shortckt
Watchen Das Blinken Lights
Premium
join:2000-12-05
Tenant Hell
| reply to CajunWon
Home UPS powered by car battery: failed
said by CajunWon  :...replacing the APC ES350 UPS battery with a standard car battery... Wondering why it only provides ~20 minutes of backup power? I looked up the info on the model ES350 and while it is one of the economy models it appears to have on board cpu since it can perform weekly battery tests and has a serial port to use with software to shutdown a computer when power fails. That being said, my experience with APC UPS units is one of these possibilities:
1- the UPS is overheating after 20 minutes running and shuts down. Overheating is definitely possible with these ES models as they don't have any cooling fan and I don't think they even have any vents. The electronics and battery are all in one plastic box, and they have small batteries so are designed with the expectation the inverter will run for a short time.
2- it has been programmed to shutdown after battery reaches x% discharge (instead of full discharge). This and many other operating parameters can be changed/monitored by using the APC PowerChute software or APCUPSD open source software, the correct cable and a computer.
3- processor thinks battery has reached full discharge because it is calibrated for original size battery instead of battery 10x capacity of original. All APC 'smart' UPS devices need to be calibrated to the batteries once or twice a year as the battery ages, so the processor can calculate and report the remaining runtime correctly via software (or the front panel for those models that have one.) While not recalibrating could cause runtime to be mis-reported by 10-20% higher under normal circumstances, if you replace the designed battery with another having a capacity orders of magnitude larger, the processor's calculation becomes meaningless.
As you have seen, the battery voltage under load is not the only determining factor for UPS shutdown in the 'smart' devices. It will shutdown sooner than expected if the battery voltage goes below a set threshold, otherwise the programming sets the shutdown parameters.
One way to confirm the reason for shutdown is to connect a computer and use the software to monitor what the UPS is doing. Another test would be to put a power supply across the battery to prevent it from discharging while the UPS runs on battery.
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watchen das blinkenlights |
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CajunWon
join:2005-12-30
Cary, NC
 ·ViaTalk
1 edit | Thanks again, appreciate your time on my little project.
1- The UPS (and the 14ga wires to my battery) should handle 2.5 amps for ~10 minutes without overheating. Both the UPS and wires remained cool to touch (not that that means a whole lot). I was drawing less than 0.7 amps for the laptop as the only connected device. The UPS began the 1 second interval alarm very soon after connecting the laptop. I disconnected the laptop and turned-off the UPS to reset and it would not come back on -even after connecting another charged/newer car starting battery. Perhaps it would have continued powering if I hadn't shut it down?
2 - Although the powerchute software does control the % discharge b4 beginning orderly shutdown, without the software the UPS is supposed to remain on until complete discharge as calculated by its' cpu. I don't think the software allows changing what the cpu thinks is a minimum charge.
3- Wonder if there's a way to hard reset the threshold of how low the battery voltage can be within the APC 350.
I'll install the Powerchute software to see what's available to change monitor.
btw: I did drain the battery significantly after several hours on my 400W car inverter and my cheap volt meter continued to read ~12 volts (could have been 11-14 volts as the scale is hard to read). It took nearly 3 hours to recharge. The inverter & wires remained cool. I would think the APC is of better quality than my Xantrec inverter. |
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drjim
Premium,MVM
join:2000-06-13
Torrance, CA
clubs:
| Not to be picky about your voltmeter, but if you can't really read the difference between "11-14 Volts", it's time to get a better meter!
I have 4 APC units here, both SmartUPS and BackUPS, and they make a big deal about running the calibration routine every time you change the battery, even if you replace it with an identical one.
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One man's Magic is another man's Engineering. |
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shortckt
Watchen Das Blinken Lights
Premium
join:2000-12-05
Tenant Hell
| reply to CajunWon
said by CajunWon :1- ...The UPS began the 1 second interval alarm very soon after connecting the laptop... I disconnected the laptop and turned-off the UPS to reset and it would not come back on -even after connecting another charged/newer car starting battery... You tried to restart the UPS with or without AC mains power applied? Some UPS models are designed to allow "cold restart" without AC and others not.
Anyway, I guess we can rule out overheating.
What happens if you just let it run after it begins the "2 minutes remaining" alarm?
