Author Topic: A123 Test ship set up (Read 2482 times)

Dennis Toth · « **on:** February 19, 2008, 08:08:15 AM »

I'm getting to the point of doing a test ship for the A123 3s2p battery with the AXI2820-8 motor, CC45 ESC, Ztron3 timer. The ship I have is a very old 1950's ship that was originally designed for an Atwood 60 on ignition. This ship has a big top hatch and lots of room for testing different set ups, its a little large at 600sq in and all up weight is 55oz, it will be quit a test. I don't expect it to be a World Beater but will be easy to work on. I have completed the motor mount (front mount 3/16" ply with cooling holes) and the battery access area.

Now I need some input on how to mount the componets. The instructions for the CC45 say it should be mounted with the LED side out. This side has the components visible. The unit comes with a clear heat shrink cover, with heat being a concern can this be removed?

To mount the ESC and Ztron can I use a Velcro strip? is this strong enough? Also should the connection wires be twisted or just tied together?

With some luck I should be ready to start set up and first test this weekend.

Best, Dennis

bfrog · « **Reply #1 on:** February 19, 2008, 09:11:31 AM »

Dennis,

Good luck, sounds very interesting.

I think that Velcro to hold the ESC and Ztron will be fine. I use servo mounting double stick tape but if you go to the hardware store and get the "industrial" strength velcro you should be fine. I use that to hold the batteries to the airframe. I also use a velcro strap around the battery. Again at the hardware store get some velcro cable straps, they have large tab at one end with a slit to pass the tail end through. Cinch them down tight around the battery against a sturdy bulkhead. Remember the batteries are heavy. Make sure they are securely attached to the plane. They have a lot of momentum on landing and want to keep going!!

I don't quite understand your question about the connection wires. All wires should be soldered or have a connector on the end. Just twisting won't work. Make sure your have good solder joints too as poor ones will cause a loss of power or intermitent signals.

Do you have a way to measure current draw? The AXI 2820/8 will draw more than the 45 amps the ESC is rated for with the wrong prop. The best solution to measuring power is a watt meter. You can get them at most electric savy hobby shops or on line. They cost about $50 and give you current, voltage, and watts. They're easy to use too. You will want to have a selection of props based on the data sheet for the motor. It's the best way to tune the performance of the system and adjust current.

Hope that helps a little. Good luck and post your results. Others will be interested in how it flies.

Bob

Dennis Toth · « **Reply #2 on:** February 19, 2008, 11:06:24 AM »

Bob,

Thanks for the input. I think the Velcro straps should work for the battery - do you put anything under it like a strip of foam rubber or just strap it to the floor?

The twisted wires are not the connection, they are soldered, this was brought up in another thread that indicated that the ESC could mis-fire from stray mag field in the wires. They talked about twisting the pairs together to eliminate this but never stated that this was needed. My thought is to just zip tie them together to form a nice bundle and I think that should work, just wondered if anyone followed up on that report.

I do have a Sears clamp-on AC/DC amp meter (discussed in another thread) that several others have used. I will start with a small prop (say a 8x6) and work up keeping a record of the rpm and amps. Reading through the threads it seems that if we pull 40amp on the ground that should drop once it unloads in the air to around 25-28 and that should be about right. The A123 battery can be pulled down to 95% without damage and so I might push the in air a little more.

How do I check the amount of amps pulled from the pack after a flight?

Last thing do you leave the clear shrink wrap on the CC45 ESC?

Best, Dennis

Alan Hahn · « **Reply #3 on:** February 19, 2008, 11:25:34 AM »

Dennis,
A couple of things.
Leave the clear heat shrink on the ESC. They sell it that way and si it should be able to handle the heat you would be producing up to the 45 Amps CONTINUOUS. I capitalize that because I bet you don't draw that much continuously, but at most just briefly at takeoff and maybe during some of the vertical maneuvers.

I guess it can't hurt to twist the battery leads, and keep the Ztron timer wires away from both the battery and motor wires. I have never noticed a problem myself.

