The correct values of power from stator and from rectifier.

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pierodn

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Hi.
Please, what are the correct values of power out ftom stator snd then out from rectifier?.
My warning light assimikator doesnt switch off the red light; it is new and i have tried with other than wirk well.
But it seems to me that even if the red light di t seitch off the battery charges.
To day i had the first run of one our after rebuilding of my Dunstall 810.
Battery at start was 11 and the same to return.
To warning light the wired G/Y goes on AL, W/N on WL, red ground on E.
All the wires are good.
What i must check?
Thanks
Piero
 
Tough question to answer because there are lots of variables like which make and model of alternator. How new is the rotor. Is the stator single phase or three phase. What model regulator/rectifier are you using.

But here are some numbers you can look for:

With a multimeter set to AC, you should expect to see around 25 volts at around 3,000 rpm.
This will fluctuate wildly (especially with no load line this), and it will be very difficult to read, but at least you’ll get some idea if the coils are giving you an output.
An old style analogue multimeter with a needle would make it easier to read.

Now set your multimeter to DC and attach to your regulator/rectifier +ve and -ve terminals. You should see 14 to 15 volts DC on your multimeter at around 3,000 to 4,000 rpm. This should be much more stable and easier to read.
At an idle of 800 to 1,000 rpm I would expect the DC output to drop to around 12 to 13 volts.

A fully charged battery will vary depending on the type it is - a typical Lead Acid battery should be around 12.6 volts.
 
gtiller said:
Tough question to answer because there are lots of variables like which make and model of alternator. How new is the rotor. Is the stator single phase or three phase. What model regulator/rectifier are you using.

But here are some numbers you can look for:

With a multimeter set to AC, you should expect to see around 25 volts at around 3,000 rpm.
This will fluctuate wildly (especially with no load line this), and it will be very difficult to read, but at least you’ll get some idea if the coils are giving you an output.
An old style analogue multimeter with a needle would make it easier to read.

Now set your multimeter to DC and attach to your regulator/rectifier +ve and -ve terminals. You should see 14 to 15 volts DC on your multimeter at around 3,000 to 4,000 rpm. This should be much more stable and easier to read.
At an idle of 800 to 1,000 rpm I would expect the DC output to drop to around 12 to 13 volts.

A fully charged battery will vary depending on the type it is - a typical Lead Acid battery should be around 12.6 volts.
Click to expand...


Hi.
The bike has a stock 1973 Commando parts: rotor, single phase stator, rectfier and zener diod.
Please what means ”+ve and -ve“?.
Thanks
Piero
 
+ve
Positive
Connected to the frame (earth)

-ve
Negative
Connected to the Brown/Blue wire via the fuse
 
gtiller said:
+ve
Positive
Connected to the frame (earth)

-ve
Negative
Connected to the Brown/Blue wire via the fuse
Click to expand...


Hi.
Let me understand better, please.
AC must be seen directly on Y/G and W/G from stator?
DC must be seen on battery or on brown/blu and positive red?
Thanks
Piero
 
Last edited:
Correct,

Your battery terminals put out a DC voltage

The Green/Yellow and White/Green wires on your Alternator put out an AC voltage

Unless you set the dial on your multimeter right, the readings won’t make any sense.


Connecting you meter directly to the battery terminals or to the Brown/Blue and Earth wires should make no difference.
 
gtiller said:
Correct,

Your battery terminals put out a DC voltage

The Green/Yellow and White/Green wires on your Alternator put out an AC voltage

Unless you set the dial on your multimeter right, the readings won’t make any sense.


Connecting you meter directly to the battery terminals or to the Brown/Blue and Earth wires should make no difference.
Click to expand...

Hi.
Here are the values:
AC14/17
DC 11/12 but!!!!!! at 2/3000 rpm come down to 7/8.
What means?
Thank you
Piero
 
The AC output is a little on the low side for an old single phase RM21 alternator, however it is just on the edge of acceptable.

The fact the DC side goes down so low when you rev the bike up means that you are drawing more power than you are producing...

It’s really difficult to help diagnose further , but I think you need to start further checking individual components and swapping them out for known good ones.


If it were me, a great place to start is to disconnect the Green/Yellow and White/Green wires from your Alternator and connect it to a podtronics type unit off the bike - put a meter on the red and black wires on the podtronics box set to DC and see what you are getting. As I said before look for 14 to 15 volts DC on your multimeter at around 3,000 to 4,000 rpm.
Dropping to around 12 to 13 volts at idle.

This will tell you if your alternator stator and rotor are ok, and whether your issue is with the old charging circuit on the bike (rectifier/zener/capacitor)

If you are still seeing 7 volts at 3,000 rpm, you will know that you have an issue with the alternator itself.



Provided the battery is charged, the bike will run off the battery for a few minutes with no problems (just don’t turn the lights on and beep the horn!)
 
Done.
But not see the value with tester.
I have used a Boyer Brandsen single phase power box (without capacitor in).
I didnt have the tester but the warning light didnt switch off to high rpm.
Piero
 
That AC voltage reading is low. Do you have another rotor you can put on to test?
 
Other thing to check is all the ground (common or chassis) wires. Sometimes connections get rusty or dirty. Cleaning the ground (common) connections sometimes helps and is usually easy. But it's a hard thing to trace if your'e looking at the hot terminals. Bad ground terminals will show up as low voltage because the voltage is being used in the bad connections.
 
