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CajunWon

join:2005-12-30
Cary, NC

1 edit

Home UPS powered by car battery

I researched the possible side effects of replacing the APC ES350 UPS battery with a standard car battery. Those that found the risks acceptable claimed many hours and even days of stand-by backup power. I selected a Marine 665 Starting battery and made certain it had a full charge when connected.

Wondering why it only provides ~20 minutes of backup power?

Power died at the house today, so I plug my laptop into this UPS. ~20 minutes later I'm running off the Laptop battery alone. Then the APC 550/UPS which powers my router/modem/ATA begins the 1-sec interval beeping. I get that battery and connect a 400W inverter which powers: Laptop; Router; Cable Modem; VOIP ATA. It's still working great, hours later and I'm still working, calling, surfing. And the battery is still reading at least 12volts, cheap analog volt-meter.

edit: Didn't fail - user error.



SparkChaser
Premium
join:2000-06-06
Downingtown, PA
kudos:3
Reviews:
·Verizon FiOS

1 edit

Re: Home UPS powered by car battery: failed

said by CajunWon:

Wondering why it only provides ~20 minutes of backup power?

Power died at the house today, so I plug my laptop into this UPS. ~20 minutes later I'm running off the Laptop battery alone. Then the APC 550/UPS which powers my router/modem/ATA begins the 1-sec interval beeping. I get that battery and connect a 400W inverter which powers: Laptop; Router; Cable Modem; VOIP ATA. It's still working great, hours later and I'm still working, calling, surfing. And the battery is still reading at least 12volts, cheap analog volt-meter.
I'm a bit confused as to what is happening. Would you restate the problem?
--
"Facts do not cease to exist because they are ignored." - Aldous Huxley


CajunWon

join:2005-12-30
Cary, NC

1 edit

How can I get hours, instead of minutes, from a large 'car type' battery attached to an APC UPS?

Especially considering the same battery then (without recharging) continues to power more equipment for many hours through a standalone 400W inverter.

My goal is to get extended protection from my APC UPS 'on the cheap'.



SparkChaser
Premium
join:2000-06-06
Downingtown, PA
kudos:3
Reviews:
·Verizon FiOS
reply to CajunWon

My guess would be that there is a voltage sense circuit that is monitoring the battery voltage and the marine battery is falling below what it (the APC) thinks a good battery is.
--
"Facts do not cease to exist because they are ignored." - Aldous Huxley



drjim
Premium,MVM
join:2000-06-13
Long Beach, CA
kudos:3
reply to CajunWon

Is this a Deep Cycle battery? If it's a "regular" starting battery, also called an SLI, it will have it's voltage drop faster under a constant load than a deep cycle battery will. It also won't last as long in this type of cyclic service as a deep cycle will.
--
One man's Magic is another man's Engineering.



CajunWon

join:2005-12-30
Cary, NC

Thanks for the responses.

Starting battery, I had a spare for this test project. It's a marine grade battery.

AFAIK: Starting batteries are able to dump voltage faster as required as they tend to have more and thinner plates. But if high amps are not required then it shouldn't drop its' volt reading any quicker. Deep cycle & heavy duty batteries should be more difficult to sulfate the plates and therefore should recover from many near full discharges. But in my application, I should discharge the battery no more than once - 5 years, avg 5 2 hour black-outs/yr, & need no more than 1.7 amps with 1 amp avg.

I'm no EE so correct me where wrong.



sdgthy

@optonline.net

Batteries that aren't meant for deep discharge will sulphate if they are deep discharged even once. Once they've begun to sulphate, it only gets worse.

A "12 volt" battery at 12 volts is quite low as fully charged they should be at about 13.8 volts. The UPS is gonna check the voltage to determine when the battery is getting discharged by checking the voltage. So although you have a higher capacity battery that could maintain current for longer at the lower voltage, the UPS has already decided the battery is nearly discharged and it's no longer safe to continue.



Axilla
Finger, Finger
Premium,MVM,Ex-Mod 2004-13
join:2001-03-26
Schofield, WI

In fact when you start getting into big "12v" batteries for backup power applications they recommend float charge voltages that can be all the way up to 14.5 volts depending on the battery type.



shortckt
Watchen Das Blinken Lights
Premium
join:2000-12-05
Tenant Hell
reply to CajunWon

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.
--
watchen das blinkenlights


CajunWon

join:2005-12-30
Cary, NC

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.



drjim
Premium,MVM
join:2000-06-13
Long Beach, CA
kudos:3

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.
--
One man's Magic is another man's Engineering.



