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Re: combining AC backup devices

Post by kw123 » Thu Sep 20, 2018 4:26 pm

power backup is ready for the next storm.. should give > 2 hours standby time in case of power loss
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Re: combining AC backup devices

Post by kw123 » Sat Sep 15, 2018 11:33 am

That’s why we don’t have a basement. [emoji16]

But we also had a 3 day power outage in the middle of dallas in winter.

Ice storm knock over trees and power lines...

E Crew can said first trees need to be cleared
Wait one day
Next crew clear out trees
Wait one day
E crew can back and said wrong cable
Wait one day
E crew came back and fixed

Now all trees next to the power lines are cut short.

Any I now have > 1 hour of standby power for the core systems:
Apc1500 w apc extra battery for Mac Pro
Apc 1500 for att finer Modem and att router and Uga gateway
Apc 1500 for ubnt 24 Port switch and some smaller stuff ip-phone gw...
And most local switch ( in the other rooms) and WiFi ap has a smaller apc



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Re: combining AC backup devices

Post by DaveL17 » Fri Sep 14, 2018 6:24 pm

We modified our UPSes with a 15kW natural gas generator. Not really that cost effective from a UPS standpoint, but they only need to last about 20 seconds. :D

Seriously though, we bought it after losing power for 3 or so days during the winter. The inside of the house got down to about 40°F and our basement became our indoor swimming pool (from ground water seepage). If I can manage it, every house I ever own will have a backup generator.

Re: combining AC backup devices

Post by roussell » Fri Sep 14, 2018 4:11 pm

I did the car battery mod several years ago, used a sealed lead acid deep cycle inside a battery box that was vented outside via a 1/2” tube. The box was a leftover from my drag racing days. The ups worked well with crazy up-times. I’ve got a few 2200VA rack mounts that all need new batteries so I’ve thought about doing it again, if time ever permits...

Terry


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Re: combining AC backup devices

Post by ELWOOD » Fri Sep 14, 2018 8:45 am

Have a few UPS that used 12 volt 7 ah batteries, when it came time to replace the batteries I used 12 volt 12 ah battery. The bigger battery does not fit
in the original UPS box, just have the batteries next to the UPS. This defiantly gives longer stand by time. Have been tempted to try the same thing using
a car or even larger truck battery. This might require a separate trickle charger to keep the big battery at full charge. Also have to keep in mind with a
car battery there might be out gassing from the battery that would cause trouble in a confined area.

Elwood

Re: combining AC backup devices

Post by lanbrown » Thu Sep 13, 2018 9:55 pm

There are also PDU's that offer dual input and they will switch over to the other input when power is lost. This would accomplish your original goal.

Re: combining AC backup devices

Post by kw123 » Thu Sep 13, 2018 9:25 pm

I have spend some time on it .. and it does not work with the regular APC devices ~<$200.. With the $500 it would work.

The cheaper ones do not deliver a proper sin wave output and the down stream APC interprets this as no power.

The more expensive ones " pure sin wave output" SHOULD work.

Putting them in parallel should NOT be tried as the 2 APC's will be out of sync and will destroy each other.

Final solution: buy the APC 1500PRO (BR1500G) $180 and the Battery extension BR24BPG $150. That extends the capacity by a factor of 3.
For my mac pro 2012 the single one gives 20 minutes and adding the battery extender gives ~1 hour total power

Karl

Re: combining AC backup devices

Post by Turribeach » Tue Sep 11, 2018 6:42 am

APC doesn't even recommend connecting them in parallel either, but I wonder how much science is in that statement.

Re: combining AC backup devices

Post by Turribeach » Tue Sep 11, 2018 6:38 am

Also this article from APC.

Re: combining AC backup devices

Post by Turribeach » Tue Sep 11, 2018 6:35 am

mundmc wrote:
I know this is probably really dumb, but I’m gonna ask it:
Why not just plug the three UPS’s into each other in series?


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See this article, connecting UPS' in series is not a good idea. I think you should connect all 3 UPS' in parallel or split the devices connected to the UPS to spread the load.

Re: combining AC backup devices

Post by mundmc » Tue Sep 11, 2018 5:45 am

DIY line voltage relays for fun! You’re too much

Re: combining AC backup devices

Post by kw123 » Tue Sep 11, 2018 5:00 am

Where is the fun in that? Yes you are right

Some advantage is that you have one that is not used Might live longer.


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Re: combining AC backup devices

Post by mundmc » Mon Sep 10, 2018 10:13 pm

I know this is probably really dumb, but I’m gonna ask it:
Why not just plug the three UPS’s into each other in series?


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Re: combining AC backup devices

Post by kw123 » Sat Sep 08, 2018 10:05 pm

here the finished box.

You MUST pay attention that Neutral goes to Neutral (white) and Line goes to Line (black).
This is why the black and white wire cross (neutral is the one with the longer slid 3rd pic ... in the US).

Karl
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Re: combining AC backup devices

Post by kw123 » Fri Sep 07, 2018 8:45 pm

I use this one:
https://www.amazon.com/gp/product/B07CT ... UTF8&psc=1 ~$24

12 Amp. is enough for my devices.

make sure it has : Double-Pole / Double-Throw Relay with 120VAC coil,

Karl

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