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Discussion Starter · #1 · (Edited)
I need one, I think. I checked for stator output w/DVM. Good there. I checked for grounding of stator wires. All good. Little idiot light (aftermarket and located on dash: "Battery condition check status' keeps turning yellow. When it does so, it affects the elec tach. It goes to zero. Understandable as they are very voltage sensitive.

Battery charges normally (Shorai with a dedicated Shorai charger) and I focused on the VRR. I'm sure there will be some to say check the batt. I suppose I can bring it to Auto Zone to have checked out. But fact it successfully charges, makes me look elsewhere.

I can get another Duc VRR from dealer or Duc Omaha. PN: 54040111C - VOLTAGE REGULATOR, price $153.58.

Or I can get a 'Ricks MotorsportElectric' with the Mosfet technology: HOT SHOT DUCATI RECTIFIER REGULATOR 10_008H. It is $152 + s/h

Any real upside for this aftermarket VRR? After all, the OE lasted 15 years and 18k miles. Don't really feel like rolling the dice if performance is less than the Duc version.

Comments? Steve
 

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Battery charges normally (Shorai with a dedicated Shorai charger) and I focused on the VRR. I'm sure there will be some to say check the batt. I suppose I can bring it to Auto Zone to have checked out. But fact it successfully charges, makes me look elsewhere.
You need to measure and report the DC voltage across the battery terminals when the engine is turning at 5,000 rpm to diagnose a bad VRR.

You should see 13.5 – 14.5 volts.

The Shorai charger will stop charging when the battery reaches a preset voltage level but only a load test can assess a battery's health.

The best way to assess battery health is to take it to an auto supply store and have them do a load test. A load test determines if the battery can deliver its rated current to a resistance similar to that of a starter motor without dropping below a voltage threshold value.

Alternatively, you can simulate this test by first charging the battery (a healthy fully charged battery should measure about 12.6 volts) and then remove the fuse to the fuel pump so that when the engine is cranked it won't start. Measure the voltage across the battery terminals as it cranks. If the voltage drops into the upper-9 volt range, you need a new battery.
 

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Discussion Starter · #3 ·
Thanks. I'll take the batt out, charge it and then take it to a shop to be tested. Simple enough to sort it out. S
 

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Hi,i changed for a mosfet regulator on both ST2 and ST4s from roadstercycle.com,very satisfied.
 

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The MOSFET regulators are known to be more reliable and provided improved (more stable) voltage regulation. I have them in the 916 and the ST4s. Both bike's electrical systems are noticeably improved after the change. I also replace the stator on the 916 with an aftermarket part, which further improves it.

When the bike is running you're not running off the battery, you're running off the bike's generator and VRR output. However, at idle the VRR output is at its lowest. If it's too low, you may be drawing from battery reserve to some extent. More important if the VRR out is low, you have noting left in reserve after powering the fuel pump, ECU, lights and whatever else to keep the battery charged and you will likely have a battery failure. The light you're talking about turning yellow is an indication of a poor charging system when the bike is running.

It has been covered to death here, a search will find much info on the steps to take to isolate a charging system fault. Starts with a voltage check at the battery terminals both at idle and then above 4000 RPM. If the voltages fall short at the battery, start stepping back to the generator.

You should also consider poor electrical connections / grounds. Before changing the VRR and stator on the 916, I was getting around 10 VDC at the gauge cluster. Some house keeping in regards to electrical connections made some improvement. Worth doing that work too.

I bought both my MOSFET VRRs off eBay used. They are easily found in the $40.00 range. Yamaha R1 and a few others are a good source. There are NEW ones on there that are cheap, but they are China knock-offs and are to be avoided. I bought the plug kits for around $20.00 and wired up my own harness. Easy and inexpensive.

Grab some coffee and read this. http://www.ducati.ms/forums/80-hall-wisdom/94947-upgrade-fix-no-more-charging-regulator-rectifier-problems.html

I bought my plug kit here: Home

Our STs require some relocation work for the new VRRs to fit. They don't fit in the air intake like the OEM. I attached mine to an extra bolt hole in the battery tray. Not very pretty, but perfectly effective. The 916 was easier, as it is already part of the battery tray and bolted right on after relocating one bolt hole.

