Dynator charging woes

[Vonkie]

Dear boffins.

Lady Devorguilla is being attended to for various. I have a specific question (one thing at a time).

I am experiencing perennial charging issues with the Dynator that PO had fitted. Hooked up to a Voltmeter, after a good drive, on idle one gets about 12.5 volts and gradual discharge. One needs about 1500RPM to start charging nicely, eventually to 13.5V. Obviously, especially with headlights and fans and stuff on, the discharge problem is capable of running the battery flat too often for comfort. The Dynator has apparently been checked out as being in proper working order.

There's a Kenlowe fitted (in front of radiator, not behind). At first, a switch was fitted to have the Kenlowe kick in later (around 90 rather than 75), to counter the discharge issue. But this made the engine run too hot on idle in traffic on hot days, and with the setting back to 75 or so, the temperature never goes over 90, and tends to hang about 80, which is clearly better, but the discharge issue is then more pronounced.

Our climate is fantastic - dry, mild to hot summers with summer rain, and very mild and dry winters.

My own experience has been that, when I have her in my custody, the charging issue plays up for the first day or so, but, because she sleeps o'nights on C-Tek, she starts the day with the battery fully charged, and after a day or so, the discharge problem is sufficiently in check that I can more or less rely on her starting reliably after trips. On first start in the morning on full choke, the ammeter will show halfway to C while idling. On no choke, especially when the engine is hot, the ammeter will bounce around halfway to D, and sometimes close to D, on idling. Revving and driving will take the ammeter back to centre, but seldom anywhere left of centre, unless the battery is low.

What are the generally acceptable operating specs for these things? The whole point of the Dynator was, after all, presumably to counter the charging weakness of the old dynamo. Any ideas on how to address this on the Dynator will be much appreciated. Otherwise a new Dynator is indicated. I would prefer not to modify too radically with alternator systems, as all the old kit (including RB340 shell) is still there.

By the way, for now I've decided to stick to the old Lucas starter, which makes a nice noise. I want to hang on to the old starter if I can.

[Whitact]

Are the pulley sizes correct? You might need smaller one on the dynator to get it to spin fast enough.
Cheers

[Heuer]

Sounds as though it is behaving like a dynamo rather than an alternator. Once an alternator is energised (usually by blipping the throttle or driving off) is should produce ~14.3v even at idle. The amount of current supplied to the battery will depend on battery state and the current draw of the car electrics. Sounds to
me as the Dynator or its regulator are faulty. Either get it checked by an auto electrician or replace it with a known good one. The "Dynator has apparently been checked out as being in proper working order" statement suggests you are relying on third party information so it would be worth getting your own report on its health.

[Vonkie]

Thanks guys.

I am indeed very much reliant on third party information.

I have a feeling that a new Dynator will end up being required.

Let us see.

[PeterCrespin]

I have a feeling that a new Dynator will end up being required.

Let us see.

Fortunately for you, you have hit upon an area of trouble-shooting where you need not rely on feelings (that can get you into a treacherous, expensive mess). This kind of thing needs instruments and not vague hopes or fervent wishes. Empirical evidence suggests a smaller puller could 'fix' your problem, as noted, but it might be a work-around instead of a real solution to the specific failed component or set up. Dynators/Dynalites are not cheap, so guesswork could be expensive. Get an auto sparks to check out the true fault and leave emotions for births, marriages or funerals. i was never that keen on Charles Aznavour anyway....

Good luck and check your temp independently of the gauge. 90 is fine for a pressurized
coolant mix in traffic. 75-ish is OK but is not essentialxif something a bit higher is nice and stabile. Kenlowes hog the current anyhow and hurt airflow slightly when not switched on if mounted as a pusher fan.

Good luck.
"Feelings, all my life is feelings,,,"

[Peter27]

I had exactly the same problem on a positive earth car, with a Dynator that was less than 12 months old. The supplier sent the unit to the manufacturer who gave it a clean bill of health. My (very) experienced mechanic begged to differ so I sent it for independent an check. Unsurprisingly the unit was not performing correctly. Original supplier was fabulous and changed the unit for a brand new unit from an alternative supplier - now working perfectly.

[Vonkie]

Dear boffins

It was established that the crankshaft pulley diameter was measured at 130mm and the Dynalite RAC007 (for Lucas C42 negative earth) pulley diameter 80mm. This is not the 2:1 minimum ratio that the specs appear to favour for these units, so we went for a smaller pulley (60mm). It seemed from the specs I could find that the standard pulley size was 63mm. I was quite hopeful that the 60mm pulley would address the charging problem.

