Thu, 21 Jul 2022 17:30:21 +0000

Member
1985 Px150e vlx2t
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1985 Px150e vlx2t
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Thu, 21 Jul 2022 17:30:21 +0000 linkquote
There is a warning on it. I'm trying to figure out why the battery won't charge. Both wires going into A and A terminals read around 20volts AC when idling and go up with reving engine. All seems normal there. With the engine running the B+ terminal reads around 1-2 volts and revving engine drops that voltage to half a volt. I tried a brand new regulator with same outcome. I currently do not have a working battery to put in to test it. And I'm wondering if this regulator won't put out a charging rate unless it has a battery connected to it. Hence the warning written on it to not dtach cables with motor running.


Pic of regulator

Thu, 21 Jul 2022 17:38:30 +0000

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1985 Px150e vlx2t
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1985 Px150e vlx2t
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Thu, 21 Jul 2022 17:38:30 +0000 linkquote
Those two purple are ac voltage. The gray lead coming from B+ terminal on the regulator goes to that capacitor. It reads 1.5 volts disconnected from capacitor and taking the reading from the regulator. If I plug it back into capacitor and take reading from battery terminals it's the same reading. I'm stumped on why the regulator won't put out 13.7 volts or higher to charge the battery. I don't know what the yellow G terminal is and what voltage it should be reading. Any help would be appreciated thank you.
Thu, 21 Jul 2022 17:41:05 +0000

Member
1985 Px150e vlx2t
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Location: newark, de, usa
 
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1985 Px150e vlx2t
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Thu, 21 Jul 2022 17:41:05 +0000 linkquote
Picture of the setup



Thu, 21 Jul 2022 18:29:34 +0000

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 08 Stella (for now)
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 08 Stella (for now)
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Thu, 21 Jul 2022 18:29:34 +0000 linkquote
I don't know that regulator, but in general, one of the outputs should be AC and the other DC. The DC side should work with or without a battery.

What's the source of that regulator/rectifier?
Thu, 21 Jul 2022 18:42:39 +0000

Molto Verboso
Joined: Sat, 15 Nov 2008 17:07:56 +0000
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Location: Seattle
 
Molto Verboso
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Location: Seattle
Thu, 21 Jul 2022 18:42:39 +0000 linkquote
Believe it or not, the G or B+ is probably a 12dc *input*

These regulators have a crowbar circuit, in that if they are not connected to a 12vdc feed, they internally disconnect. This is to protect them, as without the battery to absorb the high voltage spikes and other noise, the unregulated ac will kill them in short order.

Disconnecting them under load is a really terrible idea.

Last edited by rob hodge on Thu, 21 Jul 2022 18:54:07 +0000; edited 1 time
Thu, 21 Jul 2022 18:45:00 +0000

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 08 Stella (for now)
Joined: Thu, 16 Jun 2011 14:59:35 +0000
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 08 Stella (for now)
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Thu, 21 Jul 2022 18:45:00 +0000 linkquote
Wow. I have no doubt you're right, that just seems like a terrible design.

Does it not have a fuse on the DC+ side, then?
Thu, 21 Jul 2022 18:56:14 +0000

Molto Verboso
Joined: Sat, 15 Nov 2008 17:07:56 +0000
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Location: Seattle
 
Molto Verboso
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Thu, 21 Jul 2022 18:56:14 +0000 linkquote
chandlerman wrote:
Wow. I have no doubt you're right, that just seems like a terrible design.

Does it not have a fuse on the DC+ side, then?
It has a fuse on the output side typically, but not on the input.