ST4s installation


The high speed duct tape is to keep the Shorai charger pigtail in place!
 
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The MOSFET regulators are known to be more reliable and provided improved (more stable) voltage regulation. I have them in the 916 and the ST4s. Both bike's electrical systems are noticeably improved after the change. I also replace the stator on the 916 with an aftermarket part, which further improves it.

When the bike is running you're not running off the battery, you're running off the bike's generator and VRR output. However, at idle the VRR output is at its lowest. If it's too low, you may be drawing from battery reserve to some extent. More important if the VRR out is low, you have noting left in reserve after powering the fuel pump, ECU, lights and whatever else to keep the battery charged and you will likely have a battery failure. The light you're talking about turning yellow is an indication of a poor charging system when the bike is running.

It has been covered to death here, a search will find much info on the steps to take to isolate a charging system fault. Starts with a voltage check at the battery terminals both at idle and then above 4000 RPM. If the voltages fall short at the battery, start stepping back to the generator.

You should also consider poor electrical connections / grounds. Before changing the VRR and stator on the 916, I was getting around 10 VDC at the gauge cluster. Some house keeping in regards to electrical connections made some improvement. Worth doing that work too.

I bought both my MOSFET VRRs off eBay used. They are easily found in the $40.00 range. Yamaha R1 and a few others are a good source. There are NEW ones on there that are cheap, but they are China knock-offs and are to be avoided. I bought the plug kits for around $20.00 and wired up my own harness. Easy and inexpensive.

Grab some coffee and read this. http://www.ducati.ms/forums/80-hall-wisdom/94947-upgrade-fix-no-more-charging-regulator-rectifier-problems.html

I bought my plug kit here: Home

Our STs require some relocation work for the new VRRs to fit. They don't fit in the air intake like the OEM. I attached mine to an extra bolt hole in the battery tray. Not very pretty, but perfectly effective. The 916 was easier, as it is already part of the battery tray and bolted right on after relocating one bolt hole.

ST4s installation


The high speed duct tape is to keep the Shorai charger pigtail in place!
SS904 is dead on. I did the same swap with the Yamaha R1 RR (Shindengen FH020AA) on both a previous VFR and the ST3. Weird electrical gremlins went away.

The FH020AA has taller fins than the stock RR so it won't fit in the cowl as SS mentioned. I got around this by grinding the RR fins down a bit to gain clearance, using an existing bolt hole to secure one side and a dab of silicon on the other end to keep it in place.

Scott L.
 

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I buy used 3-phase (3 yellow wires) relays either on ebay or from MetroDuc. $40 or less.

I am using one of these on my 2-wire stator on my Moto Guzzi. Runs great! And load tested with the additional 90 W jacket, and 30 W gloves. No issues!!!
 

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I’ve replaced my 1997 ST2 R/R with a Shindengen FH020H-AA MOSFET regulator/rectifier. Designed for 3 phase but seems to taking the ST2 single phase stator output of approx.. 38A AC @5000 rpm (measured with a clamp meter (reg connected)). The reg output with a charged battery and low beam on settled around 12- 14A, so at that stage the unit is shunting to gnd around 24A. Obviously that would change depending on the current draw/load, but I would think the stator will be outputting around 38A @ 5000 rpm regardless of load on the reg output. Surprisingly the new unit only gets mildly warm. I tried a couple of cheaper units but they failed almost straight away.

I’ve made up a bracket on the horiz head, so that the reg sits in a vent in the fairing, and gets good airflow – see pic.
 

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Note that you cannot really measure the AC current with a clamp-on Ammeter. The Ammeter is designed to measure true RMS sine wave. With the RR connected, it's not a nice sine wave any longer. You get a value, but it's not realistic.

You need a shunt, and an o'scope to see what's flowing.

If you were dumping the stator's energy into a resistive load (like a bunch of incandescent lights), then it would be accurate.

BTW nice job relocating the RR !!
 
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