Supplemental Voltage Regulator Ground

[luhbo]

When the battery is at 12V and it only needs 0.5V difference to get 8A going, and on the other end the same voltage difference results in only 0.5A, then I think this should be a matter of internal resistance. I even see a chemical explanation for this. What do I miss?

But before you again call that nitpicking, the point is that once the battery is above 13, maybe 13.5V, what a good one should be right with the engine revving up, a voltage rise to 14.6 or more does not mean a relevant current load for the battery, because of the above described "observation" and because it's wired in parallel to the rest of the bike. A charged battery contains practically nothing that could get the current through in this direction.

 

Current wouldn't be the problem anyway. The voltage is the problem. Above 14V it will severly start gasing, running at a high risk to relieve the pressure and to dry out (call it ageing). So you better keep the voltage below 14V (13.8 says the battery's label). That just a side note.

[Kiwi_Roy]

It is correct that current through a diode grows exponentially with applied tension. However, it is also correct that the current is limited by the power of the source (alternator). So although growth is exponential, there are limits as to what actually can be achieved.

 

Alternator is rated at 350W, which @12V results in ~30A current. The circuit is fused accordingly. Workshop manual talks about DC 27,5A@10k RPM and I'd say we can safely assume that the regulator/diodes in it are also rated accordingly. Based on that, I don't think we have overvoltage or overamperage problem here. If we had, the fuse would burn out.

 

 I'd say the problem is related most likely related to continuos high (but stilll "legal"!!) currents passing through a thermally stressed regulator for prolonged periods, owing to both:

- bad battery or regulator-battery connectivity (high currents)

- placement of the regulator - behind oil cooler and between cylinder heads. (thermal stress)

 

The main current limiter in the charging circuit is battery's state of charge. If that does not go up quickly (within 15-20 minutes) after the engine is started, regulator will be sweating until it dies. 

Don't forget that part of the cycle the alternator is putting out less than the battery Voltage so there is no current flowing the 350 Watts is the average Wattage, I suspect the peak is 40 Amps or more, that's whats so hard on the fuse holder.

 

"Current wouldn't be the problem anyway. The voltage is the problem. Above 14V it will severly start gasing, running at a high risk to relieve the pressure and to dry out (call it ageing). So you better keep the voltage below 14V (13.8 says the battery's label). That just a side note."

 

The regulators I have pulled apart have all been set at 13.8 Volts, the problem is it doesn't measure the battery at the terminals it measures 13.8 downstream of the headlight relay so the poor battery has to put out well over 14 Volts before the regulator is happy. (unless you have added headlight relays direct from the battery)

It's easy to check the Voltage drop, measure from the battery Positive terminal to the black wire at the regulator (don't need the bike running for this)

 

My bike measured anything from 0.5 to 1 Volt, it's an 01 with two relay contacts in series with the headlight. Reseat the Start and Headlight relays and it drops back down to ~0.5 Volts

I decided this was too flakey for me and fitted a direct connect style regulator

 

Remember the regulator doesn't set the battery Voltage, it sets the Voltage between the black wire and its case, it does a great job of setting the headlight Voltage, not so great at setting the battery Voltage.

I mentioned after market headlight relays, they divert the current from the OEM headlight relay, with very little current the Voltage drop is near zero, that's Ohms Law

 

I think this is an interesting discussion, there's bugger all else happening at the moment

[Guzzi2Go]

When the battery is at 12V and it only needs 0.5V dWhat ifference to get 8A going, and on the other end the same voltage difference results in only 0.5A, then I think this should be a matter of internal resistance. I even see a chemical explanation for this. What do I miss?

What you are missing is regulator's internal resistance, but primarily the fact that battery acts as a capacitor in the circuit. Or you are simply using the term "internal resistance" wrongly. 

 

Regulator's internal resistance coupled with the fact that power input is not infinite is the reason you see tension drop below rated 14.0-14.6V when significant current flows. Even here I'd put bias on finite power, rather than internal resistance. One of the key features of a good tension source is low (ideally zero) internal resistance. Opposite for a current source. There internal resistance is infinite (ideally) or high (realistically). More likely the alternator goes out of puff before regulator's internal resistance kicks in. 

 

When a capacitor is present in the circuit, current is direct function of its state of charge, not capacitor's internal (parasitic) resistance, which is theoretically infinite. In a circuit consisting of an empty capacitor and resistor, current is at first limited by the resistor according to Ohm's law. As the time goes by and the capacitor charges, the current drops asymptotically to zero. It is not different with a (rechargeable) battery in place of a capacitor. The only difference between a capacitor and a battery is the method of storing charge. The energy needed to drive the chemical process in a battery can be compared with the energy needed to polarize dielectric in a capacitor. The effect can at best be named parasitic resistance, using the term internal resistance is wrong and misleading.

