Author Topic: Vintage Charging Systems / Indicators  (Read 633 times)

Offline n3303j

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Vintage Charging Systems / Indicators
« on: October 02, 2025, 08:11:28 AM »
Old Guzzi charging systems:
So here I am 300 miles north of home with a dead battery in the '77 T3.
Turns out the alternator rotor failed (again, open circuit). No sparks = no go. Last one from EME lasted about 45,000 miles. And I bought their premium offering.

So I started thinking about the joys of the permanent magnet rotor in my '98 V11EV. That thing never going to fail. Except back in April the solid state OEM regulator decided to stop regulating. So, instead of no spark I get percolating battery. Guess there is no way to win with charging systems ysing indicator lights.

Just venting here BUT my experiences sure make a case for a VOLTMETER on the dash rather than that dopey red light. Rotor opened mid run so I saw red on startup but indicator gave no clue to depleting battery. Voltmeter would have provided plenty oif warning.

Same with the V11. Red light said nothing about overcharging. Voltmeter would have shown abnormally high voltage at the battery. Gives me something to think about while I await extraction.

Sure makes me appreciate the magneto that was on my '66 R60/2.

'98 MG V11 EV
'96 URAL SPORTSMAN
'77 MG 850T3 FB

Offline Dirk_S

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Re: Vintage Charging Systems / Indicators
« Reply #1 on: October 02, 2025, 08:23:10 AM »
Having my own charging issues with my R80 at the moment—first the diode board, and now the regulator. Discovered the battery ground cable was loose, which hopefully explains the regulator failure. I agree about the benefit of a voltmeter. I recently bought a handlebar-mounted USB port that displays the voltage which helped me diagnose my current regulator issue. I’m curious if that voltmeter on the USB port is just as good as a dedicated voltmeter?

This is the one I bought, my second; first one crapped out a bit prematurely, hoping it was a just dud:

EXTRACTME Motorcycle USB Charger, 6.8A Quick Charge 3.0 Dual USB Motorcycle Phone Charger with Voltmeter & ON/Off Switch, Waterproof Quick Disconnect SAE to USB Adapter for Phone, Tablet, GPS - Blue https://a.co/d/7m8vlZG



« Last Edit: October 02, 2025, 10:16:29 AM by Dirk_S »
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Offline wirespokes

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Re: Vintage Charging Systems / Indicators
« Reply #2 on: October 02, 2025, 09:22:09 AM »
I've carried a spare rotor and diode board on my travels, but never needed them. A friend needed to borrow the rotor once. Of course, that's because I had the tools and parts. It was the clutch cable that broke 20 miles from the US border (I was in Canada heading into NY) that I didn't have a spare. Of course. :-)

I've heard of guys buying a car battery, strapping it to the seat and getting home that way with a dead charging system. I've also heard that with the lights off, you can make it 100 miles before the battery goes flat. Stop and recharge, then go another 100.

Offline n3303j

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Re: Vintage Charging Systems / Indicators
« Reply #3 on: October 02, 2025, 09:32:30 AM »
Once rode 125 miles to home on my fully charged Odyssey 925 after the last rotor died. But have no faith that I could make 300 miles and find a charging station en route.

But what really surprises me is the failure rate on these rotors.  It's a really simple winding of reasonably heavy wire. It should last forever. Someone is missing the basics in the engineering or manufacture if this part.

I do spin the engine and am not unhappy running continual 4,500 RPM through the hills.  No problems cruising at 5,000 RPM if wind and loads dictate it. Makes me wonder if the rotor would last longer if kept to an average 3,500 RPM?
'98 MG V11 EV
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'77 MG 850T3 FB

Offline guzzisteve

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Re: Vintage Charging Systems / Indicators
« Reply #4 on: October 02, 2025, 09:50:52 AM »
I would change supplier for rotor.
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Offline n3303j

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Re: Vintage Charging Systems / Indicators
« Reply #5 on: October 02, 2025, 09:53:16 AM »
I would change supplier for rotor.
I just did. But I've had really good luck with other EME products. We'll see how the MG Cycle iteratoon holds up.
'98 MG V11 EV
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Offline Dukedesmo

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Re: Vintage Charging Systems / Indicators
« Reply #6 on: October 02, 2025, 10:56:57 AM »
Following a recent rotor failure on my '79 LM2, I had it rewound by a local specialist. They tell me it is now better than original and so should last longer.


