Battery tenders and trickle chargers

I have been trying to get some information on battery tenders and trickle chargers. Not having much luck. Like a lot og people I have quite a few cordless tools like drills, skill saw, reciprocating saw, weed whip etc, I would like to find a tender that you can plug several of these things into, I haven't found one yet, anybody able to give me a website or anything?

Here is a four battery charger. It is only designed for 12 volt batteries though- https://www.amazon.com/Battery-Tender-022-0148-DL-WH-12-Volt-Management/dp/B000CIPHUI