F450 Batteries!!!

[parkyi]

Hi,

I am flying a Standard DJI F450 with GPS Quadcopter. I am becoming reasonably decent at flying it now and can fairly zip it up and down and around the field where I normally fly. I am using 8" props and 'Zippy compact 4S 4000mah 25C' batteries. I have 4 of these, 2 I have had a while and 2 that I have recently purchased. I have my little lipo alarm set at 3.6v, I'm getting 10-12 minutes out of them, depending how I fly and how windy it is etc...

The first 2 batteries have just these week deteriorated, I am now only getting around 5 mins from them. They are slightly ballooned, so my guess is they are knackered and from what I have read there is no way of rejuvenating them once they are done.

My question is, what has caused this? I am thinking I may have damaged them from flying too aggressively??? last week I was flying the quad down the field towards me and over my head, as it passed over my head I turned and saw my Quad heading straight towards some trees, I quickly took evasive action and turned and banked the quad around missing the trees and saving the quad from a messy crash. As soon as I had done this evasive manoeuvre the lipo alarm started bleeping. Have I drawn too much current from the battery during my evasive flying and damaged it??? and if this is so, would getting higher current rated lipos avoid this problem and can anyone recommend any? I'd still like to get around 10mins flying from them if poss.

Cheers in advance

Parky

 

[ProPilotWannaBe]

I do not think your problem is current draw. With the capacity and rating you mentioned , you should theoretically be able to draw 100 amps of current peak. I don't see you drawing that kind of current even under aggressive maneuvers on the F450. I fly a stock F450 and use 2650mah with 25-50C rating, which means mine cant handle the sustained current draw yours does, and mine are slightly warm after 8 minutes of flight.


I would suspect more how much you discharged them. I've always been told to not let my batteries go below 3.7V per cell, and no more discharge that 80% of the battery capacity. I suspect you are exceeding those on a regular basis, especially if you aren't landing right away when the alarm goes off. When you charge them ,how much current does your charger say it put back into the battery? You should not be exceeding 3200mah (80% of 4000). And are you charging them at no more that 4amps?


Btw, I'm sure you know, but the alarm going off when you pulled the hard maneuver was the battery going below 3.6V under a heavier load at that time, which probably means you were probably already sitting close or below 3.7V before the maneuver.

 

[OneStopRC]

Could also be the way you charge, it is always better to slow charge these batteries. Some will rapid charge them, just to get back out flying again, constant rapid charging will shorten the life of them. on my 2650 lipos', I will not push more then 2.2 amps into them, takes longer to charge... but they don't ever get warm when charging them. Make sure you balance charge them every so often too.

 

[parkyi]

Hi,

Cheers for your replies. I always balance charge my batteries, I have just charged them once or twice but it wasn't really any quicker so I just balance charge them all the time now.

I've just started balance charging one of the suspect batteries, the charger says it's putting 3.2A into it. I've never charged them above 4amps.

I'll give them another try today.