The awful truth about what summer does to your batteries
Battery sulfation begins as soon as a lead-acid battery discharges. This occurs as soon as the battery is no longer being charged whether or not the battery is being used:
Self Discharge is Accelerated by Temperature
For batteries that are over 25°C (77°F), the self-discharge rate doubles with every 10°C (18°F) rise in temperature.
Thus, sulfation can be a huge problem for lead-acid batteries which are:
What is Sulfation?
When the active material in the plates can no longer sustain a discharge current, a battery “dies”. Normally a car (or starting) battery “ages” as the active positive plate material sheds (or flakes off) due to the normal expansion and contraction that occurs during the discharge and charge cycles. This causes a loss of plate capacity and a brown sediment, called sludge or “mud,” that builds up in the bottom of the case and can short the plates of a cell out. This will kill the battery as soon as the short occurs. In hot climates, the following accelerate the "aging" process contributing to battery failure:
Approximately 50% of premature car battery failures is caused by the loss of water for normal recharging charging due to the lack of maintenance, evaporation from high under hood heat, or overcharging. Positive grid growth and undercharging causing sulfation also cause premature failures. Normally well maintained and properly charged deep cycle batteries naturally die due to positive grid corrosion causing an open connection. The shedding of active material is an additional cause. If deep cycle battery is left discharged for long period of time, dendrite shorts between the plates can occur when the battery is recharged. The low resistance bridge in the shorted cell will heat up and boil the electrolyte out of the cell causing a high volumes of hydrogen and oxygen. That is why proper venting and ventilation is so important when recharging batteries. Approximately 85% of premature deep cycle and starting batteries failures that are not recharged on a regular basis is due to an accumulation of sulfation.
Sulfation is caused when a battery’s State-of-Charge drops below 100% for long periods or under charging. Hard lead sulfate crystals fills the pours and coats the plates. Recharging a sulfated battery is like trying to wash your hands with gloves on.
In a hot climate, the harshest environment for a battery, a Johnson Controls survey of junk batteries revealed that the average life of a car battery was 37 months. In a separate North American study by Battery Council International, the average life was 48 months. In a study by Interstate Batteries, the life expectancy in extreme heat was 30 months. If your car battery is more than three years old and you live in a hot climate, then your battery is probably living on borrowed time. Abnormally slow cranking, especially on a cold day, is another good indication that your battery is going bad. It should be externally recharged, surface charge removed, and load tested. Dead batteries almost always occur at the most inopportune times. You can easily spend the cost of a new battery or more for an emergency jump start, tow or taxi ride.
Most of the “defective” batteries returned to manufacturers during free replacement warranty periods are good. This strongly suggests that some sellers of new batteries do not know how to or fail to take the time to properly recharge and test batteries.
Source: Greg Darden | Image by Qfamily
"Up to 84% of batteries fail prematurely from sulfation"
Lead sulfation actually starts when you remove the charging voltage from a fully charged lead-acid battery. Though the lead sulfate crystals are converted back to lead during the normal charging cycle, the real question is, if all of the lead sulfate crystals are not turned back into lead, how long does it take before they become so hard that they can not be converted?
The answer is that varies–it could be weeks or months and depends on a number of factors such as the quality of the lead, temperature, plate chemistry, porosity, Depth-of-Discharge (DoD), electrolyte stratification, and so on.
How Sulfation Accumulate In Batteries
During the normal discharge process, lead and sulfur combine into soft lead sulfate crystals are formed in the pores and on the surfaces of the positive and negative plates inside a lead-acid battery. When a battery is left in a discharged condition, continually undercharged, or the electrolyte level is below the top of the plates or stratified, some of the soft lead sulfate re-crystallizes into hard lead sulfate. It cannot be reconverted during subsequent recharging. This creation of hard crystals is commonly called permanent or hard “sulfation”. When it is present, the battery shows a higher voltage than it’s true voltage; thus, fooling the voltage regulator into thinking that the battery is fully charged. This causes the charger to prematurely lower it’s output voltage or current, leaving the battery undercharged.
Sulfation accounts for approximately 84% of the lead-acid battery failures that are not used at least once per week. The longer sulfation occurs, the larger and harder the lead sulfate crystals become. The positive plates will be light brown and the negative plates will be dull, off white. These crystals lessen a battery’s capacity and ability to be recharged. This is because deep cycle and some starting batteries are typically used for short periods, vacations, weekend trips, etc., and then are stored the rest of the year to slowly self-discharge. Starting batteries are normally used several times a month, so sulfation rarely becomes a problem unless they are undercharged or the plates are not covered with electrolyte.
Most lead acid battery additives contain EDTA, or ethalene diamine tetra acetic acid has always been known to dissolve the lead sulfate layer on the plates. There are, however, two downsides to this:
EDTA reacts with the lead sulfate to form the complex compound above.
The plates are cleaned, but active material is not returned to the battery.
