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Batteries are Cheap, Backup power is expensive

Dear Audiophiles,

To make a long story short I need to make sure my Internet devices stay on even when power is down for 24 hours, which on the South Carolina coast is realistic. 

I have an APC UPS 600VA which I though would do the job but it actually lasts less than 2 hours.  So I have been crunching the numbers and have really been surprised at how expensive an APC UPS is per minute of run time vs. modern battery based generators and DIY solutions. 

An APC UPS can be anywhere from $1.50 to $2.50 / minute of run time while an EcoFlow Delta for instance is around $0.50 to $0.75 / minute.  Not only is the EcoFlow cheaper but just has ten times better run times.  A single 1 kWh unit will keep my data closet running close to a full 24 hours.  I have too many devices in there which consume ~ 50 watts.  50 x 24 = 1,200 

I did in fact purchase a Delta 2 with back up battery for other reasons than the data closet, but when doing the research I also investigated DIY backup solutions and came across the idea of using a Renogy inverter/battery charger + 2x 12V LiFePO4 batteries.  It’s even cheaper than the Ecoflow but requires much more effort to set up.    I’ll do a full write-up on that soon. 

What have you done to back up your home devices?  

erik_squires

Showing 2 responses by phildebrandt

phildebrandt
6 posts
 

One point that hasn’t been addressed is that makes a UPS more expensive than a stand-alone battery/inverter set up is that the UPS is able to take over within Miliseconds, allowing most electronics to continue running seamlessly. That’s actually not trivial to do. 
 

If you really just want cheap battery backup nothing beats lead acid - parallel a dozen car batteries and hook up a 2kW or 4kW 12V inverter.  I did the math recently and in terms of energy-per-dollar lead acid is still way ahead. And they can easily be maintained with a cheap trickle charger. 
 

That said, we have a system with solar (roof and ground based installation for around 20kW total) and several Tesla Powerwall batteries - with us enough to keep us going indefinitely without grid power. I also have an ancient trailer-mounted 60kW diesel generator (enough for a small city block) for long periods without sunshine. The diesel in my fuel trailer will last a good while with a good fuel stabilizer. And I use it occasionally for vehicles so I cycle through it. (The generator eats about 35-40 gal/24 hrs, so with any 400 gals on hand we’ll be ok for a while)

 Now, to tie it back to Audio, I don’t hear a difference between grid power and solar/battery power.  I do have isolation transformers for my system so that might help.  When the generator is running I don’t hear anything but generator noise though …

phildebrandt
6 posts
 

Great point @erik_squires ! I hadn’t thought about that limitation when I did the calculation. That was for an old EV Restauration project (a 1910 Baker Electric) and I ended up with a stack of golf cart batteries that nicely took the place of the original Edison batteries.  I would need to look at it again. 
 

@tomrk The point about dirty generator power is very real. I think going forward I would only use an inverter generator, and I’m looking into running my generator output through one of my solar inverters (convert to 480 V DC and then let the inverter create clean 120/240V AC)

Now, inverters pollute the power with their switching frequency, typically just outside the “audible range”, at 25kHz give or take. That’s why I mentioned that I have isolation transformers to deal with that before it reaches my Audio gear

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