Author Topic: 2013 - 2015 V7 over voltage problem & poll  (Read 52929 times)

Offline pikipiki

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #60 on: February 23, 2016, 12:10:22 AM »
I've compared the wiring diagrams for the 13-15 bikes with my 2016.  They're identical in regard to the R/R.

By the way, I checked my voltage when I got home from work today.  At idle, 13.7v (great).  At 3K RPM, 14.7v (not so great).   I would not replace an earlier R/R with this one.

If its holding 14.7 from 2500 rpm up - that sounds reasonable.
If you then said you had 15.7 at 5000 that would be a problem.
I think you are ok.
Its 15v up that becomes a problem.

When I checked mine found it to be regulating at 15.v-15.1v I've done 4k miles since then. My battery does not heat and my tender shows it to be healthy. Its an AGM

Im not saying it is right but on a single phase system I think the regulated voltage should appear higher. 13.5 might be too low. 14.6 might be just right.
The capacitance of the battery increases the dc voltage as shown on a meter.
13.5 or 14.7 which you state is  the peek of the rectified AC.   With the headlight on and a single phase alternator 13.5v might not maintain the battery where it would on a 3 phase system. The voltage is maintained by battery drain. The regulator truncates the voltage and converts excess to heat it cant make 9v into 14v, it can make 20v into 14v. A single phase alternator will always produce a pulsed output and that pulsed output will continue through to the regulator output. With 3 phases a near constant regulator output is possible. The battery may prefer a pulsed charge. The capacitance of the battery will ensure other components in the system get a near constant voltage supply.
« Last Edit: February 23, 2016, 12:35:27 AM by pikipiki »

Offline jas67

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #61 on: February 23, 2016, 06:32:44 AM »

That might vary somewhat with environment (desert or frozen tundra being worse than more moderate zones), usage, and uh... brand of cycle. (Solidmount Harleys were HELL on their batteries).

So, the problem wasn't voltage over charging, but, the batteries were being shaken to death.    :evil:
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Offline jas67

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #62 on: February 23, 2016, 06:37:46 AM »
The ideal charging system voltage should be between 13.8 and 14.5 volts at normal cruise RPM.    It is OK for the voltage to dip below 13.8 volts at idle, as charging will catch up when back under way.

12 Volt lead acid batteries need at least 13.8 Volts to start charging.
14.5 Volts is the safe upper limit.

Above 14.5 Volts, the batteries will start to off gas acidic vapors.   Above 14.7 Volts they can start to boil and dry out.

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Offline swordds

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #63 on: February 23, 2016, 07:00:43 AM »
The other site is the Guzzi Tech Forum where they have an excellent description of the reasons for concern with over voltage charging from a person who sounds knowledgeable and reasonable and experienced. Anyway, it is easy to check when you have the chance and it appears to be at least a fairly common concern, I won't say a problem because perhaps some V7s are rugged enough to handle 15+ volts charging output without issues, though perhaps some accessories like electric gloves won't accept the higher voltage.
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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #63 on: February 23, 2016, 07:00:43 AM »

Offline sib

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #64 on: February 23, 2016, 08:06:39 AM »
The other site is the Guzzi Tech Forum where they have an excellent description of the reasons for concern with over voltage charging from a person who sounds knowledgeable and reasonable and experienced. Anyway, it is easy to check when you have the chance and it appears to be at least a fairly common concern, I won't say a problem because perhaps some V7s are rugged enough to handle 15+ volts charging output without issues, though perhaps some accessories like electric gloves won't accept the higher voltage.
It's a very useful and informative site.  But, bear in mind that the site is part of a commercial enterprise and the owner makes money by selling replacement parts and accessories.  So, his viewpoint can be biased.  No offense intended.
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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #65 on: February 23, 2016, 08:10:05 AM »
Gee Kev; who pissed in your corn flakes?

No pissing, I'm just asking that the "problem" be better defined.

Like the Startus Interruptus - IS it a problem, how and why?


