UPS..has anyone built a home made one? If purchased what the best one for a 3ish hour power failure

Hello...
When you are doing it, look for older used pure sine wave ones...
i use an APC SMART UPS 1500va...you can get them for pretty cheap/for free at recycle places/the bay or craigslist
Mine is gutted and fed by two car sized Marine batteries in series to provide the 24 volts...
Can go a full day with that setup, and dont even recognize if power goes or comes

Positive side effect...they normally also surge protect

Yes...you are correct...the old ones need/should go, since they are most likely dead anyway when you get that baby from a recycler/the bay or such...
I went to my local tractor surprise and got me 2 marine batteries...of the 89 bucks version...not sure if the price is still same...
Since that bad boy can draw a lot of juice, please over provision the wiring and make sure the connections are safe and fused.
I also got inspired by this dude's youtube series:
and bumped it up with all the parts he put in...and finally crammed it into an old and free MAC Aluminum Tower (guuted the useless parts out and made some good use for it)...for the optic...and cooling for the transfomer
With the little it pulls, when started, you might end up with a hole weekend without knowing that power is out, and still havent reached 50% battery

I put on on my stove.

Aims 1250 Watt 12V Pure Sine Wave Inverter Charger PICOGLF12W12V120AL

Along with 100AH AGM Battery plus 4AWG Cables.

I posted results about month ago. It seems like I can get at least 8 hours. Little less on Full Fan Speed (I bet 1/2). Have yet to do cold weather test. 1st year for stove and no cold cold weather.

BE AWARE.
Should you have a house fire with a DIY UPS device or a modified UPS device installed, you will likely have your insurance claim denied, even if the device had nothing to do with the fire.

gutlo said:

BE AWARE.
Should you have a house fire with a DIY UPS device or a modified UPS device installed, you will likely have your insurance claim denied, even if the device had nothing to do with the fire.

Click to expand...

Which is one of the reasons I went Inverter with Automatic Transfer and Big Battery instead of modifying UPS. Also had it Professional Installed along with Permit. Had to provide permit to Insurance Co. Saving few bucks not worth it in the long run.

I will run 8 hour test with hourly voltage readings later on this fall or early Winter. Today over 60f, Amazing Weather. Got things Done (Oil Change on Rig). Anyone want 3 gallons of used oil? Darn that oil was black.

Does anyone know if this will invalidate a Harman warranty? I have the Absolute 63 which has a lot of electronic components.

https://www.butkus.org/ups/ups.htm

My batteries died in Feb.. they were from 2008 (according to the sticker on it). Replaced them for under $200.

Happy to hear...
Just double/tripple check and over provision your connections and dont run without fuse...even that 24 volt is still safe to the touch, it can, when shorted cause a great firework...would be happy to see a pic of it one day when in use...
Best is as already said, they compensate high and low voltages to prevetn sensitive electronic to fry or fans to blow slow...

I use this:
https://www.amazon.com/gp/product/B000Z80ICM/?tag=hearthamazon-20
It will power my 12-year-old P-61A for an hour before the fans begin to quit, apparently, my stove is old enough that the safety shutdown process isn't available, I also checked the current draw with a Kill A Watt and it's around 120 continuous.

Hello Bobcat...
This is only a modulated sine wave "backup" ups...how does your stove like that especially the blowers?
Either way its good to have surge protection, but this little bugger is most likely not best for electronics/motors...
Happy to hear that it works for you...
Due to its 450 Watt max and lack of active cooling, i would recommend to keep the off grid time as low as possible...

@kenora
Which model were you able to grab from your Kiji?
Is that the Canadian version of Craigslist?

Model?

Cool...happy to hear...thats a great device...
If you watched the Youtube, than you know...
Is it the fancy LED display one or one of the older like mine with just indicator dots?
Already an idea how to hide the little survival setup?
On 120 watts, you should be good for endless run, as far the batteries last...without any thermal runaway of the transformer...
But do yourself a favor and connect it to a computer and set the "turn off UPS at xyz % battery charge" setting to something over 50%
Lead Acid batteries hate to be discharged...i mean 50% is already huge discharge for a LeadAcid...
And you might want to check the floating voltage...that the APC shoots out...some devices tend to raise that over time/age of components...and we dont want to build a brown gas generator right next to a fire source, right?!
A few sources in case you are getting into that stuff
http://www.jjoseph.org/notes/apc_smartups_battery_float_voltage
https://www.zombiehunters.org/forum/viewtopic.php?t=109171

Is there such a thing like UPS envy? smile
Hmmm...good old 230 Volt times...really miss real juice out of the wall

Darkwing said:

Hello Bobcat...
This is only a modulated sine wave "backup" ups...how does your stove like that especially the blowers?
Either way its good to have surge protection, but this little bugger is most likely not best for electronics/motors...
Happy to hear that it works for you...
Due to its 450 Watt max and lack of active cooling, i would recommend to keep the off grid time as low as possible...

Click to expand...

It's what Harmon recommends, the fans work just as they are supposed too, I can attest to it powering my stove for exactly an hour as the last time we lost power it lasted that long, of course, it would all depend on the outside temp and how much the demand was, if I remember correctly it was around 20 degrees, so I would say if it was much colder it wouldn't have lasted that long. I originally purchased it because I assumed my stove would safely shut down but its older than the firmware on newer models.

Thx for sharing...absolutely love that setup...great thick cables, save mounting etc...
And yes...this loss/extra usage is the price of luxury...
Just check for floating valtage settings, otherwise batteries could have a pretty short life...
Two thumbs UP