Mike Anderson · « **Reply #4 on:** February 19, 2008, 01:18:10 PM »

Quote from: Alan Hahn on February 19, 2008, 11:25:34 AM

Dennis,
A couple of things.
Leave the clear heat shrink on the ESC. They sell it that way and si it should be able to handle the heat you would be producing up to the 45 Amps CONTINUOUS. I capitalize that because I bet you don't draw that much continuously, but at most just briefly at takeoff and maybe during some of the vertical maneuvers.

I guess it can't hurt to twist the battery leads, and keep the Ztron timer wires away from both the battery and motor wires. I have never noticed a problem myself.

I've never noticed any problems in the Battery-ESC-Motor path, but I do notice some
twitching and jittering when my Strobe Tach is turned on. I should probably clarify
that by saying that I sometimes run with a "Pulse Width meter" (a servo w/ a pointer)
paralleled off the ESC, to see how the flight programmer is behaving.

I use a strobe tach because it is not confused by AC lights. When the strobe starts
to fire, the servo/pwm occasionally gets twitchy, but there is no real evidence of the
twitchiness affecting the ESC - the motor continues to run at a very solid RPM. That
is another advantage of the strobe tach - you can SEE very small changes in rpm.

But I don't know of any advantage to twisting the motor or battery leads.

Mike@

bfrog · « **Reply #5 on:** February 19, 2008, 07:56:27 PM »

Dennis,

Yes, I just strap the battery to something solid. I also put a patch of heavy duty velcro on the battery and the floor, bulkhead, whatever, I strap it to. That way it doesn't move around at all. The strap holds it down and the velcro square keeps it from sliding.

I have never had a problem with ESC, Ztron etc and interference. In fact I regularly bundle all loose wire together to keep them out of the way. I have never noticed anything odd.

Pete Mazur has a data logger that he uses and the current drop from on the ground to in the air was at least 10% on his Skyray. My guess is that's about right but it might depend on other factors. If you are pulling 45 on the ground then in the air you are probably well within the ESC's range.

The only way I know of to check how much has been used in the battery is to see what my charger puts back in. The charger I use tells me what it took to reach full charge again. If you don't have this feature on your charger I don't know of a way to measure it. Mike, do you have any suggestions??

Bob

Alan Hahn · « **Reply #6 on:** February 19, 2008, 08:42:17 PM »

Dennis,
When I was runnning my E-Nobler with 2 3s2100MAHr batteries in parallel (equivalent to a single 3s4200MAHr battery), the static amp pull was ~34Amps. When flying with the same setup, the average current fell to ~21A, with brief spikes during maneuvers up to 34A.

Both cases were with an APCE 11x5.5 prop @ 8900 rpm in governor mode.

I run my flights with a CC Phoenix 35A ESC.

Dennis Toth · « **Reply #7 on:** February 20, 2008, 07:06:34 AM »

Guys,

Wiring connections are complete last night, soldering the Deans plugs is a pain. I soldered the Motor and ESC with about 6 in of lead, mostly the motor lead it seemed like the heaver wire so I kept that and shorten the ESC leads. Wiring layout even in this wide open fuse is frustrating, but I think I have a reasonably neat arrangement. Timer arrives tomorrow and the CC Link also.

Question - since the ESC is hard wired to the motor and I need to power up the ESC to program how do I make sure that when I plug in the timer and battery pack it doesn't fire off the motor? I will of course work from outside the prop ark (or take it off) but still need to know how to do this safely.

Also, since there is no ON/OFF switch I am using the Deans plug on the battery to do this function, I understand that the timer is the control once the battery is plugged in. Once the timer is activated beside pulling apart the Deans battery plug how do you shut it down before the timer runs down (say in a short test run)?

Best, Dennis

Alan Hahn · « **Reply #8 on:** February 20, 2008, 07:24:30 AM »

Dennis,
Maxx Products makes a special plug in system which works for this
http://www.maxxprod.com/mpi/mpi-21.html
(item 6970 includes everything).
The biggest problem with it is that the connector they use takes up a lot of space inside the fuse. It doesn't fit in my ENobler, but I made the equivalent using the Dean's Ultra connector.

