Batteries are a part of every driver’s daily life and we often do not think about them until they fail to work, at which point it is too late.  The OEM (Original Equipment Manufacturer) battery supplied with your truck, assuming you bought a new truck, is properly sized for the components supplied with the truck.  If you bought a used truck there is no guarantee the batteries that came with your truck are of the proper capacity.  If post-OEM modifications have been made that increase electrical demand than higher capacity batteries may be required. 

Whether you own a new or used truck, if you are thinking about making a battery change it is best to follow the manufacturer’s recommendations when choosing your batteries.  Newer generation trucks are loaded with sensitive electronics and numerous computers, and like your home computer or laptop, your truck’s computers are very sensitive to the electricity they receive.  For the purpose of this article, the term automotive is interchangeable with truck.  It is also worth noting there are many different types of batteries for many types of applications, but for this article I’m only discussing automotive batteries.

It may help some if I list some of the more common terminology associated with batteries, in alphabetical order.  This is not an all-inclusive list, just some of the more common terms you may encounter when shopping for, or dealing with automotive batteries. Click here for the common automotive battery terms. 

Battery Basics and Types:
The basic concept for batteries consists of multiple cells wired in series within the battery container.  The battery produces power by oxidizing the lead plates and turning them into lead-sulphur-oxide.  When the battery is re-charged the plates turn back into pure lead and the acid is re-created.  This process gives off hydrogen gas which can escape, depending on the battery type, before it can re-combine with the electrolyte.   Batteries are classified based on their voltage, starting power (CCA), usage and physical size and are assigned a group number.  If you know your current battery’s group number then you can easily replace equivalent batteries by requesting the same group number.

There are three types of batteries used in the automotive industry today, flooded cell lead-acid battery, gel-cell battery and absorbed glass mat battery.

  • Flooded cell batteries are the most common type and the least expensive and have been around for over 100 years.  There isn’t much room left in this battery type for engineering improvement.  It consists of lead plates suspended in an electrolyte solution of approximately 25% sulfuric acid and 75% pure water.  The electrolyte solution is free to move around inside the battery case and because of this it is susceptible to spillage.  These batteries also generate and release dangerous explosive gasses and must be vented to the atmosphere.  This type is classified as a low-maintenance battery.  It must be mounted in an upright position and care should be taken when handling these batteries.  The electrolyte solution is very corrosive and should not come into contact with your eyes, skin or clothing.  These batteries acid-mist during charging and discharging, resulting in corrosion of the battery terminals and possible acid-damage to surrounding surfaces.  Just take a look at your battery terminals for white powdery corrosive build up, it happens on all batteries of this type.  Regular cleaning and application of a dielectric grease, or regular grease, will slow this process down.  They also make products that you can spray onto the terminals that dry into a wax like finish that will slow the battery terminal corrosion process and do not attract dirt like grease.
  • Gel-cell batteries are a step above flooded cell batteries.  Gel-cell batteries where introduced about 30 years ago and hold a few key improvements over flooded cell batteries.  Mainly they have an increased efficiency and safety features.  Their electrolyte solution is immobilized by adding silica dust to the sulfuric acid solution forming a thick putty-like gel and then sealing the battery.  They internally recombine most of the gases generated during charging, reducing evaporation, and are classified as maintenance-free.  As with flooded cell type batteries, gel-cell batteries have been around long enough there are few engineering options left to improve them.  During charge and discharge the gel electrolyte is highly viscous and can develop voids or cracks when the amperage is increased.  These voids impede acid flow and result in the loss of battery capacity.  In addition, the gelled mixture can liquefy upon charge due to the shearing action of gassing.  After the charge is complete it can take up to an hour for the acid to return to a gel state.  Overcharging or rapid charging can damage them as well.  Gel-cell batteries offer greater resistance to temperature extremes, shock and vibration than flooded cell batteries but less resistance to temperature extremes than AGM batteries.
  • Absorbed Glass-Mat (AGM) batteries are the latest type used in the automotive industry.  These represent the latest in battery technology, and were developed to provide increased safety, efficiency and durability over existing battery types.  This type is also the most expensive to purchase, typically about twice the price of flooded cell batteries.  In AGM batteries the acid is absorbed into very fine glass fibers woven into a mat to increase the surface area enough to hold sufficient electrolyte.  This type also has a double wall case construction for durability.  This battery does not have free flowing liquid electrolyte solution which has led to a DOT exemption for USPS, UPS and FedEx.  By keeping the glass mat moist with the electrolyte, gas recombination is more efficient.  The AGM material also has an extremely low electrical resistance which provides more available amps for cranking your engine.  They are lighter than gel and flooded cell batteries because they have less electrolyte.  AGM batteries are also rated at 100% capacity for charging and discharging amperage compared to roughly 35% for gel and flooded cell batteries.  AGM batteries offer much better life cycles than gel or flooded cell batteries, which leads to longer battery life.  AGM batteries are more resistant to temperature extremes and can withstand some overcharging.  They also lose very little fluid through evaporation.