DogT said:
Other thing to check is all the ground (common or chassis) wires. Sometimes connections get rusty or dirty. Cleaning the ground (common) connections sometimes helps and is usually easy. But it's a hard thing to trace if your'e looking at the hot terminals. Bad ground terminals will show up as low voltage because the voltage is being used in the bad connections.
Click to expand...
Stator AC voltage output is tested leg to leg, so, chassis grounds are out of that equation.
The fact that it is low, suggests following that while troubleshooting.
 
@pierodn - ignore the fact your red light isn’t going out.

If you are testing with the Bransden box off the bike as I suggested, your red light is still connected to the ‘old’ components on the bike, so will be irrelevant at this point.

You really do need a meter to test in this way - and it’s the easiest place to start before you have to think about taking bits off your bike.

You are also taking any earthing issues out of the equation by testing this way.
 
Hi Pierodn,

make sure your Battery is fully charged before you test your DC chargeing current, because uncharged battery is eating up most of it before fully charged.

I ruined a nice adjustabele voltage regulater until i learn this. :-\
 
gtiller said:
@pierodn - ignore the fact your red light isn’t going out.

If you are testing with the Bransden box off the bike as I suggested, your red light is still connected to the ‘old’ components on the bike, so will be irrelevant at this point.

You really do need a meter to test in this way - and it’s the easiest place to start before you have to think about taking bits off your bike.

You are also taking any earthing issues out of the equation by testing this way.
Click to expand...

Hi.
About your:

“If you are testing with the Bransden box off the bike as I suggested, your red light is still connected to the ‘old’ components on the bike, so will be irrelevant at thispoint.”

only the warning light eas still conected, not the diod zener neither the rectifier.
Sorry but may be i dont understand what?
Thank you.
Piero
 
So you have disconnected the Green/Yellow and White/Green of your alternator from the wiring on the bike.

Everything else on your bike is left as it is, including the battery which is fully charged.



Test 1
First connect the Green/Yellow and White/Green of your alternator to the Red and Black wires of your multimeter, and set it to read AC.

Start the bike, keeping your lights etc switched off - you are running the coils on battery only.

Now watch the reading on your multimeter - you should expect to see around 25 volts AC at around 3,000 rpm.


Test 2
Now disconnect the Green/Yellow and White/Green of your alternator from the multimeter.

Then connect the Green/Yellow and White/Green of your alternator to the two yellow wires on your Boyer Bransden Power Box.

You then connect the Red and Black wires of your Boyer Bransden Power Box to the Multimeter and set it to read DC.

Start the bike, keeping your lights etc switched off - you are still running the coils on battery only.

Now watch the reading on your multimeter.
At idle you should see 12 to 13 volts DC
At 3,000 to 4,000 rpm you should see 14 to 15 volts DC



This is the easiest way to test the stator and rotor unplugging only the two alternator wires and without unbolting anything from your bike.

I’m struggling to put it into simpler instructions than this.
 
gtiller said:
So you have disconnected the Green/Yellow and White/Green of your alternator from the wiring on the bike.

Everything else on your bike is left as it is, including the battery which is fully charged.



Test 1
First connect the Green/Yellow and White/Green of your alternator to the Red and Black wires of your multimeter, and set it to read AC.

Start the bike, keeping your lights etc switched off - you are running the coils on battery only.

Now watch the reading on your multimeter - you should expect to see around 25 volts AC at around 3,000 rpm.


Test 2
Now disconnect the Green/Yellow and White/Green of your alternator from the multimeter.

Then connect the Green/Yellow and White/Green of your alternator to the two yellow wires on your Boyer Bransden Power Box.

You then connect the Red and Black wires of your Boyer Bransden Power Box to the Multimeter and set it to read DC.

Start the bike, keeping your lights etc switched off - you are still running the coils on battery only.

Now watch the reading on your multimeter.
At idle you should see 12 to 13 volts DC
At 3,000 to 4,000 rpm you should see 14 to 15 volts DC



This is the easiest way to test the stator and rotor unplugging only the two alternator wires and without unbolting anything from your bike.

I’m struggling to put it into simpler instructions than this.
Click to expand...

Hi.
Done with multimeter.
AC from alternator:
1.000rpm=11,5
3/4.000rpm=28
DC from battery with Rectifier and zener diod and capacitor in:
1.000rpm=11,1
3/4.000rpm=11,3
DC from Power Box Boyer Brandsen on black and red wires (with rectifier, zener diod and capacitor all removed):
1.000rpm=14,6
3/4.000rpm=14,6.
In all this cases the warning light simulator (that is new) doesnt switch off.
Thank you for helping me.
Piero
 
Last edited:
pierodn said:
DC from Power Box Boyer Brandsen (black and red wires with capacitor out)
1.000rpm=14,6
3/4.000rpm=14,6.
In all this cases the warning light assimilator (new) doesnt switch off.
Click to expand...


http://www.boyerbransden.com/pdf/PBOX00108.pdf
"If your Norton has a charging warning light simulator [assimilator] it must not be used with the power box, remove it. If the light control is required fit the power box type PBOX00166 with charging light control."
 
L.A.B. said:
http://www.boyerbransden.com/pdf/PBOX00108.pdf
"If your Norton has a charging warning light simulator [assimilator] it must not be used with the power box, remove it. If the light control is required fit the power box type PBOX00166 with charging light control."
Click to expand...

Hi Les,
on other commando i have Podtronics with capacitor in and warning light simulator that works well.
Is Better never use warning light? and why?
Thanks
Piero
 
Last edited:
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