i use pro peak constellations, you can pick them up off ebay 2nd hand, just type in pro peak and you will see the different ones. you would also need a psu (power supply unit for them) available here http://www.technobots.co.uk/acatalog/Online_Catalogue_Power_Supplies_29.htmlhttp://www.technobots.co.uk/acatalog...pplies_29.html

the 13.8v 20a one at £50 is the one i have and it will run 2 pro peaks.

this is also a link for new chargers
http://www.technobots.co.uk/acatalog/Online_Catalogue_Universal_Chargers_28.htmlhttp://www.technobots.co.uk/acatalog...argers_28.html

i have 2 of the pro peaks, gots mine off ebay for about £30 each 2nd hand.

it may seem all this is alot of expense but you only buy it once and it will last years.