Battery Rapid Discharge Problem

[JeffSmithPhoto.Net]

I have been a drone pilot from the first Phantom, through Phantom + and for the past couple of years with the Q500 4K. I do real estate stills and video and have done a tone of both.
Because of vacation I had not used the bird for about a month and had not charged the batteries in that time. All five batteries had been working fine and I got at least 20 minute flight time on all. I got the call for a couple of drone shots that day and so didn't have time to charge them. So I shot the first shot on the first battery without incident, but needed to use a second battery to finish up. It started out fully charged, but the low battery warning came on within a couple of minutes. I landed and went to my next assignment. When I put in the third battery and started up all the lights blinked like crazy and the ST10+ showed a totally discharged batter. I switched to a new one which showed fully charged so I took her up to about 300 feet doing a few stills on the way up. After maybe 5 minutes the warnings started up. I brought it down as fast as I could, but before I could land it fell out of the sky from about 20 feet breaking the landing gear and air frame.
I repaired it over the next couple of days, calibrated the compass successfully and hovered it at a couple of feet over the lawn. Same rapid discharge of all the fully recharged batteries.
Anybody got any ideas about repair?

 

[Mike Lentsch]

Sounds like your batteries are just at the end of their life. Lipo batteries, as all lithium batteries, are damaged by being at full charge for any length of time - even after 24 hours. Lithium, especially lipo, should be stored at between 3.8 and 3.9 volts.

 

[JeffSmithPhoto.Net]

Thanks, Mike!
I hope you are right. 2 of my 4 remaining batteries have had a lot of use. Can you recommend a good charger that will let me monitor the batteries and let me store them at the correct charge?

 

[Mike Lentsch]

You'd want what's called a "hobby charger". They charge all types of battery chemistry. Since these batteries are only 1C charge allowed, you'd need a charger cable of only about 60 watts. Something like the ThunderPower TP610c would work and charge your batteries in about an hour.

Here's the catch - these batteries have proprietary "connectors". This means that you'd have to make your own jig to allow your batteries to connect to "standard" connectors. I heard that someone has done this and is selling them for the "H" batteries, anyway, but I've not checked.

For now, I just check the voltage of these batteries on the st16 screen and just have to fly around or charge a little to get into the 3.8 - 3.9 volts range. Good Luck!