Just a minor mod that I did due to the wonderful alternator or /and start motor issues that seem to crop up every so often. Or and the battery that just failed one day going from a bit iffy one morning to dead that night. A "Le Mans" battery it came with the car, (I've not come across them before). My guess is a generic cheap battery badged up for a corner motor factors somewhere, I apologise if they are a reputable brand.
I decided I needed to know what the voltage was so when I just happened to see this tiny little LED unit on an eBay store. As I was already ordering something else, it ended up being a bargain for a couple of quid. As there was a live supply near the cabin light, it was straight forward to connect there. It might not be amazingly accurate but it is a help. The draw on the battery is miniscule so I was not worried about leaving it permanently on. Usually the battery sits at 12.6v, it just happens that I took the photo after a short trip and the battery was 'settling down'.
I am sure other people would have other locations to put a gauge. Some would even have the skill to make it live when the ignition becomes live
Am I mad?