So, the problem wasn't voltage over charging, but, the batteries were being shaken to death.    :evil:

PROBABLY


The ideal charging system voltage should be between 13.8 and 14.5 volts at normal cruise RPM.    It is OK for the voltage to dip below 13.8 volts at idle, as charging will catch up when back under way.

12 Volt lead acid batteries need at least 13.8 Volts to start charging.
14.5 Volts is the safe upper limit.

Above 14.5 Volts, the batteries will start to off gas acidic vapors.   Above 14.7 Volts they can start to boil and dry out.

This sounds reasonable.

Though it varies between lead acid and AGM right? The AGM will take it (though might be damaged as well)?

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Offline tonUPRacer

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #66 on: February 23, 2016, 08:50:06 AM »
I will check mine in the spring, this is eeirly similar to the fuel filter "problem", the you need a sump spacer problem, etc. At least this one is easy to check.
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Offline swordds

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #67 on: February 23, 2016, 09:11:26 AM »
It's a very useful and informative site.  But, bear in mind that the site is part of a commercial enterprise and the owner makes money by selling replacement parts and accessories.  So, his viewpoint can be biased.  No offense intended.

Excellent point and something I should have noted. Perhaps 15+ volts is no problem for most V7s and the "concern" would go unnoticed by most owners except for the OP with the curious problem of the heated gloves that weren't working.
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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #68 on: February 23, 2016, 09:15:05 AM »
Ok, you guys enticed me to log into Guzzitech (man I hadn't been there in WELL over a year. I had an unanswered PM from 2014, I felt bad).

Here's what I posted:

OK, I was drawn over here from WG by Drlapo to check out this thread.

For the record my 2013 is at 10k miles and more than 3 years with no SYMPTOMS of problems, but I'll try to take some time to test it later this week if the weather cooperates (it's been asleep since Nov/Dec).

Meanwhile, I've got a question of threshold, specifically at what point do we say the regulators are not operating correctly.

Quote from: GuzziMoto, post: 114765, member: 363
I don't have a dog in this fight, but 14.7 volts is typical charging voltage for modern batteries.

15 volts is not really that much above standard, Once you start getting much above 15 volts I could see it being a problem. Clearly 16 volts and above is flat out wrong. The one small block I own does not have that issue, it is an older small block and struggles to meet acceptable charge voltage. I am happy when it hits mid 14's.



I tend to agree with GuzziMoto, though I'm open to someone schooling me otherwise is the threshold should be lower.

Interestingly enough I just checked the Guzzi manual for the Stone/Special/Racer - and it specifies:

Quote

Voltage on battery poles with engine speed always between 3000 - 5000 RPM

· Start the engine, after about one minute of operating bring the speed to 3000-5000 RPM,

then measure with a tester the voltage at the battery poles that must always be between

13V and 15V.


Now, I'm not one to BLINDLY accept the OEM repair literature, especially from Guzzi. But we should put some weight on it.

Todd, the ones you've seen where there was damage, was the charging OVER 15 volts? Or was it just over that 14.4 threshold? I'm guessing the former right?


I'll be curious how this plays out. But perhaps mid-to-high 14's aren't a cause for concern.

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Offline pikipiki

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #69 on: February 23, 2016, 04:15:05 PM »
With respect to the poll "Just right" ? It's just not that simple.


Above info for AgM
AGM Gel and vented batteries all have different optimal charging voltages.

Testing again I get 14.9v at all revs.
but I don't believe the output from the regulator is smooth, the damping in my volt meter may cause the reading to be a little high.
There are additional factors to consider.

I dont think anyone should get bothered about 15v but its a good idea to check your system while its healthy. A failing battery or R/R may cause a change in the regulated output or more voltage change with revs before the eventual failure.
« Last Edit: February 23, 2016, 04:45:56 PM by pikipiki »

Offline rbm

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #70 on: February 24, 2016, 05:35:20 AM »
If you want to measure ripple, switch the voltmeter to AC Volts range and measure across the terminals.  It's probably a very small voltage because the battery acts as a ballast, absorbing any ripple.
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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #71 on: February 24, 2016, 11:39:45 AM »
Piki, that's interesting (from where does it come).

