Flat battery - alternator or battery u/s ?

[gouldsborough7]

No sooner had I sorted out (nearly) my carburettor/ign timing problems, then my battery went flat! That's kit-cars for you!

Granted that the overnight temperature went down to a low single figure, but my Berli is kept in a fairly good garage. Also, I have only run the car a few times in the past 2 weeks around a 2-3 mile circuit (to test carb & ign tweaks), but the lack of life took me surprise when I turned the key. The engine turned over, but very slowly.

So this begs the question - is the battery or alternator dying, or is there a discharge for other reasons. My dashboard has a voltmeter, which seems to struggle to keep above 12 volts, especially with lights on. However, that doesn't give me any real idea on whether the battery is getting a regular charge when engine is running.

I'm tempted to fit an ammeter, which should keep track of discharges. Anyone got any ideas or similar experiences?

Cheers
Mike

[lizbillings]

Re: Flat battery - alternator or battery u/s ?

Hi Mike. Womder how old the battery is? My Berlinetta has a job to start in cold weather and sometimes needs jump leads or battery boost. Only short runs may not be helping either especially if the lights have been on.
Regards Liz

[gaddbrose]

Re: Flat battery - alternator or battery u/s ?

Hi Mike. Stick to the voltmeter, it's safer.
I had an experience on my boat which fortunately did'nt develope into a major incident. The boat has a 12volt system and uses the same equipment, and it had an ammeter fitted by the previous owner. This had big heavy cables fitted to the instrument posts which carry all the current and monitored by the gauge. I entered a long tunnel and had all lights on and pulling perhaps about 35 amps, when the whole lot shorted out, with a strong smell of burnt insulation. Checking it all out when we reached daylight, it was established that the instrument posts to which the power cables are fitted to, also hold the instrument securing clamps, and there are insulating bushes that keep the system apart, and is ok. when new. However, on that occasion when carrying that load, the old bushes failed and the whole power supply went to earth. Unfortunately, the earth wire was not man enough to carry it. so that overheated and burnt out and all the other wires in contact. What a mess. The man in the boatyard said "that's why we never fit ammeters" For what its worth ,Mike , don't!! A volt meter can give you enough info. regards Brian.

[macdonald.dm]

Re: Flat battery - alternator or battery u/s ?

Hi Mike.

Just think of the wonderful learning curve!

I understand most peeps 'in the know' actually reckon voltmeters give a better indication of overall charging condition than ammeters.

A poor alternator would allow the voltage to drop BELOW 12V. If your system can maintain 12+V when running with the lights and wipers on, it should be ok!

The only time you might expect the voltage to go much above 12V is after a bit of heavy cranking, when the output will increase to restore the battery's charge.

If you take your car to a fast-fit service centre, they should be able to test your battery in a matter of seconds. They'll probably give you the 'worst case scenario' tho'...

[gouldsborough7]

Re: Flat battery - alternator or battery u/s ?

Thanks Guys
That's reassuring to both me and wallet. I'll stick to the voltmeter, and probably get my local friendly garage to check it all out.

Cheers
Mike

[gouldsborough7]

Re: Flat battery - alternator or battery u/s ?

As a follow-up, I kept a careful watch on the voltmeter when I took my Berli to work in the daylight. I got a maximum of 13 volts with no lights or accessories switched on.

On the way home in the dark, with headlights and sidelights on, plus heater fan and radio, the gauge dropped to 11.5 volts. Fortunately, my journey home from work is only 9 miles, so even if the battery was discharging it survived the journey OK.

Doesn't look good for the alternator. I guess a recon one is called for in reality!

Just installed a small solar cell in window of my garage, which plugs into the cigarette-lighter socket. I think at best it provides 1.5amp/hr. It should help the battery a little.

Cheers
Mike

[macdonald.dm]

Re: Flat battery - alternator or battery u/s ?

Hard to know just how accurate these gauges are, but if it really dropped to below 12V the alternator clearly isn't doing its job. Unless there are poor connections somewhere.

[Dane_Rescueman]

Re: Flat battery - alternator or battery u/s ?

Hi,
I had this problem recently. I realised that with my conversion to fuel injection and electric fans my dear old Cortina Lucas alternator would not keep the voltage up as it is only a 25A alternator. Using heater, lights wipers etc used many more amps than were available.
I have shoehorned a 75A Sierra Bosch alternator in to the engine compartment and fitted a smaller pulley. The voltmeter now does not reduce below about 12.9v even with everything on.
I am reliably informed(!) that the alternator will not be bothered by the higher revs from the smaller pulley....watch this space!

[gouldsborough7]

Re: Flat battery - alternator or battery u/s ?

I don't know anything about the history of either the alternator or battery. There is a label on the battery dated 2004, which for a conventional car is no big deal, but on low mileage occasional users this might be the end of its life. (My Nissan Primera battery is 11 years old and still going strong, but that's another story!) I might replace the Berli battery as a precaution in any event, with the cold Winter temperatures more commonplace now.

