Author Topic: UPS Supercapacitor Conversion  (Read 7216 times)

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Offline BradC

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Re: UPS Supercapacitor Conversion
« Reply #100 on: December 06, 2018, 10:35:15 pm »
I'm still not seeing the downside but the test has a long way to go.

For your specific use case where it's not about availability or graceful/safe shutdown it's probably the perfect solution. What you have is the electronic equivalent of the old motor/flywheel/generator power conditioner. Smooth power and the ability to ride out minor blips, plus isolating your load from the mains just long enough to bring up the generators.
 

Offline joeqsmith

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Re: UPS Supercapacitor Conversion
« Reply #101 on: December 06, 2018, 11:48:48 pm »
Oh it'll last for a long time, don't worry.  It just doesn't have much up-time! :)

Tim
When I started the thread, I was asking for experiences with some of these very cheap capacitors.  While most of the discussions surrounded brands of UPSs and what batteries to buy, my concern is still the same, how will these cheap capacitors perform over time.   I derated them a fair amount for voltage and capacity to try and give them every chance to have a long and useful life.  We will see....

I'm still not seeing the downside but the test has a long way to go.

For your specific use case where it's not about availability or graceful/safe shutdown it's probably the perfect solution. What you have is the electronic equivalent of the old motor/flywheel/generator power conditioner. Smooth power and the ability to ride out minor blips, plus isolating your load from the mains just long enough to bring up the generators.

For the most part,  that is correct.  My goal was never to ride out more than five seconds or so. 

I mentioned early on that the cost of the batteries vs these low cost, bottom end super caps was a wash.  Someone mentioned size but as I mentioned, with the short durations I am looking at, it's a tight fit but the bank is small enough to fit into the UPS.   Some were concerned over the recovery time (how long to recharge the bank after a dropout).  So far this has not been an issue.   Someone mentioned their concern of a fire hazard and the possibility of burning down our house.   The case of the UPS is steel and the caps are well insulated.  I guess a battery could also rupture and leak acid, maybe explode.  I would guess that the case is designed to handle fault conditions like that but then again...

It does seem like a good application for them.  If the system holds up for a few years, I may invest some time in making something a little higher quality than this unit.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: UPS Supercapacitor Conversion
« Reply #102 on: February 18, 2019, 03:31:18 am »
It's been a little over 2 months from my last update.   We only had one dropout that caused the counter to increment during this time.    It was the typical secondish that we see.  I had been running some long term test at the time it occurred.  The UPS did it's job and rode it out. 

I've left the double conversion active and havn't done anything with it since turning that function back on.    The capacitors continue to run cold.   I have some filter material in front of the unit that is starting to get a bit dirty but no other service beyond the UPU's built in battery test that I have programmed to run.     

I've been thinking that after a year, I will pull the UPS and repeat my dropout test.   It may provide some insight in how these low cost capacitors are aging. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline joeqsmith

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Re: UPS Supercapacitor Conversion
« Reply #103 on: March 22, 2019, 11:18:54 pm »
We had another large storm which caused another tree to take down a line.  The power company was fairly quick and the generator was only running for a day.   Of course the UPS didn't save me with that one.   The rest were short dropouts like we normally will see and the UPS held up just fine.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline joeqsmith

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Re: UPS Supercapacitor Conversion
« Reply #104 on: May 09, 2019, 10:05:24 am »
A few days ago I was logged onto EEVBLOG, posting some BS and the power dropped for several seconds.   I thought for sure it was going to drop but it still rode it out just fine.  No other power drops to report but it was a reminder that the project is coming up on a year of testing.   The house has not burned down and the caps continue to run cold.   It continues to be one of those boring projects that just does it's job. 

On 6/28 it will mark one year and I will repeat the test below to see if I detect any changes in the hold up time.    No idea what to expect.

I am guessing with a 500W load, if it could ride out 5 seconds it would cover the vast majority of the dropouts we have.  Most of the time, I am using about 200W and I would guess the dropouts are around a second.  It's enough to have the lights flash and upset any tests I am running. 

Looks like it can hold the 300W for roughly 17 seconds.  In the ballpark anyway.   After reading the datasheets,  I had decided to run the caps well below their max operating voltage.   I think the next step is just button the thing up and see what happens over the next 5 years.  I will program the UPS to run a test on the bank every week or so.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline joeqsmith

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Re: UPS Supercapacitor Conversion
« Reply #105 on: May 10, 2019, 10:02:26 pm »
Just a couple of minutes ago, we had another dropout.   This seems pretty close to the same time as the last event a couple of days ago.   Which, come to think of it, the UPS used to frequently beep about an hour earlier (it beeps to indicate an event).   We have this stupid daylight saving time that changes the time zones.   

