help it wont start
like 128auto said, to properly test the battery you need a battery load tester, most auto shops can do this for ya for free. A battery can read 12v on a voltage meter but possibly have a bad cell or something and won't be able to supply enough current for starting. Also check wiring for possible bad connections. After that, i'd check out the starter solenoid, try jumping the solenoid trigger lead directly with a jumper wire from the positive terminal on the battery. You can also try connecting jumpers directly to the starter motor from the battery, to insure the starter will turn over.
I'm not sure what your electrical experience is, but if your confused, do go jumping wires like I said, you could cause damage if you jump the wrong things. You may want to go get yourself a HD manual and follow their electrical troubleshooting tecniques, as they'll explain some of the testing procedures in more detail and will have schematics for you to trace the starter circuitry.
Best of Luck!!
I'm not sure what your electrical experience is, but if your confused, do go jumping wires like I said, you could cause damage if you jump the wrong things. You may want to go get yourself a HD manual and follow their electrical troubleshooting tecniques, as they'll explain some of the testing procedures in more detail and will have schematics for you to trace the starter circuitry.
Best of Luck!!
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celtlion
To crank the engine, you need amperage not just voltage. Even the battery shows 12.6 volts doesn't make it a good battery. When you test the battery according to the cold cranking amp rating, it should hold above 9.6V, anything lower than that will not provide enough juice to crank the engine, especially high compression ratio engine. Unlike a multimeter, a battery tester uses carbon pile to put load on the battery during the test, multimeter is used to test the voltage only. A starter motor could draw anywhere from 200-300 amps during cranking. Hope it helps!
To crank the engine, you need amperage not just voltage. Even the battery shows 12.6 volts doesn't make it a good battery. When you test the battery according to the cold cranking amp rating, it should hold above 9.6V, anything lower than that will not provide enough juice to crank the engine, especially high compression ratio engine. Unlike a multimeter, a battery tester uses carbon pile to put load on the battery during the test, multimeter is used to test the voltage only. A starter motor could draw anywhere from 200-300 amps during cranking. Hope it helps!
ORIGINAL: celtlion
I use a Radio Shack digital multimeter to test mine - why not a multimeter?
I use a Radio Shack digital multimeter to test mine - why not a multimeter?
ORIGINAL: 128auto
1. Check battery with a tester, not multimeter
2. Check ground cable
1. Check battery with a tester, not multimeter
2. Check ground cable
celtlion, you are on the right path testing the charging system. When you test a battery, engine should not be running because the alternator charges the battery while the engine is running, even a weak battery shows 13.x volts at the time, voltage comes from the alternator. 



