Lithium starter batteries for non-type certified aircraft

The use of Lithium batteries for aircraft offers considerable weight and size savings, improved cranking power and longer service life. There are several types of Lithium batteries using different chemistries. Lithium Iron Phosphate (LiFePO4) types are the safest and of course the best choice for aircraft use. The stability of the LiFePO4 battery comes from the fact that there is no free oxygen produced in the chemical reaction.

There is no thermal runaway, even at temperatures of 160 degrees C. Other chemistries offer higher outputs for lower weight and sizes, but with lower safety margins. It is unfortunate that the authorities don’t differentiate between the various Lithium chemistries and regulations are implemented to control the most unstable types. They are all ‘lumped together’ as ‘Lithium’ batteries.

This has in particular affected the transporting and handling of all Lithium type batteries by carriers. LiFePO4 cell fires are virtually unheard of, but it is still very important to correctly install, charge and operate these batteries.

So why use a lithium starter battery in the first place?

• Weight and space saving: a LiFePO4 battery weighing 1.3Kg will comfortably start an O-360 aircraft engine and take up the same space as a house alarm battery.

• Superior cranking performance: Once you have seen how fast a lithium battery cranks an engine, you will never go back. Repeated cranking never seems to slow down and on a cold day it even gets better as the battery warms up a little.

• Long life: A correctly sized and deployed lithium starter battery will last five years and provide five times more charge/discharge cycles than a lead-acid battery.

• Availability: Self discharge is extremely low. A fully discharged 360A battery could be charged sufficiently for an engine start within 10 minutes.

• Low maintenance: No regular top up charging is required.

Infrequent battery changes means less labour costs.

So if you have decided to fit a Lithium Iron Phosphate starter battery, get expert advice to choose the correct Lithium battery for your application. Use an over voltage protection unit in your installation to protect the battery from over charging. LiFePO4batteries are particularly sensitive to over-charging. Use the correct charger and do not use conventional chargers made for lead acid batteries.

One must carefully follow the manufacturer’s instructions!

Don’t connect batteries in parallel and don’t jump start!