It agrees with SOME of the data I've found, but is at odds to what some others are saying. Here's another cross post from Guzzitech:

Do we know who makes the battery for the V7, and have we confirmed that it IS an AGM?

EDIT - NOTE (Todd has since confirmed the V7 Battery is a Yuasa AGM)

I'm under the impression that AGM batteries are a little more sturdy than traditional lead acids with regards to charge rate.

The first reference I find is in the FAQ page for Optima:

http://www.optimabatteries.com/en-us/support/faqs

See CHARGING -

Quote
Voltage measurements of the battery when the engine is running are the output of your alternator. This measurement should be about 13.3-15.0 volts, which may differ due to temperature. At average operating temperatures of 50° to 80°F, your alternator output voltage should be about 14 volts to 14.8 volts.

Also:

Quote
For regular charging we recommend a maximum of 10-amps, 13.8-15.0 volts. For float charging, we recommend 1 amp maximum, 13.2-13.8 volts.

In contrast this website seems to favor the 14.4V limit for which you are aiming:

http://batteryuniversity.com/learn/article/absorbent_glass_mat_agm

This website talks about battery charge rates, and shows rates up to 14.9 for fast charging AGMs.

https://www.victronenergy.com/upload/documents/Datasheet-GEL-and-AGM-Batteries-EN.pdf

Here's a question. Does the circuitry in this regulator not adjust to system load and battery charge need? I.E. if the battery is discharged it's going to regulate the charge rate on the higher side until the battery is properly charged AND/OR load drops meaning it can shunt more power to ground and lower the charge rate more toward 13 volts.

I.E. if people are starting their bikes (maybe some that haven't been ridden in weeks or longer over winter) and immediately putting a DVOM across the battery terminals SHOULDN'T they be seeing a high charge rate? Potentially up to 15 volts (not over)? If those same people went for a 30 minute ride and THEN connected the DVOM might they see something closer to 13?

EDIT - TODD has since replied that the charging system on the V7 does not reduce voltage once the battery is charged.

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #72 on: February 24, 2016, 11:53:19 AM »
More info:

Reading the Guzzitech thread it certainly it sounds like a lot of units are testing out of the range that even MG seems to claim is acceptable (meaning over 15 volts).

I do think it's probably prudent for all here to at least throw a voltmeter across your battery with the bike running (3-5k rpm) and check.

I absolutely agree anyone seeing > 15 Volts should replace the VR. For sure that's what I'll do if mine tests that way.

But out of curiosity because I'm still chasing the reasoning behind the Guzzi specs and what we should consider "normal".

I asked PokeyJ this on Guzzitech, but I'll repeat it here:

Quote from: pokeyjoe, post: 114787, member: 7702
I went to Yuasa's website and they specifically listed a range of 13v - 14.5v for charging.  Some of these batteries are obviously taking a lot of abuse and are still working.  Or ticking.  Who knows what will happen or when.

Where'd you find that?

In their 2014 TechManual PDF the specifically say:

Quote
When considering upgrading to an AGM battery that was not original equipment on a vehicle, check to make sure the charging system has a regulated output between 14.0 and 14.8 volts.

http://www.yuasabatteries.com/literature.php

specifically here:

http://www.yuasabatteries.com/pdfs/TechManual_2014.pdf

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Offline pikipiki

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #73 on: February 24, 2016, 01:20:48 PM »
Kev M

Here's a link, to add more confusion even AGM battery manufacturers cant agree what's the right voltage to charge at.
The chart I posted seems to suggest a cold battery can be given a high voltage and as it/if if heats the voltage must be lower - which makes perfect sence except a charging circuit is unlikely to manage to guess the battery temperature.

http://support.rollsbattery.com/support/solutions/articles/4345-agm-charging

considering voltage output from the r/r -
This is how I think it works, I say think,
There are two positive wires from the r/r I think one is a high current wire and the other is low current. both wires are connected together but the low current wire can be routed through an ignition switch. I believe the low current wire is used to measure current/voltage and is protected by a high resistance. If there is low current draw the high current wire may exceed the voltage of the low current wire causing current to flow in reverse up that wire this causes the Regulator to dump charge into the heat sink raising the current draw which lowers the voltage on the high current wire, the high current wires voltage is stabilised in this way around the voltage of the low current wire.

