I've gotten so many different answers to a.

  • 135,000 MILES
I've gotten so many different answers to a simple question, it's ridiculous. It's enough to make a simple query sound complex. My Windstar (3.8 6Cyl. SE (or so)) had to basically sit from April to November (8 Months). I only started and ran the engine five or six times. Now, the battery does not seem to hold a charge. Occasionally, a good, amped-up charge lasts a few hours. Otherwise, after idling for an hour, it will not restart the vehicle.

The battery is only 21 months old, with a four-year sticker on it. (I'm told batteries will not be guaranteed that long any longer and a three year guarantee will be used in MI;) (Sky-rockettting metal prices?)

So, do good batteries go bad if they sit, mostly unused, for four or five months? Would it have lasted if I'd unhooked the terminals? (That does have a vaguely fatal ring to it.).

Thanx very kindly, Marais
Thursday, December 6th, 2012 AT 4:35 PM

1 Reply

I don't know where you're buying your batteries from but stories you've been given sound fishy. A large part of the battery is made from recycled old batteries. There's not that much metal in them. The warranty the manufacturer offers has nothing to do with the cost of the material. It has to do with how fast the lead flakes off the plates and collects in the bottom. That flaking is normal in every battery and the manufacturer knows how fast that happens. When the material builds up high enough in the bottom of the case, it shorts that cell. That's when the battery isn't strong enough to start the engine and you have to replace it.

The manufacturer can leave more room at the bottom of the case so it will take longer for a cell to short, then they can give a longer warranty because they know it will take longer to fail. That's only half the story though. To leave that extra room they have to make the lead plates smaller. That decreases the "cold cranking amp" rating which is the standard used to compare batteries between different manufacturers. The battery with the higher CCA rating can sell for more money. Even if it takes longer for a cell to short, the battery loses strength over time as that lead flakes off. That can result in slow cranking, or more commonly, the ability to crank a non-starting engine for fewer and fewer minutes. That's not so noticeable on fuel injected engines that start right away, but it was a big deal many years ago on carbureted engines.

Most batteries will last around five years so that's what the manufacturers warranty them for. To warranty them for less lowers their value so they have to sell them for less. A lot of stores offer batteries with six and seven-year warranties. That doesn't mean they're going to last much longer than five years. It means they can command a higher price, but more importantly it means when it fails, lets say after five and a half years, you will get a prorated refund on the remaining months but that refund might go to offset the cost of the replacement battery. In other words, you may not get five dollars back. You might get five dollars off a new battery from the same manufacturer. They get to sell another battery, just at a reduced cost.

With those longer warranties, the manufacturer gets to sell them for a higher price, but they are counting on not refunding anything on the biggest percentage of them, even though they will normally fail within the warranty period. People trade their cars on different ones so there goes the battery to someone who isn't aware it's under warranty. Many warranties are only good for the original purchaser and don't transfer to a new owner. Some are smashed in crashes. After a few years, people like me forget how long the warranty was good until and can't find the paperwork.

I'm not sure what you're describing about a warranty sticker. New batteries come with a large advertising sticker on top that clearly states the warranty period and often has a toll-free number to call for help. The cost of new batteries has gone up recently in response to inflation which the government says is non-existent. Labor costs have gone up. Cost of fuel for the trucks to deliver new ones and return old ones for processing has gone up. Taxes on businesses has gone up. When we foolishly scream for "higher taxes on the rich", those higher costs of doing business are just passed onto us consumers, so we still pay in the end. The cost of some metals have gone up a lot but there's no gold or silver in a car battery.

I can't say exactly why your battery isn't holding a charge but I can offer some points of interest. First of all, generators are very inefficient at low speeds so if you leave the engine idling for long periods, it's likely no charge will go into the battery. You could even be running the electrical system partly on the battery and partly on the generator. That will run the battery down more the longer you run the engine.

Second, there is a constant draw on the batteries in cars with computers, and a '99 model will have a pile of them. The industry standard is a maximum of 35 milliamps, (.035 amps), is allowed to keep the computer memories alive unless the manufacturer states otherwise. Chrysler says at that rate a good battery will still crank the engine fast enough to start after sitting for three weeks. Cadillac allows up to 50 milliamps on many of its models. That three week period is based on a good battery with no lead flaked off the plates yet. You won't get three weeks out of a two-year-old battery. But keep in mind that's if you have the full 35 milliamp draw. Most cars have considerably less than that so it can sit longer than three weeks and still start.

Third, if a battery is fully discharged, it will take ten to fifteen minutes on a battery charger before it STARTS to take a charge. That's because it takes a while to push electrons from the plates into the acid so the acid can become conductive, THEN it will start to charge. If your charger has an amp meter and the battery is nearly dead, you will see the current stays close to 0 amps when you first turn the charger on. That current will start to increase over the next fifteen minutes or so. Once the battery reaches a full charge its voltage will go up high enough to oppose the charger's voltage so current will start to decrease. When that current comes down to around five amps, you can consider the battery fully charged. The current will never go completely to 0 amps, instead, you'll start to overheat the plates and boil the water out of the battery.

Fourth, a battery that's more than a few months old should never be charged at a high rate from a battery charger. Doing so will usually not damage it right away but it will hasten the failure of one that's about to develop a shorted cell. Automotive generators put out three-phase voltage which is very steady and easy for the battery to smooth out. Household battery chargers put out a rectified sine wave that pulses from 0 volts to maximum voltage 120 times per second. The resulting pulsing current vibrates the plates in the battery and helps knock off the already loose lead. This is especially important in the last year or two of the battery's life.

Batteries are designed to hold up a long time when they're fully charged. It's a different story when they're dead. I don't remember the chemistry lesson but the plates in a dead battery will become "sulfated". That's when a hard coating develops on them that prevents the free flow of electrons so the battery can't easily charge up or deliver a usable current. I have an '80 Plymouth Volare that I start once a year or less often and that battery is always still at full charge because there's no computers or radio to draw current when the ignition switch is off. I also have a '93 Dodge Dynasty with lots of computers. On that one I have to disconnect the battery. I only run that one about once every three years. You should not run into any problems if you disconnect your battery's negative cable when the van is going to be sitting. It's on the newer cars you have to be really worried. General Motors, Volkswagen, and BMW are the three worst. They have tricks designed in that cause various computers to lock up when the battery is reconnected. Simply replacing a bad battery has landed a lot of those cars on the back of a tow truck for a very expensive trip to the dealership.
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Friday, December 7th, 2012 AT 4:34 AM

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