I took Phoebe and Chloe out this morning with fully charged batteries, and both behaved beautifully for the first couple of flights, and then quality deteriorated rapidly – this isn’t news to me, I was specifically testing this as part of confirming safe flight behaviour for the Cotswold Jam.
Both were running with the same Gens Ace Tattu 3S 45C 2300mAh LiPo’s and although they have slightly different motors (T-motor’s MN3110 for Phoebe and MN3508 for Chloe), both motors are rated at 700kV – a nearly meaningless value which is the RPM per volt; previously Phoebe had been running with 900kV motors i.e. they spin faster with a given battery pack*.
So I think I need to upgrade both Phoebe’s and Chloe’s batteries to 4S (4 LiPo cells in series putting out a nominal 14.4V rather than the 11.1V of the 3S batteries in use). Though for the Jam, I’ll probably just take the 2 3S batteries I have both fully charged. Finances at the moment won’t stretch to £50 to replace them with higher voltage models.
P.S. I’ve just done some more testing, still with 3S LiPo batteries, but with a 5500mAh capacity on the basis that the higher the charge, the slower the reduction in output voltage, and hence more flights that are ‘safe’. Results back up my theory – I got a few more flights than with the 3200mAh batteries, with each flight showing the same symptoms of degraded performance compared to the previous.
*This sounds like complete twaddle to me; the spin speed is totally controlled by the switching of power between the 3 poles of the brushless motor and has nothing to do with the battery voltage. Surely this kV value is a rating of how much power is produced for a given voltage – said power either dissipated as heat or in rotating the props?