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Voltage regulator question


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Hey all,

 

I'm asking this not specifically for a V11, but it does apply to one as well, hence I am still posting this in the Tech Topics section instead of the motorcycle-specific one (older models in this case). Please move the topic if my "bending of the rules is not appreciated":race:.

If I were to consider installing a Li-ion battery on my V11 (actually in my V65 Florida build), there is a chance the output of the regulator will be too high for the Li-ion battery. Where an AGM likes to charge at 14.5-14.8v, most Li-ions charge at a maximum of 14.5, preferably less then 14v. Normally the solution is a different regulator with a lower voltage output, but that is expensive.

BUT, could I also solve this issue by building some resistance between regulator positive and battery positive, such that the regulator reference voltage is e.g. 0.8-1.0v higher than the actual charge voltage to the battery? This way the regulator would charge at 14.5, but the battery would actually see 13.5v.
Am I thinking too simplistic? Or would the current flow (20-25A) make it impossible to find a suitable resistor? 

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Actually the regulator is set for ~ 13.8 Volts, by the time you get some Voltage drop through the headlight relay the battery ends up a little higher say 14.3.

If the regulator reference was connected directly to the battery it wouldn't go over 13.8.

How do you do that?

Either use a dedicated relay or look for another relay that has less load on it. Adding after-market headlight relays will do that also

 

[url=https://ibb.co/4sWhKc1][img]https://i.ibb.co/bH1cQxb/Ducati-Energia-Schematic-w-Notes.jpg[/img][/url]

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16 minutes ago, Kiwi_Roy said:

Actually the regulator is set for ~ 13.8 Volts, by the time you get some Voltage drop through the headlight relay the battery ends up a little higher say 14.3.

If the regulator reference was connected directly to the battery it wouldn't go over 13.8.

How do you do that?

Either use a dedicated relay or look for another relay that has less load on it. Adding after-market headlight relays will do that also

 

[url=https://ibb.co/4sWhKc1][img]https://i.ibb.co/bH1cQxb/Ducati-Energia-Schematic-w-Notes.jpg[/img][/url]

I just wired the headlight with its own dedicated supply and a couple of mini relays to eliminate the voltage drop in the light circuit so the reg doesn't get fooled.

Ciao

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To answer the original question, no a resistor would not work.  The voltage drop across a resistor is the resistance * current.  The current will be strong on a weak battery and low on a strong battery so the voltage will vary.

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I've had a a Lithium Iron battery fitted for 5 seasons and it has not needed any change to the regulator at all.  In fact I have a voltmeter fitted.  The battery starts at about 13.2V with the 6A pre-starting load.  Once it starts the voltage slowly rises as the generator recharges the battery from the starting load and the regulator gets it up to about 13.9-14V max which the makers say is perfect.  I got it fitted by Ghezzi Brian in Italy and this was the battery they recommended.  I'm sure they have lots of experience with these.  BC battery BCTZ14S-FP-S.BC do a range.   I got it on e-bay for just over £110.  This is the second to largest LiFe battery BC make for bikes and specifically for starting.  I think they recommend the largest one for a V11, but with the Ghezzi Brian tail mod I have this is the one that fits so it's all credit to the battery that it has lasted longer than any lead acid I ever had.

It is fantastically light.  I measured the peak transient cranking current and it peaked at just under 500A!  before it subsided as the motor cranked the engine to a fluctuating 150-200A.  I do put a LiFe Optimiser battery charger/health monitor on it over the winter although if disconnected these batteries keep their charge better than lead-acid.

One other bit of experience is that they don't like low temperatures.  Below 10deg.C; the internal resistance goes up and becomes noticeable in reducing the initial starting current.  However, if it is a cold morning start, then the current does start to warm it and everything is OK.  You can either let the lights load warm it a bit first or just start it - you just get a weak initial start when you first push the button but this load warms the internals.  Above 10deg.C you are unaware of anything different and the bigger battery they recommend will almost certainly make this effect significantly smaller.

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Thanks for the answers! It is now clear to me that my know-how of low-voltage DC systems is far to limited to fully understand the mechanics behind this, but my question on fooling the system has been answered.

I'm also not aware on how much the charging system on a V65 Florida (smallblock) is similar to that of the V11. I do have another question regarding the electric system on these bikes, but I need to take a picture tonight first before I can ask. Will update once done.

If this topic needs to be moved to "older models" for any further, V65 Florida questions, please do so.

 

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I'm also not aware on how much the charging system on a V65 Florida (smallblock) is similar to that of the V11.

Other than they both charge the battery.. not much. :D

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Awesome...

Anyone who can shine a light on which part this is and it's function? I can't locate it on the wiring diagram...

Edit: it is a part on my V65 Florida, not the V11...

 

20201005-200117.jpg

20201005-200135.jpg

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30 minutes ago, Tinus89 said:

Awesome...

Anyone who can shine a light on which part this is and it's function? I can't locate it on the wiring diagram...

 

20201005-200117.jpg

20201005-200135.jpg

Its hard to know I can't judge the size, is it possibly the coil for an electric petcock

http://www.thisoldtractor.com/guzzi007/schematics/1999_V11_sport.gif  item 32

Does the red wire come from Fuse 8?

Owners sometimes remove the electric valve and replace with a manual petcock.

What is the complete part No  we can see just 083 

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8 minutes ago, docc said:

Just to clarify, I am pretty sure this part is on Tinus89's V65 Florida and not his V11 . . .

I JUST edited the initial post to clarify this indeed... Part on my V65 Florida.
All it states on there are the letters "ART" and "083".

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