Charging issue

109inches · Dec 5, 2015

Factory 200tdi 90 isn't charging or is charging very little.

Charge warning on the dash appears when key is turned to ignition as it should.

It goes out immediately once the engine is started and stays off until the engine is switched off.
However volt meter is always reading that the battery isn't charging. The volt meter is wired up correctly and works as it should. When headlights are on it then drops to the 11 volts mark indicating the battery is only discharging. All alternator wiring is fine.

I'm not bothered about replacing the alternator it's a 10 minute job to do. But I'm interested to know what failure in the charging system would cause a perfectly funtioninf warning light to not illuminate when there's an issue in the charging system?

nobber · Dec 5, 2015

Do you have a multimeter? It could be a dud battery, bad connection etc.

109inches · Dec 5, 2015

Brand new battery. Cleaned up all connections from alternator to battery and the main earthing points of the battery.

Did some tests that seemed odd. When the battery was connected and the engine running the multimeter and volt meter read 12 volts. Disconnected the main earth batter cable and the volt meter read 14 volts. The interior light got brighter when the battery was disconnected and dimmer when the battery was re connected. When the battery was connected again still with the engine running the volt gauge went back down to 12 volts

jamesmartin · Dec 5, 2015

though you shouldnt run an alt with battery disconnected, if battery is connected as normal, a test on positive terminal by using multimeter earthed to the car should read 13 to 14 volts if not alt isn charging

Kwakerman · Dec 5, 2015

Never run engine with the battery disconnected, that's one of the best ways to bugger up the regulator which will mean an alternator replacement or rebuild.

zeaphod · Dec 7, 2015

If the dash light goes out, it suggests that the alternator is producing enough voltage - although it's only proof that it's sending that on the wire to the dash lamp. The other output feeds the battery and other loads.
There is a chance that you have something draining the battery, or a partial short to earth. I would test the voltage at the battery (engine running), and remove the fuses one by one to see if anything is amiss.
Having said that, it is possible for the alternator to produce enough voltage, but little current.

trax · Dec 7, 2015

sounds like something isn't wired up correctly/shorting. if you don't get a flat battery then it's probably only doing it with the engine/ign on

why did you get a new battery?

what does the battery read when the engine and everything is off? if you have checked the cables again and everything looks ok, then a quick test is to pull fuses and see if the voltage goes to normal when the engine is on.

if that doesn't work it's proper multimeter time

109inches · Dec 12, 2015

It's got a new battery because it was stolen out of my project 110. The first day the battery went flat and we didn't know no charge was getting to the battery we just swapped in a good battery as its a daily drive and the battery was swapped just before work.

I've investigated further and taken the alternator to a specialist who tested it and said its working perfectly.
The only job to do is trace the wiring and see what's going on

Charging issue

109inches

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nobber

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109inches

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jamesmartin

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Kwakerman

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zeaphod

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trax

.

109inches

Well-Known Member

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