Problems starting car: Do I need a new battery, or something else?

The brakes on my car went out a few weeks ago. I haven’t had the money to repair it, so I just let it sit in my driveway until I saved (what I thought was) enough up. When I go to scoot it forward a bit for the tow-truck, I realize that the battery has been drained. I don’t think much of it, because I remember accidently leaving the door partway open for a day. So when I finally go to pick it up, they tell me that they left it on a charger for an entire day, and it still wouldn’t start, and they left it on the charger for part of that day too. Well, I drive it out of the parking lot, and home with now problem. After a few hours at home, I realize my car’s probably in the way for the trash pickup in the morning, and go to move it. Again, it starts up with no problem. Well this morning I go to leave to run some errands, and the car won’t start. All the lights and dingy bells work (I’m not sure about the radio), but when I go to start it, all I hear is a humming noise. I’m not sure what the problem is, or how easy it will be to fix. Is there anybody here that can give me a few pointers?

If you leave a charger on your battery for an entire day, and it still won’t charge, its time for a new battery.

It could be the battery or it could be the alternator. From the sound of it, I’m inclined to say it’s the battery, depending on how old it is. If it’s fairly new, i’d consider having the alternator checked, but if it’s over five years, it’s almost certainly over the hill. A third possibility is that there’s a drain in the system somewhere. Those can be hard to track down sometimes.

It sounds like your battery. Sure, the lights and bells work, but it doesn’t have enough oomph left to turn the engine over. Is the humming noise more of a buzzing noise when you engage the starter?

Before I’d spend the money on a new battery, I’d first pop the hood and look at the cables and battery posts. If there’s a lot of oxidation buildup, this could add enough electrical resistance to allow enough charge to get through to power the auxiliaries (lights, etc.) but not enough to actually start the car. I don’t know if it could cause the car to start sometimes but not others, but on the other hand, cleaning the cables/posts is easy and cheap, so I’d do it anyway and hope for the best.

Thanks, guys. I’m pretty sure it IS the battery (I’m not exactly sure how old it is, I’ve only had the car for 2 years, and dont’ know when the guy that had it before me replaced it.), but I didn’t want to replace that and then find out that that wasn’t the problem in the first place.

Some auto parts stores will check the battery (and, if necessary the alternator) at no charge. A few will even install the battery for you gratis. Call around and check out the stores in your area. Then all you need to do is crank up or jump start the car and head to the parts house, checkbook in hand.

Good Luck!

A good test is turn your head lights on (shining against a wall, night time is best) and turn the key. Do the lights dim/go out?

I don’t know about “humming” noises but when my starter started to go (on an 1992 voyager) all I heard was clicking. All the electronics worked but the car didn’t do anything much click.

I agree with the posters who mentioned a battery that didn’t charge in 18 hours of charging (or whatever) needs changing. Walmart probably sells some cheap batteries (unless you’re in the snow belt you don’t need anything special).

A battery drained of power (even a new one) tends to lose some of its liquid (sulfuric acid). In addition to the checks and remedies offered here, I suggest checking the fluid level. With eye protection, full clothing, and gloves on, first disconnect the battery cables, move them well away from the battery, then wipe off the top of the battery as well as possible with a dry cloth, and use a screwdriver to gently pry open the caps. The fluid level should be at the ring in the tube in each cell. If not, fill each tube (to the ring) with distilled water. Replace the caps, reconnect cables, and charge the battery (either with a charger or by running the engine).

Also, it’s been my experience that if a battery is drained of its energy, regardless of age and even after replacing the fluid, its life expectancy is reduced.

Most good quality batteries last 5 years (and then suddenly die), although I just bought a brand new Die Hard and they’ve reduced the warranty to three years … bastards!

Once you get the new battery in:

1] Start your car.
2] With it running, pull the red battery cable.

If the car dies, or doesn’t run as well, it’s time for a new alternator.

What could have happened is that your alternator went. When the garage put a charge on it, the battery powered everything until it ran down.

Another possibility is that the battery was damaged when it was drained. Sometimes when a battery is drained so low, it won’t hold the charge it once did.

Either way, pulling that red cable will tell you a lot.

One word of caution: There will be some sparking when you pull that cable. Make sure that you don’t have anything flamable nearby. Remember, battery acid is flamable, so be sure that the battery caps are on (unless you have a sealed battery).

No, it isn’t. What is flammable is the hydrogen given off as a lead-acid battery charges. From AAA:

More information is needed to reach a definite conclusion.

There’s a difference between “charged all day and won’t start” and “charged all day and the battery won’t take the charge.”

If the humming noise you mentioned is the fuel pump, and there’s no other sound (clicking, slow “ruh-ruh-ruh”) when the key is turned to the start position, there might be a problem with the ignition switch, neutral safety switch/clutch safety switch, or the starter itself.

The battery is certainly a possibility, as are the cable connections. These can be tested with the proper equipment and knowledge.

As far as the battery goes, your choice is to have it tested, or replace it and see what happens.

Disconnecting the battery with the engine running is a good way to fry the alternator.

Q.E.D. - Well, as usual, you’re absolutely right. I always thought that the acid itself was flammable, as many acids are, but a quick search showed that it is indeed the hydrogen.

At least the heart of the message, “keep sparks away” is still good advice.

On second reading of the OP, I’m not clear what’s meant by “humming noise”. Every vehicle I’ve ever been around makes either a clicking sound or none at all when trying to start with a dead battery. The humming noise, depending upon what one calls “humming” could also be the starter not engaging properly, which means the battery may not be the (only?) problem.

It is possible to have the starter tested. Either remove it yourself and take it to a place that tests them or take your car there. Some parts stores will test starters. Be prepared - some garages charge for testing a starter.

So far, so good.

This is going way overboard. Except in the handful of cases where the battery cable routing prevents removing the caps, there’s no need whatsoever to disconnect the cables in order to check the fluid. And there’s no need for eye protection, extra clothes, or gloves.

Damn, Gary T is right as well.

This isn’t my day. I’m gonna shut up about cars now.

Let’s split the difference, shall we? From here:

Damaging the alternator itself is unlikely, even on a modern vehicle, since there wouldn’t be any high current flow to damage the windings. But the resultant voltage spike can easily kill sensitive electronics–and engine computers are expensive.

Not really. I heard this once before and tried it with my '93 Accord about a week after having both the battery and the alternator replaced, with the battery at full charge. Guess what? Lights dimmed.

Tried it just now with an '02 Hyundai Elantra with a 3-month old OEM battery, fully charged… lights dimmed on that one too.

what year/make/model are we talking about?