Hi all, I got my a LaTrax Alias at Christmas (after getting a LaTrax Tetron a couple of years ago and being impressed) and am enjoying it. However, I have noticed less than impressive flight times. The website advertises up to 15 minutes flight times. I've got 2 LaTrax 650mAh batteries and for a good flight I'm getting times until the LVC sounds of 6 minutes and this can be as low as 3 minutes for one of my batteries (one always seems to be noticeable worse than the other). I am wondering if I have either been sold 'bad' batteries that have been in a shop for too long without being used (and therefore have high internal resistance) or whether there is a fault with the Alias.

To give a bit more information, if I stop flying the Alias when the LVC first sounds and then measure the unloaded voltage in the battery this is usually between 3.80V and 3.85V. From the images here and here (which are taken from here and here), this would imply the battery still has 40% to 50% charge remaining. If I then charge the batteries from this point they reach full charge (4.17V) in 25-30 minutes. However, if I rest the battery for a while without charging (whilst I use the the other battery) and then plug it in again and fly gently, I can usually get a good couple of extra minutes flight out of the battery. If I measure the unloaded voltage again at this point for the better battery I can get it down to 3.70V and for the worse battery it gets down to 3.75V. Once I get the batteries down to this voltage by flying a second time, the charge time is much closer to the expected 40 minutes.

Iíve tried to do some basic calculations of what the internal resistance might be. If I assume the internal resistance is dropping the voltage from 3.85V to 3.70V (0.15V drop) whilst flying and there is a current of 5 Amps (which would give a runtime of ~7 minutes using 90% of the battery is charge) then this gives an internal resistance of 0.15 / 5 = 28 mOhms. This is pretty high for a single cell battery based on the information here and would imply the batteries are Ďbadí and need replacing.

Has anyone else had any similar issues or experience. I am relatively new to LiPo batteries but do people think my logic above makes sense? Any thoughts would be welcome!