Flight time?

[saqueeb]

I have a copter x 450 pro with a 13T pinion on a CopterX 430XL 3500Kv Brushless Motor with a 50A ESC. I am running 2 different batteries at the moment.

Zippy 25c 2200mAh and I get about 4 min out of these if I use them in the 80/20 method.

Sky Lipo 40c 2200mAh and I can get 6-7 min out of these using the 80/20 method.

Does this seem about correct? The Sky Lipo batteries seem to have much more power than the . Is that just the difference between 25c and 40c?

I should add I am just learning and all I am doing so far is just hovering, not ever hitting full power on the stick, flying 1-3 ft high. So I don't feel like I am really stressing the batteries.

[Wolfpackin]

Originally Posted by saqueeb

Is that just the difference between 25c and 40c?

No, the C rating is the amount of amperage the battery can supply. Capacity determines the flight time, along with other factors, and that's measured in mAh's.
But the higher C batteries would feel more powerful if the amperage it can deliver is used. And in that case the flight time could be reduced.

Hovering will typically use more amperage than gentle forward flight because of transitional lift.

That said, I fly for a little over 6 minutes on my CopterX using the equipment listed in my signature doing FF, piro's, flips, roll, loops etc. Note that I use a 12t pinion.
That keeps my within 80% capacity used.

EDIT to ADD: And that's using 25C Zippy 2200mAh's also.

[saqueeb]

What would I notice by switching to a 12T pinion? I have one and a 14T. Is here any big advantade for a beginner to switch from the 13T? longer flight times?

Thanks.

[Wolfpackin]

Yes, moving down in pinion size will yield lower headspeed and typically slightly longer flight times. And the opposite is true for moving up in pinion size.

This assumes no change in throttle curves.

[saqueeb]

What do u use to determine low voltage?
I am using this little Lipo digital low voltage/alarm that plugs into the balance plug. I notice that when set to 3.7v/cell it goes off on the Zippys when they are actually only at like 3.85v/cell. Just recharged the Zippys and they only took 1300mAH to refill. Where as when also set to 3.7v/cell on the Sky Lipo's it does not go off before reaching about 3.75v/cell and I just charged those also and they took 1700mAh to refill which is almost 80% of the 2200mAh.

I'm thinking I should just fly each for a set time say 5 min and then re charge one of each and then see what I get out of each. Maybe that little meter is just a piece of junk?

[Wolfpackin]

The low voltage alarm reads the voltage under load. When you hook up to the charger it reads resting voltage.

The higher C batteries hold thier voltage under load better than the lower C Zippy's.
So, when the heli draws amperage from the Zippy the voltage is dropping to the LVC (alarm) sooner or at a higher resting voltage.

Voltage is not the best determining factor of capacity, partly because of this voltage drop.
The best way is to use the capacity put back during charging and set the timer accordingly.

I never use a LV alarm and I never let my ESC hit LVC.
I time my flights and know when to land to keep within 80% capacity used.

[saqueeb]

Ok thank you and I assume the only way to do that is by flying for say 6 min and then stop and recharge and see what went back in and do the math... And repeat until I hit as close to 80% with out going over.

Thanks for all the help!

Also do you know if it is possible to charge multiple 2200mah batteries at the same time? I Have a b6ac charger. Or am I aski g for a fire, or worse?

[Wolfpackin]

Originally Posted by saqueeb

Ok thank you and I assume the only way to do that is by flying for say 6 min and then stop and recharge and see what went back in and do the math... And repeat until I hit as close to 80% with out going over.

Exactly.

Originally Posted by saqueeb

Also do you know if it is possible to charge multiple 2200mah batteries at the same time? I Have a b6ac charger. Or am I aski g for a fire, or worse?

I don't know your charger but there are ways to parallel charge multiple packs if you have a charger and power supply capable of putting out sufficient wattage and the correct balancing boards or hookups.

Originally Posted by saqueeb

Thanks for all the help!

No worries.

[RUN4COVER]

Hi there!

On a new battery I will fly it one time to see what time it takes to trigger the esc low alarm.

Then I place the battery on my charger set to "discharge @ a 1amp setting" and immediately read the voltage per cell "under load" as it is discharging. Then I reset the charger to charge my battery.

This does two things, first it lets me find the absolute longest flight time for a particular battery and second, it confims that the dicharge level of the battery was acceptable for the flight time observed according to the ESC low voltage cutoff.

Next I then subtract one minute off the tested flight for safety and use that number for my normal flights from then on.

For example:

I recently recieved the wrong battery in the mail, I ordered a 2200mah for my trex 450 and they shipped a 2650 mah battery.

So I adjusted the center of gravity and gave this larger (and heavier) battery a try just for fun.

I could hardly believe it!! 11 minutes of easy cruisin!!

So as stated above, when all was said and done I am now flying this particular battery for nine minutes just to be safe.


Here is a link to a thread with some good battery talk.

https://www.helifreak.com/showthread...47#post3553947


Cheers R4C

[saqueeb]

thank you both for all your help!