Frequently Asked Questions - Aircraft Batteries


Q: Why can’t I use a typical car / truck battery in my aircraft?

A: Amongst other things, a typical car / truck battery is not capable of providing the high electrical current required by an aircraft.


Q: Why should I use ground power to start my aircraft?

A: While an aircraft’s battery is capable of starting the engine/s or auxiliary power unit (APU), this function is not recommended on a recurring basis. The starting of an engine or APU puts an enormous strain on a battery and as such, shortens the life of the battery. Furthermore, if the battery is not sufficiently charged after starting, the battery will slowly deteriorate and may eventually fail. Perhaps most importantly, starting an engine with a less than fully charged battery may cause unnecessary engine wear and even damage.


Q: What does the Ampere hour (Ah) rating on my battery actually mean?

A: The Ah rating on a battery is a measure of the battery’s capacity i.e. how many Amps can the battery deliver and for how many hours. For example, a 12V 90Ah battery (C10) can deliver 9A for 10hr where C10 is the rate of measurement. Most aircraft batteries are rated at the C1 rate in which case a 12V 90Ah (C1) battery would be able to deliver 90A for 1hr and far more than 9A for 10hr.  The current discharge characteristic of a battery is not linear and is obtained from the manufacturer’s graphs i.e. a 12V 90Ah battery will not necessarily deliver 4.5A for 20hr.


Q: Why are aircraft batteries “so expensive”?

A: Aircraft batteries are manufactured to far stricter tolerances than most other batteries and are of a far greater quality than most other batteries. Also, aircraft batteries use higher quality components and are tested far more vigorously than most other batteries.


Q: What cables should I use to connect my battery?

A: This depends entirely on the application of the battery. If for example the battery is being used to start a turbine engine where the current drawn on a start is often greater than several hundred Amperes, a 95mm² cable is recommended. If however, the battery is being used to power a low-power strobe light, a much smaller diameter wire of say 5mm² could be used.


Please feel free to submit any questions, answers, comments, thoughts or queries that you may have to Aztec by email.