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Old Feb 19, 2013, 06:41 PM
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United States, AZ, Tucson
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Question
Highest Voltage Pack

What is the highest voltage pack that is typically used in ALE gliders?

Thanks,

John
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Old Feb 19, 2013, 09:06 PM
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Well, I am flying a 65C, 1.3A capacity, 3 cell battery. Optimal voltage is 11.1V, but fresh off the charger is is closer to 4V/cell minimum, so I am at 12V or higher. It is capable of better that 930 watts, but from testing, I am drawing somewhere better that 300W+. When I finish a flight and pull a battery, it is not even warm to the touch, it is not even breathing hard.

I am flying a 69oz TD type ship on a Hacker A20 with a 4.2:1 gearbox turning a 16x10 prop.

Marc
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Old Feb 19, 2013, 10:23 PM
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I have been testing various combinations of ThunderPower 65C packs (850 and 1300, 3S and 4S packs) under carefully controlled conditions on the bench. (These tests were primarily to test various motor/propeller combinations, but I gathered battery data while I was doing this.)

The takeaway from these tests is my recommendation that these cells be used at LESS than 50C rates for 30 second ALES motor runs. Under these conditions, a battery starting at 80 degrees and operated in an unventilated glider nose will have about a 40 to 45 degree temperature rise with max temp being realized about a minute after the end of the motor run. While 125 degrees sounds pretty warm, it is not as hot to the touch as you might think. And manufacturers generally recommend that operating temperatures not exceed 140 degrees. Factor in a 95 degree day, and you are getting pretty close to the manufacturer limit.

Practically, this means that you can operate the 850's at about 42 amps (400 or so watts for the 3S, 500 or so watts for the 4S). [In actual operation at these rates, the output voltage will be somewhat lower than the nominal voltages]. The 1300's are good for about 65 amps (650-700 watts for 3S, around 900 watts for 4S).

I have had good results with the Thunderpowers operating them at 50C or below with no failures of any packs since they were introduced (a far and a half ago?).

I am just setting up for some in-plane tests using my Eagletree V4 and I will update when I get those finished. I intend to try a little ventilation on the fuses to see if there is any difference -- I do not suspect that it will make much difference since the temperature buildup occurs over a short period.

I operate these packs at the high rates cited because I am trying to balance planes which have very narrow fuselages with long noses which stick the motors out pretty far. For the less finicky, keeping these 65C packs down in the 35C to 40C range will give you more launches and, as Marc suggests, lower operating temps.

Happy Landings,

Don

BTW: I have attached graphs from one set of tests on an 850 4S pack which shows about 600 watts of output on a 30 second motor run and a 45 degree temperature rise from 85 degrees. This is pretty typical of my other results. An 850 3S pack should easily put out 450 watts without overheating.
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Last edited by dharban; Feb 19, 2013 at 10:34 PM.
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Old Feb 19, 2013, 10:32 PM
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Thanks for all of the detailed info. I should've explained why I was asking...

I'm assisting with the hardware design of the Bluetooth OpenAltimeter and one of the features is dual pack voltage monitoring (rx & motor, if that configuration is used). I'd like to ensure that we're covering the highest input likely to be seen. Currently we're good up to 18.8V, so it appears that we have things covered.

Thanks,

John
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Old Feb 20, 2013, 02:25 PM
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Quote:
Originally Posted by dharban View Post
I have been testing various combinations of ThunderPower 65C packs (850 and 1300, 3S and 4S packs) under carefully controlled conditions on the bench. (These tests were primarily to test various motor/propeller combinations, but I gathered battery data while I was doing this.)

The takeaway from these tests is my recommendation that these cells be used at LESS than 50C rates for 30 second ALES motor runs. Under these conditions, a battery starting at 80 degrees and operated in an unventilated glider nose will have about a 40 to 45 degree temperature rise with max temp being realized about a minute after the end of the motor run. While 125 degrees sounds pretty warm, it is not as hot to the touch as you might think. And manufacturers generally recommend that operating temperatures not exceed 140 degrees. Factor in a 95 degree day, and you are getting pretty close to the manufacturer limit.

Practically, this means that you can operate the 850's at about 42 amps (400 or so watts for the 3S, 500 or so watts for the 4S). [In actual operation at these rates, the output voltage will be somewhat lower than the nominal voltages]. The 1300's are good for about 65 amps (650-700 watts for 3S, around 900 watts for 4S).

I have had good results with the Thunderpowers operating them at 50C or below with no failures of any packs since they were introduced (a far and a half ago?).

