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Thread: Volt meter reads 11 volts

  1. #1
    Join Date
    Apr 2013
    Posts
    81

    Default Volt meter reads 11 volts

    Driving to work this morning I noticed that my volt meter reads 11 volts. I bought a new battery a few months ago. Is this normal? Should I be concerned, and start investigating further?.
    1997 Caterham, BDA
    1991 Miata, supercharged
    2017 VW GTI

  2. #2
    Join Date
    Feb 2017
    Posts
    42

    Default

    Not normal. It could be faulty gauge, battery or alternator.

  3. #3
    Join Date
    Sep 2017
    Location
    Midlands of SC
    Posts
    23

    Default

    How many volts show across the battery when you check it with a hand held voltmeter when the car is running?
    If only 11 volts, it is not charging and may be a bad alternator, or a possible loose or cut wire. Or a loose or corroded battery ground wire(s)

  4. #4
    Join Date
    Apr 2013
    Posts
    81

    Default

    Thanks for the input guys. Will check later in the week.
    1997 Caterham, BDA
    1991 Miata, supercharged
    2017 VW GTI

  5. #5
    Join Date
    Apr 2012
    Posts
    149

    Default

    Remember that in a car with a generator or alternator the battery is only involved when starting the car. Once the engine is running the generator or alternator (if working properly) provides all the electrical current the car needs (and also recharges the battery for that next start). So, as mentioned in post #3 the low voltage reading you're seeing tells you something else is amiss as it is not an indication of a bad battery.

  6. #6
    Join Date
    Apr 2013
    Posts
    81

    Default

    I checked with my hand held volt meter tonight. It correlates with the volt meter in the car, but reads consistently about 1 volt lower.

    At idle, the VM in the car reads around 11V. When I rev to 3k or so it moves up to around 13V. Hand held meter on the battery reads around 10 at idle and 12 when revving. Battery is a lawn tractor battery, new this year. Turning on the headlights drops the voltage by about 1/2V.

    Do these numbers seem reasonable, or low? If low, what's my next step?
    1997 Caterham, BDA
    1991 Miata, supercharged
    2017 VW GTI

  7. #7
    Join Date
    Feb 2017
    Posts
    42

    Default

    How hard is the alternator to get off? If you can take it to some place like Autozone they can check the output for free.

  8. #8
    Join Date
    Sep 2006
    Location
    Southeastern Pa.
    Posts
    2,813

    Default

    I seem to recall that i have a pulley that effectively slows down the spin rate on my Alternator to allow for the higher rev range when on track. I think it doesn't begin to charge at less than 3000 rpm.

    Maybe something similar in your case?
    Mangia bene, Ridi spesso, Ama molto, Guidare veloce

    2000 Caterham Superlight #123
    1.8L VHPD Rover K Series
    2009 Caterham SV
    2.3L Cosworth Duratec

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