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Very High Amps

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Akiri
Posts: 9
Joined: Sun Aug 20, 2017 3:06 pm
Location: Winchester UK

Very High Amps

Post by Akiri »

My 1968 V8-250 is fitted as standard with an AC 11 alternator with 4TR voltage controller and a dashboard ammeter.On start up the ammeter shows near maximum charge for more than 10/15 minutes.Then the gauge slowly drops to half max and remains there.
During long journeys the battery runs flat and must not be receiving charge.The 4TR was suspected and now has been replaced with new units several times and a new battery fitted but the problem persists. The alternator is working correctly. Any suggestion would be most welcome.
Akiri

bakergh
Posts: 109
Joined: Wed Feb 24, 2016 1:57 pm
Location: New Forest, Hampshire

Re: Very High Amps

Post by bakergh »

I think you need to check that the battery is being charged. You will need a voltmeter to first check the battery voltage without the engine running. It should be 12.8 volts for a fully charged battery. Next start the engine and run it above tick over so that the alternator is charging.
The measured battery voltage should now be between 13.9 and 14.3 volts if both alternator and 4tr are working correctly.

How do you know the alternator itself is ok? One of the common failures for an alternator is diode failure which could explain your problems.


Graham

Akiri
Posts: 9
Joined: Sun Aug 20, 2017 3:06 pm
Location: Winchester UK

Re: Very High Amps

Post by Akiri »

Thank you Graham for your reply. Have carried out battery checks and all seem OK but still high charging rate persists.
Can the 4TR UNITS be the cause? I have tried several new items with no improvement.
The flat battery may be caused by Kenlowe as It happens after long run. Will disconnect.
Akiri.

User avatar
Kbeal
Posts: 148
Joined: Mon Feb 15, 2016 9:01 pm

Re: Very High Amps

Post by Kbeal »

Can you borrow another alternator known to work? Seems like that's the only piece of the system you haven't replaced / checked out.

Kevin

bakergh
Posts: 109
Joined: Wed Feb 24, 2016 1:57 pm
Location: New Forest, Hampshire

Re: Very High Amps

Post by bakergh »

The flat battery is unlikely to be caused by the fan. The alternator should easily be able to supply the necessary current.
Some history of the car might help us help you.
Have you run this car with the charging working correctly?
Has this fault suddenly become apparent?
Is the battery losing its charge while the car is not being used?

Graham

Ian Hastings
Posts: 163
Joined: Tue Mar 15, 2016 3:00 pm

Re: Very High Amps

Post by Ian Hastings »

Remember that even if a battery is reading about 12.8 volts it does not mean that it is in good condition. It may well seem to be charged but not capable of delivering any strong current.

I would suggest you get the battery checked with a proper battery tester, not just a volt meter, to see what current it can deliver after you have charged it up.

tjt77
Wise Man
Wise Man
Posts: 525
Joined: Wed Mar 23, 2016 7:01 pm

Re: Very High Amps

Post by tjt77 »

The most likely suspect, given you have replaced alternator and tested battery would by the 4TR 'regulator' ..these are known to give problems ..best to use a modern alternator with internal regulator and ditch the 4TR unit altogeather..

Akiri
Posts: 9
Joined: Sun Aug 20, 2017 3:06 pm
Location: Winchester UK

Re: Very High Amps

Post by Akiri »

Thanks all for your replies. I have now changed my AC 11 alternator for an equivalent from Wosp which incorporates the voltage control unit and so dispenses with the troublesome 4TR. Slight modifications to the alternator adjustment bracketery was necessary and rewiring of the ignition warning light. As the alternator requires a voltmeter, I have replaced the ammeter with one. If it doesn’t work out, I shall return. Akiri.

John Hitchins
Site Admin
Posts: 244
Joined: Mon Feb 08, 2016 10:52 am
Location: Wellington Somerset

Re: Very High Amps

Post by John Hitchins »

If negative earth then a £3 plug in digital voltmeter is handy for cigar lighter socket, on Ebay, brilliant tool.

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