Monday, October 31, 2005

Multi-purpose UPS modifications

So, I've been modifying some UPS units and thought others might like to do it. 120VAC can kill you, so don't try this if you're not prepared or are unsure about what you're doing!

I procured a bunch of old UPS units (mostly like these) from my employer who did not want to maintain them anymore. The batteries were ALL completely dead, but the units themselves were just fine. I suspect that quite a few units like these are in similar circumstances - they don't work, and companies are happy to get rid of them so they can get newer technology (higher current ratings, USB connections, etc.).

Anyway, what I've done is to modify them to accept battery power from an external source. This makes them quite versatile and useful to anyone who uses 12 volt batteries for more than just powering a UPS. I use mine for powering many devices, not the least of which are my radios.

With the modification, my UPS units now keep my batteries charged (they float at 13.8 volts and that is usually adjustable). In the event of a power failure, they use the batteries that are attached to them to provide backup power to devices plugged into them (my computer for example). Attaching multiple or large batteries allows the UPS to provide power for longer than it would with just the internal battery. Most of them allow me to use them just like an inverter (provide 120 V AC power to devices when camping, etc.) when not plugged into utility power.

The APC units that I've been working with will charge batteries at a pretty low rate (I still need to measure with dead and fully charged batteries). They're not fast chargers by any means but they should be able to juice up a small 7 Ah battery in a day or so.

Here are the basic ideas:
  • Plug it in and see if it comes on and will power a device. If this is a new-to-you device, it's nice to know if it works properly except for having a dead battery.
  • Now unplug the thing and get to work. (You got this part without my help right?)
  • Remove the dead battery. On units less than 5-6 years old, there's almost always a battery access panel. It is dead right? Even so, try not to short circuit it just in case the UPS circuitry is the problem and the battery is healthy.
  • Turn the power switch on and fiddle with the buttons (mine will usually let out a dying wail as the capacitors discharge completely).
  • Find a way to get the wires that attached to the battery out through the case so you can connect other batteries to the unit.
  • Remove the existing connectors.
  • Connect an extension wire to the short ones that are left in the unit. I have been working on 400-650 VA UPS units and have found that 12 gauge copper wire (like this) works great. You'll definitely want to keep the runs as short as possible (at max draw, a 650 VA UPS can pull 33 amps at 12 volts). 12 gauge copper wire is rated at 30 amps at 12 volts, so be sure to not overload it if you have a larger UPS that could pull more that that at full load.
  • Drill a hole somewhere in the case.
  • Feed the wire through the hole (with a grommet installed to protect the wire).
  • Close up the case.
  • Attach a connector to the wire. I use 30 amp Anderson Power Pole connectors. Of course, your battery should also have the same connectors on it. It would be good to have a fuse on the battery. Many UPS units have internal fuses (the APC ones I'm using have a 40 amp fuse soldered right onto their main circuit board).
  • Plug in the UPS.
  • Turn it on.
  • Check the voltage at the connector to make sure you got the polarity right and that it is what you are expecting.
  • You may want to unplug the unit from the wall or at least turn the unit off before connecting a battery. You may not need to do this, but the first time you test a newly modified unit, it's probably a good idea. Note that some units will keep the battery charge circuit energized while the UPS is switched OFF.
  • Connect a battery. You will want to use a Sealed Lead Acid (Gell or AGM) battery only as the charging circuitry is designed for them. Using a flooded battery like you would use in a car, boat, etc. will not work as well unless you adjust the voltage of the charger.
  • Plug in the UPS.
  • Turn it on.
  • Check the voltage at the battery to make sure it is what you expect.
So, for not a whole lot of money, you can get an older UPS unit that does all of this:
  • UPS
  • 12 volt Sealed Lead Acid battery charger
  • Inverter
Great reading material on batteries is available at Battery University.

Thursday, October 27, 2005

Got my CBA (battery tester)

I've been analyzing some batteries since I got my CBA II in the mail yesterday. I was going to do some work with commercial AA batteries, but I see that someone has already done it: CandlePowerForums - View Single Post - Alkaline Battery Shoot Out

So far, I have tested about 25 batteries including several 18650 cells from a Dell computer battery pack. I located a couple of bad cells from the pack and hope that after charging, the others will prove to be decent.

I found that my 50 Ah gell cell that I was using as an add-on battery for my UPS was only capable of delivering 12 Ah @ a 5 amp rate (pretty pathetic considering that in UPS service, it would be called on to produce 20-30 amps or so). Looks like I will be finding new batteries for the UPS. At a 2 Ah rate, this battery may serve well for someone in a dorm somewhere with a handheld radio - we'll see. I ran a test at 2 amps for a while list night, but gave up because it was still going this morning. I'll probably continue testing the smallest cells (and batteries) first and move up to the larger ones which take longer to test.

Charging is going to be painful - the only Li-Ion capable charger I have is a Maha MH-C777PLUS. It's a great charger, but it's going to be slow doing one cell at a time (the best way to analyze them individually). I guess that's OK, once they're all in packs, it won't be so bad ('till I need to break 'em apart to figure out which cell has died).

Tuesday, October 25, 2005

So, I have a blog now.

Wanna know what I'm up to? Don't rely on this! I doubt I'll be very consistent about keeping it up to date.

I have a few projects going on right now:

Battery testing - still waiting for the
CBA II to arrive.

  • I plan on testing all of the batteries in the truckload of UPS units I picked up from the giveaway at work. If any are good, I'll probably see if anyone in the BYU ham club would like to use them - they were going to do a project a while back, but ended up with a battery supply problem. As for the UPS units themselves, I'll try to pair them with good batteries and see if anyone in ARES wants them.
Slide scanning - I'm on box 17 out of 33.
  • There are 50 slides in each box.
  • I figured out recently that it takes me about 4 hours to scan each box (that's about 5 minutes per slide).
  • The newest version of VueScan has really made the Infrared cleaning work well on my Minolta D'Image 5400 II film scanner.
Sled dog training
  • Itok (short for Maniitok) has gone out twice now in harness.
  • He didn't have any trouble figuring out that I wanted him to pull me.
  • He wasn't worried in the least about this big heavy guy on a bike following him while he ran as fast as he could.
  • We inherited a 4 wheel "go-cart" from the neighbors - it has a two cylinder engine mounted on the back. I'm going to take it off - my engine will be connected by a tow rope. It's a heavy go-cart (probably a bit heavier than this one), but if he gets real strong, or I can recruit some other neighborhood dogs...
ISP Switch
  • I've given up on using Digis as my ISP. The high latency and packet loss were just too much to take with my VOIP telephone service. For normal web surfing, etc. they're fine (except I didn't really like the metered traffic business).
  • I hooked my network to my son's network and after pestering him to help me with IP address issues while he was trying to sleep last night, everything works great!
  • I may have some wireless equipment to sell soon. Actually, Andrew will probably end up using it and I won't get anything for it. Oh well...

Tuesday, October 11, 2005

Mortimer M. Clark

Here's a picture of one of my relative's (my 3G Grandfather actually) who I believe was born in Cleveland, Ohio. (Mortimer married Frances Marian McGLASHAN, daughter of Robert Peter McGLASHAN and Sarah HOLMES, on 19 Aug 1862 in Oronoco, Olmsted, MN). He died 20 Jun 1911, in Alberta, Canada

Photo of Mortimer M. Clark

This is an approximately 2" x 3" metal sheet with picture on it. Is it a tin-type? I really don't know. I've got a much higher resolution copy if anyone's interested.