Battery Testing

the first thing that you should always check is the battery and the starter connection.An excessive resistance of your high amperage circuit is an overlooked problem that can cause your volts to drop in your batteries. Check to see if the cables are corroded, damaged or loose.The connections will need to be connected if you begin to notice that your battery is losing voltage. If you are using an ohmmeter, you may not be getting an accurate reading for your battery. This is because all that this meter will measure is continuity. It does not measure its ability to be able to handle a high amp current load. There are ways around this to be able to get an accurate read on your battery.

A Voltage drop test is the most accurate ways to test the connection on your battery. You will not have to disassemble anything, so it can be done quickly. Get your digital volt meter to test the voltage drop once you have successfully created a load in the circuit that will need to be tested. If your circuit or the connection has too much resistance, then some of your voltage is going flow right on through your digital volt meter. This will give you a voltage reading.


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First check your battery get a cheap digital volt meter. Free at Harbor freight with a purchase. Fully charged battery 12.6 volts Not 12.5 or 4 or 3. With the volt meter set on DC volts touch the battery and have someone start the car if the meter shows high 13.5 to 14.7 the alternator is ok if it is less replace. If you have a dead short take out every fuse and relay from the black box under hood by the battery. Remember where they go and plug them one at a time until the discharge hits and at least you will know what circuit it is.They also sell about 20 dollars a plastic meter you hold over the positive battery cable to see if the starter is drawing to much power A battery open-circuit voltage test will show the approximate state-of-charge of a battery. This test can be used if no other battery tester is available.

Before proceeding with this test, completely charge the battery. Refer to Standard Procedures for the proper battery charging procedures.

1. Before measuring the open-circuit voltage, the surface charge must be removed from the battery. Turn on the headlamps for fifteen seconds , then allow up to five minutes for the battery voltage to stabilize.
2. Disconnect and isolate both battery cables, negative cable first.

Testing Open Circuit Voltage

1. Using a voltmeter connected to the battery posts (see the instructions provided by the manufacturer of the voltmeter), measure the open-circuit voltage.

See the Open-Circuit Voltage Table. This voltage reading will indicate the battery state-of-charge, but will not reveal its cranking capacity. If a battery has an open-circuit voltage reading of 12.4 volts or greater , it may be tested to reveal its cranking capacity. Refer to Standard Procedures for the proper Micro 420 battery test procedures.


s than 13.5 alternator is bad

Try this tips:
1. Check the battery voltage at the battery with the digital volt/ohm meter. Set the meter to "Volts D/C" and touch the black meter lead to the negative battery post and the red meter lead to the positive post. A fully charged battery will measure 12.7 volts or more. A measurement of 12.5 volts is considered discharged, and the battery should be charged before any further testing. Any measurement below 11 volts indicates a severely discharged battery--the battery is most likely damaged and should be replaced. If the battery measures above 12.7 volts, proceed to the next step.

2. Check the starter for battery voltage by touching the red (positive) meter lead to the battery cable terminal on the back of the starter and the black (negative) lead to the chassis. The voltage reading should be approximately the same as the measurement at the battery. If the reading is lower than battery voltage, check for bad connections at the cables on the battery and the starter or ground cable.

Check for ignition switch signal at the purple wire on the back of the starter. When the key is turned to the "Start" position this wire should measure battery voltage. If the reading is less than battery voltage, or zero volts, check the fusible links (orange wires) on the back of the starter. If the fusible links are intact and not burned or broken, replace the ignition switch. If battery voltage is present at the purple wire, and the starter doesn't turn, replace the starter. If the voltage measurements at the starter are correct, and the starter cranks the engine over when the key is turned to the start position, proceed to the next step.

3. Remove the air duct attached to the throttle body, and spray a liberal amount of the carburetor spray into the throttle body. Replace the hose, and try to start the engine. If the engine starts, the fuel pump is not supplying fuel or the ignition module is not pulsing the injectors. Check the fuel pump fuse located in the under-hood fuse block. If it is good, check for power at the fuel pump electrical connector located near the rear of the fuel tank on the driver's side of the van. In the Chevy Astro van, power is supplied to the fuel pump by the the gray wire on the electrical connector when the engine is being cranked. If power is supplied, hitting the fuel tank with the flat side of a hammer while someone else is turning the ignition key to start will sometimes bump the fuel pump enough to allow it to start. If the fuel pump checks good, proceed to the next step.

4. Check for spark. Disconnect the coil wire at the ignition coil, and try to start the engine. If no spark occurs, replace the coil and ignition module. If a strong spark occurs, plug the wire back in, and remove a spark plug wire from a spark plug and repeat the test. If a spark is not present, replace the spark plug wires, and distributor cap and rotor.


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Check your connections from the battery to the starter with a volt meter,Set an automotive volt meter to dc volts and connect one clip to the negative pole on your battery probe the starter case with the other one,if you get a reading of over half a volt it would indicate a bad earth,also use the same method to test the posative terminals.any reading over half a volt indicates high resistance.Its no harm to give your battery a good charge every now and again as no alternator can charge a battery 100%.keep me posted.

A 12 volt battery is actually 13.2 volts fully charged. If you are reading 16 volts, you are probably getting extranious voltage from the system somewhere, especially if the vehicle is running when you check the voltage. The alternator will put out about 15-18 volts to charge the battery normally, and yours may put out 28-32 volts to charge them in series, but the batteries, when disconnected, should never read more than about 13.2 volts each. Typically, it will read about 12 1/2 volts when disconnected. COMPLETELY DISCONNECT BOTH OF THE BATTERIES. If you still read 16 volts when it is disconnected, you must have a bad meter because the battery can't produce that much voltage, no matter what. (Six 2.2 volt cells connected in series inside the case.) Put the meter on a known good battery on another car that is not running and see if you get the same reading. It sounds like the other battery is almost dead, regardless, and it sounds like your series/parallel switch may be malfunctioning. (That is the switch that puts the battery in series to run the 24 volt starter, then puts the batteries in parallel to run the remainder of the vehicle on 12 volts. This is all assuming that you have a diesel vehicle with a 24 volt starter and that is why you have two batteries.