Electrifying experiences

A couple weeks ago right after the big snow storm we had here, my APC UPS computer battery backup gave up the ghost. Since it was over 5 years old I assumed the battery had gone through one too many power cycles during a recent  power outage, so I ordered a replacement APC unit from Amazon.

When the unit arrived I plugged it in and it came up with a green flashing light, the unit was providing battery power but no AC—not a good sign. After a few hours of charging the green light changed from flashing twice every few seconds to constantly flashing—not a good sign. Finally a few hours later it started flashing red and green, beeping, and clicking—not a good sign.

I went through the manual and could not see that I was doing anything wrong so I figured I got a bum unit from China. Amazon offered to replace the defective unit but would not take it back since it contained a hazardous material—lead. So I was stuck with disposing of a hazardous unit along with the other lead acid battery backup that failed in the first place.

So a couple days later the replacement arrived. I plugged it in and turned it on—you guessed it, same flashing green light. This progressed to rapidly flashing and finally red and green flashing, beeps, and clicks—not a good sign! Monday I called APC support and they went through the checklist, confirmed a defective unit, and offered that either they could replace it or Amazon could. Well I was not about to get bit a third time so I just told Amazon to refund my money and let me drop off the dead units at the local Whole Foods. Of course they refused to accept them so I was stuck with two anchors.

Today I mentioned this to my neighbor who is an electronics geek (would make a great model railroader) and he said he had similar problems with his APC units—not a good sign. He also had checked his outlets and was seeing 137-140 volts AC—really not a good sign! I checked mine and they were coming in at 137-140 VAC.

A quick call to Duke Energy brought a guy in a truck with a lift bucket to see what we were smoking or drinking. Sure enough he got a reading of 140 VAC at the transformer on the pole that feeds both our houses—now we were getting somewhere. Within about an hour they had the old transformer off and a new one mounted in its place.

After thanking the guys for the new transformer, I checked my voltage and it came in at 124 VAC, exactly what the guy in the bucket said it should. Now here’s the part you’ll really like. I plugged in the “defective” APC units and pushed the on button, up came a solid green light with no flashing at all—a really good sign.

So what was going on? These devices not only switch to the battery when the power goes off, they also switch to battery power when it goes too high! With my AC pushing 140 VAC the unit was switching to battery, it would then discharge the battery and go into total failure mode.

So now I guess I owe Amazon for the two “defective” APC units. I also found that the original one that I thought was dead had simply discharged also because of the high voltage. I’m really glad though that the high voltage didn’t kill any of the other sensitive electronics in the house, especially my DCS240!


  • Good advice all.
    Myself, I have my AC in to the layout, connected to a switch, and I always turn it off when I leave the layout. That being said I will get another APC unit to go next to the switch.

  • I guess you now also have a UPS to use with your DCS240! We are building a new house on the highest hill in a small town and I am starting to think about surges and lightning strikes. What will make it worse is my other hobby – ham radio. There are going to be antennas higher than the house. I am going to have the electrician put in an 8 ft copper ground rod by the entrance. A near future book on my reading list is Grounding and Bonding for the Radio Amateur published by the American Radio Relay League. Advice in that book should also help the model railroad and the rest of the house.

    • Ken—actually I have an AC circuit installed in the layout with outlets scattered about. This is plugged into an APC UPS which is plugged into the house mains. We have brownouts and power interruptions almost every time there is any significant storm and I try to protect the good stuff! In your situation I would have the utility or your electrician install a whole house surge protector on the meter or the main breaker box up front.

      • We may add a whole house surge protector. I also like your idea of using a UPS for DCC. Another thing we are lookiing at is a backup generator for the whole house.

        • These can be very useful especially if you are in a rural area with above ground electric lines. In NVa we had buried lines and only lost power about once in 20 years. Down here the lines are above ground and about once a year we lost power long enough to have to dump everything in the refer and freezer about once a year. Then Duke bought them and started a major program of cutting back trees along the right of way. We haven’t had any significant power outages since then. Folks tend to forget that if you are on a well you don’t even have water to flush a toilet if power goes down!

  • Good to know.

    The batteries are only good for 5-7 years. Have replaced batteries twice in my unit both times the battery would not hold a charge, yes got 5-7 years out of each.

  • Larry
    Interesting post and information. I have a small switching layout powered by a Zephyr. Just in case I unplug the Z when not in use and I do not leave my UT4 plugged in either. Just cautious or chicken.
    Bill Michael

    • That probably is a good precaution, especially if you live in areas prone to power outages or lighting strikes. Many folks think that the DC power supply will filter that stuff out but I know of too many folks who have had to replace DCC systems after a nearby lighting strike. I have a whole house surge suppressor on my main box which is supposed to take care of that kind of thing but when the line voltage goes above the 20% safety margin you have to begin to worry about all the electronics in new appliances. Duke Energy was concerned enough to have a guy out here in just a few minutes to check out my problem and they replaced the transformer in under an hour!

  • Wow I never considered that my AC power could be messed up. Guess I should check mine just to see what it is showing. Thanks for the post.