Battery Maintenance:
Battery maintenance will depend entirely on the type of battery you choose for your operation.  All battery types are subject to temperature extremes, some more than others.  Most people know that cold weather is brutal on batteries; in fact statistics from the Battery Council International (BCI) indicate the following:

  1. When the outside temperature is 80ᵒ F, a fully charged battery has 100% of its power available to start your truck.
  2. When the temperature drops to 32ᵒ F, a fully charged battery has approximately 66% of its power available.
  3. When the temperature drops to 0ᵒ F, a fully charged battery has only 40% of its power available.

What many people do not know is that heat will also kill your batteries.  In fact, high heat is more brutal on your battery than extreme cold.  Heat speeds up all chemical reactions and since your battery works through chemical reactions, older weaker batteries are subject to failure during excessive heat.  High outside temperatures combined with stop and go traffic on overheated pavements can drive the engine compartment temperatures over 200ᵒ F.  When you add in extra heavy electrical loads such as air conditioning, power windows and all the creature comfort electronics in today’s vehicles, this can add up to battery failure.When checking your battery condition look over the batteries to locate any external damage, a battery with external damage should be replaced immediately.  Look at the terminals and clean the corrosion if present and re-apply a battery terminal protectant as mentioned above.  You can check the state-of-charge with a volt meter and compare that number to the chart below to get an approximate state of your battery:

  • 12.75 volts and up = 100% charged
  • 12.60 to 12.74 volts = 85% to 99% charged
  • 12.40 to 12.59 volts = 75% to 84% charged
  • 12.20 to 12.39 volts = 50% to 74% charged
  • 12.00 to 12.19 volts = 25% to 49% charged
  • 11.99 volts or lower = fully discharged

In closing, our batteries sit silent and hidden in the battery compartment and work on demand every time you turn the key or turn on an electrical component.  Don’t neglect your batteries.  Open the compartment and check the batteries, maintain the batteries, take care of the batteries and they will take care of you.

Look for my second article on this subject titled “Thing to consider When Buying Batteries” on Team Run Smart soon. 

Comments (6)

Craig McCue

Business owner and part-time operator of a seasonal business.

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Thank you Jackie. I hadn't heard of batteries from Thermo King but I'll be checking those out for sure.

Mark, the engine start module is probably a great idea (I don't have one). I know Bob and Linda Caffee have one in their Cascadia and if I'm not mistaking they too are very happy with it.

January 17, 2014 19:35:48 PM

One thing I've decided to do is purchase an Engine Start Module to start the truck, and AGM batteries to use for hotel services i.e. TV, satelite, heater etc so I don't have to idle. The ESM will start the engine and recharge the AGM batteries

January 16, 2014 18:05:54 PM

Great article. I love my AGM batteries. I have been running them since 2009 and have never had to get a jump start since I have been running them. I found the best ones so far are from Thermo king. They have a 4 year full replacement warranty.

January 16, 2014 12:06:31 PM

Thank you Linda and Jeff. I hope the information helps people.

January 15, 2014 13:47:02 PM

good to know

January 15, 2014 5:12:11 AM

Very nice article Craig

January 13, 2014 14:52:33 PM