Saprisa data?

[Testarossa]

The new-to-me '89 Mille won't keep its new battery charged in around-town riding. It has the Saprisa alternator and the original Saprisa regulator -- some of the WG comments suggest this regulator is a weak point in the system, and MG Cycle sells a Saprisa factory upgrade. Someone along the way added an additional ground wire from the regulator housing to a clean frame bolt, but it attaches at the regulator end with a spade disconnect, which was corroded. I cleaned that up.

Alternator warning light works but goes out at idle.

Now voltage at the battery reads 12.6 at idle (1100 rpm), 13 at 2500 rpm and doesn't hit 14 until 4000 rpm. This is with the headlight on because it's hard-wired on. Guzziology says the Saprisa output should be roughly 15v at 3000 rpm (upstream from the regulator) and with the lights on this ought to barely keep the battery charged.

What all this means is that the charging system is going to be inadequate to run grip-heaters and running lights.

Dave Richardson suggests that the updated regulator puts out more voltage at lower revs. MG Cycle wants $140 for the upgrade. Anyone have direct experience with it?

[Sheepdog]

I feel your pain. I went through the same sort of problem on my wife's Piaggio BV500. Bite the bullet and get the improved regulator, or get used to buying batteries. In my case the cost of the new/improved voltage regulator was $240 (and two batteries).

[Triple Jim]

With the LED headlight and my CDI ignition, my Mille's break-even RPM is under 2,000.  My ignition draws less than 1 amp.  The result is I have no shortage of charging current, but I would not expect to run accessories like heated anything.  The regulator is the standard Saprisa.

When I ran the CDI and H4 quartz-halogen headlight, I also did not have a problem with keeping the battery charged, so I do expect I could run a couple amps worth of auxiliary lights if I wanted to.

[charlie b]

I finally decided to go whole hog with mine and got an upgraded alternator and regulator.

Voltage still drops at idle (with halogen headlight) but keeps up at revs.  With the LED headlight it is just loafing and at idle the warning light rarely comes on (unless I have heated gear turned on).

charlie

[Testarossa]

Thanks for the feedback. I've purchased an LED H4 replacement, but it's going to take some fancy metalwork to fit it in the shell, and I have a Dyna III ready to go in at the next tune-up.

Meanwhile it's a choice between $140 for the upgraded Saprisa regulator (good for maybe 20 amps) and $500 for the EME brushless upgrade, claimed 32 amp peak and 20 amps at 2000 rpm.

[Two Checks]

My 90 Cal III has a Euro spec headlight switch so I can turn off the headlight The reg was overcharging batteries so it was replaced. On the highway I can lean on the twin FIAMMs and watch the voltmeter drop past 12 volts...

[BMCMOTO]

The voltage regulator wiring harness is a separate loom.  Terminals can be replaced and soldered which improves the system some.  I run a Datel voltmeter on mine and monitor constantly.  I've seen some wild readings from 11.2 to over 16 volts.  I have run heated jacket and gloves, risky business without the voltmeter.  Not a very good system but I've gotten by.  I would go the EME / DUCATI ENERGIA route except I aint made of money.  I have been trying to figure out if the Shindegen voltage regulators are compatible and if they might offer some benefit.  My understanding of these charging systems is limited.  I think that they are full output all the time, once up to speed, and the regulator / rectifier  burns off the unused voltage /  amperage.  At any rate I will be paying close attention if someone answers these questions.  I also have some questions about a small ammeter and shunt I purchased with the idea of having more information to work with.  The shunt allows a specially calibrated voltmeter to read as an ammeter, but does the shunt carry the starting load and does it need to be rated for the amperage that the starter would draw??  See what I mean about knowing just enough to get into trouble and maybe not enough to find my way home again.  At any rate I'll be watching /  listening.

Brian

[Testarossa]

Regarding the shunt/ammeter issue and the starting motor draw:  One reason the starter motor has its own high-amperage circuit is to isolate the rest of the electrical system from that power spike. If the ammeter is wired properly the only starting load it will see is the low amperage going through the solenoid.

[Stephan Grahn]

I had the same problem with my SP III. Turned out that the Motoplat ignition system runs at full power independent of engine revs. Changed to a Silent-Hektik ignition system and no more charging issues.

//Stephan

[Testarossa]

I did the math. The halogen headlight draws 4.5 amps (5 at idle), the ignition system about 6.6 amps (7.8 at idle). According to the chart in Guzziology, with the headlamp off I should get breakeven at about 1500 rpm, with the lamp on breakeven should be 2000 rpm and I might be able to run heated grips OR LED running lights (each 2.5 amps) at 3000 rpm. With everything on I'll need 4000 rpm. I ordered the upgraded Saprisa regulator and will monitor the system with a voltmeter. We'll see how it goes.

[BMCMOTO]

This is what I bought.  The wiring instructions are in the listing but not specific enough for me to understand.  Can any of you tell me how this shunt works in this situation and does the starter load risk ruining the shunt?

   https://www.amazon.com/gp/product/B00BYQSXPI/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

Brian

[Testarossa]

I have a similar ammeter/shunt in my camper van, wired between the battery and inverter to measure DC current going to the inverter when I use AC loads.

The starter motor can pull 300 amps. That load does NOT go through the main wiring harness, or it would toast every wire and switch in the circuit. If you wire the ammeter and shunt between the voltage regulator (the power supply) and the battery (the load) you'll be good.