Normally when you plug in, the Ztron starts counting. That's why you need something like this in a full bodied ship with the Ztron (or somehow have the battery/ESC wires outside the fuse for plugin. The JMP-2 won't start the sequence until you push the button--an advantage of sorts in this case, but you obviously need to mount it externally. The safety problem is that you have to trust the JMP-2 to behave (mine always have on a profile).

bfrog · « **Reply #9 on:** February 20, 2008, 09:17:21 AM »

Dennis,

Yes, it seems like there is a lot of wires for a small electric system and they snake all over the place. Just do the best you can. I have only built profile models for electric so far and I always end up with something that doesn't look too tidy. Use small tiewraps to hold things in place.

To program the ESC just unplug the wires from the motor. You did use the bullet plugs on the motor to the ESC, right? The ESC doesn't need to be connected to the motor for programming.

I would highly recommend the arming plug that Alan suggested. I use this on my electric carrier model and it works a treat. It is also very easy for the launch person to do and keep them safe (most CL guys are not very comfortable with electrics since they are not familiar with them). You can get out to the handle, check elevator etc, then have the pit person plug in the arming plug. The ESC chirps and starts the motor and your ready to signal release of the plane. It does take a bit of room but can be mounted anywhere since it's just extra wire to run it to a reasonable location. It should be in a place that the pit person can reach easily. Alan said he uses a Deans connector setup that he made. This works fine too but the nice thing about the arming plug is that the insertion force is lower and it is not as hard to make and break as two Deans plugs. I attach the plug part of the arming device to the airplane with a bit of string. That keeps it from getting lost between flights. Two other advantages are, you can take a quick look at the plug and see if the your safe from accidental start up and when you land you can just go to the plane and pull the plug to put everything in safe mode.

Dean Pappas · « **Reply #10 on:** February 20, 2008, 10:15:57 AM »

Hi Dennis,
Yes, the rats-nest of wiring is a pain!

Who will come up with the tidiest solution to this problem? There's a new thread in that.

Twisting or bundling tightly is a good idea: the goal is to prevent the current carrying wires from creating a large area loop. That makes a mag field antenna.
The use of a safety switch is also a great idea. Now that we are starting to design our planes around e-power, you'll find that a pair of stackpole (a.k.a. Anderson or Sermos) connectors makes a great safety switch. The greatest benefit to this style connector is that the running contact surface is not the same as the surface that takes the first contact arc. They are rated for 45A.

later,
Deann

Dennis Toth · « **Reply #11 on:** February 24, 2008, 05:45:54 PM »

Things are coming along, I decided to put in a 40A switch in the battery line as a safety. Mounted the ESC below the old motor mounts wires are neat but a pain, we need to develop a plug board approach for mounting this stuff. Last thing I am waiting on the the Ztron timer from Windy, should be here tomorrow.

I got the Castle Link on Friday and have a question - it indicates that the motor should be connected to the ESC, then connect the Castle Link (I assume to the connector that goes to the timer?), then plug in the battery and it will go to program mode. Now I don't trust these magic boxes so I'm putting a flywheel on the motor for the first go through so that if I miss a step I don't have stuff (and skin) flying all over. I take it that the timer doesn't need to be part of the ESC programing from Castle link - correct?

Best, Dennis

bfrog · « **Reply #12 on:** February 24, 2008, 07:28:57 PM »

Dennis,

No the timer is not required to program. In fact the plug that goes to the timer is the one you plug into the programmer so it would be difficult to do both.

Bob

Dennis Toth · « **Reply #13 on:** March 11, 2008, 01:42:06 PM »

All in now ready, I've done some test runs on different size props and it should be good to go for the first flight this weekend.

The tests I ran were with the AXI2820/8; A123 3s2p battery; CC45 ESC in high governor mode, gain set to 75; Ztron timer set for 64% motor start and motor end, all else default:
1) 9x5 MAS, 11,000 rpm, 24amps
2) 11x5 APC E, 10,000 rpm, 51 amps
3) 12x5 APC E, 9,000 rpm, 59 amps
4) 11x5 APC E, 9,800 rpm, 49.5 amps

Motor temp was only warm to the touch but these runs were only about a minute. Battery was not even above room temp.

