The short story:

I'd like to power my SNES with a USB battery. I believe this could be possible because:

SNES draws 9v 1.3a (11.7 watts max)

USB battery outputs 5v 2.4a (12 watts max)

this adapter transforms USB 5v to 9v with no loss of amps/overall-wattage:

http://www.ebay.co.uk/itm/112143928032

So, in theory, this should allow me to power a SNES with a USB battery charger. What do you guys think?

I'm no electrician, but the adapter I've listed above says it will output 9v and 1.5a (max). Now will that 1.5a overpower the SNES (which takes 1.3a)? Also, the listing claims a maximum of 15w, but that is impossible by my maths, as you cannot turn a 12w USB power source into a 15w output...

the long story. why do this?:

Because I live in Thailand (I own a video-game animation outsourcing company in Bangkok). Now the power in Thailand is nearly always un-earthed, and can be quite hazardous to electronics, in particular 25 year old electronics like the SNES.

Oh, and I think it'd be cool to run a SNES from a battery. I already run my framemeister from a battery (cleans up some of the swirling noise patterns that can occasionally be seen in games like SMW in the underwater/cave sections for example).

I didn't know such a thing existed, but lossless voltage up-conversion sounds misleading. Also adapter says INPUT 5 V * MAX 2.1 A which equals 10.5 W, devices need to more or less match voltage but they cannot exceed the amperage and wattage of power supplies/adapters. Also the original SNES power brick will probably put out 11V, or at least higher voltage than stated, whereas battery powered things barely reach their stated voltage. It could work depending on how much power the SNES really needs.

Why not just use a regular uninterruptible power supply, they generally include protection against voltage spikes and the like.

@eurobum: Yes it does sound dubious that the transformer would be 100% lossless, I'm sure it'll generate some heat as all transformers are somewhat lossy.

Regarding the SNES power brick. I think the opposite may be true if the SNES 10watt figure is accurate? Unless you mean it'll pull higher volts and accommodate with lower amps?

UPSs are great, but they don't protect against power systems that are not grounded. For example my laptop buzzes to the touch (as you slide a finger across the body). Not something I want to submit my 1CHIP SFC to! :D

And you're right, I hadn't noticed that the adapter takes 2.1a. Although there are similar products on amazon that take higher. There's even one that takes 2x USB inputs to supply 20 watts.

@floydeo: yes, I want to take no risks with this little project. Regarding polarity, there are various adapters that will flip it to centre positive which may work?

@floydeo: Thanks floydeo. These converters seem to come in two types, 9v or 12v. So the SNES can take amps as low as .850 ?

@floydeo: thanks! I won't be taking any risks with the SNES. I'd want to see the output measuring exactly what the traditional wall PSU can maintain before I'd even consider it.

On a similar note, check out this:
https://tinyurl.com/k9ypbvu

Which makes me wonder how long an unplugged 400w UPS would drive a SNES?

@floydeo: looks intersting! I could get a cheap junker SNES off ebay and do some testing. It appears the SNES pulls around 10v .850a, and it's quite versatile as I have a 9v 1.3a power brick for mine. Apparently higher amps don't matter (apart from the ineficiency of unused higher amps) as the SNES will simply pull what it needs.

If I'm right.... the only issue may be, as Eurobum says, that the SNES pulls 11volts from my 9v supply. And that the USB transformer won't be capable of supplying this higher voltage, and/or it won't be regulated.

@coolhand1979: What I mean by that is that voltage of power supplies can vary significantly (though there is a tolerance spec something like plus minus 5 or 10%), under load (high amperage) voltage tends to fall (droop). This is probably even more pronounced with batteries, which tend to age as their max Amperage decreases over time.

Computer circuits also age, and while they basically always need an exact amount of current (amperage), the voltage required to generate that current creeps up over time. This is just for understanding.

The other problem mentioned in the reddit topic @floydeo posted, is that the SNES connector may have reversed polarity (negative middle pin) compared to industry standards.

For PCs the rule of thumb is the powersupplies should have twice the Wmax rating of your PC components. So yeah you should try to match or exceed voltage (~+1V) but generally aim for higher amp rating for battery and power supply.

@eurobum:the level of knowledge here is extremely high. Thanks for the info eurobum and floydeo.

I assume the increased voltage requirement, due to ageing circuits, is due to increased resistance over time? I'm sure there will be hardware replacements in the future, that use a FPGA, like the analogue NT mini. Carts are already getting extremely well-made and robust clones (the morality of which I'll save for another thread!)

Regarding the polarity of the middle pin, I am currently using an adapter cable that switches my SFC pin to match my US SNES. So I have one PSU for both consoles. It works flawlessly, and I hope I can use a similar adapter when it comes to trying out my USB battery tests.

Fortunately the battery I'll be using will supply, when using the 9v USB transformer, comfortably above 850ma. I just can't be certain if it can "push" above 9v. All these adapters appear to come in 9v or 12v variants, whereas a 10v would be ideal for this test.

You can run a SNES or sfc off any 5v usb 1a charger with just a couple of simple mods. The SNES/sfc maxes out at 5v 1.5a internally (has a 1.5a super fast acting fuse). It uses a 7805 voltage regulator. If you remove the regulator and jump the in and out points you can feed the input source 5v and the system will work. The SNES/sfc uses the 10v to power the sound amp but it will work off 5v as well. You can then desolder and remove the power jack and replace it with a USB port.(will have to carefully cut it out since it's molded into the plastic av plate) if interested I can post pictures of my SNES that ive modded for component video, digital sound and USB power. I can also take a video of it being powered by a selection of usb chargers and batteries.

@coolhand1979: As an aside, you can and should look into ground fault circuit interrupter (GFCI) outlets. They are specifically allowed for use in ungrounded scenarios as they contain a little mini-breaker that protects both the GFCI outlet itself and any other outlets further downstream. Combining a GFCI with a UPS should clear up any power quality issues, at least, as much as possible without doing a full grounded rewire job.

@freedom4556: Thank you man. I actually just setup a video-game development business here in Thailand. Myself (ex Crytek) and a programmer from CDPR. We're gonna add the GFCI you recommended inline with our UPSs. Cheers!