Take the battery to any store other than Auto Zone where new ones are sold. Ask for a free 15 second battery load test to see what the reserve amperage capacity is. Amperage spins starter motors not voltage.
Year, model, and engine. They're ALL wired differently. Some are run by the computer, others not. So cough up more info
the battery is low is why it kept turning. you did not mention if it was overheating or power steering was working or not. over heating and no power steering would tell that he belt has broke or come off. if the belt is still on and tight then your alternator has quit working
Quick way to tell if your alternator is charging, touch a metal tool to the middle of the back of the case. The shaft becomes magnetized when the alternator charges.
Buy a voltmeter. Check the terminal of the battery when engine is running, Voltage should read 13 volts or above. If it is below that then you have an alternator problem. If ok,Check your battery after shutting off the engine it should read in the range of 12 volt,then check it again after an hour it should not drop dramatically if it does check again the battery this time with the negative terminal removed.If it still dropped then battery is at fault and if not you have a ground problem in your electrical.
Your battery light is measuring the voltage of the battery when it is turned off, but the alternator when it is running. If it came on while running, that is not good. On old cars you can disconnect the negative battery cable and see if it stalls, but that is NOT recommended for new cars because the battery acts like a big capacitor to smooth out the current, and wild fluctuations can do possible damage to computers. If there is a diode burned out, which can cause an alternator to fail, then those fluctuations can be severe. Charge the battery with a battery charger so that you can run the vehicle. With every thing off, check to make sure the voltage on the battery is putting out @12.5V. Turn off the climate control fan, as well as put the emergency brake on to keep the day time running lights from coming on and start the vehicle. Check the voltage on the battery with the engine running. When a battery is fully charged the alternator should put out around 14V give or take a little bit. With a discharged battery, the cars computer will have the alternator put out more power to charge the battery up faster, and it can run as high as 15V and drop as the battery charges up. If the voltage is lower than your original 12.5V while it is running, then it is your charging system. If it is higher, but just around the 13V mark, then turn the heater fan on, and observe if it drops, which it should, which means you have a weak alternator, and most likely from a bad diode. The good thing with a weak alternator, is that you can still run the car will all loads off, which means, no night driving, no fan, and no wipers. If it is bad, and not just weak, then with a fully charged battery, you can usually make it a few miles with all loads off without running into trouble, and get it to a repair shop.
If voltmeter indicated 8 volts, engine would barely crank, if at all. Check for ignition spark, and make sure battery is fully charged. Running, alternator should put out around 14.8V, not running, should show battery voltage, 12.5V or so. Many cars, while running, if you disconnect negative battery cable and engine stalls, alt. is bad.
my advice to you do not remove any cables make shore your battery is fully charged get your self a hand held meter check first water in battery if it is a newer sealed or what is called a gel battery you do not have to . check all your wiring make shore you have no bear wiring and go about all your checking first check when car is not running meter should read no lower than 12 volt run engine at about 1500rpms should about 15volts turn on all your lights radio heater a/c you should not have any voltage or very little if you have to much you have a problem you have to remove alternator have it checked on the bench
I was driving around then I noticed the battery light came on so I looked at the gauge and it kept dropping it was at like 8 volts so I got home I shut it off and tried to start it and it kept turning over an wouldn't start would that be the battery or alternator