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/
--
watchen das blinkenlights


CajunWon

join:2005-12-30
Cary, NC

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)


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


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


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.


migr

join:2008-01-04
reply to CajunWon

Re: Home UPS powered by car battery

i was wondering if there was a way to change the nominal voltage it expects to see from the batteries. i have 4 very large batteries. they arent deep cycle but it doesnt matter. if i kill them i just get new ones for free. they are capable of holding my system for up to 8 hours at 44% load on a smart-ups 1001. i added 10 bateries via terminal and that gave a massive time increase when i only have a 9% load on it but as soon as i add my server to it which has 9hdds in it and takes the total load to 44% the estimated run time drops to 0 min. all i can think is to reduce the nominal voltage expected from the batteries because they do drop voltage at the beginning but then levels off at about 24.9 volts and holds there for hours with minor fluctuations. basicly i dont want the ups to shut down my server but i still want to be able to monitor it. anyone know how to change the nominal voltage


srr2

join:2001-12-20
Bethlehem, PA
Reviews:
·RCN CABLE
reply to CajunWon

14Ga wire? That's probably your problem. You should assume currents of 40A to 50A for operating an inverter. I'd use nothing smaller than 8Ga or even heavier depending on how long the leads are.

The currents drawn by inverters can be very high. Milliohms make a difference. In large stationary UPSs with this type of battery it's not unusual to find 0000Ga interconnects.


migr

join:2008-01-04

im useing 16mmcable from the 2nd set of batteries and 5mm from the 1st set to the ups, the 5mm lengts is only about 500mm long

i would have thought that was more than adiquit being as i have connected it to the existing wireing inside which is 5mm or less?


migr

join:2008-01-04
reply to srr2

on your advice i have replaced the cabling from the 1st battery set to the ups with 16mm which is about 5 x the size of the 10g that is internal, i had to leave about 30mm of 10g at the end as it is soldered directly onto the board of the ups and my 16mm will be impossable to solder there. it made no difference sorry m8, any other ideas


TheMG
Premium
join:2007-09-04
Canada
kudos:3
Reviews:
·NorthWest Tel

You'd have to look at the UPS circuitry. By luck there might be a potentiometer in there or some resistors that set the reference voltage or sensitivity for the ADC it probably uses to sample the battery voltage for the CPU.

To do that though, you need a good understanding of how these types of circuits work. Otherwise it will mean absolutely nothing to you. Don't just go in there turning random pots if you are not sure.



SmokChsr
Who let the magic smoke out?
Premium
join:2006-03-17
Saint Augustine, FL
reply to CajunWon

I didn't see a specific response to this particular point, but your #14 wire is too SMALL.. You'll need at a minimum #10, if you have extended the leads from the UPS at all. The Voltage drop on the wire along with the dropping voltage of the battery could very easily account for the early shut off. Also make sure you have good solid connections at every point in the path.

Keep in mind that when you are trying to draw 0.7 amps @120V for your laptop that equates to at least 7.0 Amps (if their were no losses {which there are}) at 12V from the battery. In the real world you are probably drawing between 11-15 times the amount of current at 12V than your load at 120V.



SparkChaser
Premium
join:2000-06-06
Downingtown, PA
kudos:3
Reviews:
·Verizon FiOS
reply to CajunWon

There are 2 threads going here. The first is 3 months old and mentioned 14GA.

The latest by migr See Profile who is using 16mm (about 5GA) and 5 mm (about 10GA) (damn metric wire)



CajunWon

join:2005-12-30
Cary, NC
reply to SmokChsr

said by SmokChsr:

when you are trying to draw 0.7 amps @120V for your laptop that equates to at least 7.0 Amps (if their were no losses {which there are}) at 12V from the battery. In the real world you are probably drawing between 11-15 times the amount of current at 12V than your load at 120V.
Didn't know of this DC/AC Amp multiplier, would be nice to learn more of this aspect through on-line reference. My uneducated thoughts are that (given the same load requirement) there should be no more Amps delivered from a large battery than the oem battery if 6' of 14ga wire introduces negligible line loss.

btw: still using this setup which has worked well through a few power outages and many brown-outs.


