Do what Gama said, or if you don't want to/can't make it yourself buy one from these guy's...
http://centralds.net/en/
I bought one from there on hOughy's recommendation I think it was, when I asked in the forum a month or 2 ago. It works like a dream, no more battery problems!
I have mine running from my 40 amphr SLA, 240v was no use to me.
Roger.
PS. The bought version is MUCH more expensive than the DIY version, so if you can do it yourself, you'll save yourself a serious packet of money.