I believe you must have stated the voltages wrong meaning that when you disconnect the hot lead the battery should read at least 12vdc , with the draw 10vdc . A good battery with the truck running everything hooked up should read between 13.6vdc and14.8vdc . A fully charged hot battery (hot meaning) fresh off a charger can easily read 13vdc plus . Any time a battery reads less than 12vdc it has either been discharging and needs charging or has a bad or weak cell. If a battery not connected reads less than 10vdc it probably has a bad cell or a cell going bad .The true determination can be made with a hydrometer or load tester . A fully charged battery during the cranking process should never drop below 9.6vdc or under a 10 second load test . This at the same time is also determined by the batterys cca cold cranking amp rating as to how long it will remain above 12 volts while being cranked . You have either a large draw or a bad cell in your battery for it to be reading 10vdc if you have just shut the truck off . Batterys with a bad or going bad cell can be brought back to full voltage with a 2amp charge applied over night. The battery has a charge but lacks amperage to preform its specified task without losing voltage thus when used at all causes an immediate voltage drop. One of the easiest ways to isolate what circuit the draw is on is with the engine not running is at night remove the negative battery cable then touch the cable back to the post if you see a spark. In your case with the draw you seem to have should be a substanical spark and will appear blue in color. To determine which circuit the draw is being produced on start pulling fuses and relays on at a time and do the terminal touch test again, no spark no draw . Each time replacing the fuse or relay after the test is preformed , if it is not the culprit , put it back to ensue not placing the incorrect amperage fuse or relay in the wrong place .You will have circuits that have a little draw until the computer shuts them down such as interior lights or dash lights, that when that fuse is removed the temporary draw will reside. If you have a draw on a circuit and it kept blowing fuses ,a larger fuse is not the answer. Fuses are for a certain amperage determined by draw and size of the wire on that circuit . Placing to large a fuse on a circuit with a draw could melt the wire casing and ruin a wiring harness by melting into other wires and possibly causing a fire and burning everything up. I'm with Shane on Napa parts , you buy cheap chit you are asking for trouble. If you bought your alternator at auto zone God help you they sell two grades , good ones and cheap ones. I would start by reading your voltage then dissconnect the positive wire to the alternator and then read the voltage again. If there in lyes your problem your voltage should increase . Does your battery drop below 12vdc if it is fully charged if allowed to sit over night disconnected from everything if so your battery has a weak cell . It is common for batteries with a bad or weak cell to loose voltage overnight when temptures drop below 50degrees F. Try the things I have listed and get back too me. I apologize for the book but it is written in laymens terms and should be easily understood . I will check in tomorrow to see any additional info. you may have. I am packing up to head to a new gig in Florida , yep Ducks flying south . I hope my information helps you......................Duck
Live Like Your Dieing , If You Can't Run with the BigDogs Stay on the Porch . Never Put Off Until Tomorrow What You Can Do Today .Tomorrow May Never Come.Be Honest That Will Earn You Respect . You Get Paid to do It Once not Twice .
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