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 Voltage drop when ignition ON & min. voltage to start

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tjo
Montanarolo
Montanarolo


Posts : 15
Join date : 2016-11-15

PostSubject: Voltage drop when ignition ON & min. voltage to start   Mon Nov 28, 2016 10:30 pm

Two observations on my GRiSO 1100 regarding the starting misery...

1) on my GRiSO the 'relay click-no start' phenomenon starts at 12.0V (on the dash). If there is shown 12.1V, it starts. Is this on all Grisos like this?

2) when I turn the ignition on (dashboard awakes, tail light and front light on) the voltage starts dropping dramatically. Basically 0.1V dropping every 4-5 seconds. When it gets to 12.2V I turn the ignition off as I still would like to start the bike. Additional info: battery is new and fully charged (around 13.1V measured on the battery pole before turning the ignition on), and otherwise charge whilst engine on seams fine, as it is around 13,2V (showing on dash) for a minute or so after the starting procedure drained the battery a bit and around constant 13.5V (shown on dash) regardless of rpm, (didn't check it over 4000 rpm though) after a minute or so whilst riding or idling.

That's pretty absurd, the ECU, dash and two 5W light bulbs can not be responsible for such a drainage.

Did anyone else experience such a voltage drainage just by turning the ignition on?

Many thanks in advance

Tom
GRiSO 1100 - 2006
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Oz1200Guzzi
Don Abbondio
Don Abbondio


Posts : 1780
Join date : 2014-03-13
Age : 62

PostSubject: Re: Voltage drop when ignition ON & min. voltage to start   Mon Nov 28, 2016 11:31 pm

Tom, there is also the fuel pump, injectors, coils, dash and a host of other related items that also consume power as soon as power is on. I suspect your battery or your earths are not good. If you have a lead/acid battery, it should be able to deliver the standby current (without reducing the battery voltage) for a period of minutes.

Check your main earth under the starter cover and maybe move them to the gearbox mounting bolt above your main earth, and making sure it is tight - your voltage may well recover just by doing this alone. The main earth point has been well documented to come loose or corrode, thereby providing you with a less than ideal situation for starting. I actually sheared mine off (the mounting stud under the main earth point) and had to make a new one as well as rethreading the hole in the aluminium.

Let us know what you find.
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tjo
Montanarolo
Montanarolo


Posts : 15
Join date : 2016-11-15

PostSubject: Re: Voltage drop when ignition ON & min. voltage to start   Mon Nov 28, 2016 11:46 pm

Hi Tony

I suppose even an brand new correctly specificated (18 Ah) AGM lithium battery should be able to to deliver the standby current (without reducing the battery voltage) for a period of minutes, so I exclude that the fault is at the battery. I however do have an older acid yuasa battery in storage that I will fit and double check first.

If that does not help then I will look at the earth as you said. Let's hope it will be that, even though there is no other sign of electrical malfunctioning. I mean as long as the 12.1V is there, the bike starts cold and warm easily. I would expect a total lack of starting regardless of voltage if the earth contact is corroded or lose but hopefully I am wrong and it will be that simple to solve the problem.

Can you by any chance confirm that the ECU block on starting intervenes at 12.0V?

Kind regards
Tom


Oz1200Guzzi wrote:
Tom, there is also the fuel pump, injectors, coils, dash and a host of other related items that also consume power as soon as power is on. I suspect your battery or your earths are not good. If you have a lead/acid battery, it should be able to deliver the standby current (without reducing the battery voltage) for a period of minutes.

Check your main earth under the starter cover and maybe move them to the gearbox mounting bolt above your main earth, and making sure it is tight - your voltage may well recover just by doing this alone. The main earth point has been well documented to come loose or corrode, thereby providing you with a less than ideal situation for starting. I actually sheared mine off (the mounting stud under the main earth point) and had to make a new one as well as rethreading the hole in the aluminium.

Let us know what you find.
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Oz1200Guzzi
Don Abbondio
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Age : 62

PostSubject: Re: Voltage drop when ignition ON & min. voltage to start   Tue Nov 29, 2016 1:26 am

I believe that is the case. On some early models (maybe yours even) you could get a diode and capacitor plug in rig (genuine MG part) that tricked the ECU into seeing the correct voltage and performing a start. Don't know how they engineered this out of the system, or if they did some other trickery. Italian 'lectrics eh?
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tjo
Montanarolo
Montanarolo


Posts : 15
Join date : 2016-11-15

PostSubject: Re: Voltage drop when ignition ON & min. voltage to start   Tue Nov 29, 2016 7:57 am

Oz1200Guzzi wrote:
I believe that is the case. On some early models (maybe yours even) you could get a diode and capacitor plug in rig (genuine MG part) that tricked the ECU into seeing the correct voltage and performing a start. Don't know how they engineered this out of the system, or if they did some other trickery. Italian 'lectrics eh?

yes Tony I know about these diode and capacitor plug in rig (genuine MG part) that were supposed to trick the ECU into seeing the correct voltage and performing a start. However I also read on forums that it often did not do the job.

