Century were a very old battery manufacturer in Sydney, in the 1990s they became part of GS Yuasa.
I have used their batteries in industry and personally for decades, also used imported Yuasa (Korean) in cars late 1980s these normally lasted 6 years!
Century storage batteries with good maintenance practices would last 5-6 years in our diesel generators.
Most common replacement battery in 4WDs is the Century Yuasa "Overlander" and a Century storage battery if you have a fridge.
Anderson Plugs (dual) are the best battery disconnect plugs available -
the smaller 50Amp should be sufficient for Astro
only loads.
For PSU DC connections I prefer the Hella polarised plugs & sockets - most popular interior connectors for boats and 4WD - limited to max 15 Amps, or continuous load of approx. 10 Amps:
4916 Hella Socket - insulated:
http://db.hella.com.au/cgi-bin/catal...ew&flmaint=329
4914 Hella Plug:
http://db.hella.com.au/cgi-bin/catal...ew&flmaint=332
Equivalent (cheaper) Jcar "Merit" plug PP2090 (water resistant) is also good:
http://www.jaycar.com.au/productView...s&form=KEYWORD
Note the equivalent Jcar Mertit socket is not recommended.
Using the above you will have reliable connections. A suitable range ammeter can monitor you loads. If you intend to use long leads from any DC power source, measure the voltage across the load end and under load full load. You would be surprised how much voltage drop occurs in the 10M light gauge leads supplied by some mount manufacturers.