batchman
Burning Hunk
Except when electronics run at their capacity they get hot, and if not well designed they get hot enough to damage themselves - especially if run at capacity for a long time.
HTH,
- Jeff
Homemade Battery Backup
- Thread starter TimfromMA
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Except when electronics run at their capacity they get hot, and if not well designed they get hot enough to damage themselves - especially if run at capacity for a long time.
HTH,
- Jeff
I've only had 1 power failure lasting more than an hour in the 6 years I've owned the house and that one ocurred in the late summer.
Once per year, I like to pull the plug on the APC and let it run on battery for a few hours just to make sure everything is working. Once done, I will disconnect the batteries from the APC and throw them on a proper marine battery charger.
I keep the APC connected to the batteries all summer to trickle charge them.
what a killer idea using a UPS for a PC as a 12v to 120v inverter. passed on several large 1,000 watt UPS at garage sales that had dead batteries for less than $20 .. that dead UPS has a 1,000 watt sine wave inverter inside.
400 watt UPS to my PC has an external 12v PB battery much larger than stock.
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mass_burner
Minister of Fire
![[Hearth.com] Homemade Battery Backup](https://www.hearth.com/talk/data/attachments/129/129569-288707e1af651309f4734e5bc6353365.jpg?hash=LN9A1KBQ_U "[Hearth.com] Homemade Battery Backup")
![[Hearth.com] Homemade Battery Backup](https://www.hearth.com/talk/data/attachments/129/129570-f475efd2da98897f61c81ede3d9fbd6d.jpg?hash=TWTqAk-JEr "[Hearth.com] Homemade Battery Backup")
Batchman is correct here, maintaining the float charge will not be an issue for the APC, however recharging a depleted jar wil max out the charging sys,
Now triple or quadrupel that with the added Ah capacity you've created and voila, there will be a failure.
I would look into an added charging sys for this.
Great idea though, and looks to be fairly well done!
SmokeEater
Feeling the Heat
This isn't a battery backup, but I thought an interesting photo of a little hydro plant that my brother and I built.
Attachments
![[Hearth.com] Homemade Battery Backup](/talk/data/attachments/129/129614-be803c684a32a0744b29697a29d45a87.jpg?hash=br-HeYb6YM)
Nice install! What incentives/subsidies does Massachusetts offer for solar installs? Is that grid-tied, or a standalone backup?
KodiakII
Minister of Fire
I am surprised that UPS runs your stove without damaging it or at least making your motors hum. It (that particular UPS) is a "stepped approximation to a sine wave" not a pure sine wave model. Being a St. Croix owner for a number of years I was informed when I bought mine that anything other than pure sine wave would damage the stove.
It runs great. You would never know it's running on an APC.
Before the APC I tried a stove sentry (not the pure sine wave model) and the stove did not like it AT ALL. I was going to upgrade to the pure sine wave stove entry when I got the APC idea. I did alot of experimentation in the middle of my living room floor before moving it downstairs and running an electrical line up inside the wall.
![[Hearth.com] Homemade Battery Backup](https://www.hearth.com/talk/data/attachments/129/129619-0ccaf66edc9461e4d3cd06b170b32ebe.jpg?hash=9Ry8YppYhj "[Hearth.com] Homemade Battery Backup")
Before the APC I tried a stove sentry (not the pure sine wave model) and the stove did not like it AT ALL. I was going to upgrade to the pure sine wave stove entry when I got the APC idea. I did alot of experimentation in the middle of my living room floor before moving it downstairs and running an electrical line up inside the wall.
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Very nice. So during a long outage, do you think you would average using about 1200 Watts (while it's recharging the batteries) throughout the day and maybe 600 Watts through the night? Or am I being too optimistic on the battery usage?
Technically no. I must physically flip the switch from grid to inverter. But it is a battery bank connected to an inverter. Just happens to be charged by solar panels.
Off grid. I believe it was a 20% rebate federal at the time. Do not recall the state incentives.
SmokeEater
Feeling the Heat
My thoughts some time ago were similar to your setup. My electric energy supplier has a day/night rate that differs. At one time the night rate was about half that of the day rate. It would make sense to charge batteries during the night and run the home on the bank during the high rate times. My usage durilng the whole day was about 30 kWhrs so I calculated that if I could store about 60 kWhrs of energy that I would not only cut my energy use in about half, but would have a 2 day backup in case of an outage without the use of a noisy generator. Sure would work and the inverters I chose were two pure sine wave from Xantrex at 120 volt each. I could connect them to my panel through a switch and would have my 2 pole single phase 240 v supply. The batteries i chose were the 2 volt per cell industrial lead acid connected up for a 24 or 48 volt input. Higher if I could to reduce wire size. Expensive though.
In the interest of not totally hijacking this thread, sorry OP, I wil provide the calculation to determine how much runtime you can get from a amp/ hr battery rating vs load.
In my case the XXV draws 120 watts max (no igniter). This is all fans and auger moter running.
So first thing to calculate is the amperage draw for 120 watts on a nominal line voltage of 120v.
Amps=watts/volts. So the XXV is drawing 1 amp.
Next determine the amperage draw when the source voltage differs because the inverter must step up the battery voltage to 120v. The conversion is Batt Amps Draw = Amp draw @ line voltage * ( line voltage/ batt voltage) .
So the in the case of a 1 amp source draw the inverter must pull 5 amps from my 24 bank to supply 120 volts at 1 amp.
To calcuate total run hours ( complete discharge of the bank) use the equation RunHours=BattAmpHours/DrawAmps.
So 740 amp/hrs / Amp draw = 148 run hours. I would never take the bank down that far. Maybe 50% depth of discharge. So 148 * .5 = 74 hours.
Now the experienced may note that there are many other variables that come into play here when we start talking discharge rates. These Maths do not take into account battery discharge for different C rates (amp draw) or battery temperature. But for anything under the C20 rate they provide conservative values on quality deep cycle batteries.
SmokeEater
Feeling the Heat
I can't give you a price that's accurate. The dam was existing but we put a lot of time and material into it. It was an abandonded power plant and the turbine you see was made by BLH of the famed railroad engines. It weighs about 20 tons and is rated at 750 kw. There is another newer turbine generator mounted in a vertical position that we bought and installed. The purchase price alone was about $485,000. Still had to be installed. That machine was installed in 1984 and is a 600 kw Francis unit with a 600 kw direct drive Westinghouse generator that you can see the top of in the background inside the red steel railing. All together the place is on the market for about $2M. It generates between 5 and 6m kWhrs/year.
Now i'm paranoid that my ups is too close to my stove. i actually have it sitting on the left... you can almost see the corner of it in my avatar, that black line is the start of it.
it's been there 2 years now, now hydrogen bomb. should i move it? it's a cyberpower, unmodified.
it's been there 2 years now, now hydrogen bomb. should i move it? it's a cyberpower, unmodified.
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