Discharging deep cycle 12v battery





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  1. #1
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    Default Discharging deep cycle 12v battery

    Hi

    I've had a CTek D250S fitted into my National Luna PPP in lieu of the NL solenoid. I'm using my old crank battery in the PPP which (apparently) no longer had sufficient CCA capacity to crank the car reliably - it was spec'ed incorrectly to begin with but ended up serving me well for 5 odd years.

    I'm wanting to test how many hours I can get out of this aux power rig. To what level can I discharge the Deltec deep cycle without damaging it?

    Alex
    Last edited by AlexFl; 2013/08/21 at 08:58 PM. Reason: Spelling
    '02 Disco 2 TD 5 facelift, auto & Terrafirma +2" (retained air in back with +2" spacers) & what next

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    It is regarded good practise not to discharge a D/C beyond 50%.

    Never, ever allow your (lead-acid) battery to drop to below 10,5V.
    Eggie.

    "Do not go where the path may lead, go instead where there is no path and leave a trail."
    - Ralph Waldo Emerson.

  3. #3
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    Thanks Eggie. Excuse my ignorance (and I really don't want to damage the battery further than it apparently is) but does that mean that I can take the D/C down to 6V? Wonder why the NL battery monitor is then only marked down to appr. 11V.
    '02 Disco 2 TD 5 facelift, auto & Terrafirma +2" (retained air in back with +2" spacers) & what next

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    Quote Originally Posted by AlexFl View Post
    Thanks Eggie. Excuse my ignorance (and I really don't want to damage the battery further than it apparently is) but does that mean that I can take the D/C down to 6V? Wonder why the NL battery monitor is then only marked down to appr. 11V.
    If you take the battery down to 6V it's cooked. What Eggie means by 50% is to not drop the amps down to more than 50% of its capacity.

    Regards
    Alvin

    2000 Land Rover Discovery 2 V8 ES Auto - Me
    2010 Hyundai i20 1.6 - SWAMBO
    1996 Toyota Tazz 1.3 - "Pool" car

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    Thanks Alvin. How would one measure this?
    '02 Disco 2 TD 5 facelift, auto & Terrafirma +2" (retained air in back with +2" spacers) & what next

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    Quote Originally Posted by AlexFl View Post
    Thanks Alvin. How would one measure this?
    Let's say your battery has 105Ah (amp hour) capacity. 50% of that would be 52Ah.

    52Ah x 12V = 624 Watt Hours of energy.

    So effectively, you can power a 10W LED light for 62 hours, or a 100W something for 6 hours, then your battery would have been discharged to 50% of its capacity.

    Regards
    Alvin

    2000 Land Rover Discovery 2 V8 ES Auto - Me
    2010 Hyundai i20 1.6 - SWAMBO
    1996 Toyota Tazz 1.3 - "Pool" car

  7. #7
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    Quote Originally Posted by AlexFl View Post
    Thanks Alvin. How would one measure this?
    A common way is to simply check battery voltage. It is probably easier to do and more telling when the battery is no longer in top condition.

    The blue curve applies to a static battery, i.e. one that has been left to "settle" properly after any charging or discharging.

    Note that these curves are not absolute (not 100% accurate), but provide a handy and quick way to get a good idea of your battery's charge status.
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    Eggie.

    "Do not go where the path may lead, go instead where there is no path and leave a trail."
    - Ralph Waldo Emerson.

  8. #8
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    Thanks Alvin & Eggie.
    '02 Disco 2 TD 5 facelift, auto & Terrafirma +2" (retained air in back with +2" spacers) & what next

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