I don't know what the output of my alternator might be. Although I don't have many extras to power: cooling fan is on the engine, and lighting is nothing special.

Can anyone tell me how to identify the output of the alternator?

Cheers
Mike

[Dane_Rescueman]

Re: Flat battery - alternator or battery u/s ?

Mike,

Many types of alternator were fitted to the Cortina. Mine had one of the three types of Lucas. The most use types are:
Bosch G1 output 28A
Bosch K1 output 35 or 45A
Fensa output 35A
Lucas 15 ACR output 28A
17 ACR output 35A
18 ACR output 45A
My Bosch 75A alternator has no markings but has a single post connector for a ring terminal. The Lucas types used the three pin plug. I do not know what the Fensa ones use to connect.
I enclose an example of the Lucas alternator; in this case an 18ACR. Thes do have tags on them as I have shown.
Try yellow pages for a local auto electrician. I have always found them happy to give info over the phone.

[gaddbrose]

Re: Flat battery - alternator or battery u/s ?

Hi Mike,
On the Lucas unit, if you have no identity tag on the alternator, then an easy way was to look at that central laminated band around the body of the alternator, a very rough guide used to be that a band about an 1" wide would be about 45 to 50 amp.capacity, 1/2" band would only give about 25 to 30 amps. However, on a car our size, I would have thought that you would want at least 45 amp capacity to cater for all requirements. According to my tame supplier, the standard alt. is now being marketed with a 70 amp capacity not that you would use that, but it is the "standard." Incidentally, when you are running normally, and no lights on , a healthy battery , altern. and system should register between 13 and 14 volts. regards Brian.

[gouldsborough7]

Re: Flat battery - alternator or battery u/s ?

Thanks guys
I've found a small plate on my alternator with 14v 55a 20 and Ford. I guess this is a 55 amp unit. Also, the battery is a 36AH 300A model. I suspect that whoever fitted the battery in the past was guided partly by its smallish size. My local shop has this listed for 1600cc Pinto, whereas mine is 2000cc, plus the additional problem of a Piper 270 fast road cam.

With no lights or accessories ON, my voltmeter shows around 13 volts, but soon comes down to 11.5 volts when gear is switched on. I might try to double-check the meter with a multimeter for confirmation of accuracy.

In any event, I think I might go for a new battery, with as much oomph as I can get into the space. The problem is the close proximity of inlet manifold, which I suspect will have to come off to get battery in and out.

Cheers
Mike

[macdonald.dm]

Re: Flat battery - alternator or battery u/s ?

Hi MIke.

55 amps is a fairly powerful alternator, and should be able to cope with your demand. Once your engine is running, the battery size is almost immaterial - it's the alternator that does all the work.

Where does your battery earth strap go to - bodywork/chassis or engine block? Is there a decent earth strap between the engine block and chassis? I'm wondering if there's a dodgy, high-resistance connection somewhere that could be to blame?

[gouldsborough7]

Re: Flat battery - alternator or battery u/s ?

Hi Dannie
I think I've sussed it out. I borrowed a mate's expensive multimeter, that reads fairly accurately to 0.5volt. Took my voltmeter out of the dashboard, and connected it straight to the brand new battery I've just taken the plunge and purchased. Voltmeter showed 12.5v whereas the multimeter showed 13v. Tried the little adjustment gubbins on the back of the voltmeter, but it didn't do anything. So took of the glass and bent the needle to 13v. Haven't tested it in action yet, but I am fairly confident it will read at least 12v! So the alternator can continue in service for a while longer!

Now is the problem of fitting the new battery to car. The one I bought has some more grunt, being a 45amp/hr with 390A starting capacity (or whatever it is called) compared to the old 1600cc Cortina one of 36amp/hr and 300A.

Hope I can get away with leaving inlet manifold in place. Although if forced to remove it, the opportunity will be there to check for a bad seal to the head - just in case this is a factor in my difficulty in getting the engine to run sweeter.

While doing the battery, I'll take your hint & clean up the connections on both earth and starter motor connections. Might fit an additional engine to chassis earth strap as well.

Cheers
Mike

[greyV8pete]

Re: Flat battery - alternator or battery u/s ?

Mike. I had starting problems with my Hunter (Rover V8 3.9i) . After replacing the battery I found that the battery earth clamp had been getting hot enough to melt the clamp itself, due to the wire clamp screws not being tight and only connecting on one or two strands of copper! As it's all in the boot near the fuel tank this was a bit worrying. Try and get the old fashioned bolt type clamps where the battery and earth wires are soldered in. Avoid the type with the screws as they are rubbish. The cheap after market copies are even worse at they have a very small cross section between the clamp and the wire connector.