TunerMaxima3000

iTrader: (4)

Please keep in mind, these are VERY BASIC checks, this thread is designed to help you get the ball rolling and figure out where you need to go. Consider this your first step if you have the below listed issues. If your issue isn't listed here, or is much more complex, please Google search for your issue, there is probably a thread answering every question you have, sometimes with instructions. If that doesn't work, post a new thread.

Battery/Brake light on?
Car won't start, cranks slow, clicks?
Lights dim, gradual loss of power, car dies while driving?
Battery drains overnight?

There are some tests you can do simply with relatively cheap tools. Some are not the most accurate methods, but they can get you on the right path. I’ll focus as much on tests you can do without expensive tools or paying a shop to check something.

You kind of need a Multi-Meter for these tests, that is one of the most essential tools needed to check over the basic Charging/Starting system.
Good news is the basic ones are only around $15-20



No ‘tools’ method:
With car idling, remove the negative terminal, you’ll need a 10mm wrench or socket to loosen it. If the car continues to run, the alternator is charging strongly.
This method can be inaccurate, an alternator that is just a bit weak might not run the car, but might have a ton of life left in it, that’s one reason i prefer other testing methods for this one, but this is a very quick check that helps if you don’t have a Multimeter handy.

With Multi-meter:
-Install multi-meter on battery positive and negative. Set to DC Voltage.
Car off should read around 12.4 Volts, roughly.
With car running it should read between 13.4 and 14.6 Volts

-If the voltage doesn’t go up when you start the car, and while the car is running it gradually goes down slowly, your alternator isn’t charging the battery.

-If it’s charging above 14.6 Volts, the alternator is OVERCHARGING, this is actually WORSE than not charging at all. This can be a bad alternator, or bad ground, it’s not usually anything else.

NOTE: IF YOU FIND THE BATTERY IS NOT GETTING A CHARGE, YOU STILL NEED TO DO MORE DIAGNOSIS, DO NOT JUST REPLACE THE ALTERNATOR. YOU SHOULD BE CHECKING FUSES, BATTERY TERMINALS, BATTERY GROUND, ALTERNATOR GROUND, ETC BEFORE YOU CONDEMN THE ALTERNATOR. ALTERNATORS ON THESE CARS ARE EXPENSIVE AND A P.I.T.A. TO CHANGE (EXPENSIVE IF YOU ARE PAYING SOMEONE TO DO IT)


You should not have more than a 0.05 Amp load when the car is off. That’s about the maximum acceptable parasitic load for a car.

-Switch your multimeter to AMPS. Change the wire terminal as needed to measure AMPS. With the battery connected and only the hood open, lock the car. Wait 2 full minutes until the security system arms fully and the car goes into ‘sleep mode’.

-Disconnect the negative battery terminal, install your multimeter in series to measure the Amperage. This means one end on the Negative terminal, and one end on the negative wire that you just removed.
The Multimeter will now be the ‘link’ between the wire and the battery terminal.
-Record your Amperage.

If it is in excess of 0.05 Amps, you need to track down the source of the drain, 9/10 it’s caused by an aftermarket setup, sometimes one you didn’t even know was on your car (prev. Owner).

If it’s below 0.05 Amps, your battery draining issue is likely due to a bad battery or alternator, or both. The battery can’t hold it’s charge anymore, or isn’t getting charged enough when the car is running.,.

Hope some of that info helps with initial checks, if you have completed these checks and don’t know where to go next, ask away!

Amerikaner83

iTrader: (17)

to add to the multimeter and aperage...some meters have two places for amperage...please use the one that is more...use the 10A instead of the 300mA for example, else you'll read OL (which is infinite) since you would have just blown your meter's internal fuse.

NmexMAX

iTrader: (22)

To the BATCAVE, I mean stickys.

03GLEmaxima

I just took automotive electric 1 for my auto tech school including starting, charging, and lighting systems. My instructors stronngglllyyy urge you to never ever remove any battery terminal while the car is running. This worked back then on old school vehicles that do not have complicated computer systems. But the problem is there can be voltage spikes to the very sensitive computer systems and it could easily damage it. So buy a **** multimeter...

Oh and for the parasitic drain testing you can add the battery acid leakage test. This tests your battery to see if there is any acid on your battery that will cause the two terminals to be connected via the acid on the battery and causing it to drain. We performed this test on my car and the battery looked perfectly fine but completely failed the leakage test.

Set the multimeter to millivolts d/c connect negative to negative battery terminal and using the positive side run it along the plastic in between the two posts. if you get any reading what so ever clean the battery with water and baking soda then retest.

TunerMaxima3000

iTrader: (4)

Great input guys! I totally forgot about that surface discharge test, nice addition.