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testing , testing.

Submitted by robert_tuck on Tue, 24/04/2018
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Electrical

I switched the lights on and a bit surprised at the yellow glow! ,it was only the weekend when i did a 150 mile blast around Sussex and a similar trip last weekend.The 99 has a 12v system with zener and a 2MC and always shows a healthy charge on the ampmeter ,the battery is not old and was only at 9v but charged up to 14.4 with the intelligent charger. Are there any decent articles on the site for checking thro the system?

Submitted by kevin_bell on Wed, 25/04/2018

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Hi Robert

Type in 'Excellent Electrics Manual' for an ... err, excellent electrics manual! I bought it and it is brilliant.

Good luck with the testing.

Kevin

Submitted by anthony_curzon on Wed, 25/04/2018

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The Surrey Branch will be having a talk by our own electrical boffin Henry Dulat on the second Wednesday of the month in May, so may be you could come along and listen to his talk. Henry would also be able to help you with your electrical problems. Every one is welcome and the club room is at the Stepping Stones, in Westhumble, in Dorking. The event is listed in the events column on the web site. We normally start at about 8 to 8.15pm.

Submitted by robert_tuck on Wed, 25/04/2018

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Thanks guys I will try to make it there.Tested the batt voltage ,went from 12 off to 131/2 --14 once the engine running, so it is charging .Noticed the rear brake sits too high and may have the light on .PSR8 is orriginal so will check for bad connections /resistance also alt snap connectors. Ampmeter internals were a bit loose .

Submitted by ian_soady on Wed, 25/04/2018

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A battery should show more than 12 when not actually charging - fully charged would be around 12.7 (normal lead acid). Perhaps your battery is past its best?

Submitted by robert_tuck on Thu, 26/04/2018

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Started up today, Battery voltage 12.3 ,probably 3/4 charged. Battery voltage 13.5 under medium revs ,unclipped zener and voltage went to 14.5 ,so it would appear zener is restricting the charge . I think the A-Reg One is the best solution as it has a greater reserve capacity to handle the surplus charge and simplifies the system.

Submitted by alan_osborn on Fri, 27/04/2018

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The A Reg 1 is the only choice over the Zener/rectifier system but the idea above that it 'has a greater reserve capacity' is of no real value. The regulation supplied by the A reg 1 has a greater voltage stability ie the voltage of A reg is usually quite correct, while the Zener can be variable, I do not mean it changes, but each Zeners working voltage can be high or low and it will stay there. The fact that it just 'bleeds off' the excess power makes it a much simpler way of regulating the alternator but the result with regarding the charge rate depends on the voltage as described above. A low volts Zener will tend to keep the charge down to the battery while a too high zener will tend to allow over charging BUT the lead acid battery will often accommodate a bit of excess charging. We have had Zener systems for 50 years now, some of them are still going strong. I have sold quite a few A reg1, but there is a failure rate, as of course there is quite a bit of electronics inside them.

The other thing to note is that 'intelligent' chargers often cannot bring back a flat battery, so a basic charger to get a couple amps into it for 5hrs or so is what you need to start with.

Submitted by robert_tuck on Sat, 28/04/2018

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Over the last two weeks the 99 has been ridden very much harder than is normal ,keeping station with a Fireblade and Yamaha mt09 ,it blew bulbs, melted a rectifier and the zener is now acting up. I think its clear that I'm asking too much of the old girl and that it needs a greater capacity to dissapate excess energy being produced .The regulator should cope with about 50% more watts than the zener . The "inteiligent" charger sometimes has difficulty in recognising whether its a fully charged 6v battery or a very low 12v and so will do nothing. I usually give the battery a 2amp charge for a few minuits to get it up to a sensible reading that the "thinking charger" can read.

Submitted by ian_soady on Sat, 28/04/2018

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I don't think you're asking too much if the parts are in decent condition. What sort of rectifier do you have? I used to use a solid state (Maplins bridge type) on my Commando which was fine except when the alternator developed an intermittent open circuit (or short) which sent spikes through the rectifier causing it to fail (of course, in deepest France 300 miles from the ferry - the tale of how I managed the trip is something of an epic!).

