[SOLVED] How to 'Combine' or Maximize UPS Battery Power? (Noob)

[Anonymous user]

I have very limited experience with UPS' so I apologize for what may be considered a seemingly dumb question. I currently have an ATS connected to two different sources (both different utility circuits) so this is where I'm coming from.

I'm getting ready to pick up two APC SUA1500RM2U's for a small project at home. I know that daisy chaining is not supported and in general not a smart thing to do so I won't be going down that route. But I'm trying to figure out the best way to utilize & maximize the battery life out of both UPS'.
Taking what little I know about ATS', I planned on plugging the ATS into each of the UPS' then plugging a few devices into the ATS. It would look something like this

!http://juli.us/support/forums/UPS.png!

And from where I'm standing...
? If both utility sources connected to ATS #1 go out...
? ...Then ATS #2 kicks in drawing power from UPS1...
? ...And when UPS #1 goes out ATS #2 switches to UPS #2 until it dies or power is restored.

I am aware & recognize this may not be ideal, but since I don't have access to 20+Amp outlets or a generator, I don't know what else to do. Please help me to understand why this either won't work or why its not a good idea.

What's the best way to setup the equipment so I can use one UPS then the other? OR,
How can I set it up so that power is drawn from both UPS' at the same time?

Many thanks!

Message was edited by: Phylum

Message was edited by: Phylum

Message was edited by: Phylum

[BillP]

hello,

i have never seen a set up like this to be honest with two ATS units. generally I'd see utility #1 and #2 feeding separate UPSs directly and then connect one of the ATS inputs to each UPS.

a few concerns that I have (assuming these are APC Rack Mount ATS units):

1.) I would not be surprised if ATS #2 briefly switches sources when UPS #1 and UPS #2 switch to battery due to output distortions on the UPS.

2.) I don't think it is a good idea to have two ATSs in general. I would not recommend connecting an ATS directly to utility power or direct to a generator. It should be connected to a UPS. ATS #1 is going to be prone to power blips and other issues and if both sources have an issue, the ATS will turn off and ultimately you'd run both UPSs down unnecessarily

3.) If I were helping you with this, I'd eliminate ATS #1 from the set up. It will cost less and make more sense and avoid unnecessary situations which could be other points of failure.

I'd also ask that you review knowledge base FA156201 @ http://www.apc.com/site/support/index.cfm/faq/

If you set it up the way that I suggest, if utility 1 goes down, the UPS #1 (or whatever the preferred or current source is) will go to battery and the ATS will not see an issue until the UPS runs out of battery power, then it will switch to the secondary source and will deplete that UPS's battery which gives you double the runtime (sort of) and will hopefully be enough time for utility to come back online.

I hope this helps you out.

[Anonymous user]

Thanks for taking the time to reply - I greatly appreciate it!

I understand your points and value your comments. I can pick up a few smaller UPS units to help protect against surges and brownouts and place them between the ATS and Utilities 1 & 2.

I only have one concern with your recommended setup: the ATS will draw from the backup battery if one source goes out. Consider the following example:
1. ) I plug UPS1 into Utility 1 and UPS2 into Utility 2
2. ) Utility 1 goes out
3.) ATS does not switch over to Utility 2 because its still being powered by the battery backup.
a.) So even though there's still one utility power source, we're not leveraging it.
4.) Meanwhile Utility 2 is still up & running but I'm draining the battery of UPS1 unnecessarily.
(The same would also be true if Utility 2 went out: the ATS would be using battery power on UPS2)


My objective is to use utility power as long as possible, and only use UPS as a last resort when both utility sources are out:
1.) Utility 1 goes out, then everything should draw from Utility 2: UPS', systems, networking gear etc
a.) This way the UPS' are still being charged by Utility 2 for as long as possible!
2.) Utility 2 then goes out, everything should draw from one of the UPS' (I don't care which is 'first' but for the sake of the example, lets just say UPS1)
3.) UPS1 then supplies power until it dies
4.) When UPS1 dies then UPS2 supplies power until it dies
Make sense?

Other than implementing ATS' I don't know how to accomplish this.

At first I was hoping for something like a dual-input Y-power cable, sort of like this...
!http://di1.shopping.com/images/pi/11/f6/36/21700230-200x200-0-0.jpg?p=p12.abeea8e8a88e0e54bbcc&a=2&c...!
Except that it would need to be 2 males to 1 female of course. Sure I could get a couple of female to male & male to female adapters but I don't like that.

Message was edited by: Phylum

[BillP]

i understand what you mean. i can just tell you that we don't design the ATS to be directly connected to a generator or utility power. are utility #1 and #2 two separate circuits in a household?

[Anonymous user]

I'll pick up a pair of UPS' this weekend to make sure the ATS gets good power.

And yes, this is a household. From time to time (albeit rare) Utility 1 goes out but Utility 2 is still running fine. When this first happened I thought it was a fuse but when I checked the fuse it was fine. This prompted me to check outside where I noticed all the households were without power.

[BillP]

interesting. well now i understand your scenario a little bit better now.

[Anonymous user]

(You should bear in mind that both configurations I discuss below are not recommended / supported by APC, but they've worked well for me - your mileage may vary.)

At a number of colocation sites I have 2 power drops into each cabinet. They go to different distribution panels (circuit breakers) and different generators along different conduit routes - as diverse as it is possible to be. At one of those colocation sites, the facility equipment is known to be problematic, and they've had generator / UPS / wiring failures quite a few times. (None of that stuff is APC. I'd say what it was, except that the brands wouldn't mean anything to you and would let people figure out what colocation site I'm talking about.)

I've had APC ATS units (the original SU042 ones) in each cabinet (without UPS's) for over 10 years and have never lost power to my equipment, except for post-9/11 when the generators ran out of fuel after a couple days of operation. During those years, many other tenants have lost power due to failures in the site's power generation / distribution. I'm very pleased with the performance of the APC gear.

At another, much more modern site, power can be ordered in one of two ways - UPS protected, 0-transfer-time or generator protected, up to a 5-minute outage. The first costs about 3x as much as the second. I selected the generator protected power to save money.

At that site, I also use a SU042 ATS. There are two drops of building power - two different panels, but on the same generator. One ATS input goes to the building power directly, while the other ATS input connects to a 3KVA rackmount APC UPS. It is set to prefer the input power from the UPS. If power fails, the transfer switch will still be pulling power from the UPS - no switchover. If the power failure continues, within 5 minutes the building generators should start up. If that happens, the ATS will never switch off the preferred input from the UPS, and the UPS will recharge. If I have a UPS failure or need to do some maintenance on the UPS, the ATS will switch over to the direct building power input. The APC UPS was selected to provide a 15 minute runtime on batteries, 3x longer than the guaranteed start time on the generator.

If I was looking to configure something like your environment, I'd go with my second method (1 ATS, 1 UPS). In most cases, a single larger UPS will cost less and have a longer runtime than two smaller UPS, given equal output ratings (for example, 3KVA vs. two 1.5KVA models).

You need to determine which failure modes you need to protect your equipment from and configure accordingly.

[Anonymous user · Accepted solution]

Thanks to everyone who responded. I greatly appreciate the feedback I received as well as the real-world examples/scenarios you shared.

While I don't believe I'm any closer to vetting my proposed setup, at least I'm no further away! I setup the equipment as described which in theory should do exactly what I need; in theory. I'll test this weekend.

Thanks to all!