Hi

Help needed ;)

My 1944 Triumph 3HW is showing a 3a discharge on the ammeter while the engine is idleing (all lights off).When engine is reved ammeter goes to charging and goes back to 3a discharge at idle. As soon as the engine is turned off the ammeter goes to 0. I have a modern solid state regulator installed.

Battery at idle - 6.3v
Battery at slightly reved engine - 6.8v
Battery at engine off - 6.4v

Can anyone help?

Thanks in advance

email (option): Dorianmicallef@gmail.com

The cut out points are not opening when the voltage drops on idle. There is a set up procedure for this. What you can try is to open the regulator look for the cut out bobbin there should b an adjusting screw, with the bike idling and the discharge showing wind the screw in a fraction once the discharge stops rev the engine to make sure the points close and a charge shows. This should do the trick, a bit rough and ready but has worked for me.

He mentions solid state regulator. Just live with it as long as it charges when revved.

Must have been half a sleep and not reading properly. Some of the solid state ones do this. Dynamo Regulator Ltd ones do not as the guy who runs the business and uses BSA's makes a different circuitry to stop the discharge at low revs.

Thanks for your replies.

So there's nothing to worry about?

email (option): Dorianmicallef@gmail.com

For simple instruments, these CZ27 ammeters do seem to give some odd readings but I don't understand why there should be lower battery voltage at idle than with the sngine still. There is no current draw on a magneto engine with lights off unless there is a short somewhere.

Suspicion must fall on the regulator (which make is it ?) but a quick battery substitution might not be a bad idea as a defective battery with a high internal resistance can cause some strange symptoms.

I wouldn't say there is 'nothing' to worry about as at the very least, an ammeter which shows discharge incorrectly would have little useful function and be a distraction...But with a magneto-sparked engine, it's never going to be a disaster unless you ride a lot at night.

On some solid state regs the switching diode doesn't switch off fast enough so battery voltage bleeds to earth.

Yesterday I made 70miles with the triumph. With the lights always on. Left home with the battery at 6.4v and came back with the battery at 6.5v. I guess all is ok. Right?

email (option): Dorianmicallef@gmail.com

Sounds good.

What headlight and taillight bulb wattage are you running ?

Guess if it actually was discharging through something, you would have a flat battery - after a few days ?

Hello Ian,

Basically, the normal charge Voltage for a 6V battery should be 7.4V,
So 6.8V of charge is a bit low, if it is the max.

Regarding the bleed back:
3Amp of current bleeding back to the generator is not very healthy,
And can eventually melt the winding of the soldering down.
If not now, then in the future, if the leak back grows.

I would replace the regulator.
I am using an MTML one, and it is wonderful.
MTML http://www.poseidonsys.com/mtml/
Seems to be Dynamo Regulators LTD now, so I join the recommendation.
http://dynamoregulators.com/

My model is older then the current one, at least visually.

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email (option): noam10@gmail.com

Sorry, correction...

Sould be a 7.2 Volts charging voltage for 6V rated systems, NOT 7.4V.

I confused it with the 14.4V for 12V systems.

Also, I "meant melt the soldering of winding" (At the commutator)
And not "winding of the soldering"

Had a bit of a rough day...

Noam.

email (option): noam10@gmail.com

NZ

Agree with what you say, but if it was actually discharging 3amp, it would a fried the windings by now and surely the battery would be dead flat the next day?

Hi Nigel,

NZ.. I like it !

Yes, I guess that if this was a fixed status, than it may melt the soldering,
Especially if the motor was off, and then the brushes would feed
Only one winding all the time constantly, as the dynamo was static,
And the battery would be flat dead for sure, in some 2 hours, max.
But as the 3A leak feed another pair of commutator contacts at idle all the time,
As the dynamo revolves,
Allowing each pair to "Rest" a bit and cool down. till it reaches the brushes again,
So no damage happens. (Hard to explain.. I hope I was clear enough...)
In this case, Dorian mentioned that
"As soon as the engine is turned off the ammeter goes to 0. I".

0.1A is 100mA, which is not enough to cause damage to the commutator.
It would, eventually drain the battery.

For fully charged 11 A/H battery, it would theoretically take 4 days..

Cheers,
Noam.

email (option): noam10@gmail.com

Thanks for all your replys

Noam :

"In this case, Dorian mentioned that
"As soon as the engine is turned off the ammeter goes to 0. I"."

The ammeter goes to 0 when I switch off the engine. The . is a full stop and the I is the first letter of the next sentence.

email (option): Dorianmicallef@gmail.com

Ho, I see Dorian.

My mistake then.
And I was wondering why the 1 is in "Roman"...

OK, so in this case the battery should hold the charge.
If you find where this 3Amp leaks back to, maybe you could just
Fit a strong enough diode on that line, and keep using the same regulator.
(If the flow in that line should really be in a positive direction only)

The diode would act as a "non return valve" and stop the leak.

Noam.

email (option): noam10@gmail.com

Hi Noam

Any idea how I can find the leak?

