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Voltage regulator rectifier

My 1993 California 1000 Guzzi started flashing charge light 2 years ago, would take quite a while to extinguish, but always would. Lasst year light would not go out, checked voltage at bat to be around 12 v off, and 11.8 running. Disconnected altenator, and started engine with a headlight across alternator, which came on very bright. Tried to bench test with 17 VAC across yellow leads, no output from red to case, and I do not quite know what white and black leads do. What is coming out of blk & wht ??

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SOURCE: 1979 moto guzzi v50 , red battery light on dash does not go out.

try here for a manual

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Posted on Jan 18, 2009

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SOURCE: Battery not charging

run an ohm test on the stator wires, make sure you get readings through all combinations of any 2 wires. if you don't get an ohms reading between 2 wires that means you have a broken stator winding and the stator needs to be replaced. hook up a volt meter to your battery and test battery voltage at rest (bike off), at idle (bike on and idling should be at least 12.5 - 13 volts), and steady around 3 - 4000 rpms (should be around 13-14.5 volts. if it exceeds 15 volts your regulator is bad and needs to be replaced. if all numbers are about what I said, have your battery tested. If your battery is over 1.5 years old it should be replaced anyway.

Posted on Jun 10, 2010

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1 Answer

2001 Moto Guzzi California EV won't even try to start.

pushing the start button dims the lights is a sure indication that the battery is faulty
have it load tested or replace it
charging a dead battery after a 2 year period of being flat causes what is known as sulphation of the plates and the battery will not accept a charge regardless of the charge time.

May 22, 2015 | Motorcycles

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06 gsxr 600 stalled at a stop light and wouldn't restart, already replaced the battery and stator?

It sounds like its possibly a bad regulator/rectifier. I have posted a link to a video on how to test your regulator. How to test 2 plug Regulator Rectifier for K6 K7 GSXR 750 600 1000

Jul 12, 2014 | 2007 Suzuki GSX-R 750

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Voltage regulator rectifier

Hi Mike, perform the following tests:
1. Fill acid type batteries to proper levels.
2. Charge battery overnight at 1-2 amps you need 12 volts or better after charging.
3. Make sure all connections are clean and tight especially the negative cable at both ends.
4. Hook up volt meter to battery and start engine, if meter falls below 9.5 v replace battery.
5. With engine running at 3600 RPM battery should read 14.3-14.7 volts if not continue tests.
6. Unplug voltage regulator from alternator at crankcase by front of primary cover.
7. To test voltage regulator go to:
8. With ohm meter, one lead grounded, touch alternator pin meter should read infinity, if not replace stator.
9. With ohm meter, both leads touching alternator pins meter should read 0.1 to 0.2 ohms on 1989 and later models. 0.2 to 0.4 ohms 1988 and earlier models, if not replace stator.
10. With volt meter set on AC scale, both leads touching alternator pins meter should read
16 to 20 volts AC for every 1000 RPM'S 1989 and later and 19 to 26 volts AC for every 1000 RPMS. If not replace rotor. Good luck

Jun 13, 2013 | 2011 Harley Davidson FLSTF Fat Boy

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New battery fitted but no ignition lights no power to starter, all lights indicators fuel pump works all fuses look fine can you help 2003 ev 1100 cali moto guzzi tom haggan

Hello, i haven't worked on but a few Guzzi's, but it sounds like you may have a ground issue. I would check for voltage at the ignition switch, relays & fuses. If no voltage there, check the main battery to frame ground. Then start with a continuity test from the battery to circuit box & continue until you find where the break is.... Some of these bikes, like the sport model, have 2 batteries, so if yours does, make sure that both are good....I hope this helps some.

Sep 16, 2011 | 2000 Moto Guzzi California 1100 E.V. -...

1 Answer

Regulator rectifier mid 90s hondas

you will know if the regulator/rectifier goes, if 1, all your lights go much brighter and blow when you rev the bike, or 2, if your battery is not charging. a simple test is to check the voltage at the battery with engine idling, should be about 14volts. There is nothing you can do to prevent the rectifier from going.

May 23, 2010 | 1996 Honda CB 1000 Big 1

1 Answer

I have a 1983 BMW R100RT. Potential charging problem

Hi Tom,

Typically, the charging voltage should be somewhere around 13.5VDC-14.5VDC, so you may be experiencing signs of a problem.

Before doing much else, I'd recommend you do two checks:
1) Assuming you are referring to a voltmeter mounted to the bike in your message, double check the voltage using a multimeter at the battery terminals to confirm there isn't a fault with your bike's voltmeter.

2) Because I'm unfamiliar with your particular model, I'd recommend checking the spec for your bike -- if you have a service manual, it should list the proper voltage range. Otherwise, you can probably contact a dealer or BMW tech to get the spec.

If you are below the recommended voltage range, there are a variety of possible faults.

The first that comes to mind is your regulator/rectifier circuit. The purpose of this circuit is to 1) rectify (turn the AC current generated by the engine into DC current) and 2) regulate (make the current stable at a given voltage, say 13.5 VDC, and dissipate the excess voltage as heat). Because this part turns excess electricity into heat, it's not uncommon for regulators to 'burn out."

I believe the diode board you replaced is the rectifier portion of the circuit, so it sounds like the regulator portion may need replacement. FYI, an aftermarket "reg/rec" that combines the regulator and rectifier is available for your bike (see: The advantage to switching to such a unit is that it's probably better engineered than the OEM unit (more efficient/better heat dissipation), and might last longer.

If your battery is more than a few years old, you may want to take it to a dealer or auto parts store to have checked (many will do this for free), and consider replacing it. Often one bad component in the charging system will cause other good components to fail.

Finally, here is a generic fault finding diagram that is very well put together:

Good luck!

Sep 30, 2009 | 1983 BMW R 100 RT

1 Answer

I have a CBR 1000F 1993 it charges fine when

I had the same thing happen to my CBR1100XX..

Could be both the stator/alternator or the regulator/rectifier. I'd try replacing the cheapest unit (regulator/rectifier) first. Check if the insulation on the wires going to the regulator/rectifier look burned.

FYI most Hondas are prone to charging problems.

Sep 02, 2009 | 1993 Honda CBR 1000 F

2 Answers

My 95 vortec Chev Blazer acted like the alternator was going bad lights dimmed battery quit charging. Right before the lights went out the radio started cutting on and off and the buzzer that tells you...

This is not just because of the alternator, you got to replace the rectifier circuit too. If the rectifier is not working good then the battery will not charge then you will get all the symptoms what ever you mentioned

Jul 23, 2009 | 1993 Chevrolet S-10 Blazer

2 Answers


in fact only turned over once befors starter was clicking away. Pushed it home tried again - nothing. Put battery on charger - charged up in 15 minutes - tried to start - engine turned over couple of times then click click click at starter been out this morning checked all connections and earths - charged battery up - read 13.22v when full charge light came on, tried to start up - turned over several times, getting slowwr then click click. Checked battery reading 12.17v Any suggestions - is it the battery or what else?,The fact that the voltage drops as the revs increase is very odd. However, the dash voltmeter which I assume you are using is often inaccurate. Try an alternative battery, at least to see if it starts. You could use a car battery with jump leads. With a decent battery the charging might improve too.,,,

Nov 10, 2008 | 2002 Moto Guzzi California 1100 EV

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