Why exactly is that a terrible design? The addition of this circuit is pretty much the sole reason the 80's and later voltage regulators are significantly more reliable and longer lasting than those on 60's and 70's scooters.
Thu, 21 Jul 2022 19:22:36 +0000

Hooked
Joined: Wed, 25 Aug 2010 16:47:27 +0000
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Location: United Kingdom
 
Hooked
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Thu, 21 Jul 2022 19:22:36 +0000 linkquote
An7h0ny wrote:
And I'm wondering if this regulator won't put out a charging rate unless it has a battery connected to it. Hence the warning written on it to not dtach cables with motor running.
There is no DC output whatsoever from that reg/rec as the DC part of it is a series regulator fitted into the stator return path. The B+ grey wire is the sense function input and should read battery voltage with the ignition switched on. You will need a fully charged battery fitted to test it!
Thu, 21 Jul 2022 21:28:25 +0000

Member
1985 Px150e vlx2t
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1985 Px150e vlx2t
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Thu, 21 Jul 2022 21:28:25 +0000 linkquote
Thank you guys now that I know the B+ terminal is a sense that's plugged into that capacitor it needs to read 12 voltage from the battery when it energizes that capacitor. I ordered a sealed new battery and as soon as I install it I can test it again to see if it's charging the battery.
Thu, 21 Jul 2022 22:02:24 +0000

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 08 Stella (for now)
Joined: Thu, 16 Jun 2011 14:59:35 +0000
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 08 Stella (for now)
Joined: Thu, 16 Jun 2011 14:59:35 +0000
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Location: Nashville
Thu, 21 Jul 2022 22:02:24 +0000 linkquote
The system seems fragile as I currently understand it. If there's no battery, the regulator dies? And it only works right with a healthy battery? It's the murder-suicide of charging systems

I get that it's better than came before, but a modern regulator doesn't need a battery at all. That's what I'm comparing it to.
Thu, 21 Jul 2022 22:34:55 +0000

Member
1985 Px150e vlx2t
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Location: newark, de, usa
 
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Thu, 21 Jul 2022 22:34:55 +0000 linkquote
firekdp wrote:
There is no DC output whatsoever from that reg/rec as the DC part of it is a series regulator fitted into the stator return path. The B+ grey wire is the sense function input and should read battery voltage with the ignition switched on. You will need a fully charged battery fitted to test it!
One part I'm having trouble understanding about the series regulator fitted into the stator return path. Is the yellow terminal marked G going back to the stator and going thru something to make it change to dc voltage? How does the battery get charged after the rectifier receives 12v battery signal? I'm trying to figure out the path. My battery positive lead starts at the turn signal flash relay, shared by another wire going to the fuse and then leaving there via two smaller gauge wires. I'm pointing to the two in the picture. Im assuming that silver relay is a flasher Im not sure and stumped why a battery lead goes there first even before the fuse that protects everything else.



Fri, 22 Jul 2022 00:19:09 +0000

Molto Verboso
GL, PK, PE200 with hack, Sears Rust Badge
Joined: Tue, 24 Apr 2012 23:44:25 +0000
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Location: Deep in the heart of Texas
 
Molto Verboso
GL, PK, PE200 with hack, Sears Rust Badge
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Fri, 22 Jul 2022 00:19:09 +0000 linkquote
An7h0ny wrote:
One part I'm having trouble understanding about the series regulator fitted into the stator return path. Is the yellow terminal marked G going back to the stator and going thru something to make it change to dc voltage? How does the battery get charged after the rectifier receives 12v battery signal? I'm trying to figure out the path.
The answer is long for a post so read the explanation link below of how the regulator works and use the diagram link for European cdi bike (with turn signals after 1979) for additional illustration. After reading it a couple of times and following the explanation on the diagram you should have a better understanding.

Btw, before flash sorta got shut down on the internet, the picture on how the regulator worked page showed the electricity flow path from the stator, through each part of the regulator and then to all components.

http://www.vespamaintenance.com/elec/charger/index.html

https://www.scooterhelp.com/electrics/pages/VSX1T.p200.html
Fri, 22 Jul 2022 02:52:12 +0000

Member
1985 Px150e vlx2t
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Location: newark, de, usa
 
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Fri, 22 Jul 2022 02:52:12 +0000 linkquote
Thanks again I followed the link back to find the px200e diagram. This manual I bought neither has the right diagram and no troubleshooting procedure for charging system.



