TheMG
join:2007-09-04
Edmonton, AB
 ·TELUS
| reply to migr
Re: Home UPS powered by car battery
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. |
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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. |
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SparkChaser
BURY BECK
Premium
join:2000-06-06
Downingtown, PA
 ·Verizon FIOS
 ·Comcast
| reply to CajunWon
There are 2 threads going here. The first is 3 months old and mentioned 14GA.
The latest by migr  who is using 16mm (about 5GA) and 5 mm (about 10GA) (damn metric wire)  |
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CajunWon
join:2005-12-30
Cary, NC
 ·ViaTalk
| 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. |
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SparkChaser
BURY BECK
Premium
join:2000-06-06
Downingtown, PA
·Verizon FIOS
·Comcast
| 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 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.
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"Facts do not cease to exist because they are ignored." - Aldous Huxley
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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 |
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SparkChaser
BURY BECK
Premium
join:2000-06-06
Downingtown, PA
·Verizon FIOS
·Comcast
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. |
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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. |
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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.
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Is fire supposed to shoot out of it like that?
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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? |
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migr
join:2008-01-04
| ok 1st point, how long does it take to get to 0 min, about 30 sec and it doesnt make a difference weather it thinks it has no external batteries or 12 external batteries.
i ran the calibration but it gets to 25% bat in secconds so it doesnt really get a chance. it just believes they are dead when they are not
the batteries, well i am running 2 banks of 12v batteries. the 1st bank is a set of 2 12v gel cell deep cycle batteries designed to hold up a local pay tv network for hours. they are usually mounted up power polls and linked to an inverter for years at a time. the seccond set is a set of 2 x 12v truck batteries. these are absolutetely huge. not really designed for deep cycle but have like 175 amp hours so will certainly help the up time and are tested to be fine. |
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migr
join:2008-01-04 | reply to SparkChaser
sorry m8, i wasnt having a go at you. just trying to clarify the sizes so others didnt think i was useing tiny wire. my apoligies if you thought otherwise |
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SmokChsr
Who let the magic smoke out?
Premium
join:2006-03-17
Saint Augustine, FL
| reply to migr
said by migr :i ran the calibration but it gets to 25% bat in secconds so it doesnt really get a chance. it just believes they are dead when they are not In this case I would have to soy something is flaky with the UPS. The only judge of battery that the UPS has is normally voltage. With this new information I would tend to think that the threshold voltage is set improperly. I don't suppose there is any way that the UPS was actually designed to run on 24V using 2 batteries in series is there and now you are running 12V? That of course would tend to try to overcharge the battery. |
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migr
join:2008-01-04
1 edit | no i am running 24v m8, i have 2 x banks of 2 batteries, so in total i have 4 batteries so i have 2 x bats of the same sort making up 24v then i have another 2 x 12v bats making up another 24v then i parallel the 2 banks of 24v. the origional bats were just the same but on a smaller scale and without the 2nd bank.
The unit was designed to run with 24v and thats what i have provided it with but just with larger capasity batteries. |
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SmokChsr
Who let the magic smoke out?
