Bought a Noco Genius 10 from Halfords in the UK, specifically because it could charge 6V batteries. Couldn't get it to charge anything, neither 12V or 6V. When switched on, it cycles through the charging stages until it goes green in about 15 minutes, as if it's charged the battery but clearly hasn't. Took it back to Halfords who replaced it - new unit does exactly the same. Fortunately my trust old Ctek unit comes to the rescue and charges the 12V batteries the Noco can't. Still can't charge 6V batteries. Owned 2 Noco chargers and never managed to charge one 12V battery after umpteen attempts between them. Avoid like the plague.