X-Type ( X400 ) 2001 - 2009
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Battery warning light

Old 06-26-2019, 01:55 PM
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Default Battery warning light

I have an illuminated battery warning light on the dashboard. Car is a 2002 X Type sport. The battery has not gone dead. It measures 13.2 volts with the key off and 16 volts at idle. Is it possible that the light is indicating an over charging condition?
Thanks in advance

Old 06-26-2019, 02:24 PM
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16v is way to high, suggest you get the alternator checked out.
Old 06-27-2019, 03:21 PM
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cables deteriorate and can cause this light to come on intermittently. Mine was doing same. I got new cables, but first I cleaned & tightened battery terminals, before installing the new cables.. Light has stayed off for about a year now.
Old 06-27-2019, 04:36 PM
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Thanks foxbottom. I will give this a try.
Old 06-28-2019, 12:27 PM
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I've got the intermittent light issue even though the alternator is charging fine, so I've been doing some research on this. While it's not relevant to my condition, several things I read indicate that at least in the case of the X-Type the light CAN indicate too high a charging condition. 16v is too high (and the 13v+ from the battery when off indicate it's being over charged too). You'll need a new alternator (or possible just a voltage regulator, it can be replaced separately on some alternators, I don't know about the the X-Type's).
Old 06-28-2019, 12:36 PM
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Vehicles With 2.0L, 2.5L or 3.0L Engines

The charging system consists of a 120 amp output generator and regulator assembly which generates current to supply the vehicle electrical system with electricity when the engine is running and maintain the battery in a charged condition.The generator is belt driven by the accessory drive belt.

When the engine is started, the generator begins to generate alternating current (AC) which is converted to direct current (DC) internally. The DC current and voltage is controlled by the voltage regulator, (located inside the generator), and then supplied to the battery through the main battery positive cable.

The generator is solidly mounted to the engine timing cover and is driven at 2.8 times the engine speed.Vehicles fitted with manual transmission have a one way clutch fitted to the drive pulley, which prevents torsional vibrations from the engine being transmitted to the generator.

The engine control module (ECM) can switch the voltage regulator between two voltages to optimize the charging of the battery.The low voltage regulator setting is 13.6 volts and the high voltage regulator setting is 15.3 volts, measured with the generator at 25C (77F) and charging at a rate of 5 amps. These values decrease with a rise in temperature or current flow.

The ECM determines the voltage setting of the voltage regulator. The high voltage setting is always selected by the ECM once the vehicle has started. The ECM determines the period of time that the high voltage setting is selected for.There are three different time periods selected by the ECM which is dependent upon the vehicle conditions when the vehicle is started:

The longest time period is selected if the ECM determines that the vehicle has been 'soaking' for sufficient time to allow the engine coolant temperature (ECT) and the intake air temperature (IAT) to fall within 3C (37F) of each other.

The intermediate time period is selected when the ECT and the IAT are below 5C (41F).

The shortest time period is the default time and is used to provide a short period of boost charge.

At the end of these time periods the voltage is always set to the low voltage setting to prevent the battery from being overcharged.The time periods are variable depending upon the temperature and the battery voltage.

The target voltage of the battery varies between 14 volts and 15 volts depending upon the ambient temperature and the vehicle operating conditions. Once this target voltage has been achieved, providing the vehicle has been operating for at least the shortest time period, the ECM will reduce the voltage regulator to the minimum setting of 13.6 volts.

X types are sort of susceptible to bad cables and lights battery warning. To test, start the car, turn on every electrical thing you can, (rear defrost, radio, interior lights, a/c, exterior lights, seat warmers). Let car run for 2-3 minutes and shut it off. Cup your hand over each battery post, DO NOT TOUCH!!!

If cable(s) is bad it will be cooking hot.

Last edited by Dell Gailey; 06-28-2019 at 01:35 PM.
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