Originally Posted by: rich.peachThe ony downside is that it requires a power supply as it's not big enough for a battery like the Boss units.
[u]Internal[/u] batteries are a double edged sword IME&V. I [u]generally[/u] don't use them any more, even on my full size pedals with that storage capability my tuner pedal the occasional exception.
Running any pedal off a 9V alkaline battery, mini or full size with internal fitment or not, I'd choose to run external. Why? Depending upon the pedal and what they are pulling, and loopers like the RC-3 and Loop Core pull more current than something like an analogue Overdrive, using pedals like those loopers regularly and for any duration the 9V batteries don't last long. A lot more expensive than AA cells, it won't take long putting hand in pocket on 9V alkalines before realising it would have been wiser to spend the $$ on the price of a PSU.
But the main reason is, even less duration if forgetting to unplug the TS cable (actual power on/off switching) to leave them overnight with an internal battery being slowly drained. If using 9V batteries for convenience, I use external batteries now for their obvious visual cue, and ease of changing the battery without disconnecting the pedal from the chain, unsticking its velcro from the pedalboard, fiddling about with the battery hatch latch, being so careful handling the internal wiring of the connection to the 9V battery clips etc. sigh o.O External also facilitates swapping about between pedals using the adapters hotlinked below running one or two completely flat in any session rather than three or four if only using one or two pedals in the session. These adapters are the bomb for use with 9V batteries.
That said, for running multiple pedals regularly nothing beats a pedal PSU. Reliable ones are very affordably priced today, easily power up to 8~10 pedals, which unlike daisy chain powered from a wall warts are noise free, never go flat and have circuit isolation and fault indicators to determine which pedal is an issue should one occur. I've got those too. One floater (spare and ancillary use) and one attached to my pedalboard. JFI.