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Old 09-23-2020, 02:37 PM   #1
Curious.George
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Default Fwiw: Apc ups

I've known this for ages. And, have taken steps to ensure I can't be "bitten" by it on all my UPSs.

But, apparently, forgot to "fix" one of them -- a SmartUPS C1500. No doubt because it doesn't support a NMC (which is how I manage the herd).

The symptoms are a rebooted computer -- but no "events" reported on the UPS (so, you figure it must have been a software crash). The TELL-TALE symptom is a computer that you find rebooted The Next Day... at virtually the same time (within seconds).

What's happened is the UPS has done its daily self-test and the battery -- which displays as "100%" -- was unable to support the inverter. So, power to the PC fails. The UPS comes out of the self-test (reboots) and doesn't know that anything "bad" has happened (cuz it has forgotten!). The PC reboots and all is well -- until the next day, 24.00 hours later.

The fix is to disable the self-test feature. Worst case, a battery that is in this condition (reporting 100% yet not able to support the inverter) will cause your system to crash WHEN THE POWER FAILS -- which is usually much less often than "every day"! You won't have to remember that the UPS "stages" a power failure every day as the reason why your machine is rebooted.

Eventually, I'll figure out why the battery health reported is so wrong. But, as REAL power failures are few and far between, I can put that off for a while...
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Old 09-24-2020, 08:53 PM   #2
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Default Re: Fwiw: Apc ups

The real fix is to replace the faulty battery(ies) and run a runtime calibration.
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Old 09-27-2020, 11:01 AM   #3
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Default Re: Fwiw: Apc ups

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Originally Posted by TechGeek View Post
The real fix is to replace the faulty battery(ies) and run a runtime calibration.
It's obviously more than that -- as the unit claims the battery is fully charged. A faulty battery would appear overcharged.

Note that leaving the self-test configured to run periodically just gives you more opportunities for this "shutdown" to happen. APC simply skimped on their BMS when they designed these things in the hope that "staff" would eagerly replace batteries (instead of designing for longer battery life).

[UPS should note the frequency of outages where it is deployed and adjust the battery management strategy to maximize battery "value", in those circumstances. I.e., in a deployment where outage are frequent and prolonged, you'd want to minimize recharge time to be prepared for the next outage. OTOH, where outages are infrequent or brief, the emphasis should be on being as "gentle" to the battery as possible -- to extend it's lifespan to cover more (infrequent!) outages.]

Last edited by Curious.George; 09-27-2020 at 11:06 AM..
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Old 09-27-2020, 05:44 PM   #4
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Default Re: Fwiw: Apc ups

Why not use a line conditioner so you do have the battery backup stress out so much

( one note some battery backup do have a line conditioning to some existent but I do not necessarily trust that this function does not still have a stress on the battery )

I had to this myself many years ago because of battery failure to often
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Old 09-27-2020, 06:38 PM   #5
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Default Re: Fwiw: Apc ups

my ups did self test and failed at night then in the early morning i was awoken to a car battery exploding .. this thing doesn't even have a connection to a computer . well apart from the mains power bit . yes i run my emergency power off car batteries .
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Old 09-27-2020, 06:51 PM   #6
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Default Re: Fwiw: Apc ups

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Originally Posted by sam_sam_sam View Post
Why not use a line conditioner so you do have the battery backup stress out so much
We rarely have outages. At times, we encounter "switching transients" as the utility changes how our portion of the network is fed. These are just "light blinks" but can crash some devices with poorly sized power supplies.

I believe the problem lies in how APC deals with the battery and its maintenance. They are too aggressive in getting it back online (at least, for MY needs cuz I can afford to wait 24 hours for it to replenish the charge consumed backing up my load for a 1 second "light flash").

I've been salvaging MCUs from them with an eye towards reverse engineering the code to be less aggressive in their charging strategy...

