Those who use headphones with Roku remote know how fast it eats up batteries. I hate buying alkaline batteries since they all end up in landfills. For a while I used Ni-MH rechargeable cells, but those have lower voltage and high self discharge rate, so you end up constantly charging and swapping them. Since I'm an electrical engineer and work with lithium batteries for a living, I decided to try and convert my Roku remotes to lithium rechargeable cells. I was surprised that lithium cells were available in AA size, so no need to hack the remote and make it look like Frankenstein monster. I also realized that LiFePO4 chemistry was a better fit than LiNiMnCo, since voltage profile of LiFePO4 is 2.5V to 3.65V , which is close to 2 Alkaline cells connected in series. Maybe LiNiMnCo cells would work also, but there is greater risk of damaging the cells on the low end due to over-discharge and damaging remote's voltage regulator on the high end due to 4.2V full charge voltage. Also, LiFePO4 cells are much safer and have much longer cycle life. So, I picked up 500mAh 3.2V cells 14500 size ( same as AA cells ) on Ebay along with compatible charger. Then I opened up my Roku remote, confirmed that cells are connected in series, which means voltage regulator is expecting nominal 3V. Voltage regulators always have design headroom, so feeding 3.65V maximum voltage from LiFePO4 cells should not be much of a problem. I converted series connection between 2 cells into parallel connection by cutting copper traces and soldering jumper wires, popped freshly charged lithium cells and ......... everything just worked perfectly. I use headphones with my Roku all the time and now my batteries last for 1-2 weeks between charges. I have 2 sets of cells, so one set is always charged and waiting to be swapped. I did this for all 3 Roku remotes in my home a few months ago and never had to buy alkaline batteries again.
I wonder if people would be interested in a service to convert their remotes to lithium cells? Remote would have to be mailed in for rework, with 2-3 days turnaround. I could also supply cells and chargers as kit, so people don't have to search the Ebay and mistakenly buy wrong cells, etc. I guess I could buy remotes and convert them, but it would cost more to buy an extra remote instead of sending in the existing one for rework. Any feedback? Conversion would cost $25-$30, plus USPS shipping, plus cost of lithium cells and a charger. It would pay for itself in a few months of not buying alkaline cells.