Matt75
I have one in my 200sx S15. I've had 2 in 12 years so they are pretty good.
You need a proper trickle charger as the disuse is what is killing your batteries and not the quality.
What size are you using Matt?
Yeah, I finally got with the program, and bought a smart charger for when I eventually install a battery (the car has been a work in progress for the past few years). The problem these days is finding the smaller lead acid battery (to save 4-5 kilos as well as a few $). I've got a near dead N43 sitting around now, which is the same length as the larger ones, but is 3 or 4 cms narrower, so there's still some space either side of the battery tray. I've always found them perfectly fine for cranking duties. Century still make one, but it's pretty much the bottom of their line.