« Last Edit: February 24, 2016, 01:23:54 PM by pikipiki »

Offline pikipiki

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #74 on: February 24, 2016, 01:43:13 PM »
If you want to measure ripple, switch the voltmeter to AC Volts range and measure across the terminals.  It's probably a very small voltage because the battery acts as a ballast, absorbing any ripple.
Yes the battery acts as ballast which makes it impossible (with basic tools) to measure ripple. if you removed the battery - no that wont work either because ballast is required in the circuit. Why does the regulator not have its own ballast? it may have but then again ripple in the voltage likely better for the battery charging. All I can say is a single phase inherently should produce more ripple than a three phase.

Why does Guzzi use a crappy single phase when almost all other manufacturers use 3? - not necessarily so crappy 3 phase is actually a cheaper solution.

Why is the alternator output so feeble? well the earlier v7 like the breva have a more powerful dry alternator with the same R/R. The revised engine has a different alternator - for all I know it might be a 3 phase wound as a single phase (speculation - that would be crappy the result would be a lower output alternator without changing the regulator)

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #75 on: February 24, 2016, 02:49:46 PM »
considering voltage output from the r/r -
This is how I think it works, I say think,
There are two positive wires from the r/r I think one is a high current wire and the other is low current. both wires are connected together but the low current wire can be routed through an ignition switch. I believe the low current wire is used to measure current/voltage and is protected by a high resistance. If there is low current draw the high current wire may exceed the voltage of the low current wire causing current to flow in reverse up that wire this causes the Regulator to dump charge into the heat sink raising the current draw which lowers the voltage on the high current wire, the high current wires voltage is stabilised in this way around the voltage of the low current wire.

So basically the low current wire through the ignition switch is the battery sensing circuit? Is that correct?

If so, I wonder if low voltage on the low current wire due to ignition switch resistance, leads to high charging on high current wire?
« Last Edit: February 24, 2016, 02:50:35 PM by Kev m »
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Offline pikipiki

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #76 on: February 24, 2016, 02:56:38 PM »
So basically the low current wire through the ignition switch is the battery sensing circuit? Is that correct?

If so, I wonder if low voltage on the low current wire due to ignition switch resistance, leads to high charging on high current wire?

No because on the v7 the two wires are joined as they go into the first connector. well on the circuit diagram that's how it is. but why are there 2 +ve wires. on some other bikes there are 2 wires and one goes through the ignition switch. I speculate that the regulator has 2 wires because it could be wired that way. just joining the wires as on the v7 that could be done inside the R/R.

Edit: Speculating further if designed this way - the low current wire could also be connected to a smart ecu that could provide secondary regulation.

Ask me how a rectifier works thats simple. Regulators are complicated.

Bed time reading:

http://m.instructables.com/id/How-to-make-a-reliable-motorcycle-voltage-regulato/?ALLSTEPS
« Last Edit: February 24, 2016, 03:14:34 PM by pikipiki »

Offline rbm

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #77 on: February 24, 2016, 10:55:24 PM »
Here's a question. Does the circuitry in this regulator not adjust to system load and battery charge need? I.E. if the battery is discharged it's going to regulate the charge rate on the higher side until the battery is properly charged AND/OR load drops meaning it can shunt more power to ground and lower the charge rate more toward 13 volts.
As Todd on GT pointed out, the R/R does not adjust the voltage delivered depending on the charge state of the battery. 

