Slashdot Mirror
UPS Hacking in Hurricane Season?
kengreenebaum asks: "Perhaps not the most exciting of topic; however it is storm season and I have a couple of UPS's that need new batteries. What is the best source for high quality, long lived replacement batteries for these devices? I assume it takes a special chemistry to survive continuous trickle charging and an occasional deep cycle. Has anybody tried connecting larger capacity batteries external to the UPS enclosure to attempt longer run times? (Obviously the load capacity is based on the inverter itself and can't easily be modified) Also what software do you use for monitoring and automatic shutdown on Linux? I have collected quite a few APC and Belkin UPS's 700VA or smaller as they go on rebate/sale."
Just FYI, if you have a UPS with replacable batteries (not the crap throw-away Energizer or whatever brand ones) it's very likely that the battery inside is a gel-type sealed lead acid battery. Just take the battery out and look at the markings on them. Odds are good that you'll be able to find a replacement either on eBay or any of the cheap battery suppliers online.
Myself and a number of friends of mine have acquired SmartUPS' (typically >1400) for free, simply because they are 'broken', and a battery replacement costing around US$50 or so makes them like new. Oh, and a good SmartUPS is really, really nice compared to a standard passive device.
For the batteries, if it is maintaining the voltage at a "float voltage" the batteries can be held nearly indefintly without a discharge or worry of overcharging. Lead acids have a float voltage of about 2.35 volts/cel (based on some quick googling). They will still die after some time.
But I don't know what technology, size, or how the UPSes actually using the batteries.
If I was DIY a UPS, I would have about 10 12Volt batteries (no transformers...), drive them off a full-wave rectifier, filter the power from the rectifier a bit, and then invert the power to make it back to AC and use my equipment off that. Advantage, I am always off the batteries, disadvantage, I have no monitoring ability and if I was to set the incoming voltage to the float voltage, it will probably take a while to charge.
If your using an APC ups, apcupsd is by far the best one to use. www2.apcupsd.com/
APC has a nice trade in program, take ANY UPS, send it in, and get a nice discount on a new one. Check their website out for details. (I'm sure their comptition has something too)
Now I'm sure you are still paying more than just batteries. However you get a system that is designed to work, with electronics that are not used and have no seen some unknown number of surges. You don't take a chance that the charger is broken (which may or may not break the batteries)
If you really must go cheap, inverters are getting really cheap, connect a few batteries to an inverter with a standard battery charger. You don't get monitoring, but you know when the lights go out, plus you have a lot more runtime. For extra points you can make your charger a solar system and run your computers off the grid. (Note, to get a system that doesn't waste a lot of energy you must to some research, but this theory will work)
Actually, if the UPs is worth a dam the backups aren't on a trickle charge; it should be periodically testing and charging as necessary.
Deep cycling is bad for any battery, but excercising them extends their life. I recently came across an interesting resource when doing
my own research on batteries
http://www.buchmann.ca/default.asp
Were that I say, pancakes?
I like http://www.apcupsd.org to handle my APC UPS on Linux. It works very well, and also supports some Belkin UPSes.
1. Small UPSs typically use sealed immobilized-electrolyte lead acid batteries, more commonly referred to as gel-cells. They aren't special at all, they are quite common.
2. I usually buy gel-cells cheaply at hamfests. They last quite a long time, and used ones are often a good buy. They're heavy, and while you can buy them mailorder, shipping will add up. Better to find a local supplier if you can. Lots of places sell them online though, just google (or froogle) for "gel-cells".
3. Most small UPSs have a CPU that is programmed with the approximate capacity of it's battery. Using grossly different sized batteries will likely cause the UPS to freak out, or at least not use the batteries' full capacity. Don't connect deep cycle marine batteries to your UPS's guts, it won't work right. Heck, I once had a UPS go south just because I let it sit with no battery for 6 months and the CPU lost its memory.
4. You need to be careful, because the term UPS can refer to a pussy office UPS thats basicly a bloated power strip, or it can refer to a building full of batteries capable of running a large factory for an hour. UPS components come in all shapes and sizes. A UPS is four things, and inverter, a battery charger, a battery, and an automatic switch. You can build and or buy some or all of those components separately if you wish. Look at places that sell solar power and alternative energy systems for people off the grid. All kinds of beafy power equipment.
Happy hacking!
-73, de n1ywb
www.n1ywb.com
I've used Batteries Plus to replace the batteries in my UPSs. They have the correct batteries for different types of UPSs and have been pretty reasonable on prices. They're a franchise so they're all over the US.
Slashdot: Failed Car Analogies. Amateur Lawyering. Anecdote Battles.
http://www.dansdata.com/diyups.htm
For those familiar with Dan, you know that it's bound to be interesting. What he does is somewhat of the solution described in some comments.... battery charger, batteries, inverter. He also talks about the merits and pitfalls of different batteries in UPS systems.