Time will tell I guess, though if it lasts 46 years like the original did, it won't be me replacing it...    :laugh:
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Offline chuck peterson

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Re: Vintage Charging Systems / Indicators
« Reply #7 on: October 02, 2025, 11:09:53 AM »
Making electricians out of bikers since 1929?

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Offline SemperVee

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Re: Vintage Charging Systems / Indicators
« Reply #8 on: October 02, 2025, 12:54:56 PM »
 FYI - My EV handlebar Voltmeter  -




« Last Edit: October 04, 2025, 03:38:59 PM by SemperVee »
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Offline n3303j

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Re: Vintage Charging Systems / Indicators
« Reply #9 on: October 02, 2025, 12:59:30 PM »
I like the mounting. Is it bonded into the Allen screw?
I'm all set for chargers as I put West Marine waterproof units into both bike's side covers.
'98 MG V11 EV
'96 URAL SPORTSMAN
'77 MG 850T3 FB

Offline SemperVee

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Re: Vintage Charging Systems / Indicators
« Reply #10 on: October 02, 2025, 01:16:30 PM »
I like the mounting. Is it bonded into the Allen screw?
I'm all set for chargers as I put West Marine waterproof units into both bike's side covers.

picture of specially made bolt and hand made bracket by machinist friend..


53 years of Street Riding - All Brands
2007 MG Norge - VroomHilda
2003 Cali Hydro EV
2012 Victory CCT
2007 MG RED Norge
14 Harleys 2 VStrom 1000's
2005 BMW K1200LT, 81 R100RT, 73R/75/5

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Moto Guzzi - Making mechanics out of Riders since 1921

Offline Wayne Orwig

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Re: Vintage Charging Systems / Indicators
« Reply #11 on: October 03, 2025, 08:25:43 AM »
On the later model EV, they stopped putting the stupid light in the dash. It was totally worthless also.
With a burned-out rotor on yours, not rotor current, so no light will light.

Get a simple voltmeter and be done with it. I like mine with a simple low-normal-high LED.
Scientist have discovered that people will believe anything, if you first say "Scientists have discovered...."

Offline n3303j

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Re: Vintage Charging Systems / Indicators
« Reply #12 on: October 03, 2025, 07:19:35 PM »
On the later model EV, they stopped putting the stupid light in the dash. It was totally worthless also.
With a burned-out rotor on yours, not rotor current, so no light will light.

Get a simple voltmeter and be done with it. I like mine with a simple low-normal-high LED.
Of course the rotor fails in use. So you begin a trip with red light with key on at startup. Light disappears after first rev to 2,000 RPM. Subsequently the rotor fails and you can drive until the battery is out of sparks with no clue that you are not charging the battery. In the early Bosch system a voltage indicator is a must for early warning of an actual failure. Red dash lamp will not tell you of an en route failure.
'98 MG V11 EV
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Offline wirespokes

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Re: Vintage Charging Systems / Indicators
« Reply #13 on: October 04, 2025, 11:13:53 AM »
Once rode 125 miles to home on my fully charged Odyssey 925 after the last rotor died. But have no faith that I could make 300 miles and find a charging station en route.

But what really surprises me is the failure rate on these rotors.  It's a really simple winding of reasonably heavy wire. It should last forever. Someone is missing the basics in the engineering or manufacture if this part.

I do spin the engine and am not unhappy running continual 4,500 RPM through the hills.  No problems cruising at 5,000 RPM if wind and loads dictate it. Makes me wonder if the rotor would last longer if kept to an average 3,500 RPM?
It's not the speed of rotation but the change of inertia. Hard acceleration/deceleration - that's what does it. I've been told the wires break where they come through to attach to the slip rings. The windings loosen up and work back and forth, eventually work hardening the wire which then snaps.

Offline Antietam Classic Cycle

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Re: Vintage Charging Systems / Indicators
« Reply #14 on: October 04, 2025, 03:06:19 PM »
It's not the speed of rotation but the change of inertia. Hard acceleration/deceleration - that's what does it. I've been told the wires break where they come through to attach to the slip rings. The windings loosen up and work back and forth, eventually work hardening the wire which then snaps.

Convert rotors should last forever then!  :grin:
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Offline wirespokes

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Re: Vintage Charging Systems / Indicators
« Reply #15 on: October 04, 2025, 08:40:32 PM »
Convert rotors should last forever then!  :grin:
Do they?