SparkChaser
Premium
join:2000-06-06
Downingtown, PA
kudos:3
Reviews:
·Verizon FiOS

said by CajunWon:

Didn't know of this DC/AC Amp multiplier, would be nice to learn more of this aspect through on-line reference.

All SmokChsr See Profile was saying is that the power will at least stay the same. 120V @0.7A= 84 watts, so 84watts/12V =7A that's at 100% efficiency, which it won't be.
--

"Facts do not cease to exist because they are ignored." - Aldous Huxley

migr

join:2008-01-04
reply to SparkChaser

no 16mm is more like 8guage, and 5mm is like 10guage, but i have 16mm all over now so thats not an issue, the stuff i have used is the same stuff i use in telephone exchanges to carry a constaint 63amp load to critical gear. and thats all neg 48vdc so i know its capable of doing the job. so to recap, the cable size as a possable problem has been eliminated and the terminations are also not an issue as they are profesionally done by myself, its my job



SparkChaser
Premium
join:2000-06-06
Downingtown, PA
kudos:3
Reviews:
·Verizon FiOS

1 edit

said by migr:

no 16mm is more like 8guage, and 5mm is like 10guage
Believe me, I wouldn't have a clue I looked here »www.simetric.co.uk/siwire_elect.htm It says between 5 and 6

I use metric for almost everything but wire gauge.


electric6

@ameritech.net
reply to CajunWon

said by CajunWon:

6' of 14ga wire introduces negligible line loss.

btw: still using this setup which has worked well through a few power outages and many brown-outs.
Some suggestions.
Do not waste time on the little throw away apc models. Get at least SU1000 or SU1400. These go for about $50-100 on ebay. Then get a web management card for the smart slot so that you can easily monitor what the ups is doing.
The battery thresholds are not user programmable, but you can specify external batteries and extend the run time to hours. SU1400 and bigger have internal fans, but for your load it does not really matter.
User bigger AWG wire, 6' is a long piece. Use fine stranded wire that bends easily.
AGM type batteries are sometimes available at reasonable price, a couple of 12V 100Ah AGM batteries would be a lot safer than wet cells.


SmokChsr
Who let the magic smoke out?
Premium
join:2006-03-17
Saint Augustine, FL
reply to CajunWon

said by CajunWon:

Didn't know of this DC/AC Amp multiplier, would be nice to learn more of this aspect through on-line reference. My uneducated thoughts are that (given the same load requirement) there should be no more Amps delivered from a large battery than the oem battery if 6' of 14ga wire introduces negligible line loss.
Yes the Current draw would be the same on either battery. Not having looked up this particular UPS, normally the OEM will use very short leads to the battery to minimize the line loss. When connecting longer leads to an external battery then you would want to increase the wire size to compensate for the line loss.
--
Is fire supposed to shoot out of it like that?

ericrazar

join:2007-11-04
Orlando, FL
reply to migr

When you tried running with the server you said the estimated minutes goes to 0. but you also said that this setup runs the equipment for 8 hrs on 44% load. How long does it take to go to 0 estimated minutes? Right away or after several hours? To help you out I can share what happened to me when i set my SU1000 to 10 external batteries. At first with 25% load I ran a "cal" the estimated percent left (not minutes) stayed high for several hours. It evenually got to 0% near the 12 hour point before going back to ac power (meaning finish cal).
For you I would suggest trying doing a "cal" with the new battery coding to see if it needs to "learn" the estimated minutes. Another thing you can try is to increase the number of batteries to more than 10. I found programing to 20-30 can make the ups think it has power for thousands of minutes. The number can go as high as 255 i found. I expect it will still go to 0 minutes or 0% battery left when the battery is depleted but should get there only when the battery is really dead. It sounds like your UPS thinks the battery is dead to early for some reason. If your battery voltage is still 24.9 with the 44% load then your battery pack setup is good. mine ran something like that also (12v 125 amp hr. times 2) at the 25% LOAD. what kind of batteries you using? 6volt golf cart batteries?