I've been using typical TSC battery powered fence chargers here for 18 years. The earlier ones were rather like the old automotive ignition systems. Think they had real points in there that made it go off and on. I'd have to send them back to the factory about every 6 months to be rebuilt.
Then around mid 2000s, they came out with electronic ones. I'd started with separate chargers, battery and solar panel; so, I continued with just the fence charger. I ran it off a cheap 12v utility battery that was kept charged by the solar panel. That electronic charger went for 6 or 7 years. Got a new one in place now. I keep the battery in an old plastic bucket mounted to the 6x6 post that the solar panel sits atop.
Somewhere along the line, I put a little battery tender between the solar panel and the battery to avoid overcharging the battery, as it only lasted 2 to 3 years. Well, it quit; so, now I've the panel connected directly to the battery again like a did for about the first 10 years.
Oh, I see the name of the ones I've been buying: Zareeba.
Ralph