Auto Service World
Feature   April 1, 2012   by Nestor Gula

Putting a charge in ‘er

Specialized chargers work better with AGM batteries

More and more vehicles are coming equipped with Absorbed Glass Mats (AGM) batteries as standard equipment. This is good for the industry as these batteries are lighter than standard batteries, non-hazardous and are virtually immune from freezing damage.

AGM batteries are constructed with a fine fiber Boron-Silicate glass mat and the electrolyte is contained in this substance. AGM’s do not really have any liquid that will spill and because the mats are well-secured and tightly-packed they will withstand vibrations and even severe shocks better than the standard batteries that are in the market today.

“AGM batteries have very little electrolyte or battery acid. The little electrolyte they do have is retained in a glass matt material whether they are spiral or flat plate technology design,” said Gary Mackey, the national accounts sales manager for Associated Equipment Corporation. “AGM batteries are also sealed so they don’t vent gases to the environment. Because they are sealed, they can be mounted in any position and almost anywhere in vehicle, including the passenger compartment under the seats or even in the trunk.”

Another important advantage of AGM batteries is the very low self-discharge rate that is between one and three per cent per month on average. The battery can sit in storage on in a vehicle for longer periods of time without discharging. “The life expectancy of AGM batteries is several years longer than conventional flooded acid batteries, but the cost is higher than conventional batteries; however, that should come down over time,” said Mackay. “AGM batteries can be a great replacement for flooded acid batteries if you’re planning on holding on to the vehicle for a number of years.”

The electrical benefits that AGM batteries deliver is due to them having very low internal resistance that, to a large extent, determines the battery performance and runtime. This lower resistance means there are fewer restrictions on the battery when it needs to deliver the required cranking power. The battery is also able to accept a charge more quickly.

“Although AGM batteries have a lot of advantages over conventional flooded acid batteries the one big difference is they should not be charged with a conventional battery charger, even if it is an automatic charger,” said Mackey. “Conventional chargers on the 12V setting typically put out 16 to 19 volts. Typical flooded batteries need higher voltages to fully charge. However, AGM batteries, because they are sealed and have very little electrolyte or battery acid, cannot be charged at a higher voltage than 14.4 volts. A conventional charger can permanently damage an AGM battery in as little as one hour of charge.”

Modern chargers are sophisticated, and do not just simply feed an electrical charge to a battery. The charger talks to it. “Today, most battery chargers have built-in safety features. A charger that immediately recognizes a defective battery may not attempt to charge it for safety reasons,” said Kristin Rogers an account supervisor, for Optima Batteries. “Many newer battery chargers have settings specifically for AGM batteries and some even have separate settings for Optima RedTop and YellowTop batteries. Newer chargers incorporate newer battery technology. Many newer battery chargers, or Smart Chargers, have microprocessors that collect information from the battery and adjust the current and voltage accordingly. Some have different settings for charging traditional wet cell, flooded, gel and AGM batteries.”

Even though new AGM battery technology has a much longer life expectancy than conventional flooded acid batteries, service stations should always monitor them and keep them charged properly to extend the battery’s life.

“Our new Intellamatic Smart Charger have modes to perform what is referred to as deep discharge recovery of sulfated batteries by shocking the battery to help remove scaling on the plates in the battery,” said Mackey. “Intellamatic Smart Chargers are available in a number of sizes from 10 Amp up to 70 Amp output, are computer controlled and provide fully automatic operations. These chargers are polarity protected, Perform Deep Discharge recovery of sulfated batteries, automatically test for weak or defective batteries, and have state of charge LED lights letting the operator know where the battery is in the charge process. Several units have Boost Assist to jump-start vehicles and some even have a power supply mode for extended service procedures such as vehicle re-flashing or drivability diagnostics. In the power supply mode the charger/power supply delivers 13.7 volts of clean output. Intellamatic chargers will charge by battery type so they can handle every battery type from flooded acid, deep-cycle, maintenance-free, Gel-Cell, and AGM batteries.”

“The newer chargers incorporate microprocessors and they collect information on the battery. They adjust the current and voltage according to the battery. They are fairly straight forward to use,” said Rogers. “The OPTIMA Digital 1200 Battery Charger enhances the performance of Optima and other AGM batteries, recovers a deeply discharged battery and extends battery life. It also features an LCD display for charging, maintaining and fault mode indication. With a gauge that displays battery charging and fill rate with charger mode and fault messages, it offers one of the best user interfaces on the market. Other innovative features include an integrated LED work light with ergonomically designed DC charging clamps, quick set selections that prompt users with a quick and easy selection of charge profiles by battery type.” It also can charge your iPad, iPhones, camera and anything else that can be charged through a standard USB connector. It will be available for purchase this spring.

Bosch has the portable C3 and C7 chargers that feature current charging technology and self-monitoring function. They are suitable for all types of lead-acid AGM, wet or gel batteries with voltage ranges of 6/12 volts with the C3 and 12/24 volts with the C7. They are versatile and fully automatic, microcomputer controlled battery chargers that have an easy to use one-button operation. When a battery is fully charged, either charger switches automatically to maintenance mode (trickle charging), and can be left connected to the battery to keep a high charge level when a vehicle is not being used. The larger C7 charger also offers a Regeneration Mode to recover a short term, deeply discharged battery, as well as a power backup function which supplies continuous power to the vehicle’s electrical system while replacing the battery. If an abnormal situation occurs, the chargers switch automatically to standby mode.

AGM batteries have been with us for about 15 years, but most likely will become an industry standard meaning shops should start to modernize their battery charging equipment and procedures. “First seen in the 1999 Corvette and 2000 Toyota Prius, AGM batteries were initially mostly found in specialty or higher-end vehicles. Now they are installed as original equipment by most vehicle manufacturers,” said Mackey. “Almost every vehicle manufacturer is using AGM batteries in some if not all of their vehicles, this includes domestic manufacturers such as General Motors and Chrysler, European manufacturers such as Mercedes, BMW, Jag/Land Rover, Volkswagen, and Asian manufacturers as Toyota, Lexus, Nissan, Infinity and a host of others. These new batteries are also popular in motor sport vehicles such as motorcycles, ATVs, snowmobiles, Jet Skis as well as heavy-duty trucks, farm and off-road equipment. It is estimated that there are nearly 20 million vehicles on the road today that came with an AGM battery as original equipment. This number is growing at between 15 per cent and 20 per cent per year.”

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