I am just setting up for some in-plane tests using my Eagletree V4 and I will update when I get those finished. I intend to try a little ventilation on the fuses to see if there is any difference -- I do not suspect that it will make much difference since the temperature buildup occurs over a short period.

I operate these packs at the high rates cited because I am trying to balance planes which have very narrow fuselages with long noses which stick the motors out pretty far. For the less finicky, keeping these 65C packs down in the 35C to 40C range will give you more launches and, as Marc suggests, lower operating temps.

Happy Landings,

Don

BTW: I have attached graphs from one set of tests on an 850 4S pack which shows about 600 watts of output on a 30 second motor run and a 45 degree temperature rise from 85 degrees. This is pretty typical of my other results. An 850 3S pack should easily put out 450 watts without overheating.
Great Info Don...right in line with what I need to know with my Supra-E I'm working with just now...I have a Neu 1506-5200-2d-6.7 which is rated at 12 Volts running on a TP 65C 3s 1300. I originally went with a 16x10 with the result of the ESC cutting off after 10 seconds or so when the battery voltage drops below 9 volts (tried two batteries). Runs pretty well on a 2S 65C 1300 with a 17X10 but I need more thrust than this. I am stuck for the time being with the relativly low voltage 1506 so I intend to go with a 15x8 prop to bring down the current and prevent the low voltage cutoff.
I'l love to get in the future an 1107 like what you use which woul be 2.3 oz lighter and allow a larger prop with lower current.. anyway I really appreciate the work you are doing.
Rick Pearson
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Old Feb 20, 2013, 02:48 PM
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Dumb question Rick, you need more thrust? Are you working up an F5J ship or an ALES airframe?

Marc
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Old Feb 20, 2013, 03:05 PM
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Yea more thrust....I get to 150 meters in 28 seconds.. Kinda toad like.
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Old Feb 20, 2013, 03:06 PM
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If I were doing a J I would not use the Supra
Rick
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Old Feb 20, 2013, 03:11 PM
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I was running a 5S 1300mAh pack for awhile on a geared Astro motor. I guess that is 18.5V nominal, 21V fully charged.

Quote:
Originally Posted by GotLift9369 View Post
Great Info Don...right in line with what I need to know with my Supra-E I'm working with just now...I have a Neu 1506-5200-2d-6.7 which is rated at 12 Volts running on a TP 65C 3s 1300. I originally went with a 16x10 with the result of the ESC cutting off after 10 seconds or so when the battery voltage drops below 9 volts (tried two batteries).

Rick Pearson
Rick, I would really suspect the ESC is shutting down due to over temp, not under voltage. What amp rating is the ESC? Have you tried another one?

Most ESCs go into a throttle back mode when the voltage drops, they don't shut down. I also can't see a 65C 1300 pack going low on voltage after 10 seconds on a 16x10" prop.

Kevin
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Old Feb 20, 2013, 03:49 PM
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Rick,

First, I would observe that the 1300 3S is not big enough for your application. eCalc predicts that you will be running that battery at about 70C. That, in and of itself will drop your motor volts to around 9 volts. Increasing the pack to an 1800 3S 65C with the 16x10 should get you to around 800 watts or 50C for the pack.

Second, if there is a reason you want to use a 1300 3S, drop the prop size to something like a 14x9 and you will end up around 600 watts and 50C on the pack.

Third, dropping to a 2S would require a big prop and a ton of amps to get back to the range power range that you seem to be looking for.

Finally, I would suggest that you take a look at what you are wanting your plane to do -- either in the ALES context or the F5J context. I am getting my Supra back together (probably to sell) and it had an Neu 1110 that ran around 700 watts and it had WAY more power than I could use under any circumstances for ALES or F5J. It would go straight up to 200 meters in around 13-14 seconds and it would fly out of my sight to 200 meters into 15+ mph headwind. I have switched over to the Maxa for my flying and have gotten great no wind results with less than 400 watts. I am rigging one right now with 600 watts which will take it out of my sight in 25 seconds into a 15 mph wind. I am looking at sort of a dual use system which will allow me to change prop battery combinations when there is no wind and/or when I do not need ballast. That will be more or less a 400 or 600 watt choice. I do not want to waste the allowed motor run time simply for the thrill of watching the plane scream skyward. I am pretty much of a putz flyer, but so far it appears to me that the fastest plane out of the chute in a man-on-man situation probably has a strategic disadvantage relative to "covering" other better flyers. There is no particular advantage to being the leader of the pack. You only need to have enough power to get wherever you might reasonably want to fly.

