pw5115
PW5115 UPS – Quick Post
Okay, maybe not so quick. Tonight I was playing around inside the Power Ware PW5115 UPS I wrote about here. Over the last several weeks it has been in service, I’ve run into a few problems with it, and cracked it open in hopes of finding some answers (as well as to change the noisy fan for something quieter.)
I was experiencing two issues:
- Every couple of days, the fan will randomly turn off. This happened ever since I got it, and sometimes happened every 4 days, once a week, then it happened twice in two days.
- It was no longer capable of supporting the server when mains was removed.
When I opened it, there was nothing out of the ordinary. No bulging caps of anything of the sort. I believe at this point I can attribute the problem to aging, ready to retire batteries.
This is the huge bus capacitor at the 36VDC input. It has enough power that, when the batteries are disconnected, it can fire several relays and hold them for a second, before finally dying. As well, when the battery pack is connected initially, considerable current is sucked to charge this cap, enough that a large blue arc appears, creating ozone and smoke. Awesome.
Here you can see where the buzzer used to be, removed to preserve my sanity. I don’t know if any of you have a UPS (or two) in your bedroom, but they will beep, non stop, for no reason. Power failed? Beep every 2 seconds. Battery dying? Beep continuously. If a power outage happens at 3am, this is not a sound you want to be woken up for. It has happened to me, and the adrenaline rush is actually kind of unpleasant.
To the top right of the buzzer footprint you can see a black-red-yellow wire. This is the wire going to the fan. I plan on replacing the stock turbine with a much quieter CPU fan. The turbine didn’t really even move that much air, anyway.
Uninterruptible Power Supply
Being a very technology-inclined person, electricity has an important role in much of my daily life. Many of my tools require it (I include computers in this category) and, when the power goes out, it is the absence of server noise that alerts me, not that of light. The best way to keep these devices running is with a UPS (see previous post on the subject).
Network
Above is the “defender of the Internet” – this UPS keeps the modem, router, gigabit switch (and in passing, my amplifier) powered in the event of a power outage.
This UPS was $15 at a thrift store, is rated for 350VA (so… 275W?), and originally came with a 7Ah battery. Naturally, the battery was toast. I instead ran some wire from the terminals to a 12Ah battery from a broken car booster pack. Yes, I simply wrapped the wire around the terminal.
I haven’t tested the life span, however I once left it unplugged, with my amplifier playing music, for 30 minutes without failure. Boredom led me to plug it back in. I expect it should last several hours powering only the network.
Server
The server has 8 hard drives, and consumes a fair amount of electricity (more than the small UPS can provide). Because of this, a much larger UPS is needed. While browsing Kijiji one day, it occurred to me that I’ve never checked there for a UPS before. It was a good thing I did this time:
