APC battery backup not working sometimes

Not the best UPS on the planet, but cheap at about $70.

If "a few months" means 2 months, it should still be under the 3 year warranty from APC.

How do you know? I sent a UPS back because the stupid light was burned out. (Long story, don't ask). I got a refurbished UPS back in the mail in 3 days. Instead of guessing, maybe reading the warranty might help?

How Does Standard In-Warranty Service Work Defective products may be returned to APC by the customer for replacement or repair during the standard warranty period. Defective products will be replaced or repaired and returned to the customer. Customers who must have original units back rather than replacement units due to assigned asset tags and set depreciation schedules must declare such a need at first contact with APC. It will be APC's standard practice to issue factory reconditioned replacement units in exchange for original units. The warranty on reconditioned units delivered for in-warranty service is 90 days or the remainder of the original warranty period, whichever is longer. Repaired units carry the balance of their original warranty period.

So it is written, so it must be. (Charlton Heston in The 10 Commandments)

Been there. There's a transfer relay inside. The contacts are not making good contact or the contacts are pitted from trying to switch a potential overload such as a laser printer.

Well, at least you tried calling support. Support runs on the assumption that nothing is wrong and that you must have done something strange to cause the failures. That's not unreasonable as 80% of the devices returned under warranty have nothing wrong with them.

Yep, you got it.

Well, if you're ambitious, open the box and look inside. If the relay is an open frame type (fairly common), you should be able to inspect the contacts. If the relay has a cover, it can usually be removed to reveal the contacts. My guess(tm) is that you'll find pitted contacts or a mangled relay armature.

You opened it up and you didn't look at the contacts? Sigh. Unplug the unit. Turn it off. Disconnect one lead from the battery. Tear it apart again. Look at the contacts (with a magnifier). Are they pitted? If so, clean them.

Well, if you want to risk you life, run the UPS with the covers off. If it goes into backup mode without any output again, push on the relay armature with an INSULATED wooden or plastic stick and see if the output magically appears on the load.

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# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com               jeffl@cruzio.com
# http://www.LearnByDestroying.com               AE6KS

Thanks very much for your reply, Jeff.

The relay is a PCB style DPDT:

Goodsky EMI-SH-212DCF

12V coil 8 amp contact rating at 250V

I found the datasheet for this series relay, but not the exact "DCF" part, at:

searching on the part number EMI-2P over on the left.

But, I haven't been able to find anything equivalent at Mouser.

The relay is encased in plastic, so I doubt I can get inside, but I haven't desoldered it yet.

I found 10 with a similar number for sale on Ebay for $79, but no singles.

This is a really dinky little relay to be rated at 8 amps, which is probably why it is failing.

If I could find a replacement relay, it would probably cost less to buy that than to ship the UPS back to APC - it weighs a ton.

Of course while it would be nice, it wouldn't absolutely have to physically fit - I could bridge from the PCB holes to the relay with wire - but the coil and the rating would have to be right, as well as the speed I assume.

Well, let me know if any solutions come to mind. Thanks again for your help.

Ok, I may have lied.

On page 1896 of the pdf catalog, I find:

Omron G2RL series

8 amp rating, same size and pinout

Omron part: G2RL-24-DC12

Mouser part: 653-G2RL-24-DC12

Looks like this should work. The only question would be if there is a speed issue - how fast it switches.

Decoding the part number: EMI = Appliance relay SH = Wash tight and flux proof

2 = 2 poles blank = Form C (DPDT) 12 = 12V D = DC coil C = Silver-Cadmium-Oxide burn resistant contacts F = 250V insulation

True. It's sealed for flux washing and isn't going to come apart. That doesn't stop you from unsoldering the relay, and using a hack saw blade to cut a grove around the base to remove the cover. The inside is NOT potted.

I would just love to replace the relay with a Solid State Relay, that's not going to work. It has to be DPDT and all SSR's are either SPST or DPST. That would require a redesign.

Digging through Digikey[1], I find (in order of increasing price):

etc... I haven't checked the pinout and spec sheets on all of these to make sure they're identical. Watch out for the contact material and switching speed. The original is 12msec max operate and 8msec max release. The first (and cheapest) one in the list is 8msec and 6msec respectively, which should be faster than the original. However, the contacts are AgSnO2 which is better than AgCdO contacts of the original.

Anyway, spend some time digging through the data sheet and see if I misssed anything.

Also, if you have room, you might consider using a socket:

Good luck.

