APC SMT2200i not charging

[GoNz0]

Hi, I hope to get help on this.
The story so far is.
UPS is 6 years old and at 4 years it threw the replace battery warning so I did with a new set of genuine APC batteries.
13 months later it threw a battery fault so I called APC support who diagnosed the logs and agreed the batteries were bad, I had found 1 of the 4 batteries to be bad so it couldn't hold a load. Another set of batteries were shipped in January.
Upon install it threw a charger overvoltage error but cleared after a braindead as advised as the 1st thing to do on any APC UPS when troubleshooting.
I had not given it any thought since then until it threw another battery fault a month ago, this fault cleared when I manually did a self test, APC checked the logs and agreed to send another set of batteries out as it lasted about a minute on battery power when APC were troubleshooting it with me.
I put the new set in and they read 100%, then the charger overvoltage error again so I did another braindead and off it went again quite happy ( I thought) so I left it at that.

This is when I realised I had a problem, I left the new pack in for 24 hours then did a self test, this went from 100% to around 40% charge on the self test so I left it to charge, all this time the voltage was around 55.4 in the logs, I put the DMM on the front pack and realised they were at 24.2v (so 48.4v combined)

I opened up the UPS and took a direct combined reading from the board to confirm it was about 7v out, same at the big caps that I assume hold enough for it to switch to battery power in an outage..

When you turn it off and pull the batteries then power back up it will hit 55v for a second then drop back down and fail to charge the batteries.

I now have a brand new one sat here that charges and reads the correct voltage but it is the newer model so it has some slight board changes and a newer firmware so many parts can't be swapped over to test.


So after that huge opening post does anyone know what to start looking at for the 7v difference in what the batteries are reading vs what the UPS thinks they are?

the management card sits around 55.4 all the time with the batteries connected so I assume this is whey I can't hear the relay throw in for the charging circuit like my new one?

It seems to think they are fully charged.

[TechGeek]

Re: APC SMT2200i not charging

Sounds like some voltage limiting device has/is failed/failing. Is there a smell of burned something inside the unit?

[GoNz0]

Re: APC SMT2200i not charging

I swapped out the fan maybe 2 years ago and never checked the voltage, a burning smell came out as I put a 12v in instead of a 24v. Smell was there for a while but I couldn't see if it was anything on the board. Time to remove the board I guess?

[TechGeek]

Re: APC SMT2200i not charging

The fan? That's okay. I'd pull the board and post photos of it.

[GoNz0]

Re: APC SMT2200i not charging

The fan? That's okay. I'd pull the board and post photos of it.

Thanks, boards out but I will wait until daylight rather than bouncing the flash off it. Had a good stare and nothing looks burnt or swollen so I will post some pics tomorrow. Thanks for the help.

[TechGeek]

Re: APC SMT2200i not charging

You're welcome.

[GoNz0]

Re: APC SMT2200i not charging

Here we go

[budm]

Re: APC SMT2200i not charging

Can we see the straight shot of the whole board top side and bottom side and the whole shot of the whole unit to see how the batteries are connected to the board?

[GoNz0]

Re: APC SMT2200i not charging

I can't do a shot of it connected at the moment but I can put up a pic with a crap photoshop of where the wires go, battery splits the charge so one red battery goes to the top left of the heatsink, the other bottom right. The white and black on the heatsinks head off to one of the transformers and both battery negatives go each side of the heatsink onto the board itself.

[CapLeaker]

Re: APC SMT2200i not charging

I have one of those SMT2200, about 5 years old, maybe that charging relay is bad?
I looked into my log for the battery voltage and I see 54.8V. Don't forget this unit has temperature compensated battery charging too.

[budm]

Re: APC SMT2200i not charging

So right now if you disconnect the batteries and plug the unit into the C outlet but not turning it on, do you get around 55vdc at the wires to the batteries (Batteries red W2, Batteries Black W7) ? The charger circuit is an always on power supply to keep the batteries charged even when the power switch is not on.
BTW, those two large electrolytics caps may be charged up to 55VDC for seconds and it may not drop down without the load so you may have to use 470 Ohms 10W resistor in place of the batteries to simulate about 100mA of charging current.

[GoNz0]

Re: APC SMT2200i not charging

I have one of those SMT2200, about 5 years old, maybe that charging relay is bad?
I looked into my log for the battery voltage and I see 54.8V. Don't forget this unit has temperature compensated battery charging too.

The diodes at the back of the battery cab, I think it is meant to touch the rear pack as it sticks out. It has read around ambient (it reads 1-2 low on the room) for a while now, probably due to it never charging. It lives in the dining room so no major temp variations although it spent its 1st 4-5 years up the loft powering my former office. (new 2200i is at 54.3 VDC fully charged)

So right now if you disconnect the batteries and plug the unit into the C outlet but not turning it on, do you get around 55vdc at the wires to the batteries (Batteries red W2, Batteries Black W7) ? The charger circuit is an always on power supply to keep the batteries charged even when the power switch is not on.
BTW, those two large electrolytics caps may be charged up to 55VDC for seconds and it may not drop down without the load so you may have to use 470 Ohms 10W resistor in place of the batteries to simulate about 100mA of charging current.

