the keys to extended battery life

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The Keys to Extended Battery Life

By Bob Blohm, EnerSys, Inc.

Nov 1, 2002 12:00 PM

It's easy to set the stage for

battery reliability if you know therequirements.

Performance and reliability arefunctions of battery condition inmost backup power systems. All of the maintenance effort in theworld has little meaning withoutproper installation. You can easilycut battery life in half or turnmaintenance into a nightmare with just one installation mistake.

Selecting the right battery for the job is the first step in a stationarybattery installation. Lead acidbatteries are the most popularchoice in the United States,although nickel cadmium isappropriate for some specialtyapplications. The battery industrydivides lead acid batteries into two categories: flooded and sealed. Most experts refer tosealed batteries as valve-regulated lead acid (VRLA). Some people consider themmaintenance-free, but that's not necessarily true. Table 1 (below) shows a brief comparisonof the considerations for flooded and VRLA batteries. The installation issues are similar for

both types.

Things to consider. Once you'veselected your battery, be sure toaddress the following installationissues to ensure easiermaintenance and maximumreliability.

Location.

The battery area should becentrally located for easierdistribution of power. A clean, dryarea improves safety and reliabilityof the entire system. A floodedbattery requires a separate battery room to meet various fire and building codes. You caninstall a VRLA battery in a room with other equipment and employees, but this area should berestricted. If it becomes a storage area, you'll increase fire and safety risks. You must provideadequate space around the battery system to allow for maintenance tasks.



Temperature control Temperaturehas a major effect on the lifeexpectancy and performance of any battery system, as shown in

Table 2. Considering theshortened life expectancy of abattery at high temperatures, it

may be easy to justify installingthe battery in an air-conditionedarea.

Storage

Lead acid batteries have a maximum storage time of six months at temperatures between65°F and 85°F. At the end of that time, you must either install the battery or give it afreshening charge. Try to schedule the battery arrival at the site as close as possible to theinstallation date.

Transportation and receiving

Batteries are quite fragile, so you should inspect them for freight damage upon receipt. Verifythat the water level in flooded batteries is between the level lines and that none of the plasticcontainers or covers are broken. Inspect to make sure no posts have been damaged in transit.

Seismic and floor load

Verify that any rack or cabinet in the battery room meets the seismic codes for your area.Many people do this for racks or cabinets that hold batteries, but then forget about nearbyracks or cabinets that could fall onto the batteries. Don't make that mistake. Check the totalweight of the installed system and verify it's within the floor load limits. You must consider thesafety measures involved in transporting battery cells in and out of the area. A stacked VRLAbattery can weigh as much as 1,000 lb per sq ft.

Safety

Because batteries are “chemical engines,” they can explode and cause serious injury. Whetheryou're installing the battery yourself or contracting the work out, everyone involved must befamiliar with all the battery safety issues, manufacturer's instructions, tools and testequipment, and IEEE installation recommendations. Individuals who work with batteries mustuse the appropriate personal protective equipment (PPE) and other safety equipment. You'll atleast need the following items:

• Safety glasses with side shields or chemical goggles.

• Emergency eye wash provision.

• Emergency spill containment and response equipment.

• Water and bicarbonate of soda.

• Insulated tools (avoid metal chains and jewelry).

• Apron and gloves.

Other items that may be appropriate include a battery spill kit and a battery acid containmentsystem. Once you've addressed all of the preceding issues, you can start the installation.

Installation steps.



Assemble the battery rack according to manufacturer's instructions and anchor it to the floor.Verify that dimensions, aisle widths, and clearances are adequate for maintenance access.Place cells onto the rack or cabinet, starting in the center of the bottom row and workingoutward. Be careful, though, because you can damage the posts if you use them to carry thebattery. You'll probably need a mechanical lift to get the cells from the pallet onto the rack.Follow the manufacturer's recommendations for sliding cells on a lifting table or rack, but don'tuse oil or grease that isn't specifically approved for that purpose. Note that on many seismic

applications, you must install spacers between each cell.

The battery manufacturer should supply a layout or connection drawing. Make sure you setthe cells so they connect in a series — the positive of one cell connects to the negative of the

next. You can verify that all cells are truly connected in series by reading the voltage of onecell, multiplying this by the number of cells in the system, and comparing this to the overallvoltage. A 4V discrepancy indicates one cell is installed backward.

Neutralize any spilled acid on cell covers with bicarbonate of soda, and remove any greasefrom the cell post with a rag or paper towel. Don't use degreasers or solvents.

Polish the post and intercell connector with Scotchbrite, a brass bristle brush, or approvedequivalent. If in doubt, ask the manufacturer. Don't use a wire brush, as this may damage the

protective lead plating on the copper connectors.

After applying a light coating of NO-OX grease or a manufacturer-approved equivalent to thepost and intercell connector, assemble and install the intercell connectors and bolts, andtorque them according to the manufacturer's instructions. But be careful: Bolt torque is alwaysin in.-lb, not ft-lb. Once you've finished the installation, read and record the intercell connectorresistance from one cell to the next using a micro-ohmeter. This verifies that all intercellconnectors are properly installed. You'll need this baseline data for all future maintenancechecks.

You can now connect the battery to the system and start the freshening charge. Batterymanufacturer's instructions give voltage and time values to assure the battery is fully charged,and to compensate for any charge lost during storage or transit. After the freshening charge is

completed, adjust the battery to its proper float voltage. This is usually 2.25V per cell for VRLAand flooded calcium and 2.17V per cell for antimony type. Refer to the manufacturer'sinstructions. Read and record all individual cell float voltages, specific gravities, intercellconnector resistances, and internal cell resistances. You'll need all of these readings for futuremaintenance.

The IEEE has detailed installation and maintenance procedures for flooded and VRLA batteries(Sidebar below). IEEE Standards Committee 29 has reviewed and updated these proceduresand will continue to do so as technology moves forward. Proper installation ensures feweroperational and maintenance problems, while enhancing reliability and lowering the total costof ownership.

Blohm is the field training manager, EnerSys, Inc., Reading, Pa.



Sidebar: Applicable IEEE Documents

• IEEE-484: IEEE Recommended Practice for Installation Design and Installation of Vented Lead-Acid Batteries for Stationary Applications

• IEEE-1187: IEEE Recommended Practice for Installation Design and Installation of

Valve-Regulated Lead-Acid Storage Batteries for Stationary Applications

• IEEE-450: IEEE Recommended Practice for Maintenance, Testing, and Replacement of

Vented Lead-Acid Batteries for Stationary Applications

• IEEE-1188: IEEE Recommended Practice for Maintenance, Testing and Replacement of

Valve-Regulated Lead-Acid Batteries for Stationary Applications