joolsmi16
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| posted on 22/5/10 at 07:24 AM |
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not charging?
Hi all, tried to start my xflow today and its dead... Started and ran fine for its MOT on Monday but had to jump it today.
Went for a spin to charge it up but did'nt work I could feel in the way the car drove the engine was'nt running right and when it was
switch off would'nt start from the key and a jump was needed.
Iam hoping its the alternator so what kind of voltage output should I see from the alternator/battery so I can fault find the problem??
Thanks
Jools
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rusty nuts
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| posted on 22/5/10 at 07:40 AM |
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You should be getting around 13.5v to 14.5v . Had problems with mine a couple of years ago even though it was only 2 years old, alternators
don't like getting too hot . I've since made up and fitted a heat shield between the alternator and the exhaust manifold as well as
lagging the manifold
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cliftyhanger
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| posted on 22/5/10 at 07:49 AM |
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And a lot of the "recon" alternators are absolute rubbish with a very short lifespan.
First thing though is to charge the battery with a charger. Make sure it is holding charge as they can fail with no warning. Besides sticking a new
alternator on a flat battery is not a clever idea.
As long as the battery charges and holds charge OK, then check the alternator output as above.
I prefer to get a used OE alternator in preferance to cheap recons (the last lucas acr one was about £25, how can they do anyting much apart from
clean it and bung in some crap repro useless repair stuff, and sell it for that money? it lasted about 2 years and 1200 miles) )
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joolsmi16
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| posted on 22/5/10 at 07:49 AM |
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not charging?
Okay will check later on... the engine bay is very hot and may looking into some heat protection..
jools
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tonym
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| posted on 22/5/10 at 07:50 AM |
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12v at the battery with the engine stopped rising to 14.4 with the engine running.
Take the small connector off the altenator and earth it. With the ignition switched on the charge light should light up - if not check the bulb as it
will not charge if the bulb blows. This wire is switched 12v through bulb to the altenator small terminal.
Check the large terminal at the altenator is 12v. This wire connects the battery to the altenator.
Check there is a good earth between the altenator and the engine block.
If all this fails the altenator is faulty.
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joolsmi16
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| posted on 22/5/10 at 07:54 AM |
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not charging?
The cars on its second fully charged battery so these battery are not holding or getting a charge.
Will do all the checks tonym and report back
cheers
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britishtrident
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| posted on 22/5/10 at 05:01 PM |
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A few general points to start with.
After a jump an alternator cannot charge a completely flat battery --- it just can't do it, you need to have a minimum voltage in the battery
for the alternator to charge.
It really isn't a good idea to charge a flat battery quickly, rule of thumb for maximize battery life is you should take 5 times longer to
charge a battery than it did to discharge it.
A very common problem that stops otherwise good Lucas ACR and other 3 wire plug alternators charging is the 30 amp Lucar blade connectors at the back
of the alternator make poor contact and start arcing. Back in the 1970s we used to see this quite often until we twigged what was wrong, a car would
come in not charging, a new alternator fitted everything would be fine for several months then it would stop charging again. Cure take the plastic
cover off the rear of the alternator clean the connector blades, then fit new large spade connectors to the wires, put it back together and
everything would work fine.
With a Lucas acr you should get 13.4 to 14.7 volts output with the engine running at 2000 to 3000 rpm, this should be tested with both the headlights
on and off, however to get valid results from this test the battery needs to have at least a 70% charge. During the test the headlamp should be
switched on and off again while the alternator is charging if the voltage suddenly jumps for an instant above 14.9v or below 13v suspect a duff
connection or regulator fault.
However alternators can pass this test and still have a defective diode, check for a diode leaking current back through the alternator when the
engine is off temporary connect an ammeter (a DMM with a 10 amp dc range will do) in series between the alternator and the main connections to
battery, if it shows current leaking with the engine off the diode pack is knackered.
Lucas ACR alternators are generally easy enough to rebuild parts are easily and very cheaply available.
To test a battery for a bad cell you can do a voltage drop test under load. Without a proper load tester you can approximate this with a starting
voltage test.
To do this you must first ensure the battery has at least an 80% charge and allow it to rest for several hours, eg overnight. Then simply measure
the voltage while cranking the engine (disconnect the coil to stop the engine starting), a healthy battery and starter will normally show almost 11
volts. If it shows 9 volts or below rapidly dropping to 6 volts this is a sure sign of a dead cell in the battery.
[Edited on 22/5/10 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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