The forth test was once the battery settled to running voltage of 9.9V. Pack was down 1692 mah. OK, the 11x5 will hit the 5.0 lap time I'm looking for on 60ft lines.
So this weekend the Electric Crate will fly. I will start with a 3 min flight and go from there. Thanks for all the help and information to get me up the curve you guys are great!!!!!

Best, Dennis

Dennis Toth · « **Reply #14 on:** March 23, 2008, 10:32:17 PM »

Finally got into the air on Saturday. First flight was with the AXI2820/8 motor and 3s2p A123 pack 4600 mah with 11x5 APC E prop, high governor mode on ESC, 32% motor start and end on Ztron timer held rpm to 9600. Airplane was a very old hanger queen that was built in 1950 by my uncle then rebuilt in 1964 by me. Ship is 625 sq in area and 57oz ( was 55 but needed to get some additional nose weight for balance, it's still a little tail heavy but flyable).

Flight timer was set for 3mins, all went well lap time with the 11x5 was 5.5 sec on 63.5 ft lines. It seemed OK but not great, did one loop for fun but just flew it out. Next, changed to 11.5x5.5 APC E (cut down and repitched12x6), did not recharge but set timer for 1.3mins, just to test and get lap time. This prop dropped the lap time to 4.6 sec and pulled this ship with strong authority, big difference.

At home I did one last test run to get an rpm reading on the 11.5x5.5, it was 9000. This was less than the governor setting so it looks like the governor was not governing with this prop. Checking my prop calcs I think I only need about 8700 rpm to get a 5.0 lap time which is what I would like. I will reset the timer to about 28% and check the rpm.

Checking the motor temp after all runs it was only warm to the tough and measured 97F on the meter. Battery was much less. So I think it is OK at the amps it is pulling.

Recharged the battery after what amounted to a total of 5min 40sec of run time and I had used 3564 mah (about 80%). Voltage at start of recharge was 9.65.

The thing that surprised me was the big difference in the performance of the 11.5 in diameter prop and the 11 inch prop. Reducing lap time by almost a second is a big jump in thrust and pulling power. I didn't think there would be that kind of change, as a matter of fact I thought it might go slower because of the lower rpm. One thing that did show up was problem with the wire connection through the switch. Seems like there may be either a break or partial break the when you move the deans plug a little reconnects and all seems OK. If there is a partial break could this lower power going to the motor which may have given faults performance for the 11x5 prop?

I think I need to do another test with the 11x5 after checking the wiring to make sure it was a solid run. If that checks out I will reset the rpm and test the 11.5x5.5 more, but based on the initial runs this package with the 11.5x5.5 APC E prop has what it takes.

Best, Dennis

Alan Hahn · « **Reply #15 on:** March 24, 2008, 08:30:44 AM »

Dennis,
One thing that takes a little getting use to with electrics and governors is how you change your approach to propellers---especially comparing it to glow engines.

The thing to always remember, in level flight you only need to provide the thrust to overcome the drag of the plane. The thrust is related to rpm, prop diameter and pitch. Going from a lower diameter prop to a higher diameter prop will require you to drop the rpm, even if the pitch is the same, because the concept of "pitch" speed (pitch* rpm=airspeed) is only a ballpark thing. So with a larger prop, the thrust at the same rpm is more, so if you leave the rpm constant, the airplane will have to accelerate to a higher airspeed---where the new drag force just equals the extra prop thrust---not quite, because as the airspeed increases, the thrust will drop some, but there will be a new higherr airspeed.

You can see all this on my propeller thread plot. http://stunthanger.com/smf/index.php?topic=7574.0

What I think is cool, is that as long as you stay in a family of props (like APC thin electrics for example), things are pretty predictable. I never had that feeling with glow engines, where putting on a bigger prop could go almost anyway.

Dennis Toth · « **Reply #16 on:** March 25, 2008, 09:12:52 AM »

Alan,

Thanks for the link to the prop thread, interesting information about the diameter ^4 affect. I knew that more diameter always better if you can use it but didn't realize that it was to ^4, that's big.

One question - if the power wiring had any breaks that say reduced the effective wire size in half would that reduce the current to the motor or just heat up the wire?

For information attached is pic of A123 test ship.

