Battery not charging - Regulator/Rectifier problem?

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Cooklets
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Location: Nottingham

Battery not charging - Regulator/Rectifier problem?

Post by Cooklets »

Hi everyone. As a Morini newcomer I'm working away on my 1975 Strada trying to get it roadworthy.
I don't think the battery is charging. I put a meter across the battery it just shows the 'at rest' voltage of 12.8 Volts, and doesn't change when I start the engine. I tested the output of the alternator and am getting 50V between the two yellow wires and 25V between the red and one of the yellows. I appreciate that this is not quite the 60/30V required, but not far off, and maybe if I revved it more the voltages could increase further (I am missing the electronic rev counter). So I'm guessing that the problem could be somewhere in the wiring, or be a faulty regulator/rectifier. I've tried putting a meter between the earth of the bike and the output spade of the reg/rect which connects to a brown wire, but this is showing nothing when the engine is running.
My question is - is this the right way to test the Regulator/Rectifier? And if so is mine broken? I'd be very grateful for any help from all the experts out there. If my reg/rect is a dud, I'm in the market for a new one!
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MarkB
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Re: Battery not charging - Regulator/Rectifier problem?

Post by MarkB »

I'm certainly no electrical expert, but when my own '75 Strada lost the battery charge, I traced the problem to a poor earth connection. I hope it's something as simple in your case.
"I'll have a V please, Bob."
Steve Brown
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Re: Battery not charging - Regulator/Rectifier problem?

Post by Steve Brown »

As well as what Mark said, check the output from the reg/rec at the rosso/red terminal. That's where you should be getting 13 to 14.8 volts. Also another point lots of us miss and don't even know about is that brown wire going to the reg/rec should have battery voltage when the ignition is switched on-this in turn switches the reg/rec on.
So make sure the brown wire is live with ignition on and go over all the earth points and fuse box connections including the fuses themselves.
If all that is as should be then it sounds like a duff reg/rec.
All donations to the rest home for old Camels, Leicestershire.
Al B
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Re: Battery not charging - Regulator/Rectifier problem?

Post by Al B »

The manual has a charge test procedure. Connect the meter to measure the current going in/out of the battery and read the amps with different amounts of electrics turned om or off and different revs. Don't use the starter obviously!!

Mine wouldn't sound the horn at idle with the headlight on for it's MOT. Any revs above idle and it was fine
Cooklets
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Re: Battery not charging - Regulator/Rectifier problem?

Post by Cooklets »

Thanks for your prompt replies Mark, Steve and Al.
I've already fitted a nice fat earth wire from the regulator fixing bolt to the engine.
The Regulator doesn't have a red output, just the two yellows from the alternator and a brown wire which is feeding in 12V from the battery. There is an empty connector from the regulator marked R but it's not connected to anything.
I've also checked all the fuses etc.
Putting a meter across the battery shows no amps, but a voltage figure which gradually drops as the engine is run.
I'm thinking it's time to try a new regulator/rectifier. I'll give Mdina a try.

Thanks again all!
Steve Brown
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Re: Battery not charging - Regulator/Rectifier problem?

Post by Steve Brown »

Cooklets wrote:Thanks for your prompt replies Mark, Steve and Al.
I've already fitted a nice fat earth wire from the regulator fixing bolt to the engine.
The Regulator doesn't have a red output, just the two yellows from the alternator and a brown wire which is feeding in 12V from the battery. There is an empty connector from the regulator marked R but it's not connected to anything.
I've also checked all the fuses etc.
Putting a meter across the battery shows no amps, but a voltage figure which gradually drops as the engine is run.
I'm thinking it's time to try a new regulator/rectifier. I'll give Mdina a try.

Thanks again all!
Aha! If that is a standard reg/rec it may be the red wire is missing! Do a (DC) voltage check again between that connector marked red and earth. If you get output then you're in business. That red normally goes via the fuse board/panel to the battery to charge it. On that fuse panel you should see a group of four terminal where the reds are gathered together. Just make sure it's the right group of four, obvs. If your reg/rec is giving out a charge your battery will then get it too.
Strange if it is missing and maybe a previous owner has also had electrical challenges.
All donations to the rest home for old Camels, Leicestershire.
mbmm350s
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Location: Berkshire UK

Re: Battery not charging - Regulator/Rectifier problem?

