Battery Warning Light on while driving

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k2col
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Joined: 21 Nov 2008, 12:07

Battery Warning Light on while driving

Unread post by k2col »

Hi,

Driving home last night, the battery/low voltage warning lamp came on. At the time we didn't notice any further symptoms and completed the short journey home.

This morning on the way to work, about 3 miles into the journey it happened again. This time it was raining and it was immediately obvious that the windscreen wipers stopped working! Also no indicators or interior fan. Strangely enough the stereo still worked.

I pulled over, turned off the ignition, turned it back on again (the car always starts fine - which seems to imply the battery is ok) and the problem went away!

It's been raining quite hard and I took the car into a car wash yesterday, I wonder if there is any connection?

Otherwise I tend to suspect the alternator or aux drive belt?

Knowing the Xantia, I also suspect electrical contact problems....

Any thoughts please guys?
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CitroJim
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Unread post by CitroJim »

I'd be inclined to think the alternator was showing the first signs of a slow death :(

Pop a decent digital meter across the battery and check the voltage is in the order of 14.4V whist the alternator is charging. If it is significantly below this, you can assume th alternator is not happy.

If the aux. belt was the source of the problem, there would be other signs, including noise and possible loss of hydraulics.
Jim

A bit of a Citroen AX fan...
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k2col
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Joined: 21 Nov 2008, 12:07

Unread post by k2col »

Took it to my local garage at lunchtime for a free test.

- The battery has a good voltage
- Even with lots of accessories on (lights, heated rear windshield, aircon etc) with the engine running the voltage was good - so the alternator seems alright

However:

- The battery failed a voltage drop test, and needs replacing

I bought a new battery and will fit tonight, otherwise they advised replacing the auxiliary drive belt. But as you say, I don't think a loose drive belt would quite account for the symptoms, especially as it's never been noisy. (I think the garage were looking for a chance to charge 2hrs labour)
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xantia_v6
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Unread post by xantia_v6 »

On most cars, the alternator warning light is wired so that it lights when the alternator output voltage is less than the voltage in the "ignition" circuit. It also works the other way, and the light will come on if the voltage in the "ignition" circuit is less than the output of the alternator. This is why the light flashes on breifly when the ignition is switched off.

From your symptoms I think you have a fault in the ignition switch or wiring that is causing the voltage to drop at the point where the alternator warning bulb is fed. This would explain why the wipers stopped.