Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[kallend]

..... From memory, I recall that most are reading 23 mΩ total which is about 3.8 mΩ per cell. I think the maximum I have seen is 30 mΩ which is about 5 mΩ per cell. But...i'll re-check and see. I'm either remembering incorrectly the 8 mΩ reading I stated above, or...like you say "it is time to consider replacing" it.
.....

At what temperature are you making these measurements? IR is very sensitive to temperature.

[GliderGuy]

Room temp after fully charging. About 74F. Next flying day, I will take current measurements and post.

Accuracy of the CQ3 is unknown, so this will be a relative comparison of all 10 batteries.

-GG

[Hugh Wiedman]

At what temperature are you making these measurements? IR is very sensitive to temperature.

So true, that is probably THE single most critical variable. I always measure mine at 70 degrees, fully charged and if new, after 3-5 cycles.

[mshagg]

The UP600 looks like a beast! Do they hold up well in the heat/hot weather?

-GG

Haha sorry I mistyped, it's the UP6+ not the 600! Dual 300W instead of dual 600W.

Still, this is one of the hottest, driest climates on earth, they haven't skipped a beat.

They measure IR but honestly at single digit values the quality of the balance lead will impact the readouts.

[fredmdbud]

The most useful IR measurement is at operating temperature, because that will predict the actual voltage sag at continuous draw.

IR at room temperature equilibrium works as a benchmark as assuming the same thermal coefficient across all batteries.

[Airguardian]

Some more data on my end regarding IR:

I read IR on my packs when charging them at 1C with the Revo Powerlab.
IR reading depends on temperature (and mAh size, etc, etc)... summer and winter readings are not the same but, without getting too technical, suffice to say that my 5Ah Panther batteries started at 1-2 mOhms/cell and they are now at 1.5-3 mOhms cell after 100 cycles each. Out of 6 Panther Li-Pos, only 2 got a bad cell which showed up after 100 cycles and a lot of abuse (measuring 5-6 mOhms on the bad cells). Still, with my intensive use, the batts don't seem to pack as much of a punch as they did being new, but after 100 flights I'd still call that a win, considering the abuse I've put them through...

4Ah and 5Ah Nanotech batts that I use are also in the 2-4 mOhm/cell range.

Edit: The temperature where I charge my batts will be about 10-15ºC in winter and 20-25ºC in spring/summer/autumn.
Some hot days, it may get up to 30º. ATM, I'm charging at about 20-25ºC.

[GliderGuy]

More good info, Airguardian.

Since I have no specs on the accuracy of the CQ3, I intend to use the internal resistance measurements as relative data and will watch for any developing bad trends.

Thanks everyone. Not a true MiG topic / discussion, but informative.

-GG

[GliderGuy]

If you are interested....applicable to the MiG as well / Posted in the F-4 thread:

#5003
Today, 08:13 AM

Hard surface, short runway operation / S-turns after touch down to bleed energy quickly without the need for wheel brakes.

[kallend]

Haha sorry I mistyped, it's the UP6+ not the 600! Dual 300W instead of dual 600W.

Still, this is one of the hottest, driest climates on earth, they haven't skipped a beat.

They measure IR but honestly at single digit values the quality of the balance lead will impact the readouts.

I Googled UP6+ and among the hits I got was an unboxing video. Really! An unboxing video for a battery charger!

Just because you can make videos doesn't mean you should post all the minutiae of your life online.

[locharrow]

"You are not the only one, I am lucky my field is next to home or I would be a mindless babbling fleshbag at this point..."
Hate to be the first to tell you J ......but flying is not helping you !!
Try my remedy ........

[Airguardian]

Hahahaha!
I'm not much of an alcohol guy (though I enjoy a beer from time to time when I fancy it) ;)

[flyAA]

Maidened my mig today. It flew really well! Only had one issue.

The airplane is stock except pro modeler 150oz torque horizontal stab servos and upgraded linkage. Admiral 10ch receiver with satellite and hobby eagle gyro (it was off). C.G. 7-8mm behind recommended. Slight reflex in flaps and ailerons. stock BEC. Flaps were up.

