Noco Genius 1 and it does 12 and 6 volt. All the clips and fittings are quality and large wire diameter. The charger is a plug so super lightweight. Wires are long enough to use about 10 foot from a socket. I never use my optimate now as these have become much better in use.
50 quid but you will not need another one. The boy in the garage has one running 24 hours a day for many years charging a large car battery which is working his diesel powered room heater that is usually in motorhomes. It has been well tested in the garage.
Ideal for small batteries as it cannot overcharge and 1 amp is maximum anyway.
Check the details on ebay or amazon.
2 optimates i have, the wires fall apart where they leave the unit after a few years use. Good chargers but the opposition just got better.
There are 2 on ebay 45 pounds at the moment.
Amazon, they are 39 pounds.
I also have a Noco car starter pack that will start any car with a flat battery and of course, any electric start bike. Its a Lithium pack and can be charged in the car or from any usb socket. Also a torch and a phone charger so i keep that in the boot for emergency but i do use it to start my R111 when its cold as the small battery these bikes have are just not up to turning a 2.3 litre engine. These starter packs can be one hundred pounds but if, like me you have an auto transmission, it might be what you need if out and the battery went flat.