Battery trouble?

If you are having problems with your battery, here are a few quick checks to perform,
1. You will need a digital multi meter or dmm, to do these tests.(you should have one anyway)
2. First you need to check all your cables and connections on the positive and negative sides. Make sure the cables are clean and tight.
3. Then test the battery voltage, on a fully charged battery it should be 12.66 volts, if it is much lower, the battery needs to be charged first.
4. After the battery is charged, it should be allowed to settle down for an hour or so, then perform the test.
5. Then you need to check the voltage on the battery while the starter is engaged, this is a load test of the battery with the starter and engine as the load. A good battery should not go below 10 volts on this test. If it is lower than that, the battery is going to fail on some cold morning.
The battery can have a shorted cell also, which will reduce voltage to 10.55 volts, this can happen at any time. It happened to me once when I was getting gas, after refueling, I went to start my car and nothing happened, because that is not enough voltage to engage the solenoid. And it is no use to try and jump start it because it will not work. You need a new battery right now!
You can also have a problem with an open battery, where you won't get any voltage, again the only solution is to replace the battery.
Once the car starts, the alternator becomes the source of power instead of the battery, the battery then becomes a load.
I have heard some people say to disconnect one of the battery cables to check if the alternator is charging, but I think this is not a good idea. Because the alternator will sense low battery voltage and will try to charge it at a very high output, which causes spikes, which can damage the diodes in the alternator. If you have a battery with low voltage it is not a good idea to use the alternator as a battery charger either, because the heat from working to recharge a dead battery can also damage the diodes.

Good to know.. The Polar Vortex claimed my battery. I didn't check it, I took the kids word at Sams club. Now I know.. Thanks.

There is one other thing to consider when checking a standard car battery....
Fluid level is one critical thing that many people don't know should be checked, let alone HOW to check it. And it's not just the level of the battery, but also its density of the sulfuric acid solution which is used as electrolyte. If the electrolyte level is low, the battery can be in good working and physical condition, but does not have the fluid level to produce the usual amount of electron flow thru the plates inside the battery, thus... giving you less voltage output. The electrolyte is typically a solution of about 38% sulfuric acid and 62% water. To PROPERLY check the condition of the electrolyte in your battery you should use a Battery Hydrometer. They're basically just a fancy turkey baster, so no rocket science degree is needed to use one. AND you can get em at any auto parts stores for like $10.
http://www.toolsource.com/prod_medium/119931.gif

If this sort of procedure is above your pay grade, then many places will not only check your battery fluid level for free, but often times will do a load test as well....giving you a very clear idea of what condition your battery is in. If you cant remember the last time this was done, then its been too long. This sort of test should be done at least once a year.
At the very least, checking the fluid LEVEL in the battery is something you should do semi-frequently.
I like to do a good visual inspection at every oil change.
This is easy to do, and depending on your battery, it may be as easy as popping a small cap off the top of the battery.
Some have individual caps for each cell opening like you see here:
http://t2.gstatic.com/images?q=tbn:A...eR_rpwXa0XHJyQ

And others will have larger rectangular caps which plug access to several ports at a time like this one:
http://www.thediyworld.com/img/img_t...ps-Removed.jpg

Some batteries have an external level indicator, and some do not.

----- When a battery electrolyte level indicator is located on the side of the battery.....
Clean the battery electrolyte level indicator with a cloth moistened with water, and check that the battery electrolyte level is between the UPPER LEVEL and LOWER LEVEL lines. If a dry cloth is used to clean the indicator, it is possible for static electricity to ignite a fire and cause an explosion. Is this likely, no, but it IS possible. When the battery electrolyte level is lower than half way between the UPPER LEVEL and LOWER LEVEL lines, immediately add purified water (battery electrolyte replenish solution, or similar solution available commercially) - (try not to use plain tap water unless it's an emergency) until the battery electrolyte level is at the UPPER LEVEL mark.

-----When there is no battery electrolyte level indicator on the side of the battery......
Remove the plugs from the top of the battery and look into the battery to verify the battery electrolyte level. If the battery electrolyte level is lower than the sleeve, be sure to add purified water (battery electrolyte replenish solution, or similar solution available commercially) until the battery electrolyte reaches the bottom of the sleeve.

In either case, If too much purified water is added and the battery electrolyte level goes beyond the UPPER LEVEL mark or the bottom of the sleeve, use a dropper or a turkey baster (just dont put it back in the kitchen drawer when your done) to remove water until the level drops to the UPPER LEVEL mark or bottom of the sleeve. After removing battery electrolyte, neutralize the acid with baking soda (bicarbonate of soda) and then flush thoroughly with water. Otherwise consult the battery manufacturer. If the battery is used while the electrolyte is at the LOWER LEVEL mark, the internal parts will degrade quickly, and even if the electrolyte levels are brought up to normal, they will decrease immediately,
...so please check frequently and add fluid when necessary.

If all this seems way too confusing then you may want to look for a battery inspection window.
Not all car batteries have these, and they're not always 100% reliable, but they're their none the less:
http://hostedmedia.reimanpub.com/TFH..._CARBAT_09.JPG

If the sticker that shows you how to read this little sight glass indicator is corroded, dirty, or missing, dont worry... it's pretty much an industry standard as to what they display.
http://www.autocorner.ca/images/elec..._indicator.gif

In any case, I would still recommend a full test and inspection involving the procedures already mentioned in this thread, and the ones listed above be performed on your battery at least once a year either by yourself, or by a licensed technician.

As Josh stated only distilled water should be used for topping off the battery, then charge the battery for an hour or two, at 5 amps to mix the electrolyte.
But you should not add water if the plates have dried out, from being low on electrolyte for a long time. This will just water down the electrolyte and the the battery will probably not generate enough current to crank the engine in a day or two. I don't check the specific gravity any more, as the source voltage testing gives a good test of the battery condition.