Battery Management for Emergency Response Vehicles

Issue 12 and Volume 17.

By Christian P. Koop

“Battery management” is a fairly new phrase coined for a subject that should be near and dear to anyone involved in the operation, maintenance, and repair of emergency response vehicles (ERVs). This includes an array of vehicles-polices cars, ambulances, battalion chief units, rescues, pumpers, aerial apparatus, command staff cars, and the very complex custom incident command trucks and trailers. But, what exactly is it?

To put things into perspective, think of your batteries as a bank account. If you don’t replace what you withdraw, you will soon be out of money. The same thing happens to your batteries. If you keep taking out current without recharging properly, you will end up with damaged or dead batteries. If you don’t manage your batteries properly, and this includes having a correctly sized battery pack and alternator, you will end up wasting dollars replacing batteries and alternators needlessly. It starts with good specifications but also has to include properly trained responsible operators-key essential elements to successful battery management.

Automotive Battery History

First, let’s take a brief look at the history of the automotive battery. The first modern-era storage battery was invented by Allesandro Volta in 1796. I say modern because it is believed that batteries may have been used as far back as 250 BC. Volta invented his battery about 100 years before the automobile was in its infancy years. In 1860, French physicist Gaston Plante developed the first lead-acid battery. Even in the late 1800s and early 1900s, most automobiles did not use batteries because they did not need them. Early gasoline engines used either a hot-tube ignition or the magneto to fire the spark plugs. One of the first electrical devices that required a battery was the horn, which was originally called the Klaxon from the Greek word klaxo. If you have ever heard someone blow an early automobile horn, you will quickly understand why it was given that name. Klaxo, in Greek, means to shriek.

In the very early years of the automobile, the batteries used to power the horns were dry batteries. This proved to be very expensive because they could not be recharged. At that time, wet cell (lead-acid) batteries were improving and were starting to be used more and more by automobile manufacturers because they could be recharged. When they discovered that the wet cell batteries had extra current, they started using the batteries to power other accessories such as lights. Shortly after this, the generator, otherwise known as the dynamo, was adopted, and batteries no longer had to be removed from vehicles for charging.

Changing to Alternators

Dynamos tended to overcharge batteries; that problem was resolved by DELCO with the development of the variable speed regulator. Keep in mind that the early batteries were only 6.3 volts (three cells @ 2.1 volts per cell) and by World War II, the military needed something to produce more electrical power than the direct current (DC) generator. More electrical power was found with an alternating current (AC) generator, also known as the alternator. Those technicians who have been around for a while probably remember that generators rectify the AC at the brushes. I am also fairly confident that all technicians today know that alternators use diodes to rectify the AC to DC.

In 1960, Chrysler was the first manufacturer to offer an alternator for civilian vehicles. In a few short years, most cars would be equipped with an alternator that was superior to the generator not only in current output but also in reduced size and weight. Soon afterward, the civilian truck market began to be equipped with new 12-volt alternator systems, and this eventually included fire apparatus.

The Basics of Batteries

It is important to mention some basic relative information about batteries, their main purpose, and the main types of batteries in use today.

The battery, or batteries, as the case may be, is considered the heart of the electrical system. Its main job is to provide electrical power to start the vehicle and operate all the electrical accessories when the engine is not running. It also provides spike protection when loads are turned on and off and serves to stabilize charging system voltage when the engine is in operation.

By the same token, it will provide power to the accessories when the alternator cannot produce enough. Keep in mind that lead-acid batteries do not like frequent discharging because this can cause the plates to sulfate, which will shorten the batteries’ expected lives. Discharging of batteries can easily happen at idle because today’s ERVs have so many accessories. This is the primary reason that the fast idle feature has evolved over the years. It has gone from the manual cable operated system to the fully automatic ones in use today that have programmable features. Specifying a load manager will also work hand in hand with the fast idle system and help ensure that the alternator can keep up with the most important loads while preventing the batteries from discharging.

The original lead-acid battery is still in use today along with the newer low-maintenance, dual-alloy, low-antimony, and maintenance-free calcium-calcium batteries. No matter what materials are used to construct the battery plates, all essentially store energy as a chemical reaction between the plates and the electrolyte (sulfuric acid and water mixture). Energy is released as DC and it moves in two directions. When energy is removed, the battery is discharging. When energy is replaced by the alternator or a battery charger, the battery is being charged. Taking too much energy out and too frequently is considered “deep cycling,” and this is where you can damage and reduce your batteries’ lives.