The problem now is that the belt cannot tension properly with the smaller pulley, and the next size down is too small. I am now advised one option is to enlarge the pulley on the waterpump to obtain tension on the belt.

There must be a more obvious solution to make the belt only a tad shorter? Is there a way of cutting it?

Please bear in mind I do none of this myself and this is all at a distance and hearsay. Advice would be very much appreciated, as I do believe the 130/80 pulley ratio was likely to have been the problem.

[Whitact]

Hi Frank,
Drive belts are readily available in a wide variety of lengths. A bearing & transmission belt specialist should be able to provide one the right size to solve the problem.
Cheers

[Vonkie]

Ta. Also thought so (was worried non-standard belts may be problematic).

Are there, apart from optimal size, minimum features/characteristics/specs this belt should possess?

[Vonkie]

Apologies for faux pas of self-reply.

It now appears SNGB have a special bespoke belt for this Dynalite 60mm pulley. We are ordering one and, if it does not disappear in the mail, which happens, I should have it in a fortnight.

In the meantime, I shall have dear lady D back tomorrow to play with pending streamlining of her Dynalite.

Thanks for all the assistance - I am sure the pulley size will do the trick.

[Vonkie]

Well, make the pulley smaller.

Helluva time getting the right size fanbelt.

The C19524 is too big. The C19523 is too small. The current jobbie (that fits over the current 80mm Dynalite pulley) appears to be the C19524C (that's what is stamped on it), which I understand from reading around the web is a tad bigger than the C19524, but not by much. Not by nearly enough to make me excited about the C19524 standard.

John Burton apparently advised my guy that the idea was to use the C19523 on the 60mm pulley, to fit it first and then to fit the pulley, and to do this with a helluva struggle and not to flinch when it seemed very, very tight. Well, there's apparently too little play and movement and the jockey tensioner does not do the trick. The C19523 is, in other words, much too small.

Where do I get a proper W belt with the right characteristics that would do the trick for the new 60mm pulley? It would need to be somewhere smack bang between the C19523 and C19524 - say 980mm. Going to a 70mm pulley hardly seems worth trying, as the current one is 80mm. And it just seems wrong to adjust the pulley size to fit the available fanbelts, rather than to get the right belt.

For the time being, back to the 80mm pulley, with charging (with fan running) only from about 1200RPM, and therefore mainly discharging on idle (let alone with headlights on).

Help?

[cactusman]

Afraid that still does not sound right to me. An alternator should be able to run lights or charge a battery even at idle. That is why they are better than a dynamo. Even my old dynamo will be charging and running the headlights at 1200RPM.

[Whitact]

Frank,
Have you tried somewhere like this?
https://simplybearings.co.uk/shop/Belts ... index.html
Cheers

[Vonkie]

Thanks Adrian - will let my guy know and report back.

[Series1 Stu]

Frank,
Have you tried somewhere like this?
https://simplybearings.co.uk/shop/Belts ... index.html
Cheers

Hi Adrian

I don't think that will help because this car has a duplex drive belt of which only about 6 different lengths are available. It made it very difficult to design the alternator conversions I eventually came up with. If I remember correctly the pulley was 63mm diameter.

Regards

[Vonkie]

Ja. These guys seem to do V belts only, not the double V or W. But my guy will find out, when life returns to these parts. It would be quite radical to convert to 2 V belts just to kick the Dynalite a bit - then one might as well go for an alternator kit that leaves the whole Dynator setup behind. I’d prefer not to, but it’s seriously annoying not to be able to experiment with a smaller pulley merely because I cannot get the right belt. At this rate, I might as well retrofit to the original C42 Dynamo, then at least I have inefficient charging with originality!

The quest continues. My ‘feeling’ expressed earlier may yet prove prescient, i.e. I may end up having to get a new Dynator. Let us see. All will no doubt eventually reveal itself.

[Series1 Stu]

Hi Frank

You could try one of my brackets. I had to build adjustment into my system because I junked the jockey wheel.

I'm not sure whether my pulley design would fit the dynator shaft though.

Regards

[Vonkie]

Finally got the pulley/fanbelt combo - and it appears to have made a real difference to the charging. Pulley is 60mm instead of 80mm, and charging much better - measured by voltmeter it appears to have made about 25-30% difference.

Let's hope I did not speak too soon!

New solenoid also made quite a difference.

Man it's good to have her back. Man.