Trex 800 problem with battery pack?? - HeliFreak
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Old 01-01-2017, 04:59 AM   #1
Daxy
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Default Trex 800 problem with battery pack??

After 6 months i try to fly my trex, charge my battery pack, go on feld put on, 30sec after high load ecs cut off reduced rpm... Hmm, check batery pack, voltage on each cell is about 4.15v. Can be that battery are low with current??
Here is ecs log



Battery pack: Gens Ace 6s 6000mah 45c

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Old 01-01-2017, 06:30 AM   #2
Grumpy_Old_Man
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If the batteries were very cold that could explain it. 3.3V is quite high for the LVC, you could try reducing it to 3.1 or 3.0V.

Was the battery fully charged while stored for those 6 months?.. if so that will have damaged it increasing it's internal resistance.
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Old 01-01-2017, 06:51 AM   #3
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According to the log, the T-Rex spooled up at about 600s and the low voltage cutoff occurred at about 1100s or 8 minutes and 20 seconds later. That's a bit less than what I would expect, but if the batteries aren't brand new, it's not surprising either, especially with the PWM pulse rate of 16 kHz. Standard is 12 kHz if I remember right.
How long did you usually fly before?
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Old 01-01-2017, 07:13 AM   #4
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Battery was storage at about 3.8v per cell, i have 10 flights behind with this battery at same setup from last time i make, and was just fine about 4min flying... Today tested also with 700 with same motor and ecs and the same problem happend, heli reach about 1900rmp, but when i pull full positiv he cut off immediately. I dont have 3rd battery pack to try it... 😡


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Old 01-01-2017, 12:40 PM   #5
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It's probably just the cold. I had exactly the same thing happen recently with my Goblin 630 which also uses a Castle ESC. I adjusted LVC down to 3.0V and it's been fine since.
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Old 01-01-2017, 03:07 PM   #6
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If you are experiencing this on both helis, it probably is the cold. If your batteries were stored properly for 6 months I can't see that being an issue. Unfortunately batteries don't perform that well in the cold.

However, you may benefit by your PWM being set to 12, and cut off at 3.0v/cell. Give that a try and see how it performs, you should be able to get in the air for longer then 30 seconds. My electrics still fly in the winter, just not as well as my nitro runs.
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Old 01-03-2017, 10:32 PM   #7
Dennis P
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The batteries will perform fine in the cold if they are warm when installed and flown right away as they will create there own heat will making energy for the heli. If they are installed cold and flown you can damage your packs and have LV shutdowns. I have flown lot's in the cold , have your packs warm when they are installed and flown. They will still be warm when you land even when it is -10c if they where warm when you took off.
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Old 01-03-2017, 10:39 PM   #8
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I agree, warm the packs, it makes a big difference. If they are 35-40c to start out with that's great.

LVC could be lower as well, I run 3.0v/cell on all helis.
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Old 01-04-2017, 06:30 AM   #9
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Tnx. I give a try next days as soon raining stops.. I gonna write back. ✌️️


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Old 01-16-2017, 07:16 AM   #10
Daxy
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Default Trex 800 problem with battery pack??

Bad things are happend for my T-Rex... Two cell on battery pack are completely death caused cut off and my bad autorotation..

How was all happened:

I charge battery's, check every cell looks fine 4.2 on each, check temperature 25 degrees, put in the box to they stay warm, set up caste( auto cut off 3.0v pwm back to 12) and ready to go
15 min later go on feild give a try, start up slowly make couple cycles on low head speed and looks to me very good. 1 min later put mid head speed and flying around its also very good..thinking its time to push it little bit, after 3 min high head speed soft 3D was really good. Maybe i can fly longer but i don't want to risk it. All together was ~5 min flying, i was satisfied. And second battery pack is also good.

Second day little bit worse. Spool up high head speed, soft 3D after 1min later castle cut off, i panic a little bit and landing bad, both main blade broken, and both main linkage. Not so bad how can be, but hurting anyway. One battery is puffed up and second cell 1.9v fourth cell 1.4v. Another pack is ok i give a try on 700.

Why this happend, i start to worry about this batterys?! They are not so mutch old and i dont fly them so mutch about 10~15 flights? For my 450 i have batery 4 years old and about 100 flight on each, and they are still working. Can be charger?

I order new batery pack, and parts.


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Old 02-11-2017, 07:31 AM   #11
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"current limiting" needs to be set at insensitive. Stick "PWM" to 12 or 8. Also check out the OHM's in the pack if the cell or cells read above 30 ohms there probably bad...
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