As Al says, Zeners can have different working voltages but are generally pretty reliable things.

It may be that you have a similar fault in the alternator to the one I had. It was impossible to detect directly as it was intermittent and I have to say that I have no direct evidence other than that a replacement stator fixed the problem.

I also wonder about the state of your battery.

Submitted by robert_tuck on Sat, 28/04/2018

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The Alternator is orriginal possibly an RM15 (1959 build) but has never given trouble ,although not asked to do 85mph for many years. The battery is not old and charges up well on the bench . From the sound of it new alternators may not fit without work so not wishing to add to my stock of parts that don't fit I would like to keep the old one going if possible. My concern is that when out of my sight my hooligan offspring will do the old bike a mischief!!.

Submitted by alan_osborn on Sun, 29/04/2018

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Again several partial truths above. An open circuit stator should not cause a problem but an alternator that shorts to earth will cause a bit of grief to a rectifier ESPECIALLY if you bought it from Maplins! I suspect without full knowledge of the specification of the rectifier and its usage. Perhaps if you had bought from a known electrical motorcycle parts supplier you would have been more sure of its correct specification.

The speed of the bike will not cause any problem to a correctly fitted alternator, although the sustained high speed might cause a temperature rise that bits can't cope with, the RM15 stator will be low output so if the stator does fail then your only choice is RM21 (for 12V) which means a 74mm rotor as well.

Robert T's charging a battery is also quite good, a boost on an old fashioned charger then over to the 'clever' one. I had this very trouble on our camper van battery the other day, battery so low the central locking wouldn't and the alarm got the ass ache as the batt was so low. The clever charger then refused to have anything to do with the battery until it had been 'woke up' with a few amps for a few mins, then back to 'Mr Chinese clever person' which you can ignore for a day or two.

Submitted by robert_tuck on Mon, 30/04/2018

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The Dommy did about 100 miles on the weekend with no voltage control and everything worked OK , the lights were always on so the system is effectively working as Norton intended. I will be fitting a regulator though. The Zener was a Lucas from 20 years ago so can't complain about that. I read somewhere that in the past these were purchased for use in aircraft when nothing better was found to be manufactured. I have always bought parts from recognised Norton suppliers and been prepared to pay the premium price in the hope that they use their experience to sift the wheat from the chaff and refund/replace when it goes wrong. I have had to thin out my options though!. A good supplier will also tell you if an item is a second or not up to best quality. The encapsulated rectifier had a marginal heat sink behind the engine and oil tank ,not the best enviroment. New regulators are availiable on the internet for peanuts and may do the job, I won't be buying from them.We need our specialist suppliers. Did 50 miles on my little Italian which had a weird 6v grounded coil alternator system that i have ungrounded and re rigged to 12v and an A reg one rectifier. This has been my most reliable mount for 5 years being used for holliday transport and flogged round race tracks at max revs. Perhaps I should not tempt fate by boasting about it.

Submitted by ian_soady on Mon, 30/04/2018

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Hi Al.

I believe the problem with the alternator was that the short / open circuit was intermittent hence sending spikes through the circuit. Testing with a multimeter both running and not showed no faults.

The rectifier was a full wave bridge rectifier with 35A, 280 v capacity and was identical to those sold by many bike dealers. It was fitted on a substantial heat sink......

This was all about 25 years ago so my memory may be somewhat hazy........

Submitted by alan_osborn on Thu, 03/05/2018

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Previously ian_soady wrote:

Hi Al.

I believe the problem with the alternator was that the short / open circuit was intermittent hence sending spikes through the circuit. Testing with a multimeter both running and not showed no faults.

The rectifier was a full wave bridge rectifier with 35A, 280 v capacity and was identical to those sold by many bike dealers. It was fitted on a substantial heat sink......

This was all about 25 years ago so my memory may be somewhat hazy........

Exactly as I said, the specification of the rectifier is not good enough. The Lucas item was always specified as 400V so go beneath this if you dare.

 


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