Fri, 22 Jul 2022 03:03:59 +0000

Member
1985 Px150e vlx2t
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Fri, 22 Jul 2022 03:03:59 +0000 linkquote
The diagram shows rectifier terminal G (yellow line) goes back to stator and is connected to the red line coming back to starter relay which is the battery positive lead. So now I have to figure out what that yellow line voltage is supposed to be and or what is going wrong at the stator.



Fri, 22 Jul 2022 08:47:56 +0000

Hooked
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Hooked
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Fri, 22 Jul 2022 08:47:56 +0000 linkquote
An7h0ny wrote:
Thank you guys now that I know the B+ terminal is a sense that's plugged into that capacitor it needs to read 12 voltage from the battery when it energizes that capacitor. I ordered a sealed new battery and as soon as I install it I can test it again to see if it's charging the battery.
That is not a capacitor, it's your flasher relay. It gets it's power from the ignition switch, when turned on, and also goes on to power the sense function.
To test the stator, disconnect the red and yellow stator wires and measure resistance between them. This should be very low ohms. Then do an insulation test to check that they are both isolated from earth. Voltage output between these two should be similar to the AC circuit.
Even better is a load test, put a headlight lamp between the red and yellow and start the engine. Be aware at high revs the lamp should be bright and may blow, depending on wattage, but this will show a good output.
Fri, 22 Jul 2022 13:23:12 +0000

Molto Verboso
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Molto Verboso
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Fri, 22 Jul 2022 13:23:12 +0000 linkquote
Interesting. This is great info. My Stella has been converted to a DC only system and I'm not sure if it's working properly. The battery seems to often go dead and when the charge is low, the headlight will be dim and turn signals and gas gauge don't work even at higher revs.

I'm also wondering if this causes a weak spark. My understanding that the coil(s) powering the CDI wouldn't be affected by by the drain put on them by lights, etc, but I may be wrong.
Fri, 22 Jul 2022 13:40:54 +0000

Ossessionato
Vespas 1964 GS160, 1965 SS180, 1977 V9A1T, 1983 PX150E
Joined: Sun, 17 Apr 2011 00:34:49 +0000
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Ossessionato
Vespas 1964 GS160, 1965 SS180, 1977 V9A1T, 1983 PX150E
Joined: Sun, 17 Apr 2011 00:34:49 +0000
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Location: Siam
Fri, 22 Jul 2022 13:40:54 +0000 linkquote
I've never had these problems because none of my Vespas has a battery, not even the PX with turn signals. My TV remote has batteries, but they last pretty long and are cheap to replace.
Sat, 23 Jul 2022 11:40:01 +0000

Hooked
PX150E
Joined: Sun, 28 Oct 2018 11:54:55 +0000
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Location: Florida, USA
 
Hooked
PX150E
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Location: Florida, USA
Sat, 23 Jul 2022 11:40:01 +0000 linkquote
An7h0ny wrote:
One part I'm having trouble understanding about the series regulator fitted into the stator return path. Is the yellow terminal marked G going back to the stator and going thru something to make it change to dc voltage? How does the battery get charged after the rectifier receives 12v battery signal? I'm trying to figure out the path. My battery positive lead starts at the turn signal flash relay, shared by another wire going to the fuse and then leaving there via two smaller gauge wires. I'm pointing to the two in the picture. Im assuming that silver relay is a flasher Im not sure and stumped why a battery lead goes there first even before the fuse that protects everything else.
That silver box you are pointing to is not a regulator; it is the electric starter relay. And, as others have indicated, the "capacitor" is actually the turn signal flasher.

