I want to run a few small devices from a small 12v SLA or LiPo battery. Battery will be at minimum 12v 6Ah (deep cycle of course), probably more like 10Ah if I go with my usual overkill MO. Doubling the capacity is nothing like doubling the cost, so the larger capacity is the most likely, even though I doubt this would be necessary unless I choose to use it as a full system UPS. I'll be using THIS 3A buck converter to provide 2 devices with 5v, totalling less than 1A max. This battery will be essentially a poor mans UPS. I may choose to use it on some other things too, including perhaps a USB fast (charge only) hub. I may buy a second buck converter specifically for the hub, should I even choose to run a hub, given the 3A limit of this one. Unlikely though, the only thing I would ever be likely to want the charge hub for is a couple of phones. I did consider just buying a 6v battery, but prices are similar to 12v and I've already ordered the buck converter so I figure why not? I may wish to also use a small 12v device occasionally, I can't even say what device that may be, let alone what it's power draw may be, I'm simply trying to leave myself the option. This may perhaps be the ability to use it as an actual UPS and providing 12v to the PC for a very short period, to allow proper shut down or avoid brown outs, I really haven't thought that through much as yet. This will be an internal component within my custom case, and will be mostly tasked to running battery backup to a couple of small displays and an LED clock, and potentially a RaspPI, Arduino, etc. So here's the question. There will exist within said case multiple household 240v switched sockets, from which I could run a 'proper' automotive style 240v-12v charger . I'm not sure as to the suitability of running such a charger in this way full time though. Although the mains power will occasionally be off, I'd guess that at least 95% or more of the time the power will be on and hence the battery charger constantly providing power to the battery (and hence any attached devices), and capable of providing much more than the actual current being used by devices. Although - the time the battery backup is needed may increase when I stop whining to my resident power Nazi that she has killed my 'always on' devices by turning stuff off at the wall at bedtime . To this end, I assume the trickle function of an automotive charger would be a good idea? Better than full power from say the PSU whenever it's on? Or am I incorrect? My assumption is that given batteries and devices only pull as much power as required, it shouldn't 'overfill' the battery at all or create any hazards? I also have already lying around a 240v-12v3A power brick from an old laptop. Since this will easily cope with any devices I am currently planning on using, and I have 240v available within the case, this would be perfect (and free !!) if I can simply connect the output wires directly to the battery, along with the device supply wires. Or would it be totally safe to maintain charge on said 12v6Ah battery via a 12v output from my HX1000 PSU, complete with any devices attached to the battery? Is there an intermediary circuit I should include for safety if this is a viable option?