Aircraft Battery Maintenance & Charging
Why do maintenance at all? The simple answer is that we do maintenance to preserve the usefulness and performance of the battery. Like other aircraft components, the battery needs to be inspected regularly to assure it will function and perform as expected when called upon. If we think about it, in all aircraft electrical systems the battery is the last link in the aircraft electrical emergency chain as well as the first link in the electrical system for getting the engines started.
As a reminder, Ni-Cad battery and vented lead-acid battery maintenance should not be attempted in the same room. The reason is the chemical differences in the electrolytes between the battery types. The Ni-Cad uses a potassium hydroxide (KOH)/water solution and the lead-acid battery uses sulfuric acid (H2SO4)/water solution. The problem is that if the two chemicals become mixed they will neutralize each other. Therefore intermingling tools, or even servicing the batteries in the same room, gives us a good chance for electrolyte cross-contamination, thereby chemically neutralizing each battery and rendering them useless for service. This potential for cross-contamination is somewhat reduced when servicing Ni-Cad and sealed lead-acid batteries, but all battery shops should keep them separate as well, just to be cautious.
Lead Acid Aircraft Battery Maintenance & Charging
- All aircraft batteries, regardless of whether they’re a ni-cad, lead acid or lithium, will require maintenance at some point and time. That maintenance may come in the form of an Open Circuit voltage (OCV) check, periodic check, capacity test or various other inspection criteria.
- It is important to perform these maintenance checks at the required intervals and as instructed in the prescribed maintenance instructions.
- Sulfating in lead acid batteries is a condition in which hardened sulfate builds up on the plates of the battery. The condition is usually caused by leaving a battery in a discharged state for a period of time or improper charging procedures that do not charge the battery to a 100% state.
- When charging a battery, you first need to know the type of battery and the type of charging required. Some batteries require a constant voltage while others require a constant current. If you employ the wrong type of charge to a battery it can damage the battery or even worse, it could cause damage to the aircraft and/or bodily harm.
- Some sulfated batteries can be reclaimed while others will need to be replaced. A quick check of the open current voltage following a charge can determine, to a certain extent, the level of hardened sulfate in the battery.
- Ensure you are using the proper charging technique. Follow required inspection intervals and try to never leave a battery in a discharged state for any period of time. A battery left in a discharged state, or if it is deeply discharged, should be subjected to a capacity test. Most battery manufacturers will not grant warranty for batteries that have been sulfated, so following these procedures will increase battery life and keep the battery within warranty consideration.