Apparatus, Chassis Components, Koop

Solar Panels for Emergency Response Vehicles: Keeping Batteries Fully Charged

Issue 8 and Volume 22.

Christian P. Koop   Christian P. Koop

In December 2012, I wrote an article titled “Battery Management for Emergency Vehicles” that was basically about charging systems and how important it is to keep batteries properly charged and maintained in emergency response vehicles (ERVs).

I also briefly talked about an alternative method to aid in charging a battery bank that is very efficient – solar panels. Solar panel technology has improved greatly and has become more affordable over the past few years. Its use in helping to keep battery banks fully charged is invaluable, particularly for ERVs that are relied on to start without fail for emergencies. I will delve more into solar panels in this article. But before I do, I will explain the different types of batteries available; how they differ; and, most importantly, how solar panels not only can help keep them properly charged but also can extend their lives and improve the bottom line of any organization that recognizes how important and beneficial they can be and puts them to use.

Battery Technology

Battery technology has evolved over the years. But before I mention the different automotive and heavy-duty types available today, I must give credit to the inventor of the storage battery. Allesandro Volta invented the first modern dry storage battery in 1796. The first batteries may have actually been used as far back as 250 BC. A French physicist, Gaston Plante, invented the first wet lead acid storage battery in 1860, which paved the way for the development of automotive charging systems because the dry-type storage batteries first used in the early automobiles could not be recharged. Battery technology has changed and improved significantly over the years. The lead acid storage battery has evolved into several types.

Today there are two types of lead acid (LA) batteries: starting (aka cranking) and deep cycle. Under these two LA battery types there are three subcategories: wet cell (flooded), gel cell, and absorbed glass matt (AGM). Of these three, the wet cell is available in serviceable and maintenance-free versions, or they are sealed and filled with electrolyte. Electrolyte is a mix of water and sulfuric acid that provides the path for the chemical reaction that takes place between the lead and lead dioxide plates in the battery to produce electricity.

The starting battery is the one most commonly used with ERVs and has more and thinner plates to provide high amperage very quickly for starting. The deep cycle has thicker plates to provide current over longer periods of time, although it cannot provide as much instant energy as the starting battery. Gel batteries have a nonliquid jelly type of electrolyte because silica has been added to the electrolyte. Because of this, they can be mounted in many positions. Gel batteries are designed for deep-cycle applications and typically need a reduced voltage to recharge. AGM batteries are considered dual-purpose or a cross between cranking and deep cycle. Although they have liquid electrolyte, it is suspended. Both the gel and AGM store well and do not sulfate as easily as the wet cell. Both cost much more than the wet cell and require different charge rates. Because of this, they may require specialty chargers. A cranking battery may only tolerate 10 heavy deep cycles before it kicks the bucket, while a deep cycle may be able to go 300 deep cycles.

Keeping Them Charged

In my past article, I compared batteries to a checking account. If you continuously withdraw money from your account without making timely deposits, you will go broke. The same is true about batteries: Taking out current without recharging will leave you with dead batteries. Even if you don’t kill them, you will damage the batteries and shorten their normal life spans. To better illustrate the point, someone in the industry once said, “Few batteries die a natural death – most are murdered!” Over time, this can cost an organization many thousands of unnecessarily wasted dollars.

Typically, most LA electrolyte batteries must be taken to about 14.4 volts before they are fully charged, and then the voltage has to taper off to no more than 13.4 volts to prevent gassing or boiling and eventual damage. AGM batteries need to be taken to 14.2 volts to fully charge and gel cell to 14.1 volts. This is why it is very important to use the correct type of charger for the batteries you are charging, or you can damage them. To maximize batteries’ lives, they have to be charged properly and not allowed to cycle below their normal charge voltage, which is approximately 2.11 volts per cell or 12.6 to 12.7 volts. It does not take much of a voltage drop for a battery to reach a 50 percent discharged state. A battery that has an open-circuit voltage across its terminals (no loads) of 12.2 volts has essentially been discharged to 50 percent. That is only about a half volt short of a full charge.

Heavy cycling in lead acid batteries is the biggest enemy of long battery life. Typically when batteries discharge, soft lead sulfate forms on the plates. While the battery is recharging, the lead sulfate mixes into the electrolyte solution. If the battery is allowed to stay in a discharged state for even just a few days, the lead sulfate crystallizes and forms a barrier on the plates. Over time and various charge/discharge cycles, this barrier will thicken and reduce the battery’s amperage capacity. For example, a battery that is rated at 950 cold cranking amps (CCA) may be gradually reduced to 400 CCA and, depending on what amperage the starter needs to turn over the engine, the battery may not be up to the task. The battery is essentially the heart of the electrical system, and weak batteries can wreak havoc in the electrical system. Weak batteries will also cause an alternator to run at full output in an effort to charge the batteries, which can shorten the alternator’s life and also, in turn, overheat and damage the batteries. They can also cause starter motors to run hot and will damage them over time, also reducing their life span.

Recipe for Solar Panels

Given how most ERVs are commonly operated and the fact that modern rigs will have multiple parasitic drains constantly drawing down the battery bank – such as radios, computers, flashlights, cameras, engine and transmission electronic control units, and a host of other accessories – they must be plugged into the shoreline so the onboard chargers can keep the batteries hot. The fact that most have cranking batteries that don’t like to be cycled is the perfect requirement to install solar panels. Solar panels convert sunlight to direct current electricity, making for a very efficient way to keep battery banks charged up. The larger the area covered by panels, the more amperage that can be produced. The military has been using solar panels to keep batteries from discharging on its trucks for more than 20 years.

Typically, solar panels are installed on flat surfaces such as vehicle roof tops. One of the limitations in the recent past, particularly for fire apparatus like pumpers and aerial devices, was the limited roof space. Essentially, the cab roof was the biggest area available on these types of rigs to mount the panels. But with cab air conditioning condensers, warning lights, antennae, and various other items in the way, there just is not enough real estate to mount an adequate amount of panels. Kussmaul Electronics has recently introduced a solar panel that is flexible up to a 30 degree arc that will aid in mounting more panels on uneven and cluttered roofs found on some ERVs. Kussmaul also offers voltage controllers for its panels to properly charge the different types of batteries.

Other benefits of using solar panels include being able to shut off the engine if you only need a minimal number of accessories on such as radios. This not only will reduce wear and tear on the engine and save fuel, but it also serves to reduce emissions and to help comply with anti idle laws.

Having properly charged batteries in your rig can mean the difference between the engine starting and not. This is where solar panels can be a great aid in keeping your batteries topped off and will not only save dollars by extending battery life but can also save fuel, reduce emissions, and reduce wear and tear on the rigs’ engines. That’s a big difference and one that will benefit the bottom line of any organization that puts solar panels to use.

CHRISTIAN P. KOOP retired as the fleet manager for the Miami-Dade (FL) Fire Department after 35 years with Miami-Dade County and four years in the military. He has been involved in the repair and maintenance of autos, military track and wheeled vehicles, heavy equipment, and emergency response vehicles for the past 40 years. He is a member of the Fire Apparatus & Emergency Equipment Editorial Advisory Board. 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/medium/heavy truck technician and master EVT apparatus and ambulance technician. He is a member of the board of directors of EVTCC and FAEVT and a technical committee member for NFPA 1071, Standard for the Emergency Vehicle Technician Professional Qualifications.