Battery Performance

Hi Team,
Following is the configurtaion of my copter.
450 Frame
2212/1400KV Motor
Pishwak flight controller
5500mah/25C Battery.
The weight of copter is around 900 Grams.
According to e-calc the flight time should be 20min. I know eclac is not so accurate and only indicative.
But I never get flight time more than 5min. When I try to fly more than 5 min the copter activate RTL and gets landed. Not sure what is the problem with hardware or something else
Any support avaialble ??

Gather a .bin log file from a recent flight, upload it to a fileshare service, put the link to it here so we can check that log file.
It could be your battery is not getting fully charged, or has lost capacity and is discharging quicker than it should. Even poor tuning can affect flight time.

Hi Shwan,
Here is the log file from recent fly,
The battery is fully charged to 12.6. Its a new battery (old one was 3300mah but that also had same problem of battery performance)
Please advise for tuning. I believe for auto tuning the battery will need to be last for 15 min. So I havent done it yet.

The voltage is going very low, if that battery is new maybe you need a better charger.
You should get a digital multimeter and check that the reported voltage matches the actual measured voltage.
Use the MissionPlanner battery monitor section to put in the exact battery voltage

Current draw is not excessive, but battery voltage sags a lot

Set these parameters exactly to make the battery parameters better, but also adjust a few other things

Hi Shawn,
I have updated the parametrs as advised above and set the measured battery voltage un monitor section, Still I didnt get good fly time. In face in three minutes time the battery fail activated and landed. I tried this in Auto mode with waypoint command delay for 20min.
Attaching the log file. Please help

No access to that log

It still seems like the battery is bad or the charger is bad.
Exactly what are each of those?

Did you try calibrating the voltage reading by measuring the actual battery voltage with a digital multimeter?

Hi Shawn,
Sorry. Here is the access for link

The battery is brand new. The make is build power rating 5500mah and c rating is 25C.
Charger im using is imax. Charge rate 1A.

I have measured the battery voltage with multimeter and calibrated.

Where did you get that imax charger from, and exactly what model is it? There’s plenty of cheap clones out there that probably will damage your battery.
If you have to replace that charger, is there online stores you can order from, or are you limited? Or is there somewhere reputable in a major city that can ship to you?

You should charge at 5 or 6 amps for an ordinary LiPo charge or maybe more for a fast charge.
Otherwise use balance charge at 4 amps, something like that.

A 25c battery of 5500mah capacity should do about 130 amps for short periods. Yours is lucky to be doing 15 amps.

Alter this parameter but dont change any of the others, they are correct.

There’s other things to fix up once you get the battery voltage sorted out.

I got this charger from online platform. Attached charger and battery spec.

Should I charge the battery at 4 or 5A. Or change the charger ? I will alter the parameter and check the performance.

See in the advertisement for the charger, it even says copy. Try charging at the higher rate and see if that helps.
It is typical and recommended to charge at the 1C rate for a LiPo battery.

What I see in the log is high voltage drop, along with a normal discharge curve.
This seems to indicate a normal battery capacity, but either unusually high internal resistance (that means bad quality battery), or an abnormally high resistance in the battery cabling or a connector.
Arun, can you make some measurements on that battery? For example, charge it fully (to 12.6V, using balance charge to make sure all cells are even). Then connect a digital multimeter, battery tester or whatever to the battery, and then connect a car headlight bulb. It should light brightly. Connect and disconnect the lamp several times, watching how much the voltage goes down and back up.
Your log indicates a total battery circuit resistance of roughly 0.1 ohm. A typical car headlight consumes roughly 4 ampere. So, if during this test you see roughly 0.4V drop when the lamp is connected, it means that the battery has that high internal resistance, and you should get a better battery. If instead the battery voltage remains much more stable, such as dropping by 0.2V or less, then the battery is good, and the resistance is somewhere else. In the connectors, perhaps, or in the power module.

0.1 ohm, at the 15A your copter draws, will cause over 20 watt power loss, and this will be heat! So it should be easy to feel. Just fly the copter a while, land, and immediately feel the connectors, wires, and the power module. The defective part should be hot right after flying.

If the problem is a bad battery, then the battery will get warm, but since it’s so much larger than the other parts, it might not be very noticeable, given that the software configuration forces a landing after just a short flight time.

Given that your copter is relatively lightweight, and has those 1400 KV motors, it should be able to keep flying and stable at a relatively low voltage. So you might want to modify the settings so that the software allows a lower battery voltage before forcing a landing. That should allow getting somewhat better flight time from a substandard battery. But do it carefully, go in steps, and make sure that your battery doesn’t get too hot, nor dischaerges to too low a voltage!

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Hi Manfred,
Thank you so much for the detailed explanation. Will check this out and revert for any support.

That’s all good advice, thanks for your input Manfred.
Sometimes it’s hard to know what to do or try next when you are not physically in front of the copter :frowning:

I would probably change
BATT_FS_VOLTSRC,0 to 1 rather than change the battery voltage failsafe values

0:Raw Voltage 1:Sag Compensated Voltage

Yes, I agree with that. The sag-compensated voltage in Arun’s log file looks pretty good, so sag compensation is working fine.

Team, this is the feedback for my issue. I have measured the internal resistance of the battery it is in the range of 13m ohm. I have changed the charger to original wolfpack. It seems changing the charger helped improving fly time. Thanks to Manfred and Shawn for the support.