Happy Landings,

Don
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Old Feb 20, 2013, 07:06 PM
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You correct Rick, that is a bit toad like for sure, I just figured you had a bit more horsepower to work with. I have no experience with any of the Neu stuff.

Marc
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Old Feb 20, 2013, 09:21 PM
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Quote:
Originally Posted by kcaldwel View Post
I was running a 5S 1300mAh pack for awhile on a geared Astro motor. I guess that is 18.5V nominal, 21V fully charged.



Rick, I would really suspect the ESC is shutting down due to over temp, not under voltage. What amp rating is the ESC? Have you tried another one?

Most ESCs go into a throttle back mode when the voltage drops, they don't shut down. I also can't see a 65C 1300 pack going low on voltage after 10 seconds on a 16x10" prop.

Kevin
The ESC is an Ice 100 programmed to cut off at 9 Volts and yes it did this with another one.
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Old Feb 20, 2013, 09:29 PM
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Quote:
Originally Posted by dharban View Post
Rick,

First, I would observe that the 1300 3S is not big enough for your application. eCalc predicts that you will be running that battery at about 70C. That, in and of itself will drop your motor volts to around 9 volts. Increasing the pack to an 1800 3S 65C with the 16x10 should get you to around 800 watts or 50C for the pack.

Second, if there is a reason you want to use a 1300 3S, drop the prop size to something like a 14x9 and you will end up around 600 watts and 50C on the pack.

Third, dropping to a 2S would require a big prop and a ton of amps to get back to the range power range that you seem to be looking for.

Finally, I would suggest that you take a look at what you are wanting your plane to do -- either in the ALES context or the F5J context. I am getting my Supra back together (probably to sell) and it had an Neu 1110 that ran around 700 watts and it had WAY more power than I could use under any circumstances for ALES or F5J. It would go straight up to 200 meters in around 13-14 seconds and it would fly out of my sight to 200 meters into 15+ mph headwind. I have switched over to the Maxa for my flying and have gotten great no wind results with less than 400 watts. I am rigging one right now with 600 watts which will take it out of my sight in 25 seconds into a 15 mph wind. I am looking at sort of a dual use system which will allow me to change prop battery combinations when there is no wind and/or when I do not need ballast. That will be more or less a 400 or 600 watt choice. I do not want to waste the allowed motor run time simply for the thrill of watching the plane scream skyward. I am pretty much of a putz flyer, but so far it appears to me that the fastest plane out of the chute in a man-on-man situation probably has a strategic disadvantage relative to "covering" other better flyers. There is no particular advantage to being the leader of the pack. You only need to have enough power to get wherever you might reasonably want to fly.

Happy Landings,
Thanks Don...I see the wisdom in what you say...My plan now is to move the JR 921 receiver into the wing freeing up fuse space, movin g down to a 15x8 and going with a 3S 1800, like you suggested now that I can fit a battery with a thickness greater than 18mm. I was limited to this 18mm because the battery had to side into the Supra fuse from the front through the lower sectiion. Now I will be able also to remove the battery without pulling the nosecone with motor and ESC.
Thanks again for your insite.
Rick Pearson
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Old Feb 22, 2013, 03:33 PM
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Quote:
Originally Posted by GotLift9369 View Post
Great Info Don...right in line with what I need to know with my Supra-E I'm working with just now...I have a Neu 1506-5200-2d-6.7 which is rated at 12 Volts running on a TP 65C 3s 1300. I originally went with a 16x10 with the result of the ESC cutting off after 10 seconds or so when the battery voltage drops below 9 volts (tried two batteries). Runs pretty well on a 2S 65C 1300 with a 17X10 but I need more thrust than this. I am stuck for the time being with the relativly low voltage 1506 so I intend to go with a 15x8 prop to bring down the current and prevent the low voltage cutoff.
I'l love to get in the future an 1107 like what you use which woul be 2.3 oz lighter and allow a larger prop with lower current.. anyway I really appreciate the work you are doing.
Rick Pearson

Before changing equipment check the controller settings. Set the battery cut-off to the lowest setting possible. I really doubt you are overheating the controller with a 10 second run.

Steve Neu
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Old Feb 22, 2013, 05:05 PM
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Originally Posted by sneu View Post
Before changing equipment check the controller settings. Set the battery cut-off to the lowest setting possible. I really doubt you are overheating the controller with a 10 second run.

Steve Neu
Thanks Steve...I agree and will do what you say.
Rick Pearson
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