Originally Posted by
PatrikD
BertL: Are the losses really that huge with UPS and Tunze DC pump compared to Tunze DC pump direct on batteri? In an other thread recently it's stated that the efficiency of an UPS typically is 90-95%. Not that huge! I'm a little confused by what I read about runtimes of UPS's. I've ordered a Cyberpower pr1500LCD and with 34 Ah it should be able to power the base unit , the router and a Tunze streamer for many hours. At least that is what I'm hoping.
I won't debate the point, but will defer to mathematicians and engineers out here, as it's been too long since my high school physics and college math classes. 
It's a physics thing that there will be energy loss when converting AC to be stored in a battery, then when it's converted back to DC for use -- rather than if one could store the energy directly in the battery and let DC devices use it without a second conversion. As to if the loss is more than one can accept, we each have to make that decision. You'll find people that are very happy using their DIY "car battery setups" as part of their power backup solutions. That wasn't for me, hence why I went with the largest off-the-shelf UPS I could fit within my setup.
All that being said, while my tank was cycling, the physical test I tried with a Cyberpower CP1500PFCLCD connected to a EB4 with a single Tunze 6105 via VDM and my Apex, ran in excess of 20 hours when I shut down the test as it had proven what I was after at that point. Sorry, but I forget what the UPS said it still had as power remaining when I pulled the plug on my test the next morning, but in my head to this day, the solution provided "24+ hours" of flow and my ability to communicate with my Apex during an elongated power outage. (FWIW, my Apex system was much larger so had a little more draw than just the single EB4 and a VDM, with more than a dozen modules including 3 more EB8s, and I had my programming set that it turned ancillary devices like my AFS off during a power failure with exception of that single Turbelle and it's VDM to preserve as much power as possible. My Apex was hardwired back to my office where my router is powered by an independent UPS.)
That solution would have worked just fine, but as stated in previous posts, after that test, I redid things to give me, IMHO, even more flexibility with the CP1500 UPS typically powering only my Apex and it's modules during a power-outage. (For context, I was having occasional firmware problems with the Apex freezing and loss of communication at that point-in-time even when there was power, so "what happens if I loose my Apex itself when I'm not home" became as an important a consideration for me, as what to do if all the power went out. Fortunately today, Neptune has resolved those firmware lock-up and inability to auto-reboot problems that some of us were having, so it's not as big of a consideration with the Apex now being more bullet-proof once again.) Anyway, I incrementally installed a MP40 with dedicated battery backup, and it was that flow I had my tank depend upon during a power-outage as Fallback statements and profiles allowed me to put the MP40 into a slower and more appropriate tank flow pattern for my situation (that would go into effect even if the MP40 lost communication with the Apex -- which isn't possible with Turbelle's). Since I would then have well-more-than-a-day access to my Apex with that big UPS powering only it and the Aquabus, I could in theory manually turn on one of my 6105s that was plugged into the EB4 also powered by the CP1500 if I needed to for some reason. I spent a lot of time thinking through various scenarios and placing dual devices on separate EBs, circuits, etc for maximum flexibility. Fortunately, I never had to use any of it in a real power outage situation of any significance. My choices could be debated, I know. There are many alternatives with what seems like a never-ending set of pros and cons.
Good luck with your project.
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