car battery isn’t holding a charge

[sean]

my car has been having problems with battery going flat for no reason at all i check if i leave lights on and i never do and the battery is only 1-2 years old should i get a replacement or is there something i can do ???

Topic

[Brian]

Many parts stores will do a free check of the battery. Autozone will completely charge it up first within a few hours for free too, because a flat battery can test wrong.
Does your battery have two removable plastic rectangular caps on top? If yes, pry them loose to inspect fluid level. Is there a slimey residue on the top of the battery? That can conduct electricity and cause a constant drain. If the fluid level is low, do NOT add tap water to it.get a gallon of distilled water, about a buck, and Epsom salts. Disolve 1 cup Epsom salts to one gallon of DISTILLED water, then nearly top off the cells under the caps with that.
If you don’t have two removable caps, that last step won’t apply.

What year is your car?

When its off and the Doors are shut, it should not pull significant voltage. Remove only the negative terminal from the battery. Set a volt meter at 20 volts d/c, then attach one meter lead to the negative terminal, and the other to the negative battery post. It should not be registering more than 2-3 volts draw tops. If it pulls 12 or nearly so, then pull one fuse out of the underhood fuse box. Did the voltage change? If not, put that fuse back in and go to the next fuse. Continue this until the voltage drops, then you know which circuit is drawing extra power and deadening your battery.
Sometimes, a starter can sound and work great but have an internal short that drains the battery. If the battery is fully charged, that free charge test can determine if the starter is causing it.
I hope this helps.
Also, if the top of the battery is slimey, use a mixture of warm water and baking soda with an old toothbrush to clean it until it no longer foams. NEVER use any kind of soda pop or come to clean the.battery.

[sean]

ok im in australia so autozone isnt here but i did go our version called supercheap auto and there wasnt anything wrong with it and my car engine and fuses have been replaced so they couldnt be a problem and i keep my battery clean at all times but i noticed that my battery sits on metal because it is in the boot so i but some wood on it so see if that fixes the problem.. thank you for the reply gave me ideas to look up and helped

[Rob Jorgensen]

Does the vehicle sit for long periods of time without being driven?

[sean]

sometimes it sits for a week but not often

[Tom]

You need to do a parasitic draw test. There is a circuit in your car that is drawing more power than it should when the car is off. The parasitic draw test will help you to determine which circuit the problem is in, then you can troubleshoot the circuit and figure out exactly what is causing the problem.

[Bill]

(1) Make sure you do not have your ignition left in the accessory position when you pull the key out (especially some older cars the key will pull out even if the car is in accessory).

(2) Once you follow the other things… check your alternator and alternator belt.

Old timer tip – Put a light coating of Vaseline on your battery posts… This prevents corrosive glup on the terminals. 🙂

[sean]

my car wont let the key out unless the car it fully off cant pull key if still in accessory. cant be the alternator or belt because i recently changed it out. will do a parasitic draw test thanks for the help guys

[Tom]

Just because you recently replaced a part does NOT mean it is good. I have had a brand new alternator fail in under a week! It isn’t a bad idea to charge the battery fully, make sure battery connections are clean and tight, make certain the alternator belt is tensioned properly, then start the engine and check voltage at the battery. With the engine running, you should be at, or very near 14.2 volts at the battery. Anything much below that would indicate a problem somewhere in the charging system.

[sean]

will do thanks for the tip

[EricTheCarGuy]

Start by checking the battery itself. When batteries get old, they don’t hold a charge. If the static charge isn’t at least 12.6v, it could be bad. Load test it to see if it passes. If it doesn’t, replace the battery and see if the condition still exists. More info on this, and videos on the tests I mentioned can be found here.

http://www.ericthecarguy.com/faq/solving-automotive-electrical-problems

Good luck and keep us posted on what you find.

[sean]

hey thanks eric tried everything you said and ended up being bad and so was the alternator so yea had to change both wasnt a fun task snce bmw love to make it hard to fix there cars -_- thanks for the tips everyone helped alot

[Author]

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