While in France on holiday in BBM69 we visited Keith and Carol Fair, (See Holidays 2005). During our chats Keith Pointed out the possibility of using a DC to DC converter to power a Garmin Satellite Navigator. Some time later I obtained the hardware then forgot about the project. However, on sourcing a new charger for BBM I realized that the connection would be ideal for the sat nav project as well.
The charger is an AccuMate 6-12, it is a versatile, 4-step automatic charger and maintainer for 6V and 12V lead-acid batteries. (See photo 1).
In addition to the standard clips the charger comes with a fused lead that can be permanently attached to the battery terminals (See photo 2). The lead terminates in a Tamiya connector, I made up a matching socket and lead attached to the board of the converter. Care is needed as I was using the charging lead socket as a power out connection instead of a power in one. This reverses the normal male/female positive/negative pin arrangement. Connect the leads after the isolation switch as the converter draws a small idling current.
The DC to DC converter was a TRACO POWER THB 3-0512 That converts 4.5 to 9 volts DC to 12volts DC at a maximum of 250 mA. This has proved ample to run my old sat nav. We had a proving run with the screen brightness and volume on 100%. I made it work hard re-calculating as we went along.
However I recently purchased a new sat nav, this one has a dash cam built in. It worked fine for hundreds of miles however on a short run recently the sat nav screen went blank. It soon became obvious that the power converter was cooking. I have obtained a more up to date converter (TRACO TEL 3-0512). Unfortunately this version has a different pin layout and has dual output so a new pcb was required. A 2 amp slow blow fuse is required on the input side and a 250mA slow blow on the output. I also chose to retain the LED to indicate power was on.
I attached the leads with a plug but they could just as well be soldered to the PCB. The output is through an in car connector to match the Garmin set up. I use the hole and grommet for the horn cable as an entry to the dash board. (See photo 4). I have used this set up for hundreds of miles driving with no problems, even with the new Garmin Driveassist-50 with a dash cam in it. However it did eventually burn out.