This month's blog will explore the whys and hows of proper and safe cleaning as well as safety aspects of the task. Operational matters will also be discussed. Keeping a battery system clean throughout its service life is part of a good maintenance program. There good reasons for keeping your batteries clean, and not only so they look good.
Cleaning the Battery
A battery should be given a thorough cleaning post-installation, preferably before being placed into normal service. I'm sorry to say that I've seen this ignored over my years in the industry. Too many times, the system is loaded with construction debris, dirt, dust and other contaminants that simply sit on cell tops, sometimes for years, even on batteries that were reportedly under a maintenance plan. Cleaning should be written into an installation specification, even though it should be performed by the installer as a normal part of installation.
Throughout the service life, normal accumulations will show up on cell tops, rack rails and other horizontal surfaces known to collect dust. See Figure 1. This can be cleaned easily with a lightly water-dampened disposable commercial grade wiper. Personnel taking on the task should use the PPE appropriate for the task and voltage encountered. The PPE generally includes safety glasses, goggles or face shield insulated rubber gloves. This brief list is not necessarily all-inclusive and you or your company is responsible for proper selection and training in its use for the task at hand.
Light dust accumulation with a few droplets from hydrometer or watering activity.
On VLA batteries electrolyte tracking and spillage frequently arises from the use of a hydrometer. Care should taken to always clean up after this task, otherwise, the problem gets worse over time if ongoing housekeeping is ignored. As you read through the blog, you'll see why leaking and tracking can become a big problem.
When it comes to selection of cleaning solutions, soaps, detergents, cleansers, etc., you must follow battery manufacturer instructions. Generally, you're limited to baking soda and water for cleaning and neutralization of normal electrolyte and dust accumulations. The mixing ratio of water to baking soda remains at 1 pound of baking soda to 1 gallon of electrolyte. This makes for a heavy mix and will neutralize electrolyte easily. Rinsing, however, may be required as it is pretty heavy on the baking soda. Failure to rinse leaves white streaks all over and it's not going to make for a good looking job in the end.
With the above said, should you choose cleaning solutions, soaps, detergents, cleansers, etc. not specifically listed in the battery manufacturer's operating and maintenance instructions, you'll be on your own. There are simply too many chemicals out there that can bring irreparable damage to container and cover thermoplastics; fogging, cracking and crazing are the usual results. Battery manufacturers are not going to take time and expense to research cleaning products.
Operational Issues and Leaking Cells
Operationally speaking, a clean battery is unlikely to pose a ground fault condition to the DC system to which it is connected. Ground faults can occur when one or more cells develop a leak that eventually propagates to a grounded component such as a battery rack, stand, or support structure. Electrolyte migrates or "creeps" from the source of the leak, so left alone, it will continue until the water in the electrolyte evaporates, leaving acid staining. See Figure 2. Since the rack or stand is grounded, (if not, it should be) you have part one of the fault problem. Additional leaks to ground as well as to adjacent cells/units result in cell voltage imbalances to the extent that a technician will recognize the problem but may make a false diagnosis by failure to realize leaks and dirt may be the culprit. That is, in an otherwise properly operating battery, the voltage imbalances due to the above are perceived as a battery problem. The technician starts an equalize charge, but that has no effect to correct cell voltage other than to overcharge the cells and use more water.
Dirty cell with electrolyte tracking. Notice voltage reading across 2 cells. The meter is reading through the electrolyte track, not the terminal post. This will become a tracking problem later and cause voltage imbalances if not addressed.
Leaks and Effect on Equipment, Personnel Safety
Leaks and poor housekeeping not only contribute to operational problems like the one described above but they can be a catalyst for a battery fire. Fault current flows from inside the cell, through the electrolyte and onto the rack which will eventually cause heating of cells. Battery fires have been started this way. Additionally, touching an area where a leak has developed with the other hand on a grounded component such as the rack may present lethal voltage between the two points and you can become the conductor! See Figure 3. I have first hand experience on a 180 cell UPS battery many years ago as a junior field engineer, so I know of what I speak.
Wet cell tops can easily become a shock hazard. In this case, flame arrestors will require removal to properly clean the cell top and vent well area.
Keeping it Clean
One of the best ways to keep a battery clean, and minimize the labor-hours to clean when needed is to filter the incoming air to the battery room/area. Keep the battery room door(s) closed. Always maintain proper ventilation. It is also worth mentioning that while this blog primarily discussed VLA batteries, the same problems can occur on VRLA types. The basic difference is that technicians aren't going to be spilling electrolyte.
Rick Tressler provides battery training and education services to technicians, electricians, installers, and maintainers and others working with stationary battery systems. For information on classes, seminars and technical support, check out the website at www.ricktressler.com or contact Rick at email@example.com, 614.632.7521.