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Battery powered PC's?

PostPosted: Tue Aug 14, 2012 3:44 pm
by zzsstt
I've just connected up a new UPS, and this one has an LCD screen that tells me what it's doing. Apparently, under the minimal loading that my "24/7" nettop provides (which the UPS tells me is 73W including USB disks, router, wireless AP and satellite modem etc.) the UPS is running at 93% efficiency. Which is OK, except that it occurs to me that inside the UPS is a battery charger, inverter and various switching circuits, and inside (actually outside) the nettop is a power supply that takes 240VAC and converts it to the various low voltages that the computer actually uses.

Is this the optimum way of doing this? Perhaps a 12VDC ATX power supply running directly from a battery might be more efficient? Especially in a PV-battery-inverter scenario?

Edit:
I realise this is chasing "single watt" savings and therefore not financially viable. It's just for fun!

Re: Battery powered PC's?

PostPosted: Tue Aug 14, 2012 6:15 pm
by Privatteer
Unless you have a double conversion UPS most don't use the inverter continually. They run the AC through a buck/boost controller to keep the AC in limits and output it to the device.
The inverter only kicks in on AC loss.

You can get PC's that run on 12v. ie
http://www.auspcmarket.com.au/info/SY-A1100/1720/

Re: Battery powered PC's?

PostPosted: Tue Aug 14, 2012 6:52 pm
by zzsstt
In this case I have just replaced an online (double conversion) UPS with an offline one, only because the online was too noisy - it was OK on a concrete floor but it buzzed and my suspended timber floor acted like a soundbox!

I was really thinking about off-grid use, where there seems to be a lot of 12v-240v-12v happening, though my nettop in fact uses 19VDC. I used to have a 12VDC ATX power supply (to run a PC in a car), but I have no idea how efficient it was.

Re: Battery powered PC's?

PostPosted: Tue Aug 14, 2012 8:54 pm
by Tracker
zzsstt wrote:I've just connected up a new UPS,... the UPS is running at 93% efficiency. Which is OK, except that it occurs to me that inside the UPS is a battery charger,.....Is this the optimum way of doing this? Perhaps a 12VDC ATX power supply running directly from a battery might be more efficient? ....this is chasing "single watt" savings and therefore not financially viable. It's just for fun!
.
My office needs cooling in summer and a bit of heating in winter, because of the heat generated from the various computers and especially the "Cat Attracting" UPS's.
It is a marvel to see the cat balanced on top of the small UPS.. I am confident that my UPS's are not of the best kind.. :oops: ...(well, they did come from ALDI..)

With all that heat, there is NO WAY that they are efficient.. I too am looking for that elusive alternative.. and have been thinking of a special PV system, made from old panels, charging batteries that power one of those UPS's... My 24/7 room heater would be GONE.. and the cat will be really P'eed off..
..
.

Re: Battery powered PC's?

PostPosted: Wed Aug 15, 2012 12:40 am
by Privatteer
The setup is ugly as hell currently due to lack of time. But what you see is a 48v battery system running a continuous ~200w load. Solar is 500w, 100v.
Batteries are held between 54 and 56v during the day depending on what point of the charge cycle they are in.
At night the voltage drops to 52v and the AC to DC power supply kicks in.

Eventually I have a controller that when the array volts drops below zero it will supply a higher AC to DC volts but I have had higher priorities and the shed is fracking cold at night. (The batteries are already stuffed and about 8years old)

The small breaker that is off is actually a micro double pole DC for the array. I was fixing the solar array tilt at the time. The ones that are currently exposed are for the battery/48v.
Inverter has had RCD protection added.

Compared to the MGE UPS that used to provide backup I am saving 60w just from the equipment change before the solar takes the load.

DSC00486a.jpg

Re: Battery powered PC's?

PostPosted: Tue Aug 16, 2016 1:11 pm
by Jimbo007
Jaycar sell a 12volt ATX power supply. I can't find it in their catalogue but have seen them on the shelf.