Battery, Secondary No. 22 is a red plastic cased battery pack that was used in some 700 type push button telephones. Most of these batteries are now dead or failing and the instructions below advise on how to replace the battery.
The original battery comprises of two cells marked NCB 1572A - Made in
Hyperflight.co.uk a battery pack that has the same specification and the dimensions 31mm x 22mm x 11mm so it should fit inside the original casing.
Replacing the batteries
Remove the old batteries - your have to prise these out - and then remove the lead.
Obtain cells or a battery that matches the voltage and current criteria and that will fit into the case. Try to use NiMH batteries.
Ensure that the leads are connected correctly.
Last revised: March 18, 2023