TJ Magna Sports manual - car was driving fine just last night, I went to drive it today and it has no electrics working, no dash lights or ignition.
I knew something was up when I hit the remote locking and it didn't work.

Unfortunately i don't have a multimeter or tools.

It might be BSD syndrome - battery sudden death is a possibility.
One cell goes open circuit without warning, and nothing electrical works.

Other possibilities:
You left a light on, and the battery is flat.
Check the battery connections, give them a clean. If no improvement, try a different battery or a jumpstart off another car.

Yeah definitely, but I think this one is on me.
Battery has been dying for a while (cutting out straight after starting the car) but I have neglected it for too long.

Also, I've had the car since 2011, same battery, so it would make sense i guess.

I agree, sounds like BSD to me. I had the same thing a year or two ago, car was fine in the morning and barely enough oomph in the battery to warm up the interior light filament in the arvo. Interestingly the battery still showed 12V across the terminals with no load, just bugger all amps available.

I had it happen twice to me. Both times, battery died during a pit stop on the way home and both times were just shy of 3 years.

I had it happen twice to me. Both times, battery died during a pit stop on the way home and both times were just shy of 3 years.

You're not getting much life out of your batteries. I bought the one that is currently in my 1st gen on 14th August 2008 and it is still going strong. That's 6 years 8 months so far. It is an Exide and if I remember correctly, uses some sort of calcium technology. I must take it out and make a note of the type because when it finally dies I will buy the same again. The previous one, a Bosch, lasted 5 and a half years.

I do make a habit of always buying the biggest battery that will fit.

Yep, was the battery.
Ended up with an Exide Endurance. Sure fires up much quicker now.

Photo of car in question for your time.
http://i.imgur.com/EhUZ2x3.jpg

You're not getting much life out of your batteries. I bought the one that is currently in my 1st gen on 14th August 2008 and it is still going strong. That's 6 years 8 months so far. It is an Exide and if I remember correctly, uses some sort of calcium technology. I must take it out and make a note of the type because when it finally dies I will buy the same again. The previous one, a Bosch, lasted 5 and a half years.

I do make a habit of always buying the biggest battery that will fit.
The first one was factory 600CCA which I had from new. The first replacement was an RAA 550CCA (the biggest they had) and the second replacement was an Exide 550CCA from Kmart (again the biggest they had). Interestingly, my Pajero only has a 580CCA with an ECU controlled variable charge alternaror.

Batteries can be hit or miss, even original Japanese ones. 2 Lancers in the family, original battery lasted 6 years in one - it lost so much capacity that it was good for a single attempt to start but no more, the other had an open circuit cell appear suddenly after 2 years. Usual symptoms, 12V at no load, turn the parkers on and 0V, no lights.

My experience with batteries is the the OEM battery seems to last about 2 years, and then fail. Replacement batteries then last about 5 years for me.

I had a Sigma which, after 5 years needed new rings (oil consumption, not lack of compression). I fitted the rings, and the battery which I had in the car (about 3 years old) had no hope of kicking the engine over. I bought a new battery and it was OK. I drained the acid out of the battery and kept is as a doorstop. Eventually, I bought a TM Magna, and the OEM battery in it died after 2 years. Out of curiousity, I got the doorstop out. and refilled the acid just to try it. To my surprise, it fired up really well. It lasted another 2 years in the Magna before it died.