I wonder if they switch sections of the grid at certain times of the day and if there is something going on with some of their gear.     Maybe next year, make up something better than the pedometer to record events which would log the date, time, type of event and length of dropout.    Maybe there is more to this story than just using the supercaps to ride through these dropouts.. 
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Offline BradC

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Re: UPS Supercapacitor Conversion
« Reply #106 on: May 10, 2019, 11:26:58 pm »
Has the ups got an interface? Can you monitor it with something line nut?

I monitor all mine with apcupsd. Really useful to get the emails and logs letting me know when, where and what the fault was.
 

Offline madires

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Re: UPS Supercapacitor Conversion
« Reply #107 on: May 11, 2019, 12:03:35 am »
NUT = Network UPS Tools -> https://networkupstools.org/
 

Offline joeqsmith

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Re: UPS Supercapacitor Conversion
« Reply #108 on: May 11, 2019, 12:44:47 pm »
It has an interface and came with some software but I have never used it.  As soon as I saw it was JAVA based, I discarded it.

So, I just checked and basically it looks like with a PC running 24/7 it could track the times when it switches to the battery bank.  It has other metrics like the input/output  line voltage, frequency, temperature......  Just basic stuff.

It can't seem to collect the metrics I would be looking for.    Ideally, I would like something battery powered, that can record the date/time and length of each dropout, down to a 10th of a second.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Online NiHaoMike

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Re: UPS Supercapacitor Conversion
« Reply #109 on: May 11, 2019, 12:54:30 pm »
It can't seem to collect the metrics I would be looking for.    Ideally, I would like something battery powered, that can record the date/time and length of each dropout, down to a 10th of a second.   
Old smartphone/laptop, Raspberry Pi, or whatever low power computing platform recording the mains with a sound card connected via an attenuator.
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Online bicycleguy

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Re: UPS Supercapacitor Conversion
« Reply #110 on: May 11, 2019, 02:20:14 pm »
@joeqsmith
Just noticed thread.  In response to first post.  In a Davis weather station sending unit acquired 2005, that sits outside with a 3x4 inch solar cell and a supercap to power the rest of the day.  Failed in 2009 when after about 5 heavy overcast days no signal.  The leads were severely corroded.  Replaced with 2 NessCap 2.7V, 10F from digikey.  Lasted better than 10 years when some other chip failed from corrosion.  The caps are still good looking for a project.  They were discontinued at Digikey but are the same physical size as these 50F ones for the same price today:  https://www.digikey.com/product-detail/en/nesscap-co-ltd/ESHSR-0050C0-002R7/589-1004-ND/946804

I highly recommend them.

Edited:  Just read the whole thread.  Here's some more data.  The transmitter operates correctly when the supercars are as low as .31V.   Typically around 2.6V, but never higher than 2.65V.  Never measured the currents.  At the time I replaced the original cap I didn't suspect electrolyte leakage so didn't check for it.  The ~4x5 inch board is not conformally coated and gets lots of spiders and bug droppings and the 2019 failure was on the main transmitter chip which is only rated for 80% humidity!  (This is up on a pole with the rain gage, temp and humidity sensor, hot days in the sun the caps must be over 90F  90% humidity)  I replaced the original cap with two in parallel with no other circuitry.

To Davis Instruments credit the current boards ship with conformal coating.
« Last Edit: May 11, 2019, 03:28:02 pm by bicycleguy »
 
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Offline joeqsmith

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Re: UPS Supercapacitor Conversion
« Reply #111 on: May 12, 2019, 04:48:36 am »
Old smartphone/laptop, Raspberry Pi, or whatever low power computing platform recording the mains with a sound card connected via an attenuator.

I have yet to own a cell phone.   :-DD  If I roll something for it, I will just convert the AC to a digital signal and time the pulses.  I could just use the relay that I have today that runs from the wallwart drive it.   

@bicycleguy
A friend of mine gave me a Fluke 189 that still has the original super cap installed.  I've had to replaced a few of them that started to show some oxidation and one that had really high leakage.     

After writing this, I thought  I've had that meter for a while now and had bought spare caps.  Decided to pull it back apart and replace it while I was thinking about it.  Noticed the batteries were low and sure enough.  See attached.   :-DD   All four of my old Fluke 18x's now have new caps.   

On the flip side, I had a tablet that the PCB was damaged beyond repair after the cap leaked after a a few years.  I had two of these tablets and when I looked at the second one, the cap was just starting to go.   

So depending on several factors, the life could be a couple years to well over 20. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 


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