Supplemental Voltage Regulator Ground

[Scud]

This topic comes up quite a bit in other threads and I just ran a new ground wire - so here it is.

 

I sanded the paint off the frame behind the nut that secures the fuel-pump bolt (which passes through frame on 2002 and earlier, external pump, models). From there, I used a 12-gauge wire with crimp connectors and heat shrink to follow the original ground wire. This more than doubles the ground connection - and it's shorter and not mixed in with the rest of the harness.

 

The original ground wire had gotten hot a few times (note blackening at the connector). This bike only has about 12,000 miles on it, but that type of heat is a disaster (fire or electrical failure) waiting to happen.

 

 

Obviously, you don't need to remove the engine and subframe to do this (I've got other "stuff" going on). But seeing it in this condition made me wonder if Moto Guzzi relied on the grounding between the case of the regulator and the front sub-frame, which is steel. If the regulator is well-connected to the subframe, it would then be connected to the spine frame at four points (one of which is the round bare metal area in my photo). But these areas get corroded. I sanded them and will apply DC-4 electrical grease on assembly - so there is a third ground connection.

[docc]

Well done. Those are the "through bolts" on the early V11 with external fuel pump that I use for duplicate regulator/ timing chest grounding/ horn grounds/ headlight grounds. The same points should be still be on the later frame?

[Scud]

The frame on my 2003 has the unused holes. It also has the unused studs where the fuel filter is mounted on the earlier models. Those studs would make an easy ground point. In fact, I was wondering if it would be better to ground the battery to the steel frame at that point, rather than to the aluminum transmission case.

[docc]

The frame on my 2003 has the unused holes. It also has the unused studs where the fuel filter is mounted on the earlier models. Those studs would make an easy ground point. In fact, I was wondering if it would be better to ground the battery to the steel frame at that point, rather than to the aluminum transmission case.

The spark plugs fire back through the engine case grounds. Yet, grounding the frame seems smart. This is why I ran a braided ground strap from the timing chest to the frame where you have grounded the regulator.

 

Can't have too many grounds . . .

[Kiwi_Roy]

Scud,

         I know of at least 3 VIIs that let the magic smoke out of the loom, the main ground connection back at the gearbox gets loose or perhaps it breaks connection at the battery terminal because of lead oxide. When you go to start the 160 odd Amps to the starter tries to find it's way back to battery Negative, the main grounds disconnected so it finds the regulator is connected to the battery and goes that way, the small black wire gets red hot and melts into the other wires in the loom.

I have thought about disconnecting the small black wire and forcing the regulator return current through the chassis but I'm reluctant to do that for the following.

Suppose the main ground is disconnected, the alternator Voltage 60+ gets to the ECU and other sensitive stuff and could cause an expensive mess, at least this alternative small wire lets the battery clamp the voltage to a safe level.

 

When the bike is new chances are it's getting a good ground through accidental contact with the regulator bracket, when this goes rusty and it has to rely on the small black wire the Voltage drop caused by current flow lowers the battery Voltage.

 

BTW when mine worked loose it still cranked but slowly, luckily I figured out what had happened before the smoke started.

I found the main ground lug under the small screw holding the seat release lock, it worked loose with constant use of the release, it's now under one of the gearbox bolts where I can keep an eye on it.

Guys probably think I'm rabbiting on when I say to use Vaseline on the battery terminals but it's stood me in good stead for 50+

[Kiwi_Roy]

The Aluminium case is a better conductor, far better than a No 4 copper wire. I have been suggesting that a strip of Al sheet metal from the regulator to a timing case screw might be even better than a wire because it's the same metal all the way and it might look nicer but I haven't done it to mine as I have an after market regulator that doesn't need the case grounded

I have a new extra headlight ground connected to one of the chassis bolts under the tank

[Scud]

As it sits now, the bike will have two regulator grounds in parallel. 1) The original, smaller copper ( I estimate at 16 gauge) wire that goes from the regulator back to however it connects to ground through the loom. and 2) the new, thicker (12 gauge) and shorter copper wire that will attach to the same point at the regulator, but goes directly to the frame.

 

By my simplistic way of thinking about electricity, the majority of current will follow the path of least resistance. I assume the new, thicker wire to the frame will carry most of the current now - thus preventing my loom from getting overheated.

 

Aren't the engine, transmission, and frame basically one big lump from an electricity perspective? I mean, they have several metal-to-metal connection points.

 

Is it better to split that second ground as Docc has done? To go from regulator to aluminum engine case, then from case to frame?

