4play
Member Since: 24 May 2020
Location: Shropshire
Posts: 33
  
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Hi, as soon as I turn the engine off the voltage drops instantaneously to between 11.8 and 12.1 volts. When running it is 14.4. When off the approx 12 volts maintains for days with the car locked and alarmed so I don’t think that there is a drain. Could be the battery but just wanted to check before replacing it in case this situation could possibly be normal????
Thanks in advance of any thoughts.
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 26th Feb 2024 10:54 pm |
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timmyt79
Member Since: 18 Oct 2016
Location: Pemrokeshire
Posts: 585
  
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100% duff battery sorry to say 
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| 26th Feb 2024 11:06 pm |
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timmyt79
Member Since: 18 Oct 2016
Location: Pemrokeshire
Posts: 585
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your alternator is charging at correct voltage but at 12v a (12v) battery is dead...Im surprised its actually starting tbh!
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| 26th Feb 2024 11:07 pm |
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4play
Member Since: 24 May 2020
Location: Shropshire
Posts: 33
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I meant to say that I am reading the voltage through a cigarette lighter plug in adapter. This low voltage situation has been around a few weeks of car use. I think I recently read that the AGM batteries can function at a lower voltages.
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| 26th Feb 2024 11:19 pm |
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Hardware
Member Since: 28 Jun 2016
Location: Hiding under the M60
Posts: 12709
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Mine shows similar figures via the secret menu ... I replaced the battery and they improved marginally.
I'm psyching myself up to look at the earth straps.
She starts on the button every time, no hesitation at all.
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| 26th Feb 2024 11:56 pm |
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itsaguything
Member Since: 20 Dec 2023
Location: Manotick, On
Posts: 146
  
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This theme keeps coming up.
A battery is fully charged if it can maintain at least a voltage of 12.6v. Some AGMs are at full capacity at larger voltages.
If the battery is at 12.3v, it is at 50% capacity, which is not sufficient for a modern vehicle with their many electronic devices.
If replacing the battery, do fully charge it prior to installation. Rarely are new batteries fully charged when purchased.
A battery can not read 14+ v. You are reading the generators voltage. 2015 LR4 HSE Lux Aintree Green
2013 LR2 HSE Radiance Red
2007 XKR Jaguar Racing Green
2005 XJR Jaguar Racing Green
2002 S-Type R British Racing Green
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| 27th Feb 2024 4:10 am |
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