Battery supplier Saft has clarified that Airbus installed and delivered the first A350-900 equipped with rechargeable lithium-ion batteries to a customer at the end of last year.

Saft also confirms that the A350-900 entered revenue service in January with the batteries certificated by the European Aviation Safety Agency (EASA).

The launch of revenue service follows certification of Airbus' battery installation and design by EASA, says Airbus executive vice-president of engineering Charles Champion.

Airbus is still waiting for the US FAA to certificate the lithium-ion batteries for the A350-900, he adds.

Airbus originally designed the A350-900 using rechargeable lithium ion batteries to serve as a back-up power source for the avionics system and to start the auxiliary power unit.

But Airbus was forced to sideline that plan due to the Boeing 787-8’s battery troubles. In January 2013, fires erupted on two 787-8s within nine days after lithium-ion batteries overheated on both aircraft. The FAA ordered the fleet grounded for almost four months while Boeing redesigned the installation to prevent the cells within the batteries from causing damage to the aircraft if they overheat and vent.

The 787 fleet returned to service in three years ago. One more cell venting event was reported in January 2014, but the redesigned installation prevented the overheating battery from damaging the aircraft. A separate battery fire on an Ethiopian Airlines 787-8 at London Heathrow in July 2013 involved a non-rechargeable lithium battery for the emergency locator transmitter beacon, but that incident was caused by a manufacturing error.

Airbus believed it had come up with a more conservative design for the A350-900 battery system, but replaced it with a nickel-cadmium battery for initial deliveries, representing a previous and well-understood generation of aircraft batteries.

Lithium-ion chemistry can store more energy in a lighter package than nickel-cadmium, but can be more volatile. The 787-8 uses a GS Yuasa-designed system that stores 72Ah of energy in eight 3.7V cells, whereas the Saft batteries on the A350-900 store about 45Ah of energy between 14 3.6V cells.

Additionally, Airbus divides the power requirement between four lithium ion batteries, compared with two larger batteries used by Boeing. Finally, Saft serves as both the maker for the battery and the battery controller, while Boeing divided these functions between GS Yuasa and Securaplane.

A previous version of this article, citing Charles Champion, had stated incorrectly that the first lithium-ion batteries to be installed in an A350-900 would not be delivered to a customer until the end of the year.