Where cam i get a new lipo battery for my dji 3 pro controller

I don't know.   I heard they are hard to find.  And apparently the 300A battery is harder to find than the other two.  That's what I hear.  

Hello!
You can't buy a battery to the remote controller . Only dji service have them and can change them

If you are out of warranty, you could try to replace it yourself. I replaced mine a year ago and the RC controller is still working fine for my P3P. The battery I used is a Gens Ace 3500 mAh 2S1P Rx-Tx battery (bought from Amazon). If you do this, you must be aware that the new battery will not have an internal balancing circuit. This means that you should arrange to access the balancing plug on the Gens Ace from outside the RC controller. A cheap Li-Po tester will then do the job. Check out the photos below...

There are various Youtube vids of users replacing with normal LiPo's ..... and as "johnsr" shows - you have then the matter of charging / balancing. But that is easily solved by using the balance lead of the battery as he shows exiting the case. eBay has many of the 2S / 3S balance chargers and all you have to do is plug the lead into it and it will do both charge and balance in one go. No need to use any other item.





Both are only about $5 each and do a good job with auto-cutoff when full charged.

Nigel