SIP Speedo wiring

[Nelly]

I'm on with sorting this SIP speedo. Here's a query aimed at those who have fitted one to a DC Wassel set up.
The instructions say to wire the positive to a switched 12vdc. My thought is if it's switched off from the power, it's going to lose all the saved data etc. A battery back up will only last so long. On the other hand if you connect it to a permanent 12vdc will the speedo stay illuminated constantly? If it switches off, how does it know to switch off? I would have expected a switched 12vdc and a permanent 12vdc as you find on car audio.
Any feedback appreciated, cheers.

[Eden]

I presumed it wrote the settings to memory on a small chip, I maybe wrong.
Im sure the rtse1000 unit saves the settings in this way.

mine is switched on and off via the lights, so its only on if the lights are on as its good practice to always ride with lights on.

[Wack]

The speedo has a built in memory so the settings don't change when the motor isn't running on an AC system. It should work better on a DC feed.

[Nelly]

Thanks for the replies.
I did a little bit of experimenting tonight to check the wiring for the speedo using a 12vdc power supply wired direct to the speedo system.
Wiring direct to a permanent 12vdc will leave the speedo on constantly, not good.
I've wired it in parallel with the existing lighting loom. As most people know who have done the wassel set up, the power is on constantly to the loom which leaves the horn and brake light on even after the ignition is off. Normally connecting the speedo system in parallel to the loom would also leave the speedo powered constantly too. A possible solution is to use the method Eden has done and wire the speedo to the lights.
My solution has been to utilise the accessory switch on the SccotRS ignition switch to energise a 30A relay which will power the loom and the speedo when the ignition is switched on. I've wired a cigarette lighter type socket into the toolbox, but wired that on an unswitched supply in case I want to power stuff with the ignition off.

[Nelly]

The wiring is now complete, here's where the Vespa PX battery tray was squeezed in. The back wheel is still easily removed with it in place and it just squeezed under the SX 200 panels without catching. I mean just. Note the relay just above left of the battery, this is switched from the Scoot RS ignition and isolates the complete bike electrics when the ignition is off.