I had no idea these battery packs existed until I visited SP-Forums.com
Thanks guys!
This is my rig at the moment

(+M-AUDIO AV40 reference speakers)
Korg
MicroKorg XL+, Korg
MicroSampler, Electro Harmonix
45000 Looper, Boss
BR-800, Roland
SP-555 , Roland
SP-404sx. [
Jamman Looper & all others not pictured]
Waiting on an
MPC 1000 in the mail,

it will be installed where the headphones are.
SP-404sx & MicroKorg XL+ bought new, all others cheap used eBay or Craigslist trade
Here is my current mobile setup..

Both Korg keyboards and the 555 run off a single battery. One charge (approx 8-12 hours) will last for more than 6 hours with the above connected. That's the longest I had the setup running with sounds coming continuously from all three (before I turned everything off). Also, the battery is great with my
Roland FP-2 12v 2A keyboard, which has built-in speakers & line in for these guys. I use it for my

outdoor gigs with an EHX 45000, both powered from the single battery with stock cords. With a splitter, I can run my entire studio setup off one battery pack (including FP-2 [for speakers], USB Hub[fan, light X 2, & recording with/charging cell phone] lol).

The SP-555 runs
excellent off this battery pack alone.
I would guess using the microphone input in Phantom power mode would drain the battery quicker,
I have had no issues.
Here are the things I have connected to the SP-555 - -
Note: I am in NO WAY affiliated with these eBay sellers. 
These were simply the cheapest variants of the products I have purchased at the time of posting & tested/verified to work with the SP-555.....
You can find the battery
HERE, and the polarity switch adapter
HEREI also recommend
THESE TIPS for those who own devices from different manufacturers. Both Korgs need Adapter Type "G" (yellow tip) from this kit (or similar)
Let me know your experiences or other battery setups for the 555 !
Love goes out to everyone making use of these tools & doing their own thang!
Love also to all the 'nay sayers' for keeping ideas fresh and conceptions re-analyzed.
Mods of SP-Fourms - please don't can me for advertising pertinent, useful eBay links!
- your friend Cubilas