[Kiwi_Roy]

No your setup will be fine as long as the main battery ground is intact (battery negative to chassis)

Starter return current will normally go from the starter thru the chassis and back up to battery negative thru the main ground wire.

 

But if the main ground is missing the return current will go direct to the regulator case or thru your new wire to the regulator case then the only

way it can get back to the battery is through the original you think is No 16.

It will be ok for a few seconds then melt it's insulation and melt into other live wires in the loom shorting them to chassis.

 

 Here's a picture, the black wire is to the left of the injector, all the insulation is gone off it and from the colour it's been red hot. 

[docc]

Since the battery grounds to the gearbox and my regulator case grounds to the timing chest (it's bolt into the engine block), I don't think this ground path is "split."

 

I have a separate case ground from regulator to the frame, and the ground strap from the timing chest to the frame, AND the factory black ground wire that goes through the loom to the (junction block for) the negative battery terminal.

 

Because I've grounded the horns and headlights to the frame, I wanted that point grounded back to the timing chest/engine case.

 

Of course, that's probably way over the top, but it *evolved * that way. In my way of thinking, the frame is the redundant, not primary, ground path.

[Scud]

Thanks Roy. I'll proceed as intended. As for Vaseline - remind away. However, MartyNZ convinced me of the value of the Dow Corning DC-4 compound. I think it has all the benefits of Vaseline, but withstands higher temperatures.

 

Docc. By split, I was referring to using two wires, not the way the current flows. BTW, I think your "redundant" ground has probably become the primary from a current-flow perspective. Shorter wire = less resistance. Thicker wire = less resistance. Malapropism alert: "short and thick does the trick."

 

And just so I am clear that I understand the purpose of this supplemental ground... as I understand it, the extra ground improves the charging and offers some protection against excess heat in the wire loom due to the fact that the original ground was too "long and thin." ...but there is still a problem if the battery ground works loose.

[Kiwi_Roy]

Yes, the regulator doesn't set the battery Voltage directly, it sets the Voltage between its black wire and the regulator case, it only happens to control the battery Voltage by association, if the case is not grounded properly it can be pushed to below ground potential and so the battery goes down accordingly.

 

Note: This applies only to the OEM or after market ones that sense the Voltage at the headlight circuit.

 

 

What might be a really interesting experiment, remove the OEM Ducati Energia regulator from the chassis and just leave it connected to the battery by the black wire then with the bike running measure the Voltage between regulator case and chassis at different revs.

Measure the battery Voltage as well then solidly ground the regulator and repeat the test.

 

Dow Corning DC-4 is not as good as Vaseline, how could I threaten my camping buddy with a name like that LOL

[docc]

Using the steel frame for grounding relies on it being bolted to the aluminum engine and gearbox (with steel fasteners) still grounding back to the battery through the negative battery cable at the gearbox. The conductivity of the fasteners concerned me because of the electrolytic corrosion between dis-similar metals, so I add the ground strap back to the timing chest bolt.

 

My primary regulator case ground is a 10g straight to the timing chest.

[Scud]

To satisfy my curiosity, I installed the battery (with it's freshly powdercoated tray  )

 

Resistance from battery negative terminal to:

• Stock regulator ground wire: 0. This is expected, because the wire goes directly to the battery.
• Bare spot on spine frame: 0.
• New grounding point on frame (fuel-pump through-bolt): 0. This is without even having the engine installed. It uses the connection between the spine frame and the transmission. 
• For comparison, a bare bolt on the upper triple clamp had resistance: 15 ohms, IIRC.

 

There will be a lot more connection points when the engine is in. So this confirms my hypothesis that the frame and aluminum cases are just one big lump from an electrical perspective.

 

However, I noticed an easy way to add a ground the rest of the way to the battery. I had previously run a battery charging cable behind the headlight for easy access and to power accessories. So I cut the negative wire, added two crimp-on terminals and stuck them on the fuel-pump through-bolt.  This provides an extra measure of safety in case the primary ground works loose. I used DC-4 again (not vaseline) so I missed the opportunity to threaten my neighbor when he visited.

 

This also gave me an excuse to play with my new ratcheting crimpers. OMG, they are so much better than the stamped steel ones. A real pleasure to use. Moto Guzzi is making another electrician... they've been doing that for almost 100 years now.

[docc]

 

This also gave me an excuse to play with my new ratcheting crimpers. OMG, they are so much better than the stamped steel ones.

I'd like to get a look at those . . . .    . . . .

[Chuck]

 

 

This also gave me an excuse to play with my new ratcheting crimpers. OMG, they are so much better than the stamped steel ones. A real pleasure to use.

I'd like to get a look at those . . . .    . . . .

 

 

Ya think?