How about convert u joints? Do they last forever? Seems like the should.

Offline Kiwi_Roy

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Re: Vintage Charging Systems / Indicators
« Reply #16 on: October 05, 2025, 01:41:46 AM »
Its not just Guzzi Rotors that fail, a friend asked me to look at his 450 Honda not charging, it had an open rotor.
Yes a Voltmeter is a good idea I have put them on quite a few bikes, On my V7III Special I see voltage from 12.5 - 14.2
Connect it to part of the wiring that is lightly loaded so you don't hav it effected by Voltage drop in a high current circuit.
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Offline Kiwi_Roy

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Re: Vintage Charging Systems / Indicators
« Reply #17 on: October 05, 2025, 01:50:18 AM »
Once rode 125 miles to home on my fully charged Odyssey 925 after the last rotor died. But have no faith that I could make 300 miles and find a charging station en route.

But what really surprises me is the failure rate on these rotors.  It's a really simple winding of reasonably heavy wire. It should last forever. Someone is missing the basics in the engineering or manufacture if this part.

I do spin the engine and am not unhappy running continual 4,500 RPM through the hills.  No problems cruising at 5,000 RPM if wind and loads dictate it. Makes me wonder if the rotor would last longer if kept to an average 3,500 RPM?

Someone suggested strapping a car battery to the bike and riding home, probably cheaper than hiring a truck.
I wonder if anyone makes a permanent magnet replacement for a wound rotor?
17 V7III Special
76 Convert

Moto Guzzi - making electricians out of riders since 1921

Offline n3303j

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Re: Vintage Charging Systems / Indicators
« Reply #18 on: October 05, 2025, 08:43:04 AM »
Someone suggested strapping a car battery to the bike and riding home, probably cheaper than hiring a truck.
I wonder if anyone makes a permanent magnet replacement for a wound rotor?
The V11 has the permanent magnet rotor. It requires a totally different regulator system since it can't limit output by throttling rotor current input.
My V11 regulator quit in the way home from Alabama so the system delivered full output to the battery. It boiled the battery.
No easy way to win without a voltmeter on the dash.
I remember the old generator cars (and my airplane, '66 C150) had an ammeter in the circuit so you could witness current flow and detect any abnormal drains. Amp & Volt meter would let you make intelligent decisions about the whole electrical system. Seems that shouldn't be a problem to build into these new digital display consoles. Might as well add head and oil temperatures as well.
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Offline Dukedesmo

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Re: Vintage Charging Systems / Indicators
« Reply #19 on: October 05, 2025, 10:41:17 AM »
I have a digital voltmeter on the dash but also a Gammatronix Battery level charge LED which is useful as it's colour coded for different charging scenarios and so less distracting than watching volts, essentially you want it to be green whilst engine running; https://gammatronixltd.com/epages/bae94c71-c5b6-4572-89a1-e89006e78fbe.sf/en_GB/?ObjectPath=/Shops/bae94c71-c5b6-4572-89a1-e89006e78fbe/Products/E




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Offline wirespokes

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Re: Vintage Charging Systems / Indicators
« Reply #20 on: October 06, 2025, 11:45:18 AM »
Someone suggested strapping a car battery to the bike and riding home, probably cheaper than hiring a truck.
I wonder if anyone makes a permanent magnet replacement for a wound rotor?
There is a permanent magnet system that can replace the bosch electromagnet alternator. I have a 76 convert and a G5 that were both converted before my ownership, so I don't know how the rotors mount. I think they mount differently, but since I haven't removed either, I don't know. In the Bosch system, the diode board and voltage regulator are two separate items, unlike the permanent magnet (Ducati) system where they're both integrated into one solid state unit.

Offline DaGootz

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Re: Vintage Charging Systems / Indicators
« Reply #21 on: October 07, 2025, 05:53:46 AM »

This is the one I bought, my second; first one crapped out a bit prematurely, hoping it was a just dud:

Here one I use on my 2002 BMW K1200RS https://www.batterytender.com/products/lcd-voltage-indicator-quick-disconnect-usb-and-usb-c-charger-adapter  It's nice with the two USB ports, I use them for power supply for my two-way communication and bluetooth receiver for my Garmin. So really, it serves three purposes.
« Last Edit: October 07, 2025, 05:55:14 AM by DaGootz »

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