Then I had a thought (Woa!). The Towsure VSR has an adjuster so you can change the voltage threshold for the charging circuit to the leisure battery to be enabled. Woud I be right in saying that - provided the threshold can be moved down low enough, you could use the device to only allow currnt to pass if voltage is above - say - 10v. The obvious thing is take it off and try it but I'd rather not fiddle with a device that is busy and working well in my car just so I can try weird experiments. Anyone able to advise?
Thanks chums