[Kiwi_Roy]

The regulator has very little internal resistance, just 2 SCRs and 2 diodes in a bridge, for a half cycle the circuit is

Alternator coil, yellow wire, diode, red wire, battery +, battery -, chassis, regulator case, SCR, other yellow back to the other end of the coils

We know that when spinning the alternator open circuit can easily reach 80 Volts

I think the limiting factor current wise is the inductive reactance of the windings.

[Guzzi2Go]

Don't forget that part of the cycle the alternator is putting out less than the battery Voltage so there is no current flowing the 350 Watts is the average Wattage, I suspect the peak is 40 Amps or more, that's whats so hard on the fuse holder.

 

I don't/did not. The thing is, that semiconductors can run currents order of magnitude larger than rated, given  small enough duty cycle. 

 

For example, 1N4001 rated at 1A continuous, can run as much as 30A for a short period of time. 

 

As for the fuse, a slow blow fuse is also capable of tolerating more than rated current for some time, for example 6 times rated current for 20-100ms. 

[Kiwi_Roy]

The diodes inside the regulator are quite large but the solder holding the lead on melts letting go then it starts arcing.
The first one I was able to re-solder and it operated for another couple of years

 

The 30 amp fuses don't blow, they heat up and melt the plastic because of contact resistance in the fuse holder.
 

[gstallons]

Why didn't they utilize all 3 phases instead of 1 when they built these charging systems ?

[Kiwi_Roy]

You'll have to ask Luigi that, there's nothing wrong with single phase, many other motorcycles use it also including some Harleys.

I think 3 phase is probably the most efficient use of space but don't quote me.

Three phase certainly leads to a much smoother DC.

[amstaf]

Maybe this isn’t the right place to post a question, after all this time, but I’m having a seemingly related issue with my very sheltered 2000 V11. Just replaced the battery and voltage regulator after bringing it out of hibernation. Light Smoke and plastic like odor comes from under the tank while running. No problem starting/cranking. (Before the battery/regulator replacement I seem to remember this also. The regulator BTW failed the diode test.) I’m thinking this can only be coming from the wiring and probably from ground, judging by the attention given to this issue on the forum. Also, but maybe unrelated, number two or three fuse from rear, 5A had been blown. Any takers?

 

Or maybe I should tow it two hours down to Hamlins and have a professional fix it.

 

Thanks

[czakky]

Check your ground! Should be behind the seat lock on the transmission.

[docc]

Or maybe I should tow it two hours down to Hamlins and have a professional fix it.

Dude! Are you saying we're not professional ?!?    (Heh - we're not . . .    , just *enthusiastic!*   )

 

Check your ground! Should be behind the seat lock on the transmission.

What czakky sez. He knows of what he speaks!   Don't let your V11 try to ground itself through the loom!

[ I apologize for this, in advance, czakky! ]

[amstaf]

No, I meant I am not a professional especially with electrical stuff. Thanks for the quick info.

 

Does that seat lock just pop off after removing the two Allen head fasteners to provide access to the ground? Are improvements recommended to the ground connection? Sorry for asking as I know there’s endless info here. It makes my head spin.

[docc]

All good, man. Just teasing about.

 

Yeah, remove the seat latch release and the main ground of the negative battery cable will be under a fastener into the upper right of the gearbox.

 

Take the fastener out, clean and sand all the surfaces.

Replace with a coating of petroleum jelly (Vaseline® aka Kiwi_Roy's VooDoo Magic 'LectricumJello).

 

Consider using a "star" washer to dig into the mating surfaces as well as treating the battery terminals to the same VooDoo Magic.

 

I have learned to love Caig DeOxit electrical spray. The "gold" has both a sealant and special electrical flow enhancers (my words . . .)

Turbo-VooDoo!

 

Here's a view of the Main Ground connection from behind with no rear wheel , swingarm, or fender:

[emry]

Why didn't they utilize all 3 phases instead of 1 when they built these charging systems ?

 

Simple answer. "Cost down".

[amstaf]

Okay, I’ll post back after remedying. Wondering if I should take the tank back off to look at wiring. Tank was just painted which polished off (after 6 years) the resto/conversion with Lemans Fairing and looks so cool.

 

Docc, another of your posts( or maybe Kiwi) mentions hooking up a volt meter between the frame and the battery negative. If I do that, I should find some voltage if the ground is faulty, and if it is corrected then no voltage.

 

Thanks guys!