No need to guess. I have one too. Over time the faux signal discolours the instrument plastic on the inside. If I could be bothered to look for the original plug - I would be tempted to remove it. It's (imo) in the same league as a GiPro - which I also have and seldom refer to.
A better voltage led thingie can be had from Scotland
Eclipse and Monsoon Battery Voltage Monitors - Waterproof Precise Durable | SparkBright.
LED HEADLIGHTS are without doubt great - but I wonder at them being called ACCESSORIES. Being able to actually see at night, qualifies somewhat differently for me. Same criteria goes for FILTERS, EXHAUSTS and TUNING PARTS. They are more replacements than additions - and an accessory is by definition more an addition.
Oh! and Adaptive LED lights knock the living daylights (pun most certainly intended) out of the rest of the MeeToo LEDs at night.
Barkbuster Blizzard hand protectors have proven their worth even in summer. Fuelbot2.0 is up there.
But the best accessories I have are ones I have made to fill a need. I use my GPS speed warning on every ride. It's a SHIFT-I (shift light) driven by an HMBE GPS speed sensor. The HMBE also drives a small Koso rev counter for more accurate control. Better gauges than the Triumph ones - especially at night. Cheap Sekonda watch wrapped around LH switchgear. Waterproof and luminous dial.
For long rides - 3D mesh seat covers are stunning. Cool bum in summer and dry bum in rain. Scotsmen are however advised to wear something under their kilts. Mr
@Ishrub has skill at finding them on ebay etc.
There is also a softer 3D mesh that is aimed at Air/gel cushion replacement. I use this now for work as I am sat in front of a PC for hours at a time. It does imo beat the daylights of any air or gel cushion. If I were to reupholster a seat today - I would look for a way to use it. The place I bought mine from sells 1000's to haulage companies for truck drivers. They do M/C cushions but I have a combo now that works for me (Gel and 3D mesh)
Treat Lite2 Motorcycle Comfort Seating – Dan Medica South Ltd