The message
from "Doki" contains these words:

Is it possible to DIY up a 6V charger for old car batteries, or to buy one
cheap?

Maplin do one - but it's low powered but has the advantage of changing
to trickle when full.
http://www.maplin.co.uk/Module.aspx?...EO&U=strat1 5

Or there's plenty of 6V chargers on eBay.

http://cgi.ebay.co.uk/6-Amp-6-12V-Ca...mZ180004445102

--
Skipweasel
Pay no attention to that man behind the curtain.