I lost all control in a descending left hand turn and eventually gained it back after 3-4 harrowing seconds lol. I’m leaning towards an issue with the BEC. Could those high power servos be causing an overload on the stock 8a BEC?

[GliderGuy]

FlyAA- Don’t fly again until you solve this!!!!!

Are you using RF Chokes as discussed in this thread?

Need data: Pix of setup, throttle setting, flaps down or up, what things were in process of moving, battery types, what ever you can supply for review.

Thanks.

-GG

[Airguardian]

I lost all control in a descending left hand turn and eventually gained it back after 3-4 harrowing seconds lol. I’m leaning towards an issue with the BEC. Could those high power servos be causing an overload on the stock 8a BEC?

I bet.
Drop in a 20A UBEC and ideally power it off a separate 2S Li-Po pack.

Also, how is your receiver setup?
Where did you place it, are you using satellites, etc?

Ideally you should have a redundant receiver system on such a plane, and at least one of the receivers/satellites should be placed in the nose with antennas oriented smartly.

Please, send pics of your receiver and antenna installation for reference.

[Hugh Wiedman]

Maidened my mig today. It flew really well! Only had one issue.

The airplane is stock except pro modeler 150oz torque horizontal stab servos and upgraded linkage. Admiral 10ch receiver with satellite and hobby eagle gyro (it was off). C.G. 7-8mm behind recommended. Slight reflex in flaps and ailerons. stock BEC. Flaps were up.

I lost all control in a descending left hand turn and eventually gained it back after 3-4 harrowing seconds lol. I’m leaning towards an issue with the BEC. Could those high power servos be causing an overload on the stock 8a BEC?

Were you able to look at the signal menu on you TX after your flight (assuming your TX has the capability) and see how many frame losses you had and if there were any holds indicating a temporary loss of signal?

[fredmdbud]

Could those high power servos be causing an overload on the stock 8a BEC?

I doubt you are getting full 8A capacity, if you are powering the BEC using the full voltage of all 6 cells. Try using 2S to power the BEC.

[flyAA]

FlyAA- Don’t fly again until you solve this!!!!!

Are you using RF Chokes as discussed in this thread?

Need data: Pix of setup, throttle setting, flaps down or up, what things were in process of moving, battery types, what ever you can supply for review.

Thanks.

-GG

-no RF chokes
-flaps up
-probably around 30% throttle
-i was in a descending left hand turn. no flaps/gear moving
-hrb 6s 5000 batteries
-my receiver is in the forward battery tray and the satellite is in the nose

Thanks for your help!

[fredmdbud]

-no RF chokes
-flaps up
-probably around 30% throttle
-i was in a descending left hand turn. no flaps/gear moving
-hrb 6s 5000 batteries
-my receiver is in the forward battery tray and the satellite is in the nose

Thanks for your help!

How are your antennas oriented, main and satellite RX's?

[flyAA]

I bet.
Drop in a 20A UBEC and ideally power it off a separate 2S Li-Po pack.

Also, how is your receiver setup?
Where did you place it, are you using satellites, etc?

Ideally you should have a redundant receiver system on such a plane, and at least one of the receivers/satellites should be placed in the nose with antennas oriented smartly.

Please, send pics of your receiver and antenna installation for reference.

Hey! My receiver and satellite are in the forward battery tray/ nose. They’re in a pretty solid spot.

i ordered a 20amp castle BEC so going to get that installed soon.

[GliderGuy]

Send a photo of your radio set up in the MiG. Also….strongly consider adding RF chokes. Research the discussions here in this thread.

My gut feeling (hunch) the loss of control is not BEC related, since you stated that no systems were in transition/moving. There’s another gremlin in your system IMO!

The experts here will be able to help you sort this out. MAN….don’t fly it again until you are sure the gremlin is gone! I sense a disaster as the outcome, otherwise.


-GG