Showing a discharge on tickover?

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shaunstaples
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Showing a discharge on tickover?

Post by shaunstaples »

I've converted to 12v for access to bulbs, charge my phone and I want to fit indicators eventually. I just wondered if this was normal?

My Dynamo is still as it was for 6v and will have this rewound later. When its ticking over the ammeter is showing a slight discharge which goes back to zero when the engine stops? It charges ok and the transition to charging is ok and varied with increase in revs. Also for it to charge more revs are needed as I've read and expected.

The Regulator is the V-Reg II (Dynamo Voltage Regulator) and I've cut the green link wire to convert to 12v
Everything is as expected apart from the discharge shown on ammeter with nothing switched on, when the engine is running below charging speed?

https://youtube.com/shorts/yTtSHDCUrBI

Sorry video is a bit shaky, but you can see discharge shown on ammeter

I have nothing to compare it with so any help appreciated thanks
Groily
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Re: Showing a discharge on tickover?

Post by Groily »

This happens because the cut-out is not always very crisp with descending rpm on some regulators. They cut out a little 'late'. You will see it with many mechanical ones too. So it is not abnormal to see an amp or two discharge at tickover.
One of the reasons I particularly like the DVR2 version of the modern electronic generation is that it does not allow a drain back towards the dynamo from the battery at tickover so you see no equivalent discharge.
I have been happy not replacing armatures and field coils with '12v' items on all my dynamo machines over the years - they have all worked perfectly well using 'just' the regulator to cover the issue. Including on my Mod 20. You just have to tolerate the slightly higher cut-in speed to which you refer (or on some bikes eg Beesa twins, gear up the dynamo drive a little).
shaunstaples
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Re: Showing a discharge on tickover?

Post by shaunstaples »

So am I right in thinking its just that the dynamo is spinning too slow now and that rewinding or changing armature/field coils would lower the engine rpm needed to balance at 12v?
I did think about gearing a while back, but dismissed it at the thought of not being able to fit a smaller gear and get the dynamo further in, was just thinking of getting more output rather than when it reaches 12v though.
This regulator was already fitted and looks well made, I was going to mount it at back of battery carrier so its out of sight and gets some air over it, then use old regulator case for a few small spares but might hold off in case I need to get a DVR2.
I haven't rode it yet, still got a few jobs to do yet so maybe it'll suit me but more like Cpt Slow these days...
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Taid
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Re: Showing a discharge on tickover?

Post by Taid »

Just a thought ..

You write of future 12v kit ..

Bear in mind that modern 12v stuff is probably negative earth and may be problematic trying to set up on a positive earth bike.

I did have my 16ms dynamo rewound for 12v neg earth, but in the end opted to fit a 12v neg earth alternator system.

On my model 31 I'm playing with a 6v to 12v convertor for the electronics, leaving the 6v system essentially unchanged except for LED lights .. but it's proving more fiddly than I thought
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Now sold ... 1956 AJS 16MS Bitsa .. HSU 414 .. rebuilt/re-registered 1987
shaunstaples
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Re: Showing a discharge on tickover?

Post by shaunstaples »

This regulator is positive earth and if I have to replace it, will go for negative earth just to make it easier. I'm just doing some indicators and having to double insulate and provide a remote earth.
I was going to stay with 6v but the step up always seem to use a lot of power, and I'm trying to save as much power to be able to run other things in future if possible?
I'm just muddling my way through, but with all choice of new equipment available, should be able to come up with something that you can be seen coming and still have enough left to charge my phone etc.
With regard to the discharge, I was just shocked how much there was! I suppose if the dynamo was spinning a little faster, everything would be the same, I just wouldn't see it?
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Taid
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Re: Showing a discharge on tickover?

Post by Taid »

I don't think you can just use a neg earth controller .. you'll have to flash the dynamo to swap it's polarity as well ..
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Groily
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Re: Showing a discharge on tickover?