Post by mbmm350s »

The Regulator doesn't have a red output, just the two yellows from the alternator and a brown wire which is feeding in 12V from the battery. There is an empty connector from the regulator marked R but it's not connected to anything.
Correct for 350s (sport/strada )
The red from the generator goes to the fuse box, and then to the battery and main switch.
Assume you checked 12V on the brown as others have said, this feeds the control side of the regulator and it doesn't function if this is disconnected or indeed if the voltage there is low (very flat or dead battery)

You can change your system from the three wire to two wire, which is more conventional (i.e more choice) and gives a little more output.
it's very simple you just don't connect the red wire from the stator to anything just insulate it well.
I have this setup on my 350 with an 18A regulator.
The two wire system was fitted to 500s.(road bikes) In days of old the 500 regulator was more expensive,
which is why the 350s (and 250s with 6V) had the cheaper regulators. But now the components could be obtained for peanuts.
The 3 wire system has only 2 thyristors, but the three wire has more like a bridge rectifier (2 diodes and 2 thyristors) so was more expensive.

If I was to get one today I would go for regulator with a charging indicator output and re-purpose the red idiot light.

You can check on the Dutch site for circuits if you fancy having a go at repairing. http://www.motomoriniclub.nl/tech.html

The 50V/25V to me means that you probably have the earlier flat sided rotor without the rear fins which would be correct.
With this rotor you need to rev quite high to get charge balance with lights too. The rotor was upgraded in 1977.
If you have any issue with starting as well it can be re magnetised the nice Mr EVguru on here can do it.

Mark
Cooklets
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Re: Battery not charging - Regulator/Rectifier problem?

Post by Cooklets »

Thanks Steve and Mark. I can confirm that there is no output from the red terminal on the reg/rec, and the photos on the Dutch web site show there is no internal connection to this terminal. Pity. There is power from the brown wire to the reg/rec, so it really does look like a replacement item is needed.
I do appreciate all the kindly advice - thanks all!
tobydmv
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Re: Battery not charging - Regulator/Rectifier problem?

Post by tobydmv »

I may also be replacing my regulator and wondering what you decided on. It'd be nice to actually find something that fits the bolt pattern. Any recommendations out there? Some of the guzzi suppliers have actual Ducati units for sale but i'm pretty sure the guzzi puts out way more juice than the morini's so might be over kill.
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Ming
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Re: Battery not charging - Regulator/Rectifier problem?

Post by Ming »

I have used a Boyer Power Box on my Strada, a Kanguro and now on a 250. They are smaller and easy to fit, with the bonus that you don't need a battery (ie, not foe electric start bikes). The Strada was fitted with it when I bought it way back. AC uses the two yellow leads with the red blanked off.
mbmm350s
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Re: Battery not charging - Regulator/Rectifier problem?

Post by mbmm350s »

Any recommendations out there? Some of the guzzi suppliers have actual Ducati units for sale but i'm pretty sure the guzzi puts out way more juice than the morini's so might be over kill
I wouldn't worry about that, the power output is limited by the generator, particularly for pre 1977 350s.

I am using a Ducati 18A two wire regulator as fitted to 500s that has the same bolt pattern and connectors.
But really any two wire regulator such as Boyer power box will be fine as Ming says.
Mark
Cooklets
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Re: Battery not charging - Regulator/Rectifier problem?

Post by Cooklets »

I finally bought a replacement Ducati reg/rec on the advice of (and from) Mdina. It cost around £80, bolted straight on, and works fine.
mbmm350s
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Location: Berkshire UK

Re: Battery not charging - Regulator/Rectifier problem?

Post by mbmm350s »

Hi
Glad you were able to sort it.
For the benefit of those coming to this thread
In the future what was the part number you
were supplied, e.g.it would be probably 34XxYy.
Was it 3 wire or two wire?
Thanks.
Mark
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