I'm currently using a cheap Warrior brand battery tender because it was given to me and works fine. I believe most guys on here may be using an Optimate charger / tender if i remember correctly from back when i asked. The Optimate 4 is what i'll probably pick up when this one gives up .
As for a USB socket to charge any devices on the fly (if that's what you meant), i use a simple one like pictured below ran straight back to the battery as it has an in line fuse......
However, if you are intending on hooking up several electrical gadgets all independently running at the same time, it can get a bit busy back at the battery end. You may then want to consider one of these options found at Eastern Beaver to wire the USB socket up to, eliminating the need for the in line fuse......
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