Some portable electronic equipment - amateur radio gear for example - uses sealed lead acid batteries. The local woodturning Club of which I'm Secretary uses a portable PA amplifier with integral speaker, powered from a sealed lead acid battery, with an integral battery charger.
Due to lockdown, the last time the PA system was used until Tuesday evening this week - the relaunch of the Club after 20 months of closure - was February 2020. Though the battery had been recharged, it didn't hold its charge, (unsurprisingly perhaps, given that it was 13 years old), so the PA system failed to work.
The dimensions of the 12V 2.9 AH battery are such that I could only find two UK suppliers, one of whom was 'Battery Trader', who supply SLA and other types of rechargeable batteries for everything from cordless power tools to mobility scooters, cameras, motorbikes and intruder alarms.
I ordered the SLA battery we needed at 11.30am yesterday. Within minutes I received an email saying it had been despatched via DPD, then an update from DPD saying it would be delivered today between 11.30am and 12.30pm as indeed it was, securely packed, within 24 hours.
I thought they deserved a mention, given that they supply such a wide range of rechargeable batteries and based on my experience, give as fast a turn around of orders as we could wish for. The PA system is now back in use.
No connection with them, other than as a satisfied customer.
https://www.batterytrader.com/