Last Piece Of The Puzzle Prior To Engine Start – Ducati Voltage Regulator Installed

One item that has been on my mind is the voltage regulator instillation … which was discussed in depth last fall. A different voltage regulator has been procured and will be installed at a different location. However, in the meanwhile, have decided to install the Ducati voltage regulator that came in the Rotax engine box to keep the forward progress going so an engine start can be attempted. When everything else is finished, will begin working out the details for the new voltage regulator and mounting location.


Normally, the wires going to the voltage regulator would be inserted into a connector plug that slides into the voltage regulator. However, because this will be a semi-temporary instillation of sorts, have opted not to insert the female spade connectors on the ends of the five voltage regulator wires into the connector … instead, will use heat shrink over the bare metal spade connectors on the ends of the wires and just slide the spade connectors onto the terminals in the voltage regulator.

Placing heat shrink tubing onto the wires to cover the bare female spade connectors. The Ducati voltage regulator that will be temporarily installed is sitting on the coolant radiator in the foreground.

The female spade connectors for all five of the wires that connect to the voltage regulator were covered in heat shrink tubing in this manner. These are the two yellow wires from Rotax engine's dynamo.


The heavy gauge yellow wires from the Rotax engine with the braided ground shield covering them were routed under the wire run from the firewall, fan folded and wire tied along with the wires from the instrument panel. These two yellow wires are the output from the Rotax engine’s dynamo and connect to the terminals marked “G” on the Ducati regulator … the voltage on these wires is a sine wave, so it makes no difference which order the two yellow wires go onto the “G” terminals (input) on the Ducati’s regulator. The two white wires (P-156) that supply power to the switch and fuse module are connected to the R and B+ terminals. Here again, it makes no difference which of the two white wires are connected to the R & B+ terminals because the two white wires are connected together. The last wire that needs to be connected to the voltage regulator is the small yellow wire (P-761) which is connected to the “C” terminal on the Ducati regulator. The “L” terminal on the regulator is not used in this application … (believe this is for an indicator light).

The five wires connected to the Ducati regulator. Fellow RV-12 builders take note, the connector body shipped with the Ducati regulator is not being used so the spade connectors are slipped directly onto the male spades on the regulator. The use of the Ducati regulator is only temporary until the mounting is finalized for the much higher current capacity Silent Hektik regulator that will be used on the DOG Aviation RV-12.


Of note: The Silent Hektik regulator has the same mounting hole spacing and could be mounted on the firewall shelf where the Ducati regulator is mounted. However, the mounting location on the firewall shelf is directly in line with the outflow of warm air from the coolant radiator and very close to the #4 cylinder’s exhaust pipe. Blowing hot air onto a high current semiconductor device is not the winning formula for long term viability.

Finished mounting of the Ducati voltage regulator on the RV-12’s firewall shelf.


At this point the DOG Aviation RV-12 is ready for the first engine start which will happen really soon. The wings have been pulled off again to improve the fit and finalize the routing of the AOA tubing which will be covered in another post.