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Ammeter query

Submitted by john_baker2 on Wed, 01/02/2017
Forums
Electrical

Auto/mc electrics is not my strong point, so please be kind!

ES2, 1962 alternator coil ignition..and the ghastly PRS8 switch unit....converted from 6v to 12v using a Boyer powerbox by previous owner...using original RM15 alt which has subsequently proved faulty...

So new RM20 rotor and RM21 two wire stator fitted .the stator wires show an output on test meter with engine running....when fitted to the two yellow powerbox wires, the red and black powerbox output wires show an output as well. Red goes to batt/red/positive earth, black goes to batt/neg (with a fuse) The batt neg terminal has a brown/blue wire running up to ammeter.

PROBLEM is that no charge rate shows on ammeter.

Test values with meter across batt terminals

Batt shows 12.6v

ign on shows 12.2v

with engine running shows 12 to 13.5

with engine running and side/headlights varies from 12+ to 13 + depending on revs.

Which implies that the alternator and powerbox are doing their job..BUT...

MEANWHILE ammeter shows -4 on ign on and -6 with lights on...and this stays the same with the engine running.

Looking at the original wiring diagram, it seems that with the removal of the original stator and rectifier wires,as reqd when connecting the powerbox, there is insufficient 'info' going to the ammeter.

Ammeter has brown/blue going to batt and rear light via stop lamp and brown/white going to PRS8 terminal 2.

This terminal 2 is wired to 10 & 12. With ign on 12 connects to 13 (rectifier) and 17 (alternator) NEITHER of which have wires any longer having been removed due to powerbox.

From here on I'm lost !!!!

As always help and guidance appreciated....and apologies if the above is long winded or rather obvious to those that know!!

Oh!..and I did check out all previous ammeter queries in the messages first...honest!

Regards John

Submitted by robert_tuck on Wed, 01/02/2017

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Hi John, sounds like the reverse of my issue, my load needs to go thro the ampmeter , and your charge needs to go through. The charge does not need to go through the psr8 but it does need to go to the ampmeter, assuming that you no longer need the current control switching that the psr8 used to do. I'm probably going to go through my wiring tomorrow so I will see how Idid it (20 years ago). The old psr8 connections and internal contacts are best bypassed where possible.

Submitted by david_cooper on Wed, 01/02/2017

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The black from the Power Box should go to the switch terminal 13 (where the original rectifier went. As it is, it is charging the battery (almost certainly fine) but ammeter only reads what's being used.

Submitted by les_howard on Wed, 01/02/2017

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Yep as David cooper says, the output wire from the PowerBox needs to feed terminal No13 on the switch. I don't know where you have taken it to currently but it seems you have it connected directly to the battery?..The original wire from the old rectifier was coloured Brown/Purple? and you might find this taped up near to the old rectifier position...Simply connect the POWERBOX output to this wire ONLY and reconnect the other end at the switch on Term 13...Otherwise just run a new wire to it.

Les

Submitted by robert_tuck on Thu, 02/02/2017

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I think Johns Problem is that the switch/ link wire /ampmeter connections are wrong.In any case the switch now does no usefull work in the charge circuit and is just somewhere to lose voltage /burn out/ come loose.All its needed for are ignition and lights.

Submitted by david_cooper on Thu, 02/02/2017

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With a Power Box the switch is still useful. If the battery is flat, the emergency setting allows the Power Box to feed the ignition without feeding the battery. Then the battery can be brought back on charge when the engine is running.

Otherwise - you need to disconnect the battery terminal temporarily until the engine is going to have the same effect. That's what I have to do since mine doesn't have the fancy switch (because it once had a magneto and is now electronic). Although bearing in mind how seldom I actually do it, it's not all that inconvenient to disconnect the battery anyway.

All of which reminds me - I need to charge my battery...

Submitted by robert_tuck on Sat, 04/02/2017

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While rigging up a feed for my heated jacket I checked and the rectified current runs from the rectifier (purple wire ) up to the ampmeter . I connected into this. Still leaves me with an ampmeter that I can't read as the variable wattage to the jacket is modulated by the radio controler with a pulse action which sends the needle like a metronome! Another re-think.

Submitted by alan_osborn on Sat, 04/02/2017

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Most of the above is correct but there is often confusion with regarding the wiring of the Ammeter. This is a way of remembering it.The load (on the system) and the charge are always connected together. The battery is always on its own on the other side of the ammeter.If the Ammeter goes the wrong way then just reverse it.There is two connections that can break this rule (certainly on older bikes) the stop light and Horn both being intermittent (and horn high current) can connect direct to the battery. Don't forget a fuse-stop lights are notorious for blowing such things.By the way the above thread sees the battery going up to 13V-not enough 14.4 is a better figure. Modern reg/rects are very prone to resistance in the wiring and connectors, watch out.

Submitted by john_baker2 on Thu, 09/02/2017

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Previously David Cooper wrote:

The black from the Power Box should go to the switch terminal 13 (where the original rectifier went. As it is, it is charging the battery (almost certainly fine) but ammeter only reads what's being used.

SPot on David, sorted, many thanks,

regards John

Submitted by john_baker2 on Thu, 09/02/2017

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Previously les_howard wrote:

Yep as David cooper says, the output wire from the PowerBox needs to feed terminal No13 on the switch. I don't know where you have taken it to currently but it seems you have it connected directly to the battery?..The original wire from the old rectifier was coloured Brown/Purple? and you might find this taped up near to the old rectifier position...Simply connect the POWERBOX output to this wire ONLY and reconnect the other end at the switch on Term 13...Otherwise just run a new wire to it.

Les

THanks Les, correct the wire was direct to the batt. Found unused loom wire and ran powerbox to 13 , ammeter now working fine.

Brilliant as I was on a club stand at Bristol m/c show and always ride there and back.

regards John

s

Submitted by john_baker2 on Thu, 09/02/2017

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Previously David Cooper wrote:

With a Power Box the switch is still useful. If the battery is flat, the emergency setting allows the Power Box to feed the ignition without feeding the battery. Then the battery can be brought back on charge when the engine is running.

Otherwise - you need to disconnect the battery terminal temporarily until the engine is going to have the same effect. That's what I have to do since mine doesn't have the fancy switch (because it once had a magneto and is now electronic). Although bearing in mind how seldom I actually do it, it's not all that inconvenient to disconnect the battery anyway.

All of which reminds me - I need to charge my battery...

NOt had to resort to that yet David, but not sure I About it being a 'fancy' switch, more of pain!!!!!!

regards John

Submitted by john_baker2 on Thu, 09/02/2017

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Previously alan_osborn wrote:
Most of the above is correct but there is often confusion with regarding the wiring of the Ammeter. This is a way of remembering it.The load (on the system) and the charge are always connected together. The battery is always on its own on the other side of the ammeter.If the Ammeter goes the wrong way then just reverse it.There is two connections that can break this rule (certainly on older bikes) the stop light and Horn both being intermittent (and horn high current) can connect direct to the battery. Don't forget a fuse-stop lights are notorious for blowing such things.By the way the above thread sees the battery going up to 13V-not enough 14.4 is a better figure. Modern reg/rects are very prone to resistance in the wiring and connectors, watch out.
AL the 13+ was on fastish tick over, not on the road and being late at night trying not to wake the neighbours.Regards John

Submitted by martyn_watson on Tue, 07/03/2017

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It's a meter that measures/displays amps.

A meter for measuring volts is a voltmeter, It makes perfect sense.

I think this is an example of a malapropism?

 


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