Post by Groily »

The step up doesn't involve loss of power (ie watts) Shaun.

You will get the same or more continuous output at revs at 12v as at 6v, with only half the current whizzing around (amps). Just takes longer to cut in, and then to achieve its state of being 'fully regulated'.

An original dynamo is nominally rated at 60W. At a normal 'system voltage' of 7.2v on a 6v system, a 60W load means the current running around is about 8.5 amps. At a normal 'system voltage' of 14v at 12v, your 60W implies not much over 4 amps flowing around. There are no completely free lunches, though, as the '6v' field coil is more stressed at 12v but I haven't had one fry ever and seldom think about it as an issue.

The modern replacement fine-wound 12v armatures are strictly limited to their nominal 60W or they will fry. DAMHIK. But they do cut in at the same engine speed as the original.

Many say - me being one - that you can safely demand 70-80W from the original windings using a good modern regulator wired for 12v. I have regularly run E3L dynamos at such loads with Oxford Hot Hands and a 35W halogen headlamp - but all the easier if you went LED up front.
Obviously, bright indicators create a demand, on and off, that can be quite high unless using LEDs there too - so I definitely would. Even using 15W bulbs, that's still an additional 30W load, or half the nominal output available just for them. 21W bulbs = 2/3rds.
I don't think a phone charger needs a whole lot - milli-amps?

I am told the LED headlamps available from Al Osborne are good - a friend with a Commando is very happy with his lights - but I don't know what reflector and glass he has, and these things can matter.

WIth the DVR2s on my two AMC twins, one with LEDs and t'other on 'proper' lights, there is never a discharge at tickover (if the lights are off!). Ditto the A10 Beesa twin I did 50K miles on between 2007 and 2021. But, coming back to it, your point about rpm is valid - Beesa twins are chain driven in the dynamo dept and there are geared up belt drive conversions which help keep things steady at low revs even with loads on. No such luck with a Model 20 though - a big headlamp etc will show up very negatively on the ammeter at tickover.

In the context of the other mods you are doing I would certainly counsel a Negative earth regulator as it is a fiddle-faddle having to isolate add-ons to achieve correct polarity. Minimising potential points of failure and the amount of electrical spaghetti is what it's about, for me anyway.

If you want a whole lot more than the rated output of these things, then you really would need to buy an Alton alternator or similar - but even there, the power available at moderate revs isn't much different from an E3L, good though the modern Altons are. They rely on permanent magnets, so their output is linear with rpm or near enough, whereas a dynamo is a more sensitive beast where the magnetic field is controlled by the field coil, fed from the armature via the regulator, according to demand. Excessive demand on a small dynamo does, however, mean that it may often never achieve its state of 'full regulation', which - while seldom fatal - does involve some stress. I think one has to be careful not to demand too much of these things!

In all cases of going beyond the norms of the day, you need a decent sized battery. I say that despite being a horrible cheapskate in that area myself - but I know I shouldn't be such a mean so-and-so!
shaunstaples
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Re: Showing a discharge on tickover?

Post by shaunstaples »

Thanks Ben, yes I read that I'd have to do that. It will be interesting to see what its like when it's rewound, might not need to replace it?
Got a few other things to get past the wife further up the list....
shaunstaples
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Re: Showing a discharge on tickover?

Post by shaunstaples »

Thanks Bill for the loan of your wisdom, some warmth under the grips is on my list, I did some crude ones with nichrome wire on a BMW some time ago that worked really well.
Would like to keep things as original as possible, whilst getting the best out of them. Negative earth would make things easier, and neater.
Encouraging what you say about original windings, might be best to try it as it is and see how it goes and I can always opt for DVR2 to improve at low revs, without re-winding.
I'm all led except speedo and side lights, and there's much more draw on side than headlight! The led headlight bulb has a grub screw and you can focus it but haven't played with that yet.
The indicator bulbs I'm trying are 12v led spotlight bulbs which are bright from a claimed 2w, they are in like a clear silicone with 2 pins out of bottom that I've soldered wires onto. Not sure how long they will last on off on.
Just trying to get it usable for todays rat-race out there...
Groily
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Re: Showing a discharge on tickover?

