I have a P3 battery 37 times charged. DJI go app says its Total Capacity 4152mAh. This means battery life is around 92%. The capacity was 4280mAh when it was charged 28 times.
The capacity decreased by 4280 - 4152 = 128mAh  during 9 charges. This means 14,2mAh drop for each charge (14,2mAh/charge). LiPo batteries are said it may be used until 80% of capacity has been reached. So, 20% drop of capacity is allowed and it equals to 896mAh.
Supposing some linearity in capacity drop vs charging cycle, the life expectancy of this battery may be around  896mAh / 14,2mAh/charge = 63 charges
For this battery, there may be 26 charges left before it shall retire.

This life expectancy is rather too few because a Lipo battery should be able to handle 300 - 400 change - discharge cycles.

I am curious what experience of capacity vs charge times you have. For the sake of safe fly, life expectancy should be known before exceeding it. Could you share your capacity and charge numbers for dji phantom 3 battery?
By knowing more numbers, we get to know more accurate life expectancy .

  

Have you tried the recommendation to drain (through flight) LiPo batteries down to about 8% and then fully charge every 20 recharges or so as a way to maintain highest battery capacity?

A full cycle of the battery will just recalibrate the the batteries internal level reference, it will be more accurate with regards to battery percentage but won't change capacity.
You are right about Lipo life expectancy but the one difference is that there is some really heavy drain on the batteries, no doubt this will wear them out much faster than cells used in something like a laptop. With intelligent batteries the values you get are somewhat determined buy how the electronics are configured for cell wear and how they limit charging. You may find they are artificially wearing out the cell value faster than the actual wear to facilitate more battery sales.
It would be interesting to see what brand cells are actually in the packs and what the wear is like.  

I have fully depleted until the battery could not switch on and there is no change in capacity. When DJI battery is charged entirely, the cell voltage is around 4.3V instead of 4.2. This may deteriorate the life.
I suppose battery rate may be between 5 - 10C and continuous 11 - 16A current overloads it.

If you are looking for expected battery life. I found a post by a customer on Amazon that stated DJI warrants the battery for 6 months and charge cycle less than 200 times. So it seems to me that DJI expects at least 200 recharges out of their batteries.

tonyPek Posted at 2016-11-28 14:51
I have fully depleted until the battery could not switch on and there is no change in capacity. When ...

I posted about this a month ago. One of the forum moderators replied that the DJI battery is designed for a higher cell voltage and the extra .1 volt is of no consequence to battery life (not exactly her metaphor)

DJI is reported to load test their batteries before shipping and that may be fine but be aware that all lipos over time will wear differently depending on the actual working load and temperature variances.

Recharge only prior to flight.

Also... Switching on the battery before connecting the charger usually results in a higher total charge percentage being reported in the pilot app.
Skint is correct on the result of deep cycling vs capacity.  

these batteries are meant to last up to 200 cycles. AFAIK the phantom 3 intelligent batteries will automatically prevent you from starting the phantom using the battery if its reached 200 cycles for the safety of the aircraft.
if you're only getting 70 charges before the battery is too damaged for you to run your aircraft there may be something wrong. but i wouldn't complain if i got only 70 charges, because these batteries can easily last around 20 minutes in the air, and 70 cycles of 20 minute flights is almost 24 hours of flight time. of course that number may shrink as you batteries capacity shrinks, but that much flight time is still plenty. i have about 13 hours of flight time and i fly my phantom all the time. ive had it for nearly 6 months or so and have only ever had one battery. the extra $100 isnt much to replace such an amazing piece of technology such as these batteries that allow you to use a far more amazing technology, the phantom.

For reference my battery showed 4298 at 98% this morning after 17 charges which puts it in the 98% of new capacity.

Im at 170 charges on one batt 25 or so on the the one i got in aug last year i cycle my batteries six monthly a full discharge and back up again .My original batt still gives around 24 mins of flight shows 3 bars on test and that one is the full 3 years old. as is my drone Never had any issues other than the ones caused when i changed my fone to a note 9 from an 8 so i kept the 8 solely to fly the drone with it`ll never ring or get a text as no sim card. A bit wasteful for an 8 but my note 4 wich was awesome with the drone  got mmc read error and committed suicide on the arm of my chair whilst i watched.      

fans3c05a217 Posted at 2017-6-4 07:14
For reference my battery showed 4298 at 98% this morning after 17 charges which puts it in the 98% of new capacity.

This is an old post, but still I don't agree with the content.  A battery at 4298 mah at 98% is equal to a battery at 4384 mah at 100%.  Just do the math.  

And 4384 mah is pretty close to 4400 mah which is OEM stock specs.  All one needs to do is turn the battery on during charging to force it to 100% charge which would then turn out to be very close to 4384 mah.

Does anyone know a good after market battery to buy?  The OEM is too expensive.