Battery Ratings

Batteries are rated by several methods, but the most common are ampere-hour (AH), reserve capacity (RC), and cold cranking amps (CCA). Anyone involved in writing specifications should become familiar with these ratings and understand their importance. For example, the RC rating of a battery is important to know because it tells you how long in minutes the battery can deliver 25 amps of current until terminal voltage (battery studs) reaches 10.5 volts. This rating can tell you how long you may expect a vehicle to operate if the charging system fails, because most engine electronic control units will continue to operate until voltage reaches 10.5 volts. In the case of an ERV, which has multiple batteries, if you know how much current it takes to operate the essential electrical components, you can calculate how long you can drive the unit before total shutdown.

Battery Management

As I mentioned earlier, good battery management starts with good specifications, and a charging/battery system should be matched appropriately and take into account all electrical loads that may be placed into use simultaneously in an emergency situation. Total connected load (TCL) is basically the sum of all the current consumed by all the electrical loads when they are operating. TCL is very important because as a rule of thumb the alternator should be able to provide 20 percent more than the TCL. If it cannot, because the TCL exceeds alternator output, you could easily overtax the alternator and your batteries. This can lead to shortened battery and alternator life and excessive downtime, which will ultimately hurt your bottom line. With today’s budgets being stretched tight, this is not a good thing.

Training drivers to recognize when discharge is occurring is a key element to keeping batteries healthy and helps to ensure battery lives are not cut short. The best way to do this is teach the drivers to understand what the ammeter and voltmeters in the instrument cluster are telling them. Voltmeter readings between 14.0 and 14.7 volts are in the normal range, and the alternator is keeping up with whatever the loads are. If the voltage starts dropping below 13, and the ammeter current readings go up, the alternator is struggling to keep up with the load. Teach them to keep in mind that a 12-volt battery is fully charged at 12.66 volts (six cells at 2.1 volts per cell), and if the voltage dips below this, discharge is occurring and that is what we don’t want. Keeping this explanation simple, it is important for drivers or operators to get a good understanding of the system. They also need to monitor gauges.

Another important aspect is that alternators were not designed to charge dead batteries. Using them for this purpose can cause damage and shorten the alternators’ lives. If you experience dead batteries, use a battery charger for recharging. If you don’t do this, it can be quite costly to any operation because today’s heavy duty alternators are very expensive to replace.

Keep Alive Memory

Not too many years ago, most apparatus had only two batteries, and when the battery switch was turned off, you could be pretty certain nothing was left on to drain the batteries-not so with today’s ERVs. With the advent of computerized controls for the engine; transmission; and a host of computerized accessories like laptops, tablets, radios, refrigerators, and others came keep alive memories (KAM). KAMs require constant battery power. So when you turn off the battery switch, there is still power to these computers. Although these KAMs do not consume much current, when you combine these parasitic drains, you can kill healthy batteries in short order if you don’t have a shoreline connected to your truck to power an onboard battery charger.

Another item to consider that will augment that onboard battery charger is the solar panel. Solar panel technology has improved considerably and is no longer as expensive as it used to be. A panel that measures roughly two by five feet can produce six to seven amps of DC. Liken it to having an onboard charger powered by the sun, which can mean the difference between having low batteries and having fully charged batteries.

Get It Right in the Specs

Battery management starts with a battery/charging system that is designed properly from the onset and that will handle real-world requirements. The most cost-effective way to ensure this is by writing specifications that take all factors into consideration. Then you ultimately end up with an ERV that is reliable and cost-effective to operate. On the other end of the spectrum is having properly trained, responsible operators. Combine these two vital factors and you will have an ERV fleet that operates at peak efficiency with minimal downtime and one that won’t take a big bite out of your maintenance budget.

If you operate a fleet of ERVs that is experiencing problems with batteries or charging systems, consider using certified emergency vehicle technicians if you are not already doing so. For those of you who want or need comprehensive information on the subject, there are various books available. Interstate Batteries offers one titled Heavy/Duty Commercial Troubleshooting Manual that I recommend for any technician working on ERVs.

CHRISTIAN P. KOOP is the fleet manager for the Miami-Dade (FL) Fire Department. He has been involved in the repair and maintenance of autos, heavy equipment, and emergency response vehicles for the past 35 years. He has an associate degree from Central Texas College and a bachelor’s degree in public administration from Barry University and has taken course work in basic and digital electronics. He is an ASE-certified master auto/heavy truck technician and master EVT apparatus and ambulance technician. He is a member of the board of directors of EVTCC and FFMA and a technical committee member for NFPA 1071, Standard for Emergency Vehicle Technician Professional Qualifications.