Nicad batteries triple radio station backup time

A switch to a rechargeable nickel-cadmium battery ensures that T-Mobile's Ben-A-Chielt radio station can now continue operation for up to 20 hours in the event of a mains power failure.

T-Mobile, part of one of the largest mobile companies in the world, has switched to a Saft NCX rechargeable nickel-cadmium battery to provide a reliable, low-maintenance source of backup power for its Ben-A-Chielt radio station, which serves remote communities in the north of Scotland including Orkney and Shetland.

The new 500Ah battery enables the station to continue operation for up to 20h in the event of a mains power failure, compared with the maximum of 6h provided by the previous VRLA (valve regulated lead acid) battery.

The radio station was constructed by T-Mobile around four years ago at a height of 287m on the Ben-A-Chielt hilltop, near to the town of Wick.

The site is mains powered from the local Scottish and Southern Electricity supply with backup power provided by a 48V battery and four Erskine TSC 1548 rectifiers capable of supplying a total of 60A.

It was a desire to further improve the resilience of the local radiocommunications network that prompted the decision to replace the battery, as Stephen Rennie of T-Mobile explains: "Ben-A-Chielt is a key site for T-Mobile, even though it serves a relatively small number of customers.

This is because many of the local communities, especially on the islands of Orkney and Shetlands, rely on it as a vital communications link".

"The remote nature of the radio station poses two main challenges for our service team.

Firstly, since the team has to cover a large geographical area it can take some time just to travel to site.

Once there, the access roads are very poor and even 4 x 4 vehicles can get stuck, especially in severe weather, so it can take even longer to reach the radio station".

"The previous 160Ah VRLA backup battery was only capable of providing up to 6h of operation and we wanted to achieve a much greater safety margin before a mains power failure causes the radio station to go off line.

By switching to the 500Ah Saft NCX battery we now have up to 20h of backup power.

This allows more time for Scottish and Southern Energy to restore the supply, or in the case of a severe outage our service team has more time to get a generator to the site.

There is also an important health and safety benefit since we no longer have to send technicians out in severe conditions, instead they can wait for a suitable window in the weather".

The NCX block battery is a sturdy cell type designed by Saft to fulfil the demanding requirements of remote or outside telecomms plants including local or access terminals, base transceiver stations, basestation controllers, optical node units and so on.

Installation of the compact, modular NCX is simple since it fits most existing VRLA (valve regulated lead acid) battery compartments with ease and uses the same charging equipment.

The combination of stable sintered/plastic bonded plate technology with flooded electrolyte and corrosion-free chemistry enables the NCX to eliminate problems such as dryout, grid corrosion, plate growth and thermal runaway.

With a much longer life, predictable operation, less maintenance and lower life cycle cost, the NCX is a realistic and attractive alternative to potentially troublesome VRLA batteries, especially in extreme operating temperatures (-20 to +40C).

The NCX modules comprise from three up to eight cells, and 38 NCX cells are recommended for a typical 48V bulk power application.

The cells are available in three capacities: NCX 80, NCX 125, NCX 160 (nominal capacity 80, 125 and 160Ah).

The Ben-A-Chielt installation comprises four strings of Saft NCX 125 cells connected in parallel to create a 500Ah capacity battery.

Back to top