I also have a Streaming Stick+ (model 3810) on my most-used living room tv, and my batteries last 3-4 months with heavy use. I realize this doesn't help you, and that many people seem to have short battery draining times, but it does show it is not a universal problem.
The only external thing I've seen mentioned that has been suggested as a possible cause is:
There is some anecdotal evidence that one cause of battery drain for those with point-anywhere remotes that connect to the Roku via WiFi-direct can be use of a router channel that is crowded by nearby routers using the same channel. The remote has to work too hard constantly sorting through the information packets from other devices using the same channel and it may accelerate the battery drain.
If you have access to your router's setup, try configuring it to use a different WiFi channel to see if this helps the situation. In the 2.4 GHz band, only channels 1-11 are supported. Channels 1, 6, and 11 do not overlap each other and so give you the best chance at reducing congestion, so try each in succession, although depending on what channels your neighbors are using other channels in the 1-11 range may work best. Also, reducing router bandwidth from 40 to 20 kHz may also reduce interference.
Roku Community Streaming Expert I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well. If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X
I have a similar issue, and I suspected it was the network, but either it isn't, or I haven't figured out the right network configuration.
I have three Roku devices: a Player 2, Ultra, and Express 4K+. The battery drain is specific to the Express 4K+. I use a home mesh wifi network, which has strong coverage in the room with the 4K+. I have tried optimizing my channel choices, but I am still going through a pair of batteries each week, sometimes within a day. It can be going along for a week with no problem and drop from 90+% to 0% in a couple hours. Based on other threads dating back several months, I wonder if a replacement is the best option.
My remote is also draining batteries. I used a VOM to test it and it showed that there is always a current flow even when no buttons are pushed. I have the 3800RW streaming stick. I spoke with my son over the weekend and he has suddenly begun having the same problem. I think ROKU recommended purchase of a new remote. That is ridiculous ROKU should give free replacements it's ROKU's fault remotes should not draw battery current when not in use. At present I put a piece of tape on one battery to form a tab so I can more easily remove that battery. So here I am with the battery cover off and one battery ajar. If ROKU doesn't step in I am going to start posting the problem and lack of support on all social media forums.. I will switch to a Firestick before I will purchase a remote.