When I 1st turn it on it spikes to around 55v for a second then quickly tapers off to the battery voltage and stays around there. I don't hear it throw in the charging relay like my new one does either.

Do I need to get a 10w resistor as I can get one here for Thursday for a couple of quid off eBay.

Not sure if that is the issue as the brains seem to think the voltage is higher than it is hence it throwing a wobbly about charger overvoltage when a fully charged pack is inserted as it shows nearly 60 volts with a freshly charged pack reading around 54v? (54v is confirmed at the battery and w2/w7)

[budm]

Re: APC SMT2200i not charging

So you are getting 54V without the batteries connected then, I was thinking that the charger was dropping way below in the 20V range, 54V is just a touch on the low side but still should be enough to charge the batteries, you can connect DC AMP meter in series with the one of the red wire to the batteries wire to see if it charging the batteries or not, red probe on the RED W2, Black probe on the + of the batteries, if is discharging it will show (-) sign on the meter, but DO NOT TRY TO RUN THE UPS IN BATTERIES MODE because the running current will be 40A or more.
60V is definitely too high

[GoNz0]

Re: APC SMT2200i not charging

To be fair the new one doesn't charge at a high voltage, it brings them up slowly as you will see with the attached log, from the bottom up I took it as it finished it's runtime calibration back to the final voltage.

I will put it back together and see if it is offering a charge when I get the chance. my fluke DMM is rated to 10a, is that good enough?

[budm]

Re: APC SMT2200i not charging

To be fair the new one doesn't charge at a high voltage, it brings them up slowly as you will see with the attached log, from the bottom up I took it as it finished it's runtime calibration back to the final voltage.

I will put it back together and see if it is offering a charge when I get the chance. my fluke DMM is rated to 10a, is that good enough?

10A for testing charging current should be good enough to check and see if the new batteries are being charged or not, just do not try to run the UPS in batteries mode, that 10A fuse will blow.

http://www.chargingchargers.com/tuto...t-charger.html

[CapLeaker]

Re: APC SMT2200i not charging

To be fair the new one doesn't charge at a high voltage, it brings them up slowly as you will see with the attached log, from the bottom up I took it as it finished it's runtime calibration back to the final voltage.

I will put it back together and see if it is offering a charge when I get the chance. my fluke DMM is rated to 10a, is that good enough?

Mine does the exact same thing, when the batteries are charging. After the bulk charge is done, it will slow down until the batteries are full, then float it.

Get a current clamp, then you have no problems with the DMM.

As I recall the unit uses four 18Ah SLA's. Two of them in series in a pack. 2 packs. So you get 48V at 18Ah in total. Each pack has their own connector, so there can be only 24V on each connector. So you are saying that the batteries are losing volts, but the voltage in the log doesn't change?

[GoNz0]

Re: APC SMT2200i not charging

Mine does the exact same thing, when the batteries are charging. After the bulk charge is done, it will slow down until the batteries are full, then float it.

Get a current clamp, then you have no problems with the DMM.

As I recall the unit uses four 18Ah SLA's. Two of them in series in a pack. 2 packs. So you get 48V at 18Ah in total. Each pack has their own connector, so there can be only 24V on each connector. So you are saying that the batteries are losing volts, but the voltage in the log doesn't change?

If you go back to the 1st post the controller reads 6 volts higher than the actual battery voltage, the main fault I am looking for help with is an error in the sensor readings.I would like to figure this one out before anything else as it may be the reason it isn't charging, if not it is a good start as it will never bulk charge if it thinks the batteries are 6v higher?
This falls in line with a fully charged battery triggering the charger over voltage warning as it is reading 60VDC+ via the sensor.

If I discharge the batteries the voltage will drop but it still has a 6V higher reading than the batteries so flat batteries that force a shutdown as they are 11.5v each =46v will read 52V via the sensor.

Even then it doesn't make any great attempt to charge them maybe a few tenths of a volt.

I was hoping to spot something swollen or cracked on the board but no joy so far.

[CapLeaker]

Re: APC SMT2200i not charging

I reread the whole thread. You reported that none of the caps "look" swollen. Did you actually test them with an ESR meter? Does the unit charge the batteries at all (if you let the batteries drain below the 7V difference)?

[CapLeaker]

Re: APC SMT2200i not charging

Another thing: Since there has been a few battery packs in there by now, did you try the calibration yet (put on a 500W load etc...)?

[GoNz0]

Re: APC SMT2200i not charging

I reread the whole thread. You reported that none of the caps "look" swollen. Did you actually test them with an ESR meter? Does the unit charge the batteries at all (if you let the batteries drain below the 7V difference)?

I don't have one & have not let the batteries drain that low as the unit shuts down when they hit 10.5v under load, that raised back up to 12v per battery or 48v total where is sat overnight doing nothing apart from saying the capacity was going up when not a lot happened as it shut down in under 2 minutes where 100% charge went down with no load to nothing in a minute.

Looks like I will have to invest in a ESR meter to progress then?

Any suggestions for something cheap to do the job?