Dynamator Conversion

[billwill]

You have a battery meter?
Yes that would be affected by polarity, you would need to swap over the terminals, if one of those teminals is the case of the meter, it might be best to do the swap inside the case.

The slow type fuel gauge works by temperature and is not affected by polarity but any voltage stabalizer associated with it might be polarity sensitive, the old type stabalizer which is basically a bimetallic thermal strip and contact is not polarity sensitive but a modern solid state version is.

I'm not sure if the two-coil balancing type fuel gauge is polarity sensitive; probably not. It depends on whether the iron bits on the rotor attracted by the coils have any permanent magnewtism.

[Concrete-crusher]

I had not realised my clock and battery meter were extras, but having looked there not on the circuit diagrams so must be. They do look very original on the dashboard.

That might explain the extra wires on. A1 terminal. I'm going to have a better look behind the dash at the weekend.

Thanks again

[Concrete-crusher]

Update

I have now put all the bits back and the engine started and she's running. The ignition light goes out and the conversion to negative earth seems ok as the rev meter is working (sort of) and the battery condition meter is looking good. A volt meter is showing 13v idle and over 14v at 3000rpm so that seems ok.

Now the odd bits. The amp meter is hardly moving. If you saw my other post it seems to be a shunt meter so does my wiring look right for that. I'm wondering if the green wire should also be connected to A1 and the solenoid to A1 wire removed ?

The other odd thing is when the headlights are on , the rev meter stops ? There is a blue main beam light on the rev meter that comes on.

When the lights are on I can see a slight movement on the amp meter - side but not much.

Regards all
Steve

[john.p.clegg]

Steve
Check the earth on the tacho casing....

John

[billwill]

The ammeter was an add on was it not, the scale readings will be correct for a particular shunt, but you might not have the correct shunt.

Only real way to be sure about that is to take it out of the car circuit and run it with a known current through the shunt and through a multimeter to see if they read te same. Use headlights as a 'load' to get a suitable current.

[dgently]

Thought I'd tack on a post to give a view on my Dynamator upgrade after a couple of months of use.

Very easy fit, works fine, makes a big difference to lights, indicators, windows, battery condition etc. But I've been surprised by how long it takes to start generating a useful charge. It takes 2/3 minutes of steady 3000+ revs before my system voltage will start climbing to settle around 14.4. Until then, it simply doesn't cut in.

As a result, I'm a good 3 miles from home before it kicks in. That's not ideal, as our typically soft days here in Ireland mean I frequently have the fan on trying to clear the windscreen + wipers + maybe lights. I realise that something or other needs to be properly "excited" before it gets going, but I suspect that delay is longer with this design?

Not a big deal, but I think I basically traded looks for some performance - I bet a fat ugly ACR would be on the job straight away.

Overall, satisfied.

[robertverhey]

My (admittedly limited) knowledge of ammeters is that the needle deflection reflects the amount of current flowing through the system, so if the battery is fully charged and healthy there shouldn't be much positive deflection with the engine running as the regulator will limit the current flowing to prevent you overcooking your battery. You can however see whether loading up the system by putting all lights and accessories on makes any difference. And you can check the amount negative deflection by switching on accessories while the engine's off (with ignition still on)

Of course in a dead short situation somewhere in the electrics, the needle will snap across to the negative, and that's usually closely followed by the smell of smoke......been there, done that!

[billwill]

Did you establish whether the inner circuit is as we discussed above.


If so you will notice that the initial exciting current flows through the dashboard indicator lamp, which will restrict the initial exciting current. You could try a higher wattage bulb in the dashboard (actually in the back of the rev counter is it not) A higher wattage will allow more current through to excite the field.

But note, if the indicator light is going out as soon as the engine is idling properly, that does mean that the alternator is already producing the same voltage as the battery and is working fine.

[rgh0]

Any alternator ( and the dynamator is just an alternator in an old style generator case) is limited to a specific output current based on its design capacity.and to a maximum output voltage of around 14.5 V. How much output current it produces at any point in time depends on the voltage in the output circuit it is sensing and alternator speed.

it sounds like you have a voltmeter in the car rather than the standard ammeter. The battery after sitting for a while and having been used to start the car will be at around 11.5 to 12 V once the car is started and running before the battery starts to recharge. The ignition light should go out immediately you start the car ( it may need a revup to 1000 to 15000 rpm to get the alternator to kick in). Once the light is out this indicates that the alternator has matched the battery voltage and is starting to charge the battery. As you drive the alternator will be putting current back into the battery and over time the battery voltage will rise to the alternator maximum output voltage of around 14.5v as it charges

How long this takes depends on the condition of your battery and how much it self discharges and on the capacity of the altenator but a few minutes is not abnormal. In addition if the volt meter is of the hot wire type like the old style smiths ones were, then they are slow to respond also. So in summary it is possible that what you see happening is to be expected.

cheers
Rohan

[dgently]

Yes, ignition light goes out immediately, so it is is certainly working. I've bypassed my ammeter, and am just surprised by how long before my (plug-in digital) voltmeter starts rising, and how long 'til it gets to 14.4.

I am assuming it's working correctly, just that it is a bit slower to get going than most. As per Rohans comment, if my battery was consistently low, that would explain it, but even when fully charged it just takes time for the alternator output to bring the system voltage up to 14v.

[Johnfm]

Just in the process of installing a dynamator.

Re: wiring - it seems that the regulator can just be removed completely if I understand correctly.

Can the existing wires be retained or is beefier wiring needed for a 45A dynamator?

[billwill]

You can remove the dynamo control box, but alternatively you can just move one wire from one terminal to another, I forget which, but we detailed it earlier this year. Then it still look original.

Part of the current will then flow through a small portion of the control box, but it will have no significant effect on the function of the alternator.

Strictly speaking you should fit a thicker wire (brown green ?) from your new alternator to the control box and then from there a thicker brown wire to the terminal on the starter solenoid. . That wire is the main feed from all the electrics to and from the battery.

[Johnfm]

Cheers Bill

I intend to to the whole relays/halogen H4 headlights thing too.

I haven't checked, but I assume that there are no relays on my headlights already (though there are 3 oil smothered realys on the left hand wheel arch under the brake servo).

My plan is 4 way realy holder, 2 fused headlight relays (1 for lowbeam, 1 for high beam), 1 relay fro wiper motor and leave one spare for future use (spotlights if I go rallying).

New fused alternator wire to starter solenoid terminal. Remove teh old regulator completely.

I need to put a battery cut out in there somewhere too - but don't want it in the boot or in the engine bay.

[billwill]

My S3 always had headlight relays, fitted by Lotus at the factory, they are the ones you mention mounted inside the left side front wheel area.

I'm pretty sure they are standard, though perhaps not back to S1 & S2.

[Johnfm]

Seems my +2 headlights are already on relays. 1 less job to do.