Post by Groily »

If you are all LED, I can't see a problem to be honest with sticking with the dynamo you have, running at 12v. Should be fine if my own fun and games with 3 machines running at 12 volts are any guide or of any interest . . .

1. My A10 Beesa always ran a 36 Watt trad BPF headlight, sometimes Hot Hands too, with standard tail and speedo. Never a problem in many miles of all-year use, often lights on. Speeded-up dynamo using a proprietary belt drive conversion was an advantage, granted, and one we can't have on gear driven machines like AMC twins obviously. 50K miles says the original dynamo was up to the job. It is still working fine with a new owner these past 2 years.

2. My Mod 20 runs a Cibié concave light with a 45 watter (superb), no problem. That's also a high-mileage all-year machine. It has run at 12v since the late 1970s when I first discovered the existence of the JG electronic voltage regulator - my example of which still works perfectly well - but I swapped it for a DVR2 when they became available. It did a brisk 165km yesterday, lights on, and does it regularly as it's my best-illuminated beast for going out in the dark. (It doesn't get light enough to switch off anything until close to 9 am in mid winter here and I'm often out by 7 am.) It has at times run with a 60/55W globe, no serious problem unless in traffic for more than a few minutes when the battery starts to take a hit. So not quite so good and I don't go there any more. Like the Beesa, it has also run with a 35 watter and Hot Hands, and no melt-downs with a continuous 75W demand. The armature has been replaced a time or two in nearly 50 years of continual use, but that's not so bad I reckon.

3. On my Mod 31 I am currently running a completely inappropriate set up, but it is usefully illustrative of the points we're exploring in this discussion.
The E3L's brush-end monkey-metal housing cracked and broke when out one day . . . and the armature got trashed for having no bearing support to speak of that end. Interestingly odorous effects! Woe!
I didn't have another E3L to hand but I needed the bike on the road with working 'lectrics the next day.
So I took the body of an old E3HM - the short version, low output, designed for use with a magdynamo on a single. I swapped over the necessary drive end bits from the E3L and fitted a new field coil and armature (lucky to have had 'em!) with a new bearing and a serviceable oilite bush for the brush end. It worked quite fine on the bench - and I was thinking 'Yay! - Now, can I get a 6v battery and some bulbs this very day?' Hmmm . . . No I couldn't of course, as they're not exactly stock items anywhere these days.
So . . . I decided I'd have to see what would happen if I ran it at 12v using the DVR2 and the Yuasa 12 battery that were on there already. Definitely not a good contender for 12v use and I tend to say to anyone who asks 'don't even think of going there - only do the 12v upgrade with E3Ls or D6 (long) Millers in good condition'.
However, needs must, so I gave it a whirl at 12v with an LED up front and standard tail and speedo. To my great relief, it cut in at not-too-stupid speeds and showed a sensible charge rate, well regulated. Phew, I thought, temporary fix, will have to do for now . . .
That was, er, some time last year . . . and what with my being idle, it's still on there despite having sorted the proper one in the meantime.

The upshot is that I am happy and confident with using standard windings in E3Ls running at 12v. The guy who runs the biz that makes the DVR2 regulator does the same - with the added drain on one of his of Boyer Bransden electronic ignition in lieu of the magneto, which is a bit of a current hog.
There are those I greatly respect who don't agree, believing it is wiser to invest in the finer-wound '12v' bits to achieve lower cut in speed. And for the health of the field winding too I think. There is certainly much merit in that for those living with traffic, in towns and so on. Horses for courses as it were. But as a country boy, I've not seen the need and I'm sticking with what I've been happy with since first buying that 12v regulator more than half a lifetime ago.
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