Darren when you say auto charger do you mean battery charger, also how much for one without the auto charger?
http://www.ebay.co.uk/itm/12V-40V-10A-Pulse-Width-Modulator-PWM-DC-Motor-Speed-Control-Switch-Governor-/370827802182?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item56570f3646That's the one you want, £10 or so from china.Works perfectly.