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  1. #1

    Enkeiavalanche's Avatar
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    Apr 2010
    Piermont,NY, back in Northern NJ now, But may be in IL soon....

    Default Avoiding Voltage Drops

    Some good tips to pass along..

    By: PB Editor
    Wednesday, July 3, 2013

    Roy Hellmund, engineering and technical specialist for Interstate Batteries, provides the following information on checking for voltage drops that can adversely affect engine performance:
    One thing that is commonly overlooked when it comes to the charging system is the potential to have voltage drops affect the operation. A simple voltage drop test can let you know if you have problems or need to upgrade the positive cable.
    This is how the basic voltage drop test would be performed: Set the parking brake and block the drive wheels, start the engine and turn on as many electrical accessories as you can to load the alternator. Using a digital DC voltmeter, connect the positive lead to the output stud of the alternator and the negative lead to the positive battery post.
    The reading indicates the voltage loss through the resistance of the cable and connections on the positive side.
    Now, move the positive lead to the alternator case and the negative lead to the negative battery post. The reading indicates the voltage loss on the negative side of the circuit. Donít worry if the voltmeter reading is negative; just treat it like a positive number and add the positive side and negative side voltage drops together to get the total.
    Generally, the total maximum voltage drop for the alternator should be no more than 0.1 to 0.2 volts. Positive-side drops can be addressed by cleaning and tightening connections or replacing the positive cable with a heavier gauge size.
    Negative side drops can be addressed by cleaning the alternator mounting surfaces and battery cables.
    The voltage drop test should also be used to test the battery cables for any issues. Test the positive then the negative side while cranking the engine. The combined total voltage drop should be no more than 0.3 to 0.4 volts.
    08 Z71 Avalanche Mods to date: K&N CAI,Hellwig Swaybars and End Links, Corsa Sport Exhaust, Superchips Programer,IPCW LOF & 3rd brake light and tails, AMI Gas door,Show Hooks and Door locks, Enkei Wheels, with Pirelli tires, StreetScene Bowties, Grant Steering wheel,Muth signal mirrors,SSBC Big Brake kit,Huskyliner Mug gards,Floor mats and Hood shield, McGard Lug nuts and locks, Bedrug, Cervini's Ram Air hood,35watt HID Fog lights, Sylvania bulbs all around ZXE's Highs and Lows, WhiteNight Back up lights,Sirius and HD Radio, SnugTop sitting on deck now Got a Softopper on now,Tempress Boat Hatches.... New Bilstein shocks are on... New Mods coming soon..... X

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  3. #2


    Good info. Thanks
    2004 Silverado 2500 Crew Cab 4x4, AMSOIL EA air filter, Granatelli MAF sensor, Throttle body spacer, Magnaflow exhaust (true dual to 2 in 1 out muffler), 6" ProComp lift (add a leaf and 5" superlift rear block), Bilstein shocks, 35's (Cooper Disoverer ST) and 4.10 gears, Rhino Liner, EGRUSA fender Flares and widow visors, extended stainless steel brake lines, firestone airbags w/onboard air compressor, Pioneer Avic X940BT navigation, Accel backup camera.
    1960 Land Rover Series II 88
    2001 Pontiac Sunfire
    2013 Toyota Avalon Limited (Wife's Car)
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