The rectifier's job is to convert AC voltage to full-wave AC voltage with a DC offset.  The job of the regulator is to smooth the full-wave AC and keep the output at a constant DC value (with some variation due to ambient temperature).  The current DRAWN by the battery to satisfy its charging appetite is dependant on it's initial charge state, the voltage delivered by the R/R and the internal resistance of the battery.  The current drawn is, by Ohm's Law, the voltage difference between the regulated voltage and the battery's terminal voltage divided by the internal equivalent resistance of the battery.  With 14.4-14.8V regulated and a battery in good condition, that creates an optimal charge current for these small AGM batteries -- about 10% of the AH rating of the battery.  When the output voltage of the R/R goes above 15V, the charge current drawn is higher (because the voltage difference is greater) to a point where it exceeds the manufacturer's recommended charge rate.  This can destroy the cells in the battery over time due to overheating.  This cycle results in higher internal resistance, which causes greater heating which causes accelerated battery degradation.

Any excess current capable of being delivered by the alternator goes to powering the motorcycle electrics, and not into the battery.  In other words, the total current delivered by the alternator is the sum of the battery charging current plus the load of the motorcycle electrics.
« Last Edit: February 24, 2016, 11:15:13 PM by rbm »
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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #78 on: February 24, 2016, 11:22:35 PM »
The R/R has four output wires -- two for ground and two for positive -- because of limitations on the PCB for the copper traces to handle the maximum current of the device.  If all the current drawn through the MOSFET was delivered through one connector joined to one trace, the PCB trace would not have the cross-sectional area needed to deliver that current without burning up.  So the manufacturer provides two connection points and doubles the volume of PCB copper through which the current can be delivered.  This goes equally for the ground wires because the same current delivered has to return back to the R/R through the ground.
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Offline pikipiki

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #79 on: February 25, 2016, 06:28:20 AM »
The R/R has four output wires -- two for ground and two for positive -- because of limitations on the PCB for the copper traces to handle the maximum current of the device.  If all the current drawn through the MOSFET was delivered through one connector joined to one trace, the PCB trace would not have the cross-sectional area needed to deliver that current without burning up.  So the manufacturer provides two connection points and doubles the volume of PCB copper through which the current can be delivered.  This goes equally for the ground wires because the same current delivered has to return back to the R/R through the ground.

Thanks:
 so its a very basic R/R unit that can only be used on a permanent magnet single phase alternator. It either works or it does not. 2 wires go in AC, 2 paired wires come out DC. If the battery, lights and other electics do not draw all the current provided by the alternator input it dumps the excess charge into the heat sink to prevent the output voltage rising during low current draw?
The alternator produces 100% power for the rpm all the time. Excess charge goes to the battery till it resists then it goes to the heat sink.
If your battery resists charge DC voltage output increases to a point where the R/R decides to dump it as heat. That point seems to be around 15v but the R/R may be effected by heat as well (but not a lot) depending if its hot or cold the regulated voltage may vary (hopefully by less than 1%, 2% well ok, more than 5% damned things junk)

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #80 on: February 25, 2016, 06:47:33 AM »
Theoretically -
Fit this between regulator and battery, use the lightbulb output to power your heated gloves,

http://www.windynation.com/Charge-Controllers/Windy-Nation-Inc/P30L-LCD-30A-PWM-Solar-Panel-Regulator-Charge-Controller-with-Digital-Display-and-User-Adjustable-Settings/-/628?p=YzE9MTc=

You will be able to monitor and control battery charge + use your gloves as a heat sink?

Jobs a good un... :thumb:

Ps think theres even a handy thermometer to monitor battery temperature. ;)
« Last Edit: February 25, 2016, 06:49:59 AM by pikipiki »

Offline rbm

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #81 on: February 25, 2016, 07:00:43 AM »
... If the battery, lights and other electics do not draw all the current provided by the alternator input it dumps the excess charge into the heat sink to prevent the output voltage rising during low current draw?
No, that's not the case.

