August 1, 2009
equipment & applications | Batteries/Chargers

Juice them for all they're worth

juice them for all they're worth

Looking to keep your lift-truck batteries going and going and going? The secret's in the maintenance and charging.

By Susan K. Lacefield

In the daily scramble to get product out the door, it's easy to overlook what's powering all that activity: your lift-truck batteries. Indeed, for many DC managers, industrial batteries are "the forgotten asset," says Tom Quinn, director of business development for Minit-Charger, a manufacturer of fast-charging systems.

That's a serious oversight. After all, we're not talking flashlight batteries here. A lift-truck battery comes with a high price tag. And like many expensive assets, it requires regular care and maintenance to stay in top condition.

How can you keep your lift-truck batteries running at peak performance levels? We asked several experts for advice. Here are their recommendations:

1. Keep your battery watered.
Mention battery maintenance, and the first thing that comes to mind is watering. As a battery runs, it loses water. That water has to be replaced —and not with just any water. Tap water may contain minerals, which could build up on the battery, shortening its life. Instead, use distilled water, recommends John Pratt, president and CEO of Multi-Shifter, a battery-handling equipment maker.

When you water matters as much as what you water with. "Water should only be added to batteries while the batteries are on charge at the end of charge and gassing, or as soon after recharge as possible," explains Ed Miller, product support manager for the Motive Power Division of East Penn, which manufactures Deka brand industrial batteries. If a battery is watered beforehand, it could boil over, adds Quinn.

As for the optimal watering schedule, that's subject to variation. For the average operation, once a week is usually enough. But a busy operation —say, one that runs three shifts seven days a week — might require twice-weekly watering, says Quinn. And a small, one-shift operation may be able to get away with watering every other week. To determine the right interval, Steve Ache, vice president of sales and marketing for battery management solutions company PowerDesigners, recommends using a battery monitoring device with a fluid level sensor.

Watering can be done manually —either by using a hose to fill the battery's cells individually or by using a singlepoint watering system, which lets you hook the hose up to one connection. For those who prefer an automated solution, there are chargers that will water your battery automatically through that single-point watering system, says Blake Dickinson, head of applications engineering for AeroVironment, which manufactures fast-charging systems.

2. Equalize your battery.
When a battery discharges, a couple of things happen. First, lead dioxide turns into lead sulfate, which builds up on the battery's plates. Although the charging process turns the sulfate back into dioxide, a normal charge is often not enough to get rid of all the sulfate that has built up, according to Dickinson. The sulfation can make it difficult to recharge the battery.

Second, over the course of a week, the electrolytes in the battery acid can separate out, with the heavy ones sinking to the bottom while the lighter ones rise to the top. If they're left stratified like this, the battery will not run efficiently.

An equalization, or extended charge, will remove the sulfate from the plates and destratify electrolytes, says Dickinson. This extended charge also equalizes all of the cells in the battery, so that the slightly weaker cells are operating at the same strength as strong cells. Eliminating that strength gap helps prevent battery failure, he explains.

3. Consider an additive.
Another way to get rid of sulfate is to use an additive. Pratt of Multi-Shifter recommends using Varix. Varix, which requires only a one-time application, flushes existing sulfate buildup off the plates and prevents additional sulfate from bonding to them. This process can lengthen the life of a new battery and improve the run time of an older one, according to Pratt. "We've had many instances where a battery that was only working for four hours was back to six to eight hours [after treatment]," he says.

4. Monitor the battery's temperature.
Make sure that your battery doesn't run too hot. "If your operating temperature stays above 115 degrees on a daily basis and doesn't drop below that point, you're asking for trouble," says Waseem Ahmad, vice president of engineering for battery manufacturer Hawker Powersource, an Enersys company.

You can determine a battery's temperature by inserting a thermometer into the cell or by taking an external reading using a heat gun. Alternatively, you can purchase a monitoring device for each battery that will track temperature as well as state of charge, peak current charging and discharging, and ampere hours consumed, says Ache.

5. Wash your battery regularly.
Washing your battery can both cool it down and make it function more efficiently. "The cleaner the copper tips on both the battery and the charger, the more efficient the transfer of electricity," says Dan Dwyer, general manager for Sackett Systems, which makes battery-handling equipment.

Batteries can be washed manually or automatically using wash cabinets. As for how frequently they should be washed, that will depend on the application, the type of facility, and the equalization cycle, says Dwyer. Typically, he recommends somewhere between once a week and every two weeks. Ahmad of Hawker suggests once a quarter.

6. Follow the 80-percent rule.
Batteries should be charged when they have reached 80 percent depth of discharge — typically eight hours for a new battery. Removing a battery for charging before it reaches that point is a waste of money, says Jim Lane, vice president of sales and marketing at battery-handling company MTC. Lane says it costs $20 on average to change and charge a battery (most of that goes for labor), so the costs of unnecessary battery exchanges can add up quickly.

7. Always use a cooled battery.
If you're changing out your batteries (as opposed to using fast or opportunity charging), allow the battery to cool down for four to eight hours after the charge, says Lane. "Heat degrades the battery faster than anything," he explains.

8. Follow the "first in, first out" rule.
One way to ensure you're using a fully cooled battery is to follow a "first in, first out" policy for battery rotation, says Dwyer. A battery management system —which tracks not only how long a battery was in the lift truck but also how long it was in the charging system —can help assure batteries are used in the correct order.

9. Don't undercharge your battery.
It might not sound harmful, but undercharging will cause sulfate to build up on a battery, reducing its capacity and ultimately its life, says Ahmad of Hawker. To avoid this, be sure to use a charger that matches the battery exactly. If you have a 1,000 amp hour battery, he says, your charger should also be 1,000 amp hours —no more, no less.

To determine whether batteries are fully charged, check the specific gravity of the acid after the charge, Ahmad advises. Each battery has a nameplate that tells what the specific gravity should be when it's fully charged. If the specific gravity does not match exactly, the charger needs to be adjusted.

10. Don't skimp on your record-keeping.
When it comes to battery maintenance, one of the biggest mistakes DCs make is failing to document battery-related activities, says Miller. Whether you use a simple paper checklist or a sophisticated battery management system, it's critical to keep records on activities like battery charging and discharging, battery change-outs, and battery rotation. Maintaining good records takes time and attention, but skipping that step is false economy. The more you know about the maintenance and performance history of these critical assets, the more you stand to save in the long run.

About the Author

Susan K. Lacefield
Editor at Large
Susan Lacefield has been working for supply chain publications since 1999. Before joining DC VELOCITY, she was an associate editor for Supply Chain Management Review and wrote for Logistics Management magazine. She holds a master's degree in English.

More articles by Susan K. Lacefield

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