I went for the relais-bypass solution kit with an extra second starting relais. This solution has been adopted by Guzzi itself first on the 2V Sport 1200 models but there is still much confusion (at least for me) about which models are affected and until which production year.

Now the previous owner wrote me back regarding the voltage drainage and says that the front light is consuming lots of Ampers. Sounds strange, as the 5W parking light should not be doing so. Anyway, will check it all and report. Only it's bloody winter termperatures here in London and it's not evident without a garage...

Kind wishes
Tom
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tjo
Montanarolo
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Posts : 15
Join date : 2016-11-15

PostSubject: Re: Voltage drop when ignition ON & min. voltage to start   Wed Nov 30, 2016 1:35 pm

Well, situation is getting worse.

1) Fully loaded battery that stays above 13V for weeks if not connected to bike.
2) I attache it to the bike, turn the key, and it's immediately only 12,5V, but it's enough to start.
3) When I come home from the ride, I check the battery voltage with ignition off, and it's 13,2V, great.
4) Only two days later I want to start the bike again, shouldn't be a problem
5) AM checking the voltage on battery with ignition off, 12,9V, well that immobilizer seems to consume a bit indeed, but 12,9 is still largely enough to get the starter motor turn.
6) I turn the ignition key, and voltage on the dash shows 11,7V!!!
7) I press the starter button, I hear the click, and voltage goes then up, to 12,2V. So I thought now it will start. Nope, even with 12,2V (on the dash), there is only the click. After a few more tries, voltage drops to 12.0V.
Cool At this point I check the voltage at the battery but leave the ignition on, so I can see the voltage shown on the dash too. 12.0V on the dash is 12.17V on the multimeter.
9) I turn ignition off, and check voltage on battery again after a minute to allow the battery to recover. And well, the battery recovers easy to 12.8V. Hence my battery is fine. But something else is very much wrong.

So long for now. It's bloody Siberian winter now in London, so I didn't get to check the main earth etc.

For the time being, I hope the relais pass-by kit arrives soon and at least the bike will start to start even when dash shows a weaker voltage.

And I also plan to add a solar charger to the battery.

Will keep the forum posted.

Wish me luck.

Tom
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Oz1200Guzzi
Don Abbondio
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Age : 62

PostSubject: Re: Voltage drop when ignition ON & min. voltage to start   Wed Nov 30, 2016 9:13 pm

Tom, do you have the aftermarket (but genuine) immobiliser fitted? If so toss it, as it does drain the battery and somewhat erratically...

Ask me how I know...
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eeyore
Squinternotto
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Join date : 2016-09-09

PostSubject: Re: Voltage drop when ignition ON & min. voltage to start   Thu Dec 01, 2016 2:25 pm

Battery voltage is no indication of the cranking power. A near dead battery can show over 12V.
Get a true check on your battery - drop test or similar and as suggested above check the connections at the battery, starter and -ve.
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tjo
Montanarolo
Montanarolo


Posts : 15
Join date : 2016-11-15

PostSubject: Re: Voltage drop when ignition ON & min. voltage to start   Thu Dec 01, 2016 3:30 pm

eeyore wrote:
Battery voltage is no indication of the cranking power. A near dead battery can show over 12V.
Get a true check on your battery - drop test or similar and as suggested above check the connections at the battery, starter and -ve.

Thanks for this. But battery is brand new and works fine as long as the GRiSO allows the starter to turn. The issue is definitely not the battery. I also still have the old Yuasa battery which is also still capable of holding a healthy 12,8V and it's the same with it. 12,8V becomes 12,2V or even less as soon as the ignition key is turned, hence something is sucking off to an abnormal degree when ignition is on.

But okay, I need to do a proper resistance test both at ignition on and off in order to see what is sucking off the juice so heavily. I know that when ignition is off, there shall be no more than 50 mA drainage, anything above that means there is a parasite.

At ignition on, it's a bit more tricky, but doing the resistance test, and pulling off the fuses one by one shall allow me to understand a bit better.

It's just bloody winter now here and I don't have a garage, so I am just waiting for a bit milder weekend.

Best wishes
Tom
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wardentm
Nibbio
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Join date : 2015-05-16
Age : 64

PostSubject: Re: Voltage drop when ignition ON & min. voltage to start   Thu Dec 01, 2016 10:24 pm

G'day Tom
Surly, your GRiSO is in the lounge room when the weather is as bad as you mention ?
Stay warm
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PostSubject: Re: Voltage drop when ignition ON & min. voltage to start   Today at 8:12 pm

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