Just decided to get my P3 out again after about 5 years in storage, batteries wont charge or even show any lights, had one plugged in for about 2 ours  now, I have tested the charger it shows about 17.4v, are they dead?

Just found this thread https://forum.dji.com/forum.php? ... D642%26typeid%3D642
Guess I have my answer

Hello there Henrys Cat. I am sorry for the trouble this has caused and thank you for reaching out. Just a friendly reminder that the lifespan and condition of the DJI Intelligent Flight Battery will depend on the totality of how it was used and stored. Hoping for your kind understanding that every electronic product and batteries has a certain lifespan. It seem that the DJI Intelligent Flight Batteries are already depleted. DJI would suggest for your to have a new battery to start flying again. Again, I am sorry and thank you.

OK thanks. so where to buy? I have looked here https://www.dji.com/uk/where-to-buy/online-stores
Both DJI store and Amazon store do not have P3 batteries.

Ebay.  New or used.  Be wary of aftermarket.  Ask appropriate questions before buying.  Good luck

No new batteries on eBay in UK and not sure I fancy second hand, even if they claim only 10 cycles etc it could still be 5 years old, asking the so called right questions wont help either, people lie ;)
There must be a popular aftermarket brand people use ?

I doubt there are many used P3 batteries that are less than five years old.  Most of my six P3 batteries are five years old.  They all fly fine.  

You would ask how many cycles and about cell balance.  The questions and answers would be documented before the sale.  If the seller lies, you can return the batteries at the seller's expense.  

Re aftermarket, you'd have to read reviews on a particular brand, then weigh the risk.  

Good luck.