Dec 09 2019

Maintenance Minute - Go Go Juice Posted 5 years 19 days ago ago by Admin

No, we’re not talking about a slow-speed chase down a California highway; rather, your lost and sometimes forgotten aircraft battery. Without it, your day will never properly start.

With the advent of improved technology, lead-acid batteries are becoming more commonplace in turbine-powered helicopters. And while lead-acids have certain advantages over the original NiCad batteries, a number of “operational” differences could reduce the effect and value of those advantages.

At the top of these differences is the lead-acid’s discharge rate, which is more linear than a NiCad. In other words, you can probably get two consecutive starts out of a NiCad with minimal output loss across both starts, but a lead-acid will begin the second start at a lower rated output than the first start. These repeated second or third starts also can reduce the performance and life of a lead-acid over time.

The solution: use a battery cart or GPU whenever possible for all starts – especially on the first start of the day, extreme cold starts, and those dreaded second or third starts. Some operators invest in small portable “starting units” that can be stored in baggage compartments. While these additional items add to the overall cost of the lead-acid, the total value still is below the cost of maintaining a NiCad.

Another operational difference: lead-acids do not like an unhealthy aircraft electrical system, i.e., a system with parasitic drains, dirty/loose connections and the like. Actually no battery fares well in this situation, but lead-acids seem to “remember” repetitive static drains and system inefficacy just like those “second” starts above.

Keep in mind, one of the biggest benefits of lead-acids is that they don’t have repetitive deep-cycle requirements every 30 to 90 days. However, that can be a disadvantage to a lead-acid since most internal damage from operational abuse will accumulate over time and eventually cut short its useful life. NiCads on the other hand get “reborn” every deep-cycle and do not typically suffer from these types of operational “memories.”

Another way to look at it: every discharge/recharge cycle of a lead-acid is like rings on a tree. And the longer time period between the discharge event and its subsequent recharge, the bigger the “ring” accumulates as sulfation begins to take place at an accelerated rate. The more lead sulfate crystals (sulfation) in a lead-acid, the less output power available and the less months/years of battery life left.

To keep sulfation at a minimum, ensure the lead-acid is maintained at its optimum static full charge. If a lead-acid experiences an extended discharge, recharge the battery with an appropriate battery charger as soon as possible. Most aircraft electrical generating systems are not designed to effectively charge a battery after such an event.  

So the next time you hit that starter button and the engine spools up quickly, giving you that nice warm start, give a nod to your lead-acid for starting your day off on the right foot.