Complex compound formed by breaking the lead sulfate bond.
Battery life is ony extended temporarily with the removal of the lead sulfate crystals and increase of reaction surface area, but the lifespan of the battery cannot be maximized where active material is not returned to the battery.
Our Infinitum Battery Desulfators however, use a different process which generates Amplitude Modulated Pulses at the resonance frequency of the crystals to shatter the covalent bonds that hold it together. This allows the lead sulfate to be reconverted once the battery is charged. A battery free from lead sulfate crystals will have its lifespan stretched to its maximum! No more premature failure due to sulfation!
Over the years, calcium has been added to lead plates to improve grid strength and conductivity, and reduce gassing and its self-discharge rate. With this, the low-maintenance or maintenance-free battery was introduced. However, the alloy plate is still consists of more than 99% lead. Whether the battery is calcium-calcium, calcium-silver, lead-calcium, or lead-antimony, it is still essentially a lead acid battery and suffers premature failure from sulfation just like any other lead acid battery. The Infinitum Desulfator reverses and prevents sulfation, typically restoring batteries to the best possible condition, maximizing its life span up to 3 times.
An excerp from Popular Mechanics:
HOW IT WORKS: MAINTENANCE-FREE BATTERIES
Like many things in life, the term “maintenance-free” is only partially true. Lead-acid batteries normally consume some of the water in their dilute sulfuric acid electrolyte during a normal charge-discharge cycle. It actually electrolyzes into hydrogen and oxygen and escapes as gas. So adding water periodically is necessary to keep the plates flooded. Maintenance-free batteries use a calcium alloy of lead instead of an antimony alloy, which reduces the amount of electrolysis.
In addition, the amount of free-standing electrolyte above the plates is designed to be much higher in a new maintenance-free battery. This means that there’s enough electrolyte to keep the plates covered even after a few seasons of normal use. So, during the battery’s normal service life there should be no need to add water. Any abnormal electrical system condition or high ambient temperatures may boil off more than the normal amount of water, however. Adding water may extend the service life of these supposedly maintenance-free batteries.
Besides the degenerative process of sulfation which occurs on 84% of lead acid batteries, there are other contributing factors you should know when buying a battery as well as maintaining one that directly affect the lifespan of your battery.
1. Regular care for wet batteries
#1 Leaving A 12V Battery To Discharge Below 10.5V
Auto start batteries are not made to be discharge below 10.5 volts. If this happens the lead sulfate formed on discharge will expand across the plates and separators and short the battery. The voltage across the terminals will measure 10.5 volts. This battery is dead and is not restorable.
The solution is simple, if you are not planning to drive your vehicle for a couple of days or weeks, make sure you charge the battery with an external charger regularly. This will dissolve the formation of sulfate as usable active material. Studies have shown however that cars are parked 95% of the time, the sulfation that is formed will crystalize and cannot be dissolved even with charging unless you use a desulfator.
SOLUTION: Charge often and use a desulfator that can potentially double battery lifespan
#2 Shocks Or Dropping The Battery
Shocks and dropping of the battery will result in active material being shedded from the plates. This leads to reduced capacity and the loose deposits can lead to a short if lodged across the plates, or if a connection across the plates is created at the bottom of the battery. These batteries are not considered for restoration.
SOLUTION: Handle batteries with care.
#3 The Forming Of Air Pockets Between Lead PLates
Air pockets form between the plates and if not dislodge that part of the plates is effectively rendered useless. Nothing can be done about this except to say that good grid design and quality separators will prevent this from happening. This is why cheap batteries don’t last, in addition to shedding of active material above.
SOLUTION: We all know the idiom - "Penny wise and pound foolish". Sometimes investing a little more in quality goes a very long way in savings.
#4 Electrolyte Falling Below The Permitted Threshold
If the electrolyte level falls too low the lead plates will oxidise with the air. This is lead oxide and not lead dioxide. The battery loses capacity. Always keep the battery top up with distilled water. Do not add acid or tap water. The fluoride and other chemicals reacts with the spongy lead and renders it useless. Shorting a battery can lead to a gas explosion in the battery.
SOLUTION: For wet cell batteries, always keep the electrolyte topped up with battery water.
Due to it low cost, hydrometers are often used to measure the specific gravity or the concentration of the sulfuric acid in a battery. The specific gravity measurement reflects the state of charge of a battery. In other words, the higher the charge level of a battery, the greater will be the specific gravity reading. Over time, all acid based batteries will experience a depletion in active material, which is normal. The more pronounced the depletion, the lower the specific gravity will be in a fully charged battery. As batteries age the capacity to hold a charge deteriorates. Therefore, an aged battery even after going through a process of desulfation, will still show a lower specific gravity than a new battery.
A more accurate diagnosis of your battery health
Why specific gravity is a poor measurement of a battery's health
DOUBLE YOUR BATTERY LIFESPAN