Premium
join:2006-03-17
Saint Augustine, FL | In that case.. It looks like the UPS battery sense circuit has a problem. |
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ericrazar
join:2007-11-04
Orlando, FL
| reply to migr
ok migr. I just read you response and it seems your UPS has an issue. Is the unit fairly new model? The apc smart UPS ones I used were built in 1999 and another in 2000. The only other thing I would ask is if you had the original dual 12v 12amp hour batteries in the unit would it work correctly at both low and high loads. I also had a newer apc 1500 model used the the DUAL 125 amp hour batteries for a test setup at my job to hold an environmental chamber up during a possible power outage. The chamber in heat mode would cycle up to 6 amps @120 for several seconds each minute and 1 amp the rest of the time. I ran a check with that setup for almost an hour before I know about the reprogramming advantage with hyperterm. So it sounds like your UPS has an issue unless it works correctly with the original batteries or you have a defect in your harness hookup that causes too much drop at higher loads making the ups think the battery is dead. |
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migr
join:2008-01-04
| the unit is 9 years old, as are the origional batteries that i took out of it so those bats are no good for anything. the cables from the batteries to the unit are top notch, its the same cabling we use to run -48vdc perminently in telephone exchanges all over australia. this cable is capable of carrying a constaint -48v @90a and the terminations are the same that i use in the exchange also. the problem is with the unit its self. i updated the unit so that it now believes new batteries were installed a couple of days ago instead of 9 years ago likt it was when i 1st aquired the unit. i think its a lost cause. atm i am running it in dumb mode. if the power goes down it will hold my rack for 8 hours and thats all that matters, but it would be nice to be able to monitor the battery status via the serial port the way it was intended. |
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ericrazar
join:2007-11-04
Orlando, FL
| ok migr. I just discovered something about one of my SU1000 that made one read much lower minute run time than the other. It has to do with the battery constant. With hyperterm after you type Y and get SM back type 0 (zero not letter O). You should get back A0 if you dont then the battery constant is screwed up. On one of my units it read 55 which gave me 20 min estimated run time on the other (A0 one) it gave 45 min. This was when both had 000 external battery packs. Raising the battery pack to 001 for the 55 unit made it work to 45 min also. I suspect your constant must be really low so that adding battery packs in hyperterm doesnt help. I also found you cant readjust the battery constant it in hyperterm. I did find you can fix it with APCFIX.exe .
»apc-fix.com/page.php?id=22
Go to the download link on that page bottom and extract the RAR file. Shut down your hyperterm or powerchute software. Run APCFIX and choose com port. Go to options in upper left hand corner and click both the battery constant auto fix and the hex code detection on. I had to close the program then and restart it then pick com port again then it automatically would fix my "0" battery constant from 55 to A0. Then when you add battery packs (with hyperterm) it should work right again and give you proper minutes with your external batteries and with powerchute running. It is good this issue came up because I have a somewhat similar problem with a apc3000 that has short run time too even with modest loads and good batteries. You made me go back and look harder for a better solution.  BTW For a 24 volt system each external apc pack equals ~36 amp hr capacity. So 5 packs equals ~180 amp hr and 10 packs ~360amphr This would help you to get the run time minutes roughly "right" when equating to your external battery setup. In your case I would adjust the battery count till your estimated run minutes equals 480 or more or so at the 44% load. It seems wet cells require you to "lie" to the UPS and say you have more batteries than actaul amphour amount. I ended up with 5 external batt setting myself for my 125amp marine batt pack.
The
www.apcupsd.com
website PDF manual has most of the info on the codes.
GOOD luck !!!! |
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public
join:2002-01-19
Santa Clara, CA
·DSL EXTREME
| said by ericrazar : It is good this issue came up because I have a somewhat similar problem with a apc3000 that has short run time too even with modest loads and good batteries. You made me go back and look harder for a better solution. SU3000 should never be used with the internal microscopic batteries at heavy load unless you like seeing flames.
Wet cell batteries used by telcos have lower terminal voltage than the sealed agm types for which the ups is preset. Hence some of your problems.
If you use apc ups's get one of the smart slot management cards and do not waste time with serial ports or terminal emulators. |
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ericrazar
join:2007-11-04
Orlando, FL
| PUBLIC :
MY SU3000 is the 5 U rack mount type with 4 x 20 amp hr gel cells. I would get only 10-15 minutes with a less than 500 watt load with old or newer OEM style gel cells. My 2200 with the same new batteries at work would last ~25 min with a 800W load. See the discrepancy? Now that I realize the battery constant issue I expect it should be a non issue once I fix the constant back to factory. At the time I put the unit aside thinking it was defective in some way. AS you see from all my earlier posts the issue is the APC UPS's use a coulomb counter feature that measures the actual amp/hours that flowed to and from the battery to determine minutes remaining. This is just like the battery circuit in a laptop. The battery terminal voltage is only part of the story. What actually happens is as the battery ages and it get discharged during an outage or during a "cal" it modifies that battery constant as the usable amphr capacity goes down. What is bad is APC doesn't seem to have a convenient way to reset that to factory other than what I found. My APC 1000 with the wet cells give excellent run time (12 hrs at 160watts) if the external batteries modules and battery constant are set correctly. While I agree that the wet flooded cells don't quite have the low internal impedance and surface charge voltage the GEL type have it is obvious the real problems are the constants and not the chemistry. |
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