We're thinking about buying a battery system to provide all of our exhibit's electrical needs. What do we need to know before we make the switch?

The obvious advantage of battery systems is the ability to eliminate or drastically reduce electrical fees, as most systems can pay for themselves in as few as three to five shows. Thankfully, cutting the cord and sidestepping in-booth electrical is easier than ever. A convergence of battery-technology advancements, improved power efficiency, and the prevalence of new low-power devices (including everything from LEDs to laptops) means that many exhibitors can switch to battery power and still offer a full exhibit experience.

Granted, if your stand is the size of a football field and your in-booth multimedia presentations rival Times Square on New Year's Eve, completely switching to battery power probably isn't feasible, at least not yet. But many small- to medium-sized exhibitors can immediately reap the benefits of batteries, and even large exhibitors can use them to simplify electricity demands and cabling nightmares.

However, before you decide to skirt the venue's electrical altogether, you first need to determine the required energy draw (aka watt-hours) of all your components and thus the necessary size of a corresponding battery system. Here's some how-to advice to help you do just that.

Calculate Energy Draw
To ascertain the total energy draw of all of your booth components, you'll need to calculate how much electricity each item draws and multiply that by the number of hours in the show. The resulting figure is called the required watt-hours for each device. After adding up the watt-hours for all of your electrical components, you'll have the total watt-hours your booth requires. So here's a step-by-step guide to determining total watt-hours. (It may help to create a spreadsheet for this purpose, but a pen and some paper will do the trick, too.)

Make a list of all of the electrical components in your exhibit (e.g., tablets, monitors, light fixtures, backlit displays, etc.) and note how many of each you employ (e.g., three tablets, five 42-inch monitors, one 29-inch monitor, etc.). Then, identify the rated power, which is the maximum watts a device draws at full load, for each. This information is found on the label or faceplate of most components. You're looking for a number with a W after it. It's usually found after the voltage info, which appears as 120V-60Hz on most U.S. appliances. For laptops, the rating is typically listed on the charging cord or the blocky transformer brick, and as a general rule, a smartphone usually takes no more than 10 to 15 watts of power.

Next, determine how many hours you'll use each component at the longest show at which you intend to use battery power. For the sake of simplicity, let's call this criteria "hours." As you determine the hours for each device, consider whether it will only be powered up when the exhibit hall is open, or if it'll need continuous power throughout the event, necessitating a much larger battery or perhaps requiring you to hook this single piece of equipment up to a traditional electrical line. For example, during a three-day show, your tablets may only be in use for a total of 18 hours, but your refrigeration unit might need constant power and thus require 72 hours.

Then, for each component, multiply the rated power (the number from each device's tag or faceplate) by the hours to get the watt-hours for each device. For instance, let's say your 42-inch flatscreen monitor has a rated power of 60 watts and you plan to use it for a total of 18 hours per show. Its watt-hours are 1,080.

Complete this calculation for each device. If you have eight tablets, for example, figure watt-hours for all eight, not just one. Then, add up the watt-hours for all of your electrical components to determine the total number of watt-hours your exhibit requires per show. With this data in hand, it's time to go shopping.

Match Energy Draw with Battery Systems
The product guides for most battery-system providers offer the following information, at minimum, for each device: watt-hours, weight, height, and pricing. While the last three factors are important, especially if you're trying to fit the battery within an existing exhibit, start separating the wheat from the chaff by looking at watt-hours. To guarantee the safety of your equipment, the battery system you choose should be rated well above the total watt-hour requirements for the exhibit. If the booth requires approximately 700 watt-hours, for example, ensure your battery has at least 1,200 watt-hours to avoid any outages on the show floor.

As you select a battery, there are several variables in the way you will use your battery that should help determine the product or products you buy. That is, if you want a single battery to power the whole exhibit for the entire watt-hours for the show, you're probably looking at a relatively large unit with a high watt-hour rating.

Or, you could buy two or three batteries with lower watt-hour ratings and spread your devices across these power supplies. In this case, you'd have more batteries, but each would have a lower watt-hour rating. This scenario might provide greater flexibility for the positioning of various components within your space and the required cabling between them and your batteries. Another option would be to purchase a battery that will power your booth for only a single day. Then, you'd bring it back to your hotel or office with you at night to recharge it for consecutive show days. Bottom line: Do the math between these various options to determine which product is right for you based on watt-hours, available storage space, cabling needs, and price.

With regard to pricing, each supplier varies, of course. But an SLA Battery Module from my company, Joule Case LLC, can run anywhere from $280 to $2,950 and range in watt-hours from 480 to 4,800, respectively. Note, however, that whatever you buy should be flexible and large enough to power all booth situations you will encounter in the foreseeable future. Alternatively, battery systems can often be leased or rented per event at prices typically less than buying power through the show's provider.