Lighting Services Blog

Not totally true… Wet type emergency lighting batteries always consume some of the electrolyte (sulfuric acid for lead and potassium hydroxide for nickel cadmium) when they are being charged. The need to refill is based on age, ambient temperature, charge rate, etc. and the established monitoring of properly maintained levels of liquid. The charging process normally produces a flammable gas mixture of hydrogen and oxygen. A short circuit, open flame or smoking during must be avoided when adding water to keep the fluid above the plates or the battery manufacturer’s indicated max fill level. Some maintenance free batteries that use calcium instead of lead require less maintenance because of the greater reservoir capacity. Adding distilled water where and when possible will greatly increase the life of these “so called” maintenance free batteries.

The National Electrical Manufacturers Association (NEMA) sets the standard for various electrical products including certain types of emergency lighting and exit signs. General specifications are as follow. The NEMA for emergency lighting is designed to withstand elements that would interfere with the normal and efficient operation of the emergency lighting unit such as wet locations, rain, and snow. The lighting heads themselves are design to be waterproof as well. The units normally come in 6 and 12v and carry D.C. lighting loads up to zero watts. Input various A.C. voltages can be requested from many many manufacturers. All units have a 90 minute run-time but can be customized for runs exceeding 1.5 hours. Most units are made of high-impact reinforced fiberglass and are extremely rugged. Most units come with a 12v 36 watt sealed lead calcium battery capable of powering remote fixtures. A number of options for this unit may be requested such as volt meter, time delays, etc. This emergency lighting is more costly than your standard units but are mandatory for specific applications.

In many of the older, wet-type (lead antimony) batteries, they are shipped with a liquid installed called sulfuric acid.  This electrolyte is energized during the charging process to maintain the proper voltage in the battery.

Emergency Lighting System batteries are like spark plugs.  At 30 or 40 thousand miles, would you just change one defective spark plug?  No.  You will probably change them all because most likely they have the same mileage on them.  Banks of batteries in large AC or DC emergency lighting systems are quite similar.  When one battery fails, the balance is not far behind.  As with the spark plugs in your vehicle, the replacement of all the batteries at the same time, when one fails is, in the long run, much more cost effective.  A major portion of the cost to perform either of the above-mentioned tasks includes travel, labor, shop time, disposal of old material, etc.  Drive to the auto repair shop 4, 6, or 8 times to replace one park plug or replace and dispose of 6, 12, 20 or more batteries one at a time versus replacing all your plugs or batteries at one time is much less costly.