Inside Logistics

Battery watering

Why a simple job is so often done poorly


December 2, 2010
by Harold Vanasse

MM&D MAGAZINE, SEPTEMBER-OCTOBER 2010: Properly maintained, industrial batteries should provide five years of reliable power. But one of the simplest battery maintenance tasks is also one of the most poorly performed: battery watering.

Over-watering a battery can cause “boil-overs,” creating a hazardous condition within the warehouse. But it also decreases the battery’s useful life because during a boil-over, sulfates are washed out of the battery, and sulfates are needed to maintain capacity. For every boil-over, the battery loses approximately three percent of its capacity. Over time, boil-overs can decrease the life of a battery by six months or more.

Under-watering can happen when batteries aren’t watered on schedule or when they are manually watered and the operator accidentally skips a cell. When a cell is skipped in a typical watering regimen, it might not get the water it needs for another week. When parts of the battery’s positive and negative plates get dry, battery capacity is decreased. And even when water is re-introduced to the dry cell—for example, at the next scheduled watering—it will not return to its previous performance. In the worst case, a damaged cell would need to be replaced entirely.

The most common factor contributing to over- and under-watering is the hand-watering of batteries. An estimated 70 percent of industrial batteries in North America are filled by hand, despite the fact that single-point battery watering systems have been available for years.

Single-point watering systems offer a cost-effective and safe alternative to hand-watering. The first single-point systems were manufactured with floats that gauge the electrolyte level.

Here’s how the pressure-dependent watering system launched in the early 1990s works. It uses water injectors on each battery cell connected to one another with corrosion-resistant plastic tubing. Each injector has its own level-sensing valve, which is powered by water pressure, ensuring precise sensing of electrolyte levels in each cell.

To fill the batteries, a hose is attached to the input fitting and a valve is opened. The water flows through the plastic tubing and, simultaneously, into each of the cells. Within 15 to 20 seconds, the battery is filled, with each cell receiving the precise amount of water needed. That’s up to 20 times faster than hand watering.

Some industrial battery suppliers believe so much in the benefits of single-point watering that they strongly recommend such systems for each battery they sell. Kris Carreiro, industrial account manager for British Columbia-based Magnacharge Battery Corporation, says, “We know our customers will be more satisfied with our batteries when they use a single-point system. Their employees are safer and more productive, they’ll have fewer performance problems and their batteries will last longer.”

Carreiro also notes that single-point watering systems are a must for rapid and opportunity charging applications, which have become increasingly common. “In rapid and opportunity charging, you don’t have to take the battery off the forklift in order to water it. These rapid charging applications typically increase battery watering frequency, too. So why would you continue to hand water these batteries, which requires taking the batteries off the forklifts, when you can simply use a single-point system to water the batteries in place?”

What’s the ROI ?

In 2006, Philadelphia Scientific surveyed users of its single-point system to determine the return on investment (ROI). Survey participants considered labour savings from the decreased time spent watering batteries, time saved due to less frequent battery changes and savings from less frequent battery purchases as batteries experienced longer lives with proper maintenance. The survey revealed that in an average 100-battery fleet, a company can expect to save approximately US$26,000 per year with an ROI of approximately 13 months.

Harold Vanasse is vice-president of sales and marketing at Philadelphia Scientific.