Alan Hahn · « **Reply #17 on:** March 25, 2008, 09:42:11 AM »

Dennis,
Nice looking plane!
About the wire, what matters in getting current to the motor is the resistance of all the wires, connectors, battery internal resistance, and FET's in the ESC. But it is also important to remember that this is all summed up in series. A very short length of smaller diameter wire will up the resistance of course, but it needs to be compared to the total.

For example, in the motor I am currently winding to try in my Nobler, I have almost 2 m of 19 AWG gauge (0.91 mm diameter) wire in each of the 3 legs of the motor. This is certainly more resistance than the lengths of battery and ESC wiring, which typically is even a larger gauge. So if you have 1/2" length of thin wire somewhere in your setup, I doubt that it will cause much change in the total current flow to the motor. However you are right that it will tend to heat up more than the surrounding wire, but I doubt by very much as long as your currents are in the 40A range or so. For example, 1/2" of 24 AWG wire (0.5 mm diameter) has a resistance of ~1 milliOhm. Since the heat is I^2*R=1.6 watts That isn't zero and certainly will heat up that segment of wire, but gives an idea on how these things go. My 2 m of 19AWG has a total resistance of 52 mOhms, to give a heating of 83 Watts for comparison. I will also note that my Nobler currents are closer to 20A in level flight, so my heating in the motor due to wire resistance is in the 20 Watt range. [Note that this isn't completely accurate because my motor is internally terminated in a delta configuration, but it is good enough for this discussion).

It certainly doesn't hurt to make an effort to reduce all possible losses---just keep it within reason is all I say.

Dennis Toth · « **Reply #18 on:** March 25, 2008, 02:21:04 PM »

Alan,

Thanks, I am have an intermittent open in one of the wires from the battery to the ESC. It is darn annoying, sometimes you switch on and nothing, then you switch off and move the wires, switch on and all is OK. I'm not sure if it is in the wire or the toggle switch but will keep hunting.

Attached is a second picture of the A123 test ship with the cowl off, shows the motor and battery layout, ESC and Timer are Velcroed in on the bottom of the motor compartment.

Best, Dennis

Alan Hahn · « **Reply #19 on:** March 25, 2008, 03:04:11 PM »

Dennis,
Well you definitely want to get that out! Otherwise you know it will somehow find a way to disconnect at the most inopportune time (like the first corner of the wingover).

Dennis Toth · « **Reply #20 on:** March 29, 2008, 09:59:45 PM »

Flew today with the 11.5 x 5.5 APC-E prop, two flights. The first was a short 1min 20sec just to check the mods I made to the controls (the ship is a little tail heavy and you have to stay with it all the time unless you are up very high, lengthened the tail horn to slow the controls) the mods helped but it is still a handfull and I will have to find a way to move the battery as far forward as the nose will allow which is only another 1 3/4", but that should help.

I had also reduced the motor start and motor end power setting from 32 (total) which gave 9800 on the 9x5 and 11x5 but had no control on the 11.5x5.5 giving an rpm of 9300. I did a short 15 sec test run to check the rpm after the first flight and with the timer reduce further to 29 and got an rpm of 9200. This seem just on the upper edge of the control range of the governor with nothing to add as the battery runs down.

The second flight was just to see were we would be on the total run time and to check temps with this prop and power setting. I set the flight time for 3min 33sec. The lap times are still to high at 4.57 sec on 64 ft lines and the run was very strong until the last 25 sec when it slowed to around 4.92sec. I when over to the ship and check the motor temp it was just warm to the touch but not uncomfortable to the touch, battery was cooler just barely warm so this seems to be and OK load and the prop has lots of pulling power even at the lower speed at the end had great line tension.

On charging the pack after a total run time of 5min 8sec it took 4059 mah out of the 4600 or about 90% with an end voltage of 9.56v (3s2p pack) which is about what we were aiming for. May calcs for the 5.5 pitch at a target of 4.9 sec lap show I need to reduce the flight rpm to around 8800. I hope going to 24 on the timer will get there and also lower the amps a little and give a little longer flight time say out to 5min 35sec. The Package is very close and if it will do the lap time and run time it should be very competitive.

