battery diagnostics

Discussion in 'Open Discussion' started by eddieguy, Dec 14, 2016.

  1. eddieguy

    eddieguy Sr. Member

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    Just seen a video about testing car batteries and the tech was demonstrating that while a load tester showed the battery was producing the amps it was rated for with good voltage the battery failed the conductance test with a conductance tester. The conductance tester showed good voltage but it showed a lot less cranking amps then the battery was rated for and showed it as a fail. The conductance tester resembles the size of a small hand held code scanner and looks pretty easy to use. Can someone educate as to how the conductance tester measures the amperage of a battery and how it can produce different results than a load tester wich seems to act like a big resistor similar to what a starter would have. Also what tester would be more accurate in showing the batterys true capacity? The video is how to tell if your car battery is really bad with kent bergsma battery clinic pt 3
     
  2. nickb2

    nickb2 Wrench. I help when I can

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    Although some may agree with me, many will not. I am old school and not not go for those fancy hand held starting and charging system analyzers such as the Midtronics or the Kent one you are referring to.

    I find that they are more of a gimick and a nuissance because of the maintenance. You need to have printer paper to show a client so that means paper and ink needs to be stocked, clean and etc. It needs to be charged up all the time and takes up valuable work bench space and I hate the infrared printer thing.

    I just use an amp claw to check starter draw in actual time on my multi-meter, use a toaster to check for a quick discharging battery. Just use the amp claw to see exactly what the toaster is drawing from the battery.

    My understating is that a small handheld unit such as this will not deteriorate a battery as much as a load test as it apply's a small ac current across the cell and measure the reciprocal of the impedance and the conductance.

    But from my experience, if a load test or two deteriorates a battery, it is due for a swap anyways.

    Where I work now, we get -40c or more and those tiny battery testers would be useless anyway. They use an integrated temp gauge on the battery clamps to base their tests on and in a cold environement like ours, most batteries would fail the midtronics tester and we would change to many batteries for nothing, when just a good recharge with a good sun charger or similar would suffice to revive a failed cold start attempt.

    I find those contraptions misleading for a beginner tech who does not know how to do proper testing and rely's simply on a printer after pressing enter a few times.

    For more info, go here on impedance and capacitance testing.

    http://www.mpoweruk.com/testing.htm
     
  3. nickb2

    nickb2 Wrench. I help when I can

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    To further hit home what I am trying to say, I have revived to good service many many times batteries that a midtronix or similar tester said they were failed.

    For a shop that wants to do quick and flashy service with such fancy and expensive tools with an on board infrared printer, I say go for it. If you don't want to pay for technical training for your techs and want to sell a shyte load of batteries, I say those hand held testers are the way to go.

    But I say that encourages waste, and lazyness.

    Teach your techs how to properly test a battery, starting and charging system before simply teaching them how to hook up a nintendo to a car who will tell them a bunch of meaningless information they know nothing about and then go forth and give an erroneous diagnostic to a client whilst they have to idea why.

    It is misleading for the client and for the one doing said diagnostic and repairs, relying on a supposedly self sustained system such as these things.

    Nothing beats tried and tested old timer checking. Experience is knowledge, and if nobody shows the young ones coming up in this trade that, these new guy's will rely more and more on these contraptions and gain no knowledge and hands on training as with a good old multimeter and scope and a load tester etc.

    Ok, I think I have said enough about that. As I say often here, opinions are like arseholes, everyone has one, that was mine.

    It may not have answered you question, but the link I gave above surely does, so read that, I am too lazy to copy paste the whole thing here since someone already wrote that valuable info there.
     
  4. billr

    billr wrench Staff Member

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    Yeah, I'm with Nickb2 on this. Those gimmicks aren't needed to test a battery, and I sure question how you can test without drawing heavy current. CCA? That is to be determined when the battery is, um... cold. For both reasons, I think that "new age" tester has to be making some iffy assumptions or extrapolations.

    In the video, the "load tester" was too small to be putting enough load for a real test, you would have seen heat-waves (or smoke!) coming out of those vents if it was putting a real cranking load on the battery. As to the VOM test, he simply was doing it wrong. You read voltage drop as you put a load on the battery, not just open-circuit. Usually just turning on the high-beams and heater blower full is plenty enough draw, maybe even more than that "load tester" he was using
     

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