Following from the change from sunglasses display to a 2.5" S-Video LCD...

Power: The LCD requires 7-12vdc. The Pi delivers 5v from pins and that's confirmed by testing to not be enough. With the dev SKROSS Reload 5 I have 5vdc 1.5amp output. This runs the unit nicely (and economically, for long periods of time), but the voltage is too low for the LCD. The sunglasses are powered off USB so no problem there, only the LCD is an issue. Now, the production idea was 6x AA batteries, which output a reasonable 8ish volts. So, the logic was, tap into that directly, and use the cigarette lighter bit as previously tested to power the Pi. Great in theory, but it turns out that the unit I have appears to be a 1amp unit. The addition of a wifi dongle to the Pi pushes consumption over the edge, so it reboots. Presuming a 1.5amp 12v car charger can be found this should be an easy-ish fix. But a bit awkward in the meantime, so will probably continue dev work with the sunglasses display.