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#531089 01/09/18 06:22 PM
Joined: Jun 2014
Posts: 29
Just Getting Started
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Just Getting Started
Joined: Jun 2014
Posts: 29
Hi,

I have a 1995 4/4 with the Zetec 1800 Silver Top engine. I have had some problems with battery charge recently and to cut the story of a long investigation short the battery tested ok and starts the engine with no problem. There is almost no drain on the battery when the engine etc are switched off (1.6mA). I have begun to suspect the alternator but it is charging the battery. What bothers me is that the ignition light does not go off until the engine reaches 1600 rpm and at that point the output voltage is 14.2 volts irrespective of engine speed. The voltage does drop when load is applied, eg lights, but not a lot. I wonder if there is something wrong with the alternator regulator which may be causing over-charging of the battery.


Any comments gratefully received.


David


David

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Suggest removing alternator and getting it checked out by a suitable professional. It could be the regulator, a faulty trio diode or even field brushes.

Having said that 14.2 volts is an acceptable charge voltage and I wouldn't expect it to vary much with normal loads as the regulator does what its supposed to do. Charge light should extinguish from the word go though.


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More than likely something else causing the battery to drain.

To be sure you can get the electrics both battery and alternator tested in situ to reveal problems with them.

I bought an AUTOOL BT360 Battery system tester it was only around £30.

It will confirm if there is an issue with the charging amongst other features.


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Make sure You alternator belt is not slipping.


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Make sure You alternator belt is not slipping.


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If the belt is tight change the alternator.

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Originally Posted By DurhamDavid
Hi,

I have a 1995 4/4 with the Zetec 1800 Silver Top engine. I have had some problems with battery charge recently and to cut the story of a long investigation short the battery tested ok and starts the engine with no problem. There is almost no drain on the battery when the engine etc are switched off (1.6mA). I have begun to suspect the alternator but it is charging the battery. What bothers me is that the ignition light does not go off until the engine reaches 1600 rpm and at that point the output voltage is 14.2 volts irrespective of engine speed. The voltage does drop when load is applied, eg lights, but not a lot. I wonder if there is something wrong with the alternator regulator which may be causing over-charging of the battery.


Any comments gratefully received.


David


Thats an odd one because normally the alternator light goes out when the alternator is generating a voltage greater than that of the battery, and therefore there is no current flow through the light. But the battery can never be as high as 14.2 v so the light should have gone out long before, To my mind this suggests a wiring issue assuming that the voltmeter is correct.

I would start by carefully checking all cable joints in circuit. Are any of them getting warm indicating a poor connection and high resistance.

Charging at 14.2 volts is perfectly normal. Indeed many regulators are set at 14.5 v

Apart from this high voltage, are there other problems?


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