The battery and other motorcycle electrics represent a load to the power source, the alternator/voltage regulator combination.  By Ohm's Law, the load will demand a certain current from the power source, assuming the power source has a fixed DC voltage output of 14.4V.  The power source will never deliver more current than is demanded of it. 

The alternator is sized to deliver more RMS AC voltage than desired and have a power capacity in watts higher than what will be demanded from it.  When the AC from the alternator is rectified, the DC component of the resulting full-wave rectified waveform is greater than the regulated output.  For example, after rectification, the resulting rectified DC input into the regulator will be 20-30 volts depending on the alternator's design, but in that region.  The regulator will output 14.4V and will try its hardest to always maintain that output.  In the best case, there will be (20-14.4)=5.6V differential across the regulator; in the worst case, (30-14.4)=15.6V.

The regulator itself is a load and has an equivalent internal resistance.  That resistance causes a power drop across the regulator which is wasted in the form of heat as the regulator attempts to adjust the output to 14.4V.  The amount of heat wasted is proportional to the load current demanded from it.

The designers attempt to overspec the power characteristics of the alternator, ensuring that the theoretical deliverable power of the alternator is never exceeded by the power demands of the load to which it is attached.  If you add extra load to the electrical system (heated gear or electronic gadgets for example) to a point which exceeds the power capacity of the alternator, the output of the alternator will drop in an attempt to service that load.  Ultimately, if the excess load continues, the alternator will fail as it will not be able to keep up with the demand and will burn out.  The point is that the alternator will not produce power up to its theoretical value, it will only produce power what is demanded of it, which is usually less than theoretical.
- Robert

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #82 on: February 25, 2016, 08:36:51 AM »
Good stuff guys thanks.

So to put it in layman's terms for owners who want to check theirs, at what threshold would you recommend a replacement regulator?

If it exceed 15? If it exceeds some lower number (for a better cushion)?
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Offline drlapo

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #83 on: February 25, 2016, 03:37:06 PM »
I did a diode check on the VR today
I got 2 sets of 0 and 2 sets of numbers so that part checks out
The numbers however are very far apart
One set is 201 and201
The other set is 569 and 564
I have no idea what that means

Offline Zinfan

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #84 on: February 25, 2016, 06:50:24 PM »
In October 2014 I had trouble starting the bike one night so I checked charging voltage (I have a 2013 V7 Stone).  At idle it was reading 15.3 volts so I replaced it with a Mosfet R/R no issues since then.  Tomorrow I will take the bike out for a ride and measure the voltage for an up to date report.

Offline Vagrant

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #85 on: February 26, 2016, 06:11:05 PM »
I just replaced the 2015 regulator with a new one. old was 17.79 last I checked at 3-4000. new one is 12.95 at idle and 14.3-14.4 at 3500. hopefully it didn't cook anything in it's 2400 miles.
HE IS FREE WHO LIVES AS HE CHOOSES
2001 EV, 2017 V7-III Blue special, 2020 V85 the fast red one!
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Offline pikipiki

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #86 on: February 26, 2016, 06:59:13 PM »
More bed time reading:

http://www.apriliaforum.com/forums/showthread.php?240785-Facts-about-shunt-based-regulators

not the easiest to follow,

it seems that if you are troubled by the low output (270w) a change to a mosfet R/R can reclaim power loss from oem R/R (upto 10%)

Also I am sure if the voltage is too high components such as lights will use more power!


canuguzzi

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #87 on: February 26, 2016, 08:27:57 PM »
If you have a parasitic drain on your battery (more than the ecu for example) then when you fire up the bike, the charging system is always going to try to charge the battery. A fully charged battery can sit at 14.4 volts for years in float.  Fully charged being the important caveat.

The charging systems on motorcycles and cars aren't designed to charge the batteries, they are designed to maintain them. They run the vehicles electrical systems and replace the charge used to start the engine (high draw) and so on. That is why, should your battery ever become discharged quite a bit, you should charge it properly, not just take it for a ride. It will last longer and perform better.

