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Old 01-17-2005, 09:46 AM   #23
GrimlokTT
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Join Date: Feb 2004
Location: Fairborn, OH
Posts: 2,237
Re: Mach won't start

As Orange mentioned, you can check for parasitic draws. As test lights are quick indications of this draw, they shouldn't be the deciding factor. As Orange mentioned, the light can still glow due to onboard electronic components. How brightly depends on how much of a draw you have. (Make sure you have the doors shut and the key is off when you do this.) What you need to use is a multi-meter to see if that draw is w/n limits. (I believe it's b/n the negative cable and negative post when disconnected?)

Regardless, I'm guessing you have a crappy battery versus a parasitic draw.

Name ____________________† Instructorís OK ______
Vehicle # _____ Make ____________ Model __________ Year _____



Battery Diagnosis Worksheet
1. Visual Inspection and Electrolyte Level: Check battery for corroded terminals (warning—it’s what’s on the inside that counts), loose or broken clamps, cracks, leaks, low electrolyte level, missing vent caps, missing or bad battery hold downs, correct size and capacity for vehicle, built-in hydrometer and acid powder on top.
Terminals need cleaning ___ Terminals have been cleaned ___
Electrolyte level is OK ___ Electrolyte level is too low ___ Other problems __________________________________
2. Determine State of Charge: Is battery up to 70% so it can be tested?
Using hydrometer: measure specific gravity of all six cells and record here: ____ ____ ____ ____ ____ ____
Are all above 1.240? Yes ___ No ___
Is there a difference of 0.050 or more between cells? Yes ___ No ___ (if yes, replace battery)
Using digital voltmeter: Remove surface charge by 1) turning on headlights for 3 minutes ____ or load testing battery 100-200 amps for 15 seconds ____. When battery voltage comes back up, where does it come to? 12.6v (100%) ___ 12.4v (75%) ___ 12.2v (50%) ___ 12.0v (25%) 11.8v or lower (0%) ___
Battery is ready to load test ___ Battery needs charging ___
3. Load Test Battery: (Capacity Test) This tests if the battery can put out enough volts and amps, that it is not sulfated. Hook up tester so you measure the amps going through the carbon pile and volts.
CCA rating ______, divided by two = ______.
Load test at this amperage, (but not too much more than 200 amps) for 15 seconds, and record the voltage at 15 seconds here: ______
Voltage is above 9.6v—passes ___ below 9.6v—fails ___
4. Check Parasitic Draw when battery turned off. Connect amp meter in series, should be no more than 0.050 amps or 50 ma after the computers have shut down.
How much? ____ OK ___ Not OK ___
5. Use Capacitance Tester. Follow instructions on screen
Pass: ____ Fail: ____ Readings: ______________________________
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