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Old 15th September 2019, 12:51   #11
SD1too
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Originally Posted by chillyphil View Post
My voltage changes depending on the demand from the vehicle, ranges from 13.7 to 14.5. I thought this variation was normal?
It sounds as if the regulator within your alternator is faulty. But before diving in there I would check the basics: security, cleanliness and low resistance of all connections at the alternator and battery.

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Old 15th September 2019, 13:51   #12
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My understanding was that the regulators job was to keep the voltage that the alternator produces between 13.5 and 14.5 volts, the idea being that most auto components could deal with this level.

Is this not the case?
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Old 15th September 2019, 15:28   #13
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The voltage can certainly be between those two values but it should be constant, not variable.

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Old 15th September 2019, 15:53   #14
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The voltage going into the battery is kept around 14 volts for a very good reason. Not to safeguard the electrical components but to prevent damage to the battery.

The battery needs never to go above bath water temperature.--If the battery starts getting hot it will start to lose H2O from the electrolyte.

The acid in the battery becomes stronger and the acid level in the battery becomes lower exposing the plates. This then reduces the batteries ability to store electricity.

14.5 will NOT make this water loss happen.

Nor will it damage any electrical components.


Sooooooooooooooo, stop worrying.----
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Old 15th September 2019, 16:35   #15
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Originally Posted by SD1too View Post
Are you waiting longer than 18 minutes after turning off the ignition Edward?

If your 2004 car has the later type of passenger compartment fusebox, the answer is as follows:

Power wash relay and fuses 28 to 36, 38, 40, 42, 44, 47, 49, 51 and 53 of the passenger compartment fusebox.

Simon
Thanks Simon for responding. I didn't realise you had to wait 18 mins. I'm going to take some new readings and post them shortly. I literally pulled out every single fuse and relay in the fusebox, and none of them stopped the current draw except removing the 50a one labelled FL3.
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Old 15th September 2019, 19:11   #16
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I understand your point about current and load, however, my understanding has always been that the voltage from the alternator will fluctuate depending on temperature and load requirements, controlled by clever electronics.

I have the ice system showing present voltage on the screen.
At rest, before engine starts it shows battery voltage, usually around 12.6
If the battery voltage is low, or there is a high load on startup, I get 14.5 volts.
During and after a long run, it typically drops to around 13.7.

Is this not one of the functions of the ECU and canbus?
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Old 15th September 2019, 19:46   #17
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I just checked my 2004 ZT 260. My charging voltage is also exactly 14.5 volts on tickover. At 2500 revs, still 14.5 volts. I never thought about this, but I have had minor battery acid leakage which caused me to remove the slightly corroded battery plate and refurbish it. I also found that someone hadn't put back in the battery drain tube properly. Since the drain was installed correctly, the corrosion has stopped. Anyone know where the voltage regulator is and should it or can it be altered to a lower voltage? My ctek charger also seems to be at 13.7. I'm taking a keen interest in my electrics just now as I have a 1.4 amp current draw from the battery with ignition off. If I remove the 50amp fuse from the fuse box, the current drain stops completely. Anyone got a circuit diagram for tracing what comes off FL3
Check your background illumination isn't remaining illuminated around the light switch after the car is locked

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Old 16th September 2019, 15:53   #18
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Quote:
Originally Posted by chillyphil View Post
I understand your point about current and load, however, my understanding has always been that the voltage from the alternator will fluctuate depending on temperature and load requirements, controlled by clever electronics.

I have the ice system showing present voltage on the screen.
At rest, before engine starts it shows battery voltage, usually around 12.6
If the battery voltage is low, or there is a high load on startup, I get 14.5 volts.
During and after a long run, it typically drops to around 13.7.

Is this not one of the functions of the ECU and canbus?
I think you will find this variation due to the internal resistance of the battery rising as it takes a charge.

Voltage being the PRESSURE of electricity.

Amperage the QUANTITY.

The ideal charge to give a battery long life is around 5 amps.
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Old 16th September 2019, 16:01   #19
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Thanks Jon,

I thought this variable alternator voltage output was normal.

Last edited by chillyphil; 16th September 2019 at 16:02.. Reason: Spelling
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Old 16th September 2019, 16:10   #20
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I would keep a very close eye on that Pete. 14.5 volts is regarded as the absolute maximum charging voltage. To put that in perspective, my C-tek smart charger is currently applying 13.71 volts when connected to my SD1's battery.

Simon
Simon. That doesn't really put it into perspective as you need to take into account the charge in the battery.

Your smart charger is applying 13.71 volts because it senses that is all the battery needs to maintain its condition.

If your sensor in your charger detects a low voltage in a battery it's charging it will increase the rate of charge to a higher but safe level.------A level ,that I said in a previous post, that will not OVERHEAT the batteries electrolyte.
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