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device to protect from draining a 12 volt battery

Discussion in 'Electronic Basics' started by [email protected], Dec 12, 2003.

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  1. Guest

    I've noticed that my new car allows draining of the 12 volt battery
    through 12 volt sockets even when the ignition is off and the engine
    is not running.

    I use to leave charging devices attached to the car at night know they
    would only charge while I drove around, but now I can't any more as
    they will drain the primary battery.

    Does anybody know of any devices that help stop current flow when the
    source is below a certain level?

    I'm also interested in attaching some of these same devices to my
    boat, but would like really only like to pull when the alternator is
    charging the primary, so perhaps I could set the threshold really high
    on the boat.

    I know there are delayed relay devices I could do this with, but I was
    hoping I could use something that would require no additional wiring
    that to the + and - of the source battery.

    Many thanks for any help or information.
  2. Larry W4CSC

    Larry W4CSC Guest

    You're not going to run the car battery down charging the cellphone 24
    hours a day, even if you only start the car twice a week. The
    cellphone or laptop will stop draining the battery as soon as their
    own battery is charged. Works great.....

    Hell, the CARS OWN COMPUTER runs 24/7/365 off that battery in new
    cars. Buy more digital gadgets and it's even worse......

    Larry W4CSC

  3. David Harmon

    David Harmon Guest

    Connect them to the accessory power lead that is switched on and off by
    the ignition switch. Install a secondary power socket wired for that
    purpose if you desire.
  4. Congratulations! BMWs are wired that way for example, and I think that
    the only correct way to do it.
    Charging a phone, laptop or other small item will not discharge your
    battery noticeably.
    Sure, this is used for thermoelectric coolboxes (which will drain the
    battery if left on for too long). I think it was around $45 or so.

    (first product listed).

  5. Guest

    Hello Larry.

    Actually looking to maintain one of those portable power
    supplies/jumper boxes with my alternator system by feeding it 12 v as
    I run.v I also charge 8 nimh batteries used by my radio sometimes too.
  6. Guest

    Exactly what I'm looking for. But the site was kinda weird in that
    they want you to buy a catalog. Did not see any buy button or find
    retailer. I'm in South Florida. Know where that product can be found.

  7. Huh? No charge for the catalogues when I tried. Call them:

    WAECO USA, Inc.

    Clinton, CT 06413
    8 Heritage Park Road

    Tel. +1-8 60 / 6 64 49 11
    Fax +1-8 60 / 6 64 49 12


  8. Priority Start:

    They make a marine model, which is more expensive <g>, but which I
    think is also ignition protected.

  9. Larry W4CSC

    Larry W4CSC Guest

    The gelcell power supply you can simply hook up in parallel with your
    other battery ONCE YOU GET IT STARTED and it will charge it fine. The
    gelcell will only charge at its own pace from a voltage regulated
    alternator, just like your car battery does. If you're using an
    outboard, it doesn't have much ampere capacity, anyway. I don't know
    who propagates this BS about lead-acid gelcells and special chargers,
    but I'm sure it's from sales and manufacturing...)c:)

    I use a 2.2AH gelcell in my good-working old analog cellular bagphone,
    an $11 generic gelcell from Batteries Plus. I charge it with one of
    those Shumacher SE-1-12S 1.5A, automatic shutoff 6-sided black boat
    battery maintainers that cuts itself off when the battery reaches
    14.2V and turns itself back on at around 13.3V. The red CHARGED LED
    is blinking away on the charged gelcell on my desk, here, as the phone
    uses some current on standby. It's a fantastic charger for these
    small gelcells. If you put an ammeter in series, it will charge the
    2.2AH gelcell about 800 ma that tapers off to 600ma before the voltage
    sensor in the charger cuts off the juice. After that, it simply
    pulses to keep the charge up. As the gelcell gets old and its
    capacity drops from lack of electrolyte gel, the charger starts
    pulsing faster and faster, which lets me know when I need to replace
    the old gelcell.

    In my work stepvan and cars, I have a matching connection with a
    simple 2.5A silicon diode that allows charging current IN to the
    gelcell, but doesn't allow the car to draw current out as the diode is
    reverse biased (just put the banded end of the diode towards the plus
    terminal on the battery in the positive lead to the car). The car
    will charge the little gelcell in about an hour from when the phone
    starts beeping to signal low battery voltage.

    I've been doing this for years. Works great.

    The NiMH batteries require a special charger to taper their charge
    rate. The deal here is to find a NiMH/Ni-Cd charger that uses
    12-15VDC to power it. Look at chargers that have wall bricks and DC
    plugs the wall brick plugs into. Read the voltage the wall brick puts
    out and buy the one that runs on a 12V brick. Then, just buy a DC
    cord from Radio Shack that allows you to plug the charger into the
    cigarette lighter socket in your car/boat/truck. The charger will
    handle the charging pulses to the NiMH cells, but from your car
    battery, not the wall brick. Charging underway, whether your boat's
    running or not, by the way! Works just as good docked.

    Larry W4CSC

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