On my 1985 US PX150E, that I bought new in 1987, I have that same original setup regulator/rectifier, and nowhere in the owner's manual there is a warning cautioning not to remove the battery.
Once, for over a week, I ran around without the battery because I was waiting for a new battery to arrive. The engine ran as usual, including the stock AC head and tail lights, while all the DC items (starter, turn signal, horn, and break light, of course, they didn't work.
That original DUCATI regulator/rectifier has never been touched, and measuring the charging voltage at the battery with motor running, it shows a charge of 13-14 V.
Sat, 23 Jul 2022 12:33:02 +0000

Member
1985 Px150e vlx2t
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Location: newark, de, usa
Sat, 23 Jul 2022 12:33:02 +0000 linkquote
sp949 wrote:
That silver box you are pointing to is not a regulator; it is the electric starter relay. And, as others have indicated, the "capacitor" is actually the turn signal flasher.

On my 1985 US PX150E, that I bought new in 1987, I have that same original setup regulator/rectifier, and nowhere in the owner's manual there is a warning cautioning not to remove the battery.
Once, for over a week, I ran around without the battery because I was waiting for a new battery to arrive. The engine ran as usual, including the stock AC head and tail lights, while all the DC items (starter, turn signal, horn, and break light, of course, they didn't work.
That original DUCATI regulator/rectifier has never been touched, and measuring the charging voltage at the battery with motor running, it shows a charge of 13-14 V.
I have the same year and model bought new by my father in 1987. I have been running the bike without battery many years as it's always dead. Someone here explained why the warning is on the regulator, it only damages the regulator if you unplug a good battery while it's running. Regulator has a 12v sense lead that disconnects itself from charge function if it doesn't sense a battery. If it's actively charging and you take away the battery it can overload it. I originally thought the regulator charged the battery. But now I'm looking at the wire schematic and it looks like once regulator receives 12v sense it must trigger the yellow lead to open and send ac voltage back to a series regulator at the stator and from there back to battery. I bought a new battery I am waiting on to arrive. Last time I replaced the battery it was pretty weak to begin with. 85 cold crank amps. I bought the battery dry and filled it with acid. I don't think I charged it long enough. And put it into the bike it started and everything ran fine but by few hours into my ride. I could no longer electric start. The blinkers went out. The battery had run out. I remember afterwards I got home put it on a battery tender and next time I restarted no problem, but again ran out battery during riding. When I checked the voltage third time after it sitting on the tender again and disconnected from bike, it read 13.3v after disconnect from tender. but an hour later after sitting with no tender it read barely over 12v. I'm starting to think the batter fell under 12 or not high enough in 12 range to activate the charge function on my regulator. I have a new sealed 120 cold crank amps battery coming and hoping that a good battery will fix the problem. I will make sure to charge it overnight this time before putting it into the bike.
Sat, 23 Jul 2022 13:31:22 +0000

Hooked
PX150E
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Hooked
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Sat, 23 Jul 2022 13:31:22 +0000 linkquote
I have read among other posts in this forums that the only regulator/rectifier that does the job correctly on this model scooter is a DUCATI one. Anything from India or Far East is suspect.
As I see it, the original regulator/rectifier system is fantastic, as long as it has not been messed with. It is made of two separate sections, the AC side and the DC side. The 2 grey wires are AC IN and AC regulated OUT. The regulated OUT is to feed the head, tail and speedo lights.
The DC part of the regulator has the B+ IN from the battery as sensing voltage, yellow out to stator that regulates its output, and the 2 black wires, one that bonds the metal case to the other black that grounds the entire unit.
At least that is my understanding of the unit.
What really fails from heat is the stator, not so much the windings, but the insulation on the input and output wires. I have had to replace my stator, but if the windings are good, the external wires can be replaced. Scooter Mercato does this service.
Sat, 23 Jul 2022 13:49:07 +0000

Hooked
PX150E
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Location: Florida, USA
 
Hooked
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Sat, 23 Jul 2022 13:49:07 +0000 linkquote
BTW, the ignition system on this model scooter is completely independent of the regulator rectifier or battery; the stator ignition wires GREEN, RED, and WHITE go straight to the CDI, also made by DUCATI and almost 100% reliable.
The green wire from the stator is from the charging coil, the red is from the pick up coil, the white is the neutral/ground. The CDI has one other green wire that connects to the kill switch.
I have over 42,000 miles on my PX,and will probably die before this motor does (rebuilt 1500 miles ago). Electrically, I have had to replace the battery 3 times, the stator once, 2 headlight bulbs and one tail light over the last 35+ years.
Sat, 23 Jul 2022 15:56:36 +0000

