A friend asked me some questions about how I installed my DVR2 on my 1955 Mondial TV 175. I was about to email him and thought that this might make a somewhat interesting blog post. You can see it in the picture above installed in the recess under the gas tank. I had to make the black bracket shown.
I suggest running the bike with the original mechanical regulator first. That way you can verify that the bike does run and that the wiring is correct. Use a voltmeter to check the following:
- Voltage at the battery with the battery unconnected
- Voltage with the battery connected but with the ignition switch off. Should be the same as above.
- Current from the battery connected but with the ignition switch off (should be zero!)
- Voltage with the ignition switch on *and the points closed* but the bike not running. I get 3.5A with the "Spia" lamp on. This is the Spy lamp on the headlamp shell that tells you the ignition is on and the battery is not charging. If you remove this lamp the current should fall to 3A. (Thus my lamp draws 3.5 - 3 = 0.5A.)
- Voltage and current with the ignition switch on *and the points open* but the bike not running. The only current flowing should be through the "Spia"; about 0.5A on my bike. If you remove the Spia lamp the current should fall to zero.
- Voltage with the bike running at idle. The Spia lamp should go off at any higher RPM.
- Voltage with the bike running at a higher RPM, maybe 3000. The Spia should be off.
These old mechanical regulators are often fairly crude in output and can overcharge a lead acid battery causing it to boil. They are adjustable, but are not very temperature stable. Note the vintage manual says the regulator should be set to 8.0 to 8.5 Volts with the battery removed! Additionally, many SLA / gel batteries have an internal fusible link, and that link can pop with overcharging causing permanent and total battery failure. Hence the interest in the modern DVR2 regulator that provides a nice constant 7.2 volts.
As we are talking about the charging system, it is imaginable that someone playing with this on a Mondial 175TV might decide to remove the dynamo's armature while looking around. If you are going to do this it is critical to remember something. The center bolt that retains the armature of the dynamo to the engine is REVERSE THREAD! If you ever need to remove the armature, remember the center bolt is loosened by turning it clockwise. I recommend leaving the armature in place as it can be delicate to remove!
So how to install the DVR2? It comes with a handy instruction sheet, but here are a few more tips. Remember this as a 6V installation.
Essentially all you have to do is:
- Remove the battery from the bike for safety.
- Connect the black ground wire on the DVR2 to a solid ground point. Remember that the gas tank may not be a good choice for that and painted screws can be a problem as well. Choose a good ground.
- Connect the brown and white wires from the DVR2 together (because this is a 6V installation) and then connect that to the battery. This is the charging side of the circuit and would be a good place for a fuse.
- Connect the yellow wire from the DVR to the +D of the dynamo.
- Connect the ggeen wire to the Field of the dynamo.
- Reconnect the battery .
1) Don't disconnect anything on the bike until you carefully document it. Label all wire ends (little strips of masking tape work well). And take pictures.
The underside of my original regulator looks like this:
Now under the engine side cover, you can find the Dynamo. You will see this part, the stator, with terminals labeled +D and F.
And here is a crude schematic of the stator:
2) So up at the regulator: after you disconnect and label the wires, you should verify that they run to the proper terminals on the stator. Just temprorily disconnect the stator wires at the terminal, and check the resistance with your ohm meter.
3) Check the wiring from the regulator B wire to the battery connector (remember your battery should be removed).
Note: Your original regulator may have multiple wires connected to the terminals of the old regulator. It is a good idea to investigate where those go as well. Consult your schematic and ohm the wires out.
4) Determine where you are going to connect the ground wire from the regulator. Remember that connecting it to the gas tank may be a bad idea, as the tank may have rummber mounts and painted mounting posts etc. I recommend running a wire where you connect the negative side of the battery to the frame.
5) Add fuses to the circuit as appropriate. I'm not an expert on this! But the idea is that if there is a short anywhere on your bike the fuse blows before anything is damaged. I rewired all of my Mondial so my wire colors are not the same as anyone elses. And I moved circuits as I wanted. So don't look at my wiring diagram and expect it to be like yours! At any rate, on my diagram you can see I have three fuses. One fuse is on the battery, another fuse is on the +B side of the regulator and the last one is built into the headlamp switch and protects all of the lamps and headlamp, except for the Spia.
6) Now connect up the DVR2 I added a set of bullet connectors between the DVR2 and the wiring system of my bike. In this pic you can see the bullet connectors and the colors of the DVR wires and the colors of the wires on my bike. Note my bike wire colors will be different than yours!
And there you go. Add a bracket to hold the DVR2 to the tank and you are just about done.
7) As the last step I recommend running all the voltage and current tests you did at the beginning. Everything should be the same except for the voltages with the bike running. You should get a nice solid 7.2 Volts out of the DVR2 at any RPM.