Securaplane Emergency Batteries

Sealed Lead Acid Battery Advantages

Securaplane Emergency battery systems use Hawker Sealed Lead Acid (SLA) batteries instead of  Ni-Cads.  While Ni-Cads excel in low voltage, full-discharge, high cycle applications (i.e.: power tools), they do not perform nearly as well in extended standby applications, such as emergency battery packs.  Conversely, while sealed lead acid batteries are not an optimum choice for high cycling, they are the best choice for standby applications, in terms of performance, no maintenance, transportability, and cost.

Hawker sealed lead acid batteries have proven to be highly reliable in over 15 years of aircraft emergency battery applications. 

NO “REVERSED CELL” CHARACTERISTICS 

With Ni-Cads, it is necessary to attempt to match as many as twenty individual cells in order to prevent unbalance and thus cell reversal during end of discharge.  When a Ni-Cad does reverse, very high pressure and heat result.  The result is often pressure seal rupture, and in the worst case, an exploded cell.

With the type of Hawker sealed lead acid batteries Securaplane uses, cell matching is inherent in each battery.  And since the batteries are made by a highly automated process, battery to battery variance is held to better than one percent.  

Securaplane also incorporates a battery-to-load automatic disconnect when the battery reaches an end-of-charge  voltage.  This significantly reduces battery deterioration, while using what amounts to only seconds of power. 

KNOWN CHARGE STATE 

It has always been extremely difficult to determine (by voltage) the energy content of a Ni-Cad battery, due to memory effects.  In contrast, the energy of a sealed lead acid battery can be measured in terms of voltage when tested under a known load, and if it has been uncharged for an hour.  Securaplane emergency batteries include a front mounted, momentary switch that allows determination of the energy content of the battery pack. 

NO MEMORY CHARACTERISTICS  

Ni-Cads have an undesirable characteristic which is caused by constant overcharge and no (or infrequent) discharges, as in standby applications.  It is technically known as “voltage depression” and commonly, but erroneously, called “memory effect”.  This characteristic is only detectable when a full discharge is attempted.  Thus, it is possible to believe a full charge exists, while in fact it does not. 

Sealed lead acid batteries DO NOT EXHIBIT the voltage depression (memory) phenomenon, and therefore do not require scheduled deep cycle maintenance as do Ni-Cads. 

BATTERY SELF DISCHARGE  

The self discharge rate of a Ni-Cad is very high, averaging approximately one (1) percent per day at room temperature.  This becomes one of the serious (if not the most serious) shortcomings in standby aircraft applications.  Conversely, the Hawker sealed lead acid battery loses only .15 percent per day (at room temperature). This is seven to ten times lower than Ni-Cad batteries. 

TEST EQUIPMENT  

The Ni-Cad based emergency battery pack requires a relatively complicated piece of test equipment due to the complex characteristics of the Ni-Cad.  Since Hawker sealed lead acid batteries do not possess these temperamental  characteristics, it is not necessary to purchase special battery maintenance equipment.  With the Securaplane emergency batteries, important operational parameters, including capacity, can be tested while the unit is still installed on the aircraft. 

SCHEDULED MAINTENANCE  

Ni-Cads must have a scheduled annual (or sooner) energy test performed on the bench because of their inability to have their energy level measured on the aircraft, and because of their notable “memory” shortcoming. 

Securaplane has designed the XL series units for a “NO REMOVAL MAINTENANCE CONCEPT”.  The units are designed to inform the operator if a battery is failing.  It is even possible to test the failure detection circuits simply by pressing a BITE button.  This concept significantly reduces FAA paperwork and maintenance workload.