Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) 4/4 Charging system

I'm investigating a fault with the charging system in my 1998 4/4 (1.8 silver top Zetec).

Symptoms: With the ignition switched on (engine not running) I can switch on the headlights ok. With the engine running, if I switch on the headlights they are ok for a moment or two then they fade out and the tacho also dies but the engine still runs ok. Its as if, once the engine is running, there is no power available for the lights & tacho.

I have checked the battery with a proper battery tester (Topdon BT200) and it is ok and fully charged.

I haven't checked the alternator yet but:
My first question is would this car have a so-called Smart Charging System as I understand that a Smart Charging System may make alternator diagnosis more complicated as the charging rate involves the ECU.
My second question: Can anyone give me the part number for the alternator?

I believe Ford used machine regulated alternators on early Zetecs. Your fault as described is a little odd but may be caused by a faulty onboard alternator regulator as clearly battery volts should be higher with engine running. Could you check battery voltage across terminals with multimeter with/without engine running and with/without headlamps on.

Thanks Richard
What are machine regulated alternators - is this the same as Smart Charging via the ECU?

I should be able to do those battery voltage checks on Wednesday, possibly Thursday.
I may even be able to use the Topdon to check the alternator - Although it claims to be able to test alternators I am not sure if it will give a valid answer because of the possible Smart Charging System. Hence the question re.Smart Charging

Also suggest checking headlights with ignition switch in normal running position but without engine actually running. (To see if it related to an ignition switch problem?)

Machine regulated refers to the fact the alternator is regulated by an onboard device as distinct from a remote one, in each case by varying the field current to control the max voltage the battery receives from the alternator stator. Modern cars employ dedicated circuitry within the ECU to control the field remotely I whilst also providing a lower voltage float mode when battery is deemed fully charged much like a smart battery chargers but with the advantage of responding efficiently to changes in load. Remote regulation also provides voltage sensing at the battery rather than machine, compensating for any voltage drop.

Whatever system a car uses you should be seeing above 14 volts at the battery after a start, assuming revs are a little over idle, in order to replenish after the battery drain.

Good advice from Richard as usual.

Just for info I used to own a MY2000 Silvertop Zetec and the alternator was pretty basic and certainly not of the smart charge type, somewhere I've got a Haynes manual for the relevant Ford Focus (Mondeo ?) which has some tech data

Do you have spot lights. Wired into the headlights which are activated when high beam is selected. if after market and wired incorrectly although through a relay could be an issue there. I have seen strange wiring in the past where aux lights were wired incorrectly and caused all sorts of issues if a fuse or relay has failed. Do the side lights illuminate and stay illuminated when the engine is running and not running?

I'm fairly sure the silver tops had a rudimentary alternator which had the charge control attached ie self regulating. Have you checked all other electrical functions, perhaps when you put the multi-meter across the battery., Battery with no load should should read close to 12.6v and with engine running in the region of 14.2or3v. Whilst observing the running charge you could initiate a load IE turn the heater on to full blow and the alternator should accommodate this very quickly.
What happens when you flash the high beam with the engine running and headlights switched off?
Gaufridus, I'm sure you are not the first person who has encountered this. If I look at it from this distance my first thought is that, headlights come on with ignition on yet when alternator charges after starting they go out..... I'd be looking for a relay fault and or wiring that is isolated by some failure of a component or a short but, if Richard hasn't come up with an instant solution then it might be a bit of a methodical slow assessment!

Here's the Haynes Ford manual extract for the Alternator fitted to yours Gaufridus

Before you attempt, remember the usual safety stuff...moving drive belts, pulleys etc, and also NEVER disconnect battery or alternator leads whilst running as this will blow the diode pack !

Well, I checked the battery this morning:

Static situation - (red isolator swtich = off, therefore nothing switched on). Battery = 12.5 volts
Isolator switch on, engine running. Battery = 14.0 volts at tickover.
Switched headlights on - all is ok, no headlight fade. Battery = 13.88 volts at tickover
Engine running switched other loads on (wipers, heater, headlights) all is still ok
Ran the engine for 15-20 mins untill the radiator fan kicked in & out a few times - rechecked lights etc. all is still ok.

The problem seems to have disappeared, still quite concerned so I'll keep checking it every so often. A complete mystery but here's hoping!

Thanks for all your suggestions
I'll repost if the situation occurs again

Geoff

Those measurements all seem normal. You probably had a bad connection somewhere in the headlight chain. This includes the headlamp or dip switch - already had to change mine.