Lidls currently have smart chargers in at thirteen quid or so. They have several modes and are suitable for bikes as well as cars. There is a display for voltage as well as state of charge of the battery in a bar display. I've been using a more basic Lidls smart charger (no display) for some years with no problems.
I have one and using to float charge GSXR battery. It seems well build and does not overcharge and has different charging current control curves. The "Mode" button failed, but was cheap fix.
