Hi Everyone,



I`m designing a camera accessory that draws up to 1.5A at 5V, and protected 18650 batteries seem to be the best solution for running it all day. I`ve picked up some important safety tips from reading the forums, and will now not include a built-in charging circuit for safety, but I`d like to run my thoughts by to make sure I`m not making some obvious mistakes.



The inner width of my enclosure is 141mm, so there is just room for 4 protected 18650s:



- == == + (Battery door on this side)

+ == == -



Due to the width constraints at least two of the batteries have to be run in series. It works, but is this kosher with protected cells? If so, is there any advantage safety-wise in running in 2S2P configuration vs 4S? 4S would make the battery door design easier as it would just connect the two batteries together, in series I`d need a wire running back to the other side of the enclosure. The voltage regulator can handle up to 17V (TPS62111).