Battery dead?

Discussion in 'Car and Van Talk' started by WaterBoy75, Sep 22, 2018.

  1. WaterBoy75

    WaterBoy75 Member


    My car has power for all the accessories (radio etc) but when I turn the key it literally dies (clock resets) and therefore will not start.

    I put a multimeter on the battery and I noticed when I turn the key the voltage goes from about 12v all the way down to 3v. Does this sound like the battery is most likely the culprit of the issues?

  2. Rulland

    Rulland Screwfix Select

    Battery failing when load applied, new battery time I reckon.
    WaterBoy75 likes this.
  3. WaterBoy75

    WaterBoy75 Member

  4. Isitreally

    Isitreally Super Member

    Voltage test on a battery doesn't always show if the battery is good for cranking power, cars today require a lot of power just to start and batteries have a habit of just failing.

    Try jump starting it and put a volt meter on to the battery when running, it should be around 14 volts, this will tell you the alternator is good.
    WaterBoy75 likes this.
  5. WaterBoy75

    WaterBoy75 Member

    Okay thanks. Just to check - if I jump it and the voltage is around 14 I know the alternator is okay and it is just the battery which is at fault?
  6. Isitreally

    Isitreally Super Member

    Almost certainly.

    Out of interest when was it last running and you haven't accidentally left any lights on, including glovebox light,
  7. WaterBoy75

    WaterBoy75 Member

    Hey - nope no lights on. Over the last three months has randomly died when starting (clock reset - as if I had competely drained the car) about 3 times. Then it would magically start with zero issues.

    Today I was driving it fine for about 15 miles. Suddenly it won't start at all.
  8. Peter208

    Peter208 Active Member

    Could be a bad earth connection.
    DIY womble and Isitreally like this.
  9. KIAB

    KIAB Super Member

    And still don't rule out the alternator,& a faulty starter can also drain a battery.
  10. Isitreally

    Isitreally Super Member

    Before you buy a battery, pop to Halfords and ask them to test it, you don't have to buy from them (way cheaper out there), but at leastnuoull know if it is the battey, from what you have said it could be as said above a bad earth connection.
  11. WaterBoy75

    WaterBoy75 Member

    Okay thanks. I will test that with the multimeter in the morning.
  12. Isitreally

    Isitreally Super Member

    Alternator check above.
    How can a faulty starter drain the battery, its dead until called for by the ignition via the solenoid.
  13. Isitreally

    Isitreally Super Member

    Test what.??
  14. WaterBoy75

    WaterBoy75 Member

    Thanks. Can I just carry the battery in, since the car won't drive now?
  15. WaterBoy75

    WaterBoy75 Member

    Thought you can test continuity on the grounding points for resistance?
  16. KIAB

    KIAB Super Member

    solenoid failure on starter can drain down a battery, as can a diode failure on a alternator.
    DIY womble likes this.
  17. HarDeBloodyHarHar

    HarDeBloodyHarHar Active Member

    Yes, a short in the starter(when ignition turned). Especially if the battery recovers to run other electrics.
  18. DIY womble

    DIY womble Well-Known Member

    Is the solanoid not fused?
  19. KIAB

    KIAB Super Member

    Most likely, but current draw might not enough to blow fused.
  20. wiggy

    wiggy Screwfix Select

    Just get a new battery the risk of being stuck at the side of the road is not worth it
    DIY womble and Isitreally like this.

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