Recently, I purchased a UPSONIC UPS 1500 from eBay. (For the curious:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=5125677805&ssPageName=STRK:MEWN:
IT) It was labelled "as-is," so I assumed it was dead. I was right. But I figured if either half worked (charger or inverter), or even the batteries, I'd have something fun to play with. As expected, I got soaked a bit on the shipping, but all's fair when you're shipping primarily iron and lead, right? It's GIANT.
It arrived looking as though it had been dragged behind the truck, rather than riding inside. Each part was placed in a cardboard box, with no packing materials whatsoever. Needless to say, corrugated cardboard doesn't stand up to the rigors of 100+lb cargo.
The battery unit arrived first, on a Friday. The DHL man was angry. I wasn't there when he arrived (it shipped to my office), so I couldn't tell him what it was. But my co workers informed me that I was not his favorite person.
It clunked when I picked it up. (For that matter, so did my back!!) Something was loose, so I cranked it open (17 screws... ugh!) and found that one of the brackets had come loose and the batteries were sliding around. Looked like no serious damage, so I clamped them back down. I also had the chance to notice they were four 12V 45Ah SLA's in series. Probably toast, but we'll see. They were reading 0V.
The UPS unit arrived on the following Monday. It was only slightly lighter. The DHL man said if I wanted to complain, he'd file a report on how crappy they were packed. I said ok. So, yes, I plugged it all in and it was stone cold dead.
Ever the hacker, I pulled apart the unit. I studied it for several days (I mean, 30 minutes at a time, or so), probing this and that, trying to figure stuff out. I'm not so good at this stuff. But today, I finally had the eureka moment that I was looking at an electronic catch 22. All my AC power coming in went to this big relay before it went about its business... but the relay was powered by stuff after the relay, so it never turned on. Because the relay was off. Because it wasn't powered. Because the relay was off. Huh?
I finally figured out that the unit expects the batteries to be working, duh. Battery power is used to close the primary relay and connect the unit to AC power to get the whole game moving. Since my battery pack was at zero, then there was nothing doing.
Feeling more bold, I... uh.... "shunted" the relay and the cooling fans came on. That was weird... nothing else happened. I probed the bus bars on the 120V side of the transformer... okay... and the low volts side was dead. Desperate, I checked the bus bar itself. BAM... SPARK! I heard the relay click, the transformer went "brrreaoewrrrrrrr" and a green LED came on the front of the unit. Whoa.... It's alive.
So it turns out one of the spade connectors from the transformer came loose from its bus bar. Of all things.
I put my meter across the battery cables, and read 55V. Sure enough... if the batteries aren't molten slag, they're probably charging. I shut off AC power after 10 minutes or so and read the battery voltage.... 8V. Okay, it's a start. 30 minutes later it was 24V. I'll let it go overnight and see what happens.