But, it's not risen to a high enough level of importance to preempt any of the more interesting things I'm working on (I can always just buy/rescue batteries to kick the problem down the road)
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Old 09-27-2020, 07:56 PM   #7
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Default Re: Fwiw: Apc ups

If you ever figure out how to make this less aggressive please post what you did to fix this issue
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Old 09-27-2020, 10:29 PM   #8
Curious.George
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Default Re: Fwiw: Apc ups

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Originally Posted by sam_sam_sam View Post
If you ever figure out how to make this less aggressive please post what you did to fix this issue
As I said, the RIGHT solution is for the UPS to "take notes" about the conditions its been operating in (after all, it is likely on 24/7/365!) and how often it encounters outages, how long they are, how deeply the battery discharges, how long before the NEXT outage, etc.

That's far too much work for me -- as I already KNOW how the UPSs are "taxed" by my loads and local power.

So, I'll just tweek things to fit THAT sort of operating environment instead of trying to "do it right" (APC isn't paying me so why should I do their work for them?)
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Old 10-03-2020, 10:00 AM   #9
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Default Re: Fwiw: Apc ups

Please check out the APC Smart-UPS float voltage experiment:

https://www.badcaps.net/forum/showthread.php?t=7872
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Old 10-06-2020, 08:54 PM   #10
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Default Re: Fwiw: Apc ups

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Originally Posted by Per Hansson View Post
Please check out the APC Smart-UPS float voltage experiment:

https://www.badcaps.net/forum/showthread.php?t=7872
You can't "fix" the problem by tweaking the analog portion of the circuit. You need to add smarts to how (and when) you apply charging rules. You do that by tweeking the code in the microcontroller.
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Old 10-11-2020, 12:01 PM   #11
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Default Re: Fwiw: Apc ups

I didn't know you had access to the APC source code.

I think you mentioned elsewhere that you do not buy original batteries from APC.
That is good because they are crap and have a lifetime of 2 to 3 years tops in my experience.
For me I have had great success with CT Leader batteries that have a 10 year design lifespan.
I have gotten from 5 to 7 years out of them which I think is phenomenal.
Elfa orderno: 169-47-907 CT Leader CTH17-12 for use in APC Smart-UPS 1500
Elfa orderno: 169-10-293 CT Leader CTH7-12F1 for use in APC Smart-UPS 750
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Old 10-11-2020, 12:28 PM   #12
Curious.George
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Default Re: Fwiw: Apc ups

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Originally Posted by Per Hansson View Post
I didn't know you had access to the APC source code.
I don't. Instead, I "pull" the MCUs from UPSs and decompile the code. They aren't particularly complex devices (the only complexity resides in the NMCs and understanding those isn't essential to understanding how the UPS is designed to operate -- esp as many treat NMCs as "options").

They're relatively trivial devices, few I/Os, etc. And, obviously built around hardware that doesn't place battery life at the top of its priorities. (I can't begin to tell you how many "bulging batteries" I've encountered in APC products)

Quote:
I think you mentioned elsewhere that you do not buy original batteries from APC.
That is good because they are crap and have a lifetime of 2 to 3 years tops in my experience.
They are also overpriced.

Quote:
For me I have had great success with CT Leader batteries that have a 10 year design lifespan.
I have gotten from 5 to 7 years out of them which I think is phenomenal.
Elfa orderno: 169-47-907 CT Leader CTH17-12 for use in APC Smart-UPS 1500
Elfa orderno: 169-10-293 CT Leader CTH7-12F1 for use in APC Smart-UPS 750
Thanks for the tip. Most of my batteries are rescue from UPSs that I'm not otherwise interested in rescuing (we see A LOT of discarded UPSs... pallets at a time!). For that reason, I've tried to only use UPSs that are (mechanically) built around 12V 7.5AHr batteries -- typically 4 of these in a "module".

One reason I'm hesitant to rescue the Matrix 5000 is that it is built around 75AHr batteries... considerably harder to come across and very expensive to replace!
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