[Old Jock]

This is what I bought.  The wiring instructions are in the listing but not specific enough for me to understand.  Can any of you tell me how this shunt works in this situation and does the starter load risk ruining the shunt?

   https://www.amazon.com/gp/product/B00BYQSXPI/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

Brian

As Testarossa states the starter circuit is isolated and the current your starter motor pulls goes through the thick wire from battery to solenoid at the starter motor. The solenoid is just a hefty relay, well its a bit different inside but the application is very similar. The shunt would only see the current pulled to engage the solenoid, like the pilot or switch side of a relay. I think typically that's around 40-50A for a split second then drops to around 10A. As also stated the current the starter motor draws is somewhere typically 250-300A, so were it wired directly, ITS NOT, it would fry the shunt.

The shunt in that diagram is measuring the current after the load, i.e. on the negative side, its simply an accurate, low value resistor and yes all the current flows through the shunt that the circuit draws.

So the current flow in the diagram is Power Supply + to Load +; Load - to Shunt; Shunt to Power Supply -

What the "Ammeter" is actually measuring is the voltage difference across the shunt, as resistance is known then Volts are proportional to Amps

The Saprisa as I remember are single phase, permanent magnet alternators so they push max output for any given RPM, they are unregulated. This means that the Regulator has to sink any excess power as heat, to control the voltage to the battery............ ....hard life for the regulator.

If/When mine fails on the Sport 1100 then I'm going the Shindengen route, its the reg/rec of choice for Ducati owners.

John 

[BMCMOTO]

See this is where I get lost, the starter current can't go through the shunt is that correct?  If starter current can't go through the shunt then how does one attach the shunt to show current flow in the electrical system.  I get that the starter draw is too high for the shunt.  I can't place the shunt between the battery - and the chassis -, all the starter draw would go through it.  So using this diagram please show me, tell me, where do I hook up the shunt.  I really am a dolt sometimes and I think this is one of those times.

http://www.thisoldtractor.com/guzzi007/pdfs/1987_California_III.pdf

Brian

[Old Jock]

Ok I see where you are coming from.

As I understand it you are quite correct Brian; to place the shunt between the chassis and battery negative would let it see starter motor current.

The shunt can be placed on the positive side instead.

This of course would be a Cali 3 with its weird alternator with what I think is a center tap going to the battery.

There is some speculation on how it works on this thread

http://wildguzzi.com/forum/index.php?topic=85835.msg1354733#msg1354733

So now I throw my hands up and admit I'm unsure, as I'm not clear if the reg feeds the system through, or partially through, that center tap

Kiwi Roy or Wayne Orwig are your best bets............... .............If they don't chime in here try dropping a PM to Roy he is very helpful and knowledgeable

John

[BMCMOTO]

Instead of cluttering this up even more I'll start a new thread.

Brian

[Kiwi_Roy]

See this is where I get lost, the starter current can't go through the shunt is that correct?  If starter current can't go through the shunt then how does one attach the shunt to show current flow in the electrical system.  I get that the starter draw is too high for the shunt.  I can't place the shunt between the battery - and the chassis -, all the starter draw would go through it.  So using this diagram please show me, tell me, where do I hook up the shunt.  I really am a dolt sometimes and I think this is one of those times.

http://www.thisoldtractor.com/guzzi007/pdfs/1987_California_III.pdf

Brian

If you combine the two red wires, the one on the battery and the one terminated on the solenoid terminal put them on one terminal of the shunt, connect the other terminal to battery+
Note; the main starter wire goes straight to the solenoid as before.
The Ammeter only measures the current going to and from the battery but not starter.

To test, turn the lights On, the ammeter should read Negative 4 or 5 Amps
Start the motor, when you rev it up it should read Positive by an Amp or two.

The instructions are very vauge about the power supply. it may be when you wire it to 12 VDC it won't work in which case you may need to run it from a small battery.
3.Please note that the power supply terminal shares same ground wire with the tested terminal. Therefore, the tested terminal of ammeter must be connected between the negative pole of tested device and the negative pole of power supply for tested device    Don't ask me what the heck that means
There is no point trying to measure the start current as it will max out at 99.9 Amps
You need to feed the electronics from a switched circuit so it doesn't drain the battery if left on for long periods.

[Old Jock]

I just Knew Roy would have a fix!!!!

[Testarossa]

Well, I installed the $140 "update" Saprisa rect/regulator. It has seven terminals instead of four, and instructions not to use the extra three. Installation requires either snipping off the unused spades or trimming the plastic female plug that mates the regulator to the wiring harness. I trimmed the plastic.

Result was disappointing. The new box outputs no more power at low rpms (which is what I wanted) and maxes out at 13.5v at higher speeds. The original box hit 14v at 4000 and 14.3 and 4500 and up.

So I'm back to the original regulator. Someday when I feel flush I may go for the 28-amp Ducati charging system sold by EME for $500. Meanwhile I'll try to fit an LED headlamp, with a switch to turn it off as necessary. I now find, too, that Dave Richardson sells an "improved" regulator for $90 -- wish I'd seen that sooner.

And if anyone needs a shiny used-only-ten-miles seven-spade Saprisa rectifier-regulator, ping me. Vendor doesn't take returns on electrical equipment.