[1] If you're using Digikey's relay search page:

you can select more than on filer criteria in a given column by holding down the shift key.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

Well, that one is silver/nickel per the data sheet. The AgSnO2 version would be RT423012, which DigiKey doesn't stock.

But this one:

74

is silver/nickel with gold plating - per the datasheet. Would that be worth a couple extra bucks?

AgNi looks OK for contact material.

It has a bit higher resistance than AgSnO2 and will therefore run warmer if you load the relay to the maximum. However, since the UPS is rated at 550VA at

115VAC, you're limited to about 5A max on the contacts anyway. That should work.

It's a bit difficult to decode what the data sheet says about the contact material. It sorta hints that there are several different types of contact material, but doesn't offer any part numbers to distinguish them. Dunno.

If it's gold, I would suggest that it's a bad idea. Gold plating is only for a "dry" load. It's primary purpose is to provide low contact resistance in circuits that do not carry any current. The slightest arc across the contacts, the few millionths of gold plating instantly disappears, leaving a rather miserable connection to the intermediate nickel plating between the gold plating and copper contacts.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com               jeffl@cruzio.com
# http://www.LearnByDestroying.com               AE6KS

1

I ordered this one today from Digikey. Came to $5.27 with shipping. It should be here Saturday or Monday, and I'll do the switch-out and see what happens.

I guess there's always the possibility that the problem will turn out to be something else, but the fact that the problem is intermittent, and that the UPS behaves normally in all other respects, makes it seem likely that the relay contacts are responsible. But, you know, it's only $5 either way.

I really appreciate your help with this.

The relay arrived this morning, and I've installed it, and everything works fine so far. Of course I don't know for sure that the relay was the problem because it was an intermittent problem to begin with. But I've gone through about a dozen tests with the new one and it hasn't failed to work. So I'd say this looks promising.

I have to keep the old relay in case I ever need to send the unit in under warranty. So I won't be taking it apart. But, it does rattle when I shake it, which I think is not a good sign.

Anyway, time will tell. Thanks again for your help.

By the way, I assume the lead-free solder they're using now has a higher melting point than the 60/40 I use - it was a bear to get the thing unsoldered with my 30W iron. Ended up having to add some of my solder to the pins, then braid it off, two or three times before it all wicked up and the holes opened up.

And Digikey is amazing. I ordered late Thursday afternoon, and it arrived in the mail Saturday morning, all for $2.20 postage. Hard to beat that.

Congrats, so far.

It might be a spring. Some DPDT relays have two springs, one of which might have come loose. With a spring missing, the tension on the normally closed contacts will be reduced, possibly causing the symptoms.

A 30 watt iron will work, but I prefer something with a thermostatic control and at least 60 watts. The idea is to solder hot and quickly, so that the heat affected zone is minimal. A low wattage iron may get up to temperature eventually, but I'm into instant gratification.

Mixing unleaded and lead-tin solder is a bad idea. However, I do it all the time because I absolutely detest unleaded. I clean off as much solder from the pads and pins with a solder sucker, and then apply the lead-tin solder. If you get a dull surface finish, you still have some residual unleaded solder in the mix. Suck and remove it all, and try again.

I use solder braid only when I can't get a solder sucker onto the PCB. The problem is that it takes much more heat to remove solder with braid. If the PCB has tiny traces, or is made from phenolic, the traces will delaminate. That can happen with a solder sucker, just less often. If I have to unsolder many pins, I use an antique desoldering station:

Yep. Great service from Digikey. Mouser, Allied, and Newark are other good sources of parts and pieces. I prefer Digikey because I like their online search tool which came in handy trying to find the relay. However, I will confess that I buy quite a few parts on eBay, because it's much cheaper.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

Well I'm going to declare victory and withdraw from the field of battle.

It's been a week now, and the UPS has passed the boot test every morning without fail. And as luck would have it, in our 100-degree weather there have been two short-term power outages (two that I know of because I was at the computer each time) and the UPS switched into backup mode perfectly each time.

So it appears the problem definitely was the relay, and my replacement operation was successful. And all for less than the cost of shipping the UPS back to APC. Plus, if something goes wrong in the future, I'll know what to do.

Thanks very much for your help, Jeff.

THX for the feeback.

Saludos (an alle Vernünftigen, Rest sh. sig) Wolfgang

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Wolfgang Allinger, anerkannter Trollallergiker :) reply Adresse gesetzt!
Ich diskutiere zukünftig weniger mit Idioten, denn sie ziehen mich auf
ihr Niveau herunter und schlagen mich dort mit ihrer Erfahrung! :p
(lt. alter usenet Weisheit)