I have four MP batteries that have been used less than twenty charges and work fine except for the fact that they are swelling. The battery swells and disconnects from the craft. The drone fell to the ground like a rock, luckily from only a foot, the first time. A different battery swelled as well and the drone disconnected during flight. My only option to bring it home was the rth button. These batteries are only a year old and function fine apart from the swelling. Am I forced to buy new batteries? What is the normal life expectancy? Thank you

normal life expectancy depends on how the batteries have been stored and taken care of. when stored and used correctly and without having suffered knocks or bumps the batteries should last a number of years. By example 2 of my 4 batteries are my original batteries from march 2016. 2 years later and my flight duration per battery is typically around 15- 18 min landing with about 25-30%. There are a number of risks in using swelled batteries 1- they could explode at any time 2. the warped battery may cause it to push out of its clips and fall out the drone. If your batteries are within 1 year age they are in warentee and dji will replace them. If older than 1 year then unfortunately you will have to buy new batteries. Read up on how to properly store unused batteries - this will (probably) save your new batteries from going the same way.

Bekaru MP UAV Posted at 2018-10-14 13:24
normal life expectancy depends on how the batteries have been stored and taken care of. when stored and used correctly and without having suffered knocks or bumps the batteries should last a number of years. By example 2 of my 4 batteries are my original batteries from march 2016. 2 years later and my flight duration per battery is typically around 15- 18 min landing with about 25-30%. There are a number of risks in using swelled batteries 1- they could explode at any time 2. the warped battery may cause it to push out of its clips and fall out the drone. If your batteries are within 1 year age they are in warentee and dji will replace them. If older than 1 year then unfortunately you will have to buy new batteries. Read up on how to properly store unused batteries - this will (probably) save your new batteries from going the same way.

Thank you for sharing your experience. Initially, I thought it was just one battery that actually had wrinkles around the edges from swelling, but a second battery almost had a loaded ejection when I removed it from the clips. The batteries are right at a year old. I've stored them in the fireproof bags with a rubber protector for the contacts. They live in my backpack, unmolested, when not being flown. With four batteries, they have plenty of time to cool before charging. I usually fly through all four and then recharge at home. I discharge them completely every ten charges. I really don't know what I could do differently to avoid the swelling. They work fine, apart from the swelling, but I'm now worried the drone may crash if I continue to use them. $250 replacement cost is nothing to sneeze at. I'm really disappoint with this experience. Any ideas, specifically, what might cause swelling?

Thanks again for caring enough to share.

Swelling is generally caused by excessive heat, vast changes in temperature and/or moisture getting into the battery. If the batteries are set to auto discharge (where they warm up) and you have them wrapped tight in a fireproof bags inside a backpack that can cause swelling as the generated heat has nowhere to escape... That is why batteries should be stored at a constant temperature of around 20-25c when not in use and kept away from direct sunlight, damp, water etc.
Do not fly with swollen batteries - you could lose your drone or even worse, they can catch fire! Dispose of them at a professional battery dump (not in your bin) and note that batteries are only under warranty for six months or 200 charge cycles whichever occurs first. All lipo batteries will degrade over time - whether that is weeks, months or years is down to how you maintain them (and a bit of luck). Also, I wouldn't suggest discharging batteries completely to 0% - I'd say no less than 5% and every 20 cycles would be better than 10. Use a slow deep discharge as again, flying the battery down to 5% quickly will make them very hot and excessive heat is usually the main cause of swelling as is storing them fully charged for prolonged periods.

If those batteries are swollen, get rid of them if DJI doesn't replace them on warranty... you'll then have to buy new ones. Better to play it safe then fly on shot batteries. Have flown tons on miles on many different batteries and I've never experienced swollen batteries ...only some have gotten hot...I cool them off then reuse but they never swollen. Have you kept them in a hot car or hot room temps? Have they taken a fall?

Well, I will tell you from my experience with Yuneec q 500 battery. Once I forgot to unplug the charger and it stayed on for the night.
When I woke up the battery was swollen from overcharging.
So the life expectancy dropped from 18/20 minutes to just 13 minutes flying.
And now the battery is dead completely, it won’t even charge, charging error it gives and it’s useless now, just a brick
I bought a new one,  but those b@stards aren’t cheap, 65 euros.

Fly safely
Alex

Be careful and if I was you I would keep them outside in a ceramic container with a lid or something.  This is what one of my 4S lipo's did shortly after swelling that I had for about a month in my RC car. The smoke eventually got so bad that you couldn't see my back yard at all from looking out of the back window. Smelled horrid too.