Battery tenders are not good chargers, they are float maintainers designed to maintain a fully charged battery at optimum charge.

The battery need both proper voltage and amps to charge. Checking volts only doesn't tell you the true state of charge for a battery.

An analogy that might help some is that the battery stores amps, not volts. A battery at 12.7 volts doesn't mean it can start your bike, why you can check the battery for voltage and yet get slow turn and click click click.

Offline rbm

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #88 on: February 27, 2016, 12:03:09 AM »
An analogy that might help some is that the battery stores amps, not volts. A battery at 12.7 volts doesn't mean it can start your bike, why you can check the battery for voltage and yet get slow turn and click click click.
I'm sorry but that's not a good analogy, and is misleading.  Volts are a measure of potential and amps are a measure of flow. Volts are like measuring the potential ability of the battery to supply its store of energy. Current is the flow of of this energy store from higher potential to lower potential. Clearly, one can't store something that is in motion.   Consequently, a battery that is in poor condition cannot supply a connected load with the energy it demands when it demands it, because internal resistance impedes the delivery of current (i.e. amps). 

A better analogy is like a water tank, a faucet and a pipe.  The tank is the battery, the pipe is the internal resistance and the faucet is the load.  The tank has the potential to deliver its full volume of water (i.e. potential)  through the pipe to the faucet).  If you measure the volume of water in the tank, you get an idea of its potential.    If the pipe is large, the water will flow freely from the tank when the faucet is turned on;  in the same way a fully charged battery is able to deliver full current to a load when it's demanded.  If the pipe is corroded and clogged with sediment (like internal resistance exhibited by a battery in poor condition) then the water cannot be delivered at the same rate when the faucet is opened.  This is like the starter motor failing to turn over even though the battery appears to have the potential to do so.
- Robert

2011 Moto Guzzi V7 Racer
1987 BMW K75 @k75retro.blogspot.ca

Offline pikipiki

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Re: 2013 - 2015 V7 over voltage problem & poll
« Reply #89 on: February 27, 2016, 02:33:31 AM »
A battery does store Amps not volts - thats not an analogy thats a fact.
A batterys capacity is measured in Amp hours.

A battery can be charged at even 16v that might be just fine for short duration rapid charge but when we talk about maintained and float the batterys natural rest voltage fully charged is 12.8v (although there is a complication that a battery may for short duration minutes hold upto (think) 13.8v) If you connect it to a higher voltage it will have no choice to accept more charge which it cannot store, the battery would heat up.
 Things that effect how much it would heat up are, its ability to convert the charge into stored energy (none on a fully charged battery), its ability to disipate heat, the number of amps the supply can provide (spare amps not necesarily that many on a V7), the potential difference in volts between supply and battery and the internal restistance to charge of the battery which it seems is not constant and may be much higher when the potential difference is lower? (batterys seem to need about 1v pd to charge)
Ideally you check the R/R and it shows somewhere between 13.8v and 14.8v and that should be OK because with a PD of less than 2v on a fully charged battery the battery will have some resistance to charge and what extra charge it receives it will disipate (i.e. the battery is sitting in float)

Now V7 R/R apears to be set at 15v which confuses because that seems to be too much for float charge but its not so much as to be clearly wrong. That does not mean its not good it means its in a grey area that is very hard to understand. It might be that the low power rating of the V7 alternator and the characteristic of PMA / stator not to stress under short circuit keeps the system in harmony (until lights are changed for LED and then there is spare amps to do battery damage?) It might be the fact that the DC from the single phase alternator is highly choppy pulsed unlike a smooth 3 phase delivery so volt meters read a little high due to their internal damping or the choppy DC is acceptable at a higher voltage.

Regarding R/R output it should not vary by more than 0.5v when measured ar any rpm above 1500.

Regarding overcharging Im wondering if sticking a thermometer strip on the battery would be a better way of monitoring than measuring if worried about 15v

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Shipping in USA Only. Awesome quality. Back by popular demand. All proceeds go back into the forum.
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