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Old Sep 26, 2012, 10:20 PM
Registered User
Canada, QC, Montreal
Joined Feb 2011
335 Posts
looking for a way to use the battery load loss

I have an hexa, power system :
dji 30 amps esc, 650 kv motors, 10x5 cf props, batterys 4s 4500mah 25c turnigy nanotech.
- FC Naza with gps
Here is my problem : I have a load loss of 0.7 volts meaning that i only get 5 to 6 minutes of flight time before my battery goes dead with a load loss. So when flying my batterie cells goes down to 3.5 volts but when I unplug my batteries are still good with 3.8 volts per cell.

There must be a way to use my batteris all the way?

thanks for any help
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Old Sep 27, 2012, 09:15 AM
Out of helis, sanity returning
Tallahassee, FL
Joined Feb 2009
2,144 Posts
When you recharge that battery, how many mah are you putting back?

You can't really get everything out of a battery- conventional wisdom is that using 80% of the available mah is about right. Sorta-kinda, if you know what I mean. There is a wiggle factor I guess.

The best way is just to keep track of how much mah you put back when you charge. Voltage doesn't really tell you much.
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Old Sep 27, 2012, 09:19 AM
Stop me before I build again!
United States, NY, Albany
Joined Sep 2012
1,320 Posts
4500mAh * 25C = 112,500 or 112A peak draw..

30A * 6 = 180A peak on the motors alone. ( 650kv seem to suggest that 20A ESC's are all that's needed, but that's still pushing your 25c battery during peak loading )

I think you need to be looking at much higher rated batteries. ( I'm a noob, so double check before making any changes ).
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Last edited by brontide; Sep 27, 2012 at 09:31 AM. Reason: 20a comparison.
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Old Sep 27, 2012, 12:35 PM
we dont NEED roads!
AcroFPV's Avatar
United States, CA, Rocklin
Joined Aug 2012
3,423 Posts
650kv and 10" props??

Maybe try 11" props and see if you get more flight time.

4500mah 4s i would think you could get more than 6min. I use 2200mah batteries and can get more than 6min with my Tricopter.
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Old Sep 27, 2012, 10:43 PM
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United States, SD, Rapid City
Joined Nov 2011
1,936 Posts
12in might be good too. also as brontide said, im pretty sure the v drop issue is from the batery not being able to supply enough current. get a higher c battery like 45c 4500mah
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Old Sep 30, 2012, 03:03 PM
Registered User
Germany, BY, Gestratz
Joined Oct 2008
244 Posts
If the batteries have 3.8 v without load, you can assume that there is a capacity of about 40 % left. If you use 2700 mAh in 6 minutes, the average draw is about 27 amps. Everything is fine. Make the low voltage alarm to 3.3v. Then you will get another 2 minutes flight time.

If kv of motor is realistic, get 12*3.8" props, maybe even 13" will work, and you will get another 2 minutes...
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