Aircraft Maintenance: Winter battery care

Winter often means long intervals between flights, which can spell trouble for aircraft batteries. Every time you fly, your alternator and voltage regulator are working to keep your battery charged and healthy. However, as soon as you shut down, your battery slowly begins to lose its charge and degrade internally. It’s just a fact of life and battery chemistry.

All aircraft batteries, both flooded-cell “wet” batteries and sealed, absorbed glass mat batteries, require regular use in order to perform at their peak—that means putting them through cycles of discharging and recharging without reaching critically low voltage levels that can permanently damage the battery. Critically low batteries begin a process of sulfating, where lead sulfate crystals form on the negative cells, reducing their effectiveness and eventually shorting them out. Neglecting an aircraft battery until it can no longer start the aircraft can inflict irreversible damage. Cold winter temperatures bring additional issues because batteries perform at their best when they are warm (but not hot). In fact, a very cold battery will not properly take a charge at all. You’re left out in the cold with something that can’t help you, and you can’t help it.

The ideal solution is, of course, to fly the aircraft regularly for long enough periods of time to effectively allow the aircraft’s own systems to charge the battery and keep everything healthy. During periods when that isn’t possible, other options are available.  Intelligent battery charging systems such as the BatteryMINDer are specifically designed to monitor the voltage and temperature of the battery during charging, providing the right amount of charging at the right time. Frequently called battery tenders, these systems have the added benefit of automatically switching to trickle charge and “de-sulfating” modes that can reverse some amount of minor damage that may have occurred to the internal chemistry of the battery. These aircraft battery-specific chargers are well worth the money, especially considering that using automotive chargers can damage aircraft batteries. According to the experts at Concorde Battery Corp., common automotive chargers are set to charge at voltage levels that are too high for the design of aircraft batteries. The result can be overcharging, boiling or venting of the electrolyte, and permanent damage to the battery.

If at all possible, the battery should be kept warm during the charging process. If your engine has a preheater and your battery is in the cowling, that may be more than enough to accomplish both tasks at the same time for several hours before each flight. As I’ve written previously, I’m a big fan of remote-control switches that can allow you to control power to your aircraft in advance of your flights. You can use these same switches to control the engine preheater and battery charger (on separate switches).  Optional external charging ports, such as those available from companies including BatteryMINDer, can make the process even more convenient and prevent having to remove the cowl or access fuselage-mounted batteries for charging.

For more extended periods, you may need to remove the battery and take it inside to be properly stored and charged until regular flying season returns. Aircraft batteries are expensive, and it pays to protect your investment. Getting the motivation to venture out into the cold to practice the art of flying can be challenging enough. Being proactive about caring for your battery will ensure that your shoveling gets rewarded with the blue skies and stunning winter landscapes that make it all worthwhile. Until next time…happy flying!