part of the system? It doesn't matter how we setup everything, the connecters only pass 3 to 5 amps
Ok guys, don't we still come back to our connecters being the weakest part of the system? It doesn't matter how we setup everything, the connecters only pass 3 to 5 amps
I no longer use a standard connector anywhere between my batteries and my rx / Power Expander. I use Deans connectors which are capable of 50 amps. I have now supplied 50 amps to the rx / Power Expander (well, maybe only 30 or 40 amps depending on the wire size). Now each servo gets its own lead from there. We have to use a standard connector at this point, but it only feeds current to one servo, so the 3 amp rating is fine.
Jim