Battery question

[Socaljj]

I think I know the answer but just want to check. I have 2 Yuneec batteries both Manufactured in 2016 and have over 75 charge discharge cycles. I use a DY3 charger and all cells are 4.2 volts when fully charged. I independently checked each cell and they are 4.2 volts. To eliminate the charger I put them in the Yuneec charger and they are fully charged.

I go to fly and when they drone connects to the st16 it reports 16.4 volts. I turn on the props and the reported charge goes to 15.4. I raise the drone to 5 feet and the reported charge goes to 14.8.

Time for new batteries?

thanks
socaljj

 

[Eagle's Eye Video]

In a short answer... probably.

The parameter you are missing is key. The DY3 does not measure Internal Resistance... a high IR would cause such rapid voltage drops. If you get new batteries, consider investing in a 3rd party charger that provides the reading of IR. You will also need some adapter cables that will plug into the replacement batteries.

Note: With batteries in good condition, you will still have those intital voltage drops... but it will be more like 16.4 to 16.1 with prop startup and maybe 15.6 on takeoff...

I am going to assume from your username that you are in the Southern California area, and that neither your ASL nor temperature when flying, are going to play into this scenario.

 

[Mrgs1]

Mine always show 16.6 volts before take off. the rapid voltage drop could be a problem, there getting old and past there best, i have some weird behavior with my ULTRAX Batteries they drop from 16.6 volts to 15.6 volts after takeoff but then they slowly discharge,so i still get a good flight time, they have low IR. just the take off drop. Some Power 4 batteries, don't drop as rapidly during the take off, but only last just as long. In ideal conditions, say a nice warm evening the range can be 10 to 15 minutes , maybe a bit more, winter and windy conditions, drop it significantly, flying style can help with flight times, not extreme flying rapid ascent etc, how they've been looked after you is a big deal, they need TLC, I'm afraid there is no way of turning back the clock, once there aged then it's pretty much over, there's no miracle cure.

 

[PatR]

IR is the key to determining cell state. It’s normal to see a voltage drop as soon as the motors start, with even mote of a drop as motor speed is increased. That’s all part of Ohms Law where as amperage increases voltage decreases. How long it holds at 15.8v or so before dropping further is more important. 15.4 is a bit too much of a drop though.

You need to establish cell IR values for a better battery assessment but I suspect the batteries are wearing out.

 

[Mrgs1]

I'm afraid nothing lasts forever.