Member
1985 Px150e vlx2t
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1985 Px150e vlx2t
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Sat, 23 Jul 2022 15:56:36 +0000 linkquote
sp949 wrote:
BTW, the ignition system on this model scooter is completely independent of the regulator rectifier or battery; the stator ignition wires GREEN, RED, and WHITE go straight to the CDI, also made by DUCATI and almost 100% reliable.
The green wire from the stator is from the charging coil, the red is from the pick up coil, the white is the neutral/ground. The CDI has one other green wire that connects to the kill switch.
I have over 42,000 miles on my PX,and will probably die before this motor does (rebuilt 1500 miles ago). Electrically, I have had to replace the battery 3 times, the stator once, 2 headlight bulbs and one tail light over the last 35+ years.
The picture of the red one is the original factory rectifier. The blue one on the bike is the replacement piaggio one not made in India. It's old stock in sealed bag from a while ago. Everything else on the bike electrically, including all the bulbs are original. The bike has about 2200 miles on it with full rebuild I did at around 1900. I did buy one India cdi at rebuild and it failed almost immediately. The 30 year old original is back on it. Side note, the India made fuel petcock also failed. SIP parts are better quality and have been my replacement source since. Here's my rebuild post in here.

1985 px150e rebuild
Sat, 23 Jul 2022 19:51:23 +0000

Hooked
PX150E
Joined: Sun, 28 Oct 2018 11:54:55 +0000
Posts: 205
Location: Florida, USA
 
Hooked
PX150E
Joined: Sun, 28 Oct 2018 11:54:55 +0000
Posts: 205
Location: Florida, USA
Sat, 23 Jul 2022 19:51:23 +0000 linkquote
An7h0ny wrote:
The picture of the red one is the original factory rectifier. The blue one on the bike is the replacement piaggio one not made in India. It's old stock in sealed bag from a while ago. Everything else on the bike electrically, including all the bulbs are original. The bike has about 2200 miles on it with full rebuild I did at around 1900. I did buy one India cdi at rebuild and it failed almost immediately. The 30 year old original is back on it. Side note, the India made fuel petcock also failed. SIP parts are better quality and have been my replacement source since. Here's my rebuild post in here.

1985 px150e rebuild
I love your rebuild photographic documentation. You have the same rear rack I have. I should be doing a complete strip and repaint like you did. Mine is full of scratches and chips all over it, and even my wife has been telling me to get it done, now that I am retired. I don't mind that CEV 9350 US DOT tail light, but I changed mine to Euro type and put the Vespa one on my 1973 Honda CB 350 Four motorcycle, because it looks way better than its original ambulance-style one.





Sat, 23 Jul 2022 21:15:36 +0000

Member
1985 Px150e vlx2t
Joined: Thu, 14 Jul 2016 14:35:46 +0000
Posts: 24
Location: newark, de, usa
 
Member
1985 Px150e vlx2t
Joined: Thu, 14 Jul 2016 14:35:46 +0000
Posts: 24
Location: newark, de, usa
Sat, 23 Jul 2022 21:15:36 +0000 linkquote
sp949 wrote:
I love your rebuild photographic documentation. You have the same rear rack I have. I should be doing a complete strip and repaint like you did. Mine is full of scratches and chips all over it, and even my wife has been telling me to get it done, now that I am retired. I don't mind that CEV 9350 US DOT tail light, but I changed mine to Euro type and put the Vespa one on my 1973 Honda CB 350 Four motorcycle, because it looks way better than its original ambulance-style one.
That rear rack has a backrest not on in the picture but I do keep it on there. That was a option my dad bought when he bought the scooter. I actually like the taillight, looks good on the Honda. The rebuild was the best part of me taking ownership. I love this scooter.
   

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