Dorian

email (option): Dorianmicallef@gmail.com

Hi Dorian,

I guess you measured the 3Amp leak back with a multimeter.
Measuring the current with a multi-meter on Amp is done "Inline".
The easiest way is either to connect one of the battery poles THROUGH
the multi-meter, (never mind which pole)
Or to replace temporarily the bike's ammeter with a multi-meter.

Sorry for the long explanation, I just wanted to make sure that
Everyone understands that Current (Amp)I measured inline,
Whilst Voltage is measured parallel.

SEE HERE

Anyway,the electric loom branches to a "Contributor", which is the
Regulator output, and "Customers", which on the M20 are basically the lights,
As there's not much more on the bike..

If the total of charging is greater then what the customers draw-
You would see charging, and if it is the other way round, the ammeter
Would indicate discharge.

What you want to do, is to disconnect one branch at a time, and see if the
Leak disappears.
You can either measure one branch at a time, or measure the main lead
(Connection to battery) and see when the 3A leak stops,> after which
One of the branches was disconnected. when it does, you found the leak.

My guess is that it is one of the connections to the regulator.
If this line should really carry current only in the battery direction
And not back, fitting a diode on this line should mend the leak.

The diode should be cheap, few Pounds at max, and you can buy it
At any electronic parts shop off the shelf.
If you buy, just make sure it can carry some 5Amp or more,
So it would not burn up.
Few diodes can be connected in parallel in order to split the load
(2 units of 3Amp in parallel can carry 6Amp)but as a diodes also has
Some minimal leak back, parallel diodes would have greater leak,
But not nearly as much as 3Amp.
It worth mentioning that the diode has a flow direction:
The (+) should connect here: --->I---- (This is more or less the mark on the diode)

SEE DIODE SIGN

Hope that helps.
Good luck,
Noam.

email (option): noam10@gmail.com

As your dynamo will be putting out a max of 60 watts (rewound long Lucas type) @ 6 volts, this = ~10 amp.

As per NZ - you could fit a suitably rated diode inline, however finding Diodes with a big enough current (amp) rating can be a trial if you do not have a 'Rapid', 'RS' or similar supplier available (people from all over the world seem to contribute to this forum!).

One very good source of high current (amp) diodes is in the back of an automotive Alternator.
Or better still, someone who 'refurbish' alternators - as they usually have new ones available for not much money (~£1-1.50 - UK).

You will still get some small leakage to earth through a Diode - so for long term storage (over winter) its better to disconnect the battery.

Shouldn't really be getting this problem though as any decent regulator should already have this diode in circuit ....?

NigP

When the engine is off there is no discharge, discharge occurs only when the engine is idleing.

email (option): Dorianmicallef@gmail.com

Noam

I will try, but I'm not very good with electricals.

Will get back to you when I find some time to check it.

Thanks

email (option): Dorianmicallef@gmail.com

DM - sorry I missed that point.

Hmmmm - strange, but I don't think its anything I would worry about, such a small discharge through a rotating dynamo should'nt damage anything.

I must admit, when I made my own regulator, I got a charge (very low) at almost any engine speed - even when kicking over...?

May be the start of a Dynamo fault, but I wouldn't worry about it - you have a magneto to get yourself home ...

Hi Dorian,

No problem, good luck with that.

Now, reading Nigel's post, I think I missed something:

I was offering to put a 5Amp rated diode, cause I was thinking on the 3Amp leak,
But if the same line with the leak back is also the one which carry
The max' 10Amp of charge, then you would need a diode which is rated
For at least 10Amp.

Here, for example, you have 3x 10A diodes for less than 1 Pound:

http://www.ebay.com/itm/5pcs-10A10-10-Amp-1000V-10A-1KV-Axial-Rectifier-Diode-/281336839622?pt=LH_DefaultDomain_0&hash=item4180fb7dc6

Or 15Amp for less than 1 pound, or best offer...

http://www.ebay.com/itm/2pcs-New-MUR1560-MUR1560G-15A-600V-UltraFast-Rectifier-Diode-/251623113662?pt=LH_DefaultDomain_0&hash=item3a95e803be

Gool luck,
Noam.

email (option): noam10@gmail.com

Hi Dorian,

No problem, good luck with that.

Now, reading Nigel's post, I think I missed something:

I was offering to put a 5Amp rated diode, cause I was thinking on the 3Amp leak,
But if the same line with the leak back is also the one which carry
The max' 10Amp of charge, then you would need a diode which is rated
For at least 10Amp.

Here, for example, you have 3x 10A diodes for less than 1 Pound:

http://www.ebay.com/itm/5pcs-10A10-10-Amp-1000V-10A-1KV-Axial-Rectifier-Diode-/281336839622?pt=LH_DefaultDomain_0&hash=item4180fb7dc6

Or 15Amp for less than 1 pound, or best offer...

http://www.ebay.com/itm/2pcs-New-MUR1560-MUR1560G-15A-600V-UltraFast-Rectifier-Diode-/251623113662?pt=LH_DefaultDomain_0&hash=item3a95e803be

Gool luck,
Noam.

email (option): noam10@gmail.com

Isn't it strange, but I never think of buying electrical bits from Ebay ...

Universal, worldwide, I guess?