There have been a few threads discussing the possibility of powering a limelight independent of the pdp. Has any team successfully executed this or is it still just a possibility floating around and if so, how did it work out?
Additionally, I have seen only one robot that might be using a external battery: 148. Would anyone from 148 be able to confirm they used an external battery?
Consensus seems to be using a COTS boost converter in some form and a USB battery pack that can support the required output current to said converter.
The text from the 2021 rules gives me an idea though…
COTS USB battery packs with a capacity of 100Wh or less (20000mAh at 5V) and 2.5 Amp max output per port, or batteries integral to and part of a COTS computing device or self-contained camera (e.g. laptop batteries, GoPro style camera, etc.) may be used to power COTS computing devices and any peripheral COTS input or output devices connected to the COTS computing device provided they are:
A. securely fastened to the ROBOT,
B. connected only using unmodified COTS cables, and
C. charged according to manufacturer recommendations.
Milwaukee just so happens to sell (or, sold, as this specific item is discontinued iirc) what is effectively a COTS USB battery bank, which is powered by their M12 battery system. It also just so happens to have a 12v output: M12™ Cordless Power Port
Of course, in cruel irony, that 12v cigarette lighter port is rated for 3A, nipping my remarkably tame rule circumventing in the bud.
Edit: sorry for rambling on, but there may be another solution!
I forgot that their jackets also use straight 12v (barrel jack), and a similar adapter that still includes USB: M12™ Charger and Portable Power Source
All rated ports (the one USB) are under the limit. This seems like enough to a gray area for someone to give it a try, and considerably safer than most of the sketch COTS USB 12v boost converters.
Edit Edit: even the random Chinese accessory providers are out to get me :
Best case, grey area that should probably be legal. Such is FRC
I wonder if someone would be willing to make a COTS boost converter (with some arbitrary microcontroller attached to make it a computing device) that accepts multiple of REV’s USB to JST cables… That might be a bit harder to un-loophole in the 2022 rules.
I have serious doubts if USB packs that conveniently also have 12V 2.5A outputs would hold up to any kind of scrutiny from the refs or the community. I hope someone asks a question in Q&A.
I agree that some kind of allocation needs to be made for computing devices - if someone sold a COTS limelight with integrated battery, it would make any other solution on the market obsolete. Likewise, full-on laptop computers with 19V integrated batteries are also legal. But allowing teams to stack on device after device, each powered by a different COTS “USB” battery pack, is not the solution; neither is using COTS Y cables, buck-boost cables and multiple barrel jack adapters to try to squeeze enough juice into a tensor board for a small competitive advantage. I’d love to see FIRST embrace USB-PD for computing devices and their peripherals.
I mean, them’s the rules.
This particular rule was clearly written with a certain type of battery pack in mind; if a provision specified that only the USB ports could be used then that’s a different story, but nobody thought to add that in the various revisions we’ve been given.