Best, Dennis

Alan Hahn · « **Reply #21 on:** March 30, 2008, 12:28:04 PM »

Dennis,
What was the type for your 11-5 prop? Since the 11-5.5 seems to be near the edge of your voltage, even when you reduce the rpm down to 8800, you might think about getting an APC 11-7 E, which should allow you to drop your rpm down another 5-600 rpm or so (a guess) and give your ESC the overhead to increase the throttle when needed.

I am a little surprised that you are so close with total voltage. Do you have any idea what the battery output voltage is when under load--even just the static load? My E-nobler with a 3s2p 4200mAHr lipo battery setup had plenty of capacity left at the end of the flight to keep the rpm constant on my APC 11-5.5 E, and it was using "only" 2100mAHr @8900rpm for a full pattern. Battery voltage at the end of the flight (but under prop load) was 10.35V.

Dennis Toth · « **Reply #22 on:** March 30, 2008, 09:09:04 PM »

Alan,

The control range for the APC E11.5 x 5.5 (cut down and repitched from an APC E 12x6) was on the edge with the timer set to motor start - motor end of 29. At the start of the flight was 9300 rpm that gave a lap time of 4.57sec. At the end of the total 5min 35sec elapsed run time the voltage was 9.56v. At the end of the second flight I was turning 4.92 sec lap times. The flat run voltage is round 9.9V.

What I needed to do was reduce the rpm to 8800 to lower the lap time to 5.0. I made this change to the timer by setting motor on - motor end to 24.

I did the test run and it hit 8800 rpm with the APC E 11.5 x 5.5 flight prop so I think it is now in the control range and should do the whole flight. I hope to get out during the week to flight test.

Best, Dennis

Dennis Toth · « **Reply #23 on:** April 13, 2008, 12:11:49 PM »

Success !!!!!!!!!!!!!!!!!

I have now flown the A123 set up with the AXI 2820/8 and an APC E 11 1/2 x 4 1/2 prop also an 11 3/4 x 4 1/2 , both work great with the 3s2p A123 pack from Mec. This was in my test ship which has 625 sq, 57 oz. Lap times were 5.25sec on 63.4 ft lines. Flight time was 6 min and the governor was set for 8800 rpm which it held for both props through the flight. I am going to increase the pitch to 4 3/4 to bring the lap time to 5.0.

This package seems to pull like a good 46. Battery draw down on the 11 1/2 prop was 77% ending voltage was 9.78 (3.26 volts per cell) on the 11 3/4 draw down was 83.4% and ending voltage was 9.69 (3.23 volts per cell). Motor was luke warmer (my guess is 115F ish) but not hot to the touch, battery was just barely warm.

At $110 per made up pack from Mec with the ability to charge 1000 cycles, 30 min recharge (could go faster with the right charger, mine is a TP 610C and is limited to 10 amps, I have it set a 8 for now) and no risk of spontaneous fires (Dewalt offers the A123 's in commercial construction cordless tools), this is the setup that makes sense even if there is a few oz more weight (total wt motor, ESP, Timer, A123; 4.5+.5+19 = 24oz). A purpose built 590 sq ship with a film cover should be able to come in at 25oz with a total wt of 49oz.

I am stating the new ship today a modified Tutor II.

Best, Dennis

Alan Hahn · « **Reply #24 on:** April 13, 2008, 05:02:30 PM »

Congratulations--it does feel good doesn't it!

Dennis Toth · « **Reply #25 on:** April 13, 2008, 07:53:56 PM »

I ran three tests this afternoon with the 11 3/4 x 4 1/2 the pitched up 11 3/4 x 4 3/4 APC E and the pitched up 11 1/2 x 4 3/4 props all ran at 8800 rpm. The 11 3/4 x 4 1/2 pulled 53 amps, the 11 3/4 x 4 3/4 pulled 53amps and the 11 1/2 x 4 3/4 pulled 52 amps (at 4 1/2 it pulled 51 amps). I intend to test fly both the 11 1/2 and the 11 3/4 this week to see which pulls up top better. Logic says the 11 3/4 should but since when they were both pitched at 4 1/2 they both pulled the ship at the same lap time the only difference that I can think of is in reaction time to load, might be that the small 11 1/2 will react faster, we'll see,

Best, Dennis