450 Battery issue

[billryalls]

After successfully flying my clones i got the nuts to take out my (for me) expensive Trex 450 Pro. It was flying (loong hovers) great exzcept that it likes to turn coounter clockwise if i take hand off stick. ANYway i was hovering it low bringing it back to me when it just DROPPED out of the air. THANKFULLY it was only a 3 foot drop and nothing got hurt but what if i was 40 feet up?? Is this normal for batts to just run out without warning? Im using turnigy nano-tech 2200 mah 45-90c batts this battery was 14.6 volts when plugged in and 9.9 when i checked after flight.

 

[Slobberdog]

It looks like you hit the low voltage cut off, never got there myself but I thing it's supposed to pulse a little as a warning, if you was close to the ground not using to much head speed then it could just drop like it did.

Set your timer for 4.5 mins and see what that gives you when you land, I know its easy to get caught up in the moment but you should not let your batteries get that low it's not good for them at all.

 

[Derek]

Here's the thing...these lipo batteries really don't like to be drained beyond 80% of their original capacity. If you take the 9.9v that you had, when the heli dropped, it's because you were at 3.3v per cell. Now, you are probably going to get mixed opinions on this, but a lot of us won't drain our batteries beyond 3.7v per cell.

Charge your battery back up and go fly for 3-4 minutes. Connect a cell checker to the balance port and see what it says for each cell. There are many inexpensive cell checkers available and they are pretty easy to get a hold of. Some of them are small enough that you can leave them connected to the balance port and once the cell checker sees that the battery is getting low, it will beep at you.

Here is the LVM that I use. It can check up to 6S lipo's
http://www.trendtimes.com/hobbico-pro-series-lithium-voltmeter-lvm-2-6s-lipo-hcap0275.html

Here is another one that you can leave connected to the balance port and it will beep at you when a low voltage is reached
http://www.ebay.com/itm/like/151120038860?lpid=82

 

[billryalls]

Thanks guys! I do have a checker and will do as suggested. Thanks again.

 

[Derek]

I keep my cell checker with me each time I'm out flying. Especially for the first few flights. Just as Kev said above....set your timer for 4.5 minutes and go fly. When your timer goes off, land the helicopter. Use the cell checker.

The way that I do it, if I am still well above 3.7v per cell, I know that I can add a bit more time on the next flight. If the battery is below 3.7v per cell, I'll shorten my timer on the next flight.

Good luck buddy!!!

 

[Andydrew1964]

I'm on the same trip this morning , I'm up to 7 mins of flight time and still got 3.82v per cell , I think I'm gonna leave it there , I don't think my thumbs can take more than 7 mins at a time lol

 

[Derek]

There's nothing wrong with that, Andy! If you stop flying and you still have 3.82v left....no worries at all. That's about the usual stopping point for me, as well.

 

[Stambo]

To add to this, most semi decent chargers will tell you how much mah they put back in when you charge the batteries.
So if we work on the 80% figure 2200x80%=1760.
If you put back in more than 1760 mah you need to fly shorter times.
I personally start at 70%.
Bear in mind this is with a new battery and assuming the manufacturers stated capacity is correct so monitoring voltage is also critical.
I have a few of these from Hobbyking, they have adjustable warning voltage and are really LOUD!!
Also remember that when you land and check voltage it is in a no load condition.
The voltage under load will be .2v or more lower, depending on how you fly.