2 - Although the powerchute software does control the % discharge b4 beginning orderly shutdown, without the software the UPS is supposed to remain on until complete discharge as calculated by its' cpu. I don't think the software allows changing what the cpu thinks is a minimum charge.
On some models, the remaining battery before the UPS shuts off. This setting is saved in eeprom and UPS obeys it stand-alone, without any outside software control. Useful if UPS is used to power non-computer items.
3- Wonder if there's a way to hard reset the threshold of how low the battery voltage can be within the APC 350.
Don't know for certain, different models have different capabilities, but my guess would be the dead battery threshold is hard coded into the firmware... however there are some trim pots on the logic board.
...I would think the APC is of better quality than my Xantrec inverter.
Sometimes that can be a bad thing. IMO the "smart" devices are sometimes too smart for their own good.
Along those lines, (just thinking out loud here) could the battery control circuit be thrown off by the internal resistance of the battery? Such a large battery must have different electrical characteristics than the original gel cell.
The folks who created APCUPSd have spent considerable time reverse engineering and documenting the APC brand UPS. Per their manual the CS/ES models are treated, for programming purposes, as "smart" devices just like higher end Smart-UPS.
»www.apcupsd.com/
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watchen das blinkenlights |
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CajunWon
join:2005-12-30
Cary, NC
·ViaTalk
| apcupsd software is interesting, but appearantly not applicable to my setup.
Following a little more research, and to aid others considering this DIY approach to extended UPS protection:
The APC350 cannot know the battery reserve capacity unless using the PowerChutePro software for recalibration. That process would require the APC to fully charge a drained battery -not good for the battery and likely not good for the APC charger. Also the Powerchute software, if running, would perform a shutdown within 3-5 minutes -therefore the software cannot be used with an oversized battery.
Since the APC doesn't know the battery capacity it will begin the 1 second sound warning within 3-5 minutes of power outage, but will continue to output proper current until depletion. If turned Off, the APC will not restart without Utility power present (therefore mine didn't actually fail).
The oversized battery must be externally charged every 6 months and recommended to 'shake' the battery every 6 months.
Use this calculator to estimate reserve time on your chosen battery. Simply input the battery amp our rating and your total equipment hourly usage in amps. »www.smartgauge.co.uk/calcs/peukert3.xls
Amps = Watts/Volts
e.g. 15" monitor 40 Watts; basic desktop PC 85Watts
125 total Watts divided by 120 US Utility Volts = 1 amp/hour
I believe I read the APC350 peaks at 2.5amps but will overheat if sustaining that current.
(again, I'm no EE -just regurgitating what little I've read. YMMV) |
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ericrazar
join:2007-11-04
Orlando, FL
| reply to shortckt
I found you can reprogram com port smartups with a hyperterminal program to "fool" the ups there are more external batteries. the powerchute software should be able to do it on XL series units but when running regular smartups the power chute shows the external batteries as a "grayed" unchangable field.
»www.apcmedia.com/salestools/ASTE···0_EN.pdf |
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ericrazar
join:2007-11-04
Orlando, FL
| I just finished running a new cal for my apc smartups 1000 VA unit after reprogramming it to think it has 10 external batteries like a 1000xl unit using the hyperterminal example link before. I modified My smartups 1000 to use two external 125 amp hour marine batteries in series where before recoding the unit would have similar run time of only 40 or so minutes even with the large batteries. Now I just got 12 hours of discharge from the setup running a 24% ups load (~160 watts) for 12 hrs. For those of you who have a RS232 com port smartups 1000/1400/2200/3000, you should be able to recode them as well to think they have up to 10 external batteries even though they are not the XL series type UPS's. The only issue is the internal charging circuit for the 1000 va ups will take a long time to recharge an external battery that large. I will look into that issue as well eventually with some external supply to charge the battery set.
»www.apcmedia.com/salestools/ASTE···0_EN.pdf |
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mworks
join:2006-06-13
Faison, NC
| One thing to watch when you extend a ups run time is cooling inside the ups. Some were not designed with cooling to allow for several hours running and will overheat causing failure.
I have an apc ups that I extended the run time on with external batteries , but I placed a 12v dc fan inside the case to help with the heat. |
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