UPS misconceptions

Cool thanks never knew that and also now know why a clients stuff went boom.
 
We just installed a double online APC UPS after having to replace our servers mobo twice this year. The monitoring tools on it are really cool as it logs the voltages from the wall continuously - reports show some very unstable current coming into our building! Nice thing about the model we got was the ability to daisychain mulitple external battery packs to the ups for extended runtime. Was expensive, but feel so much better having it - more so for the power conditioning than the blackout protection.
 
Messugga said:
Want to know a secret? You can do this with any UPS.
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Can't. The charger normally isn't big enough. That's why APC make their XL models - bigger charger and an external battery plug. Even with his APC, it isn't recommended to daisy chain the full 10 batteries.
 
zamicro said:
Yes you can. The only problem if the charger is small, is that it will take a long time to recharge.
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facepalm.jpg


edit: why don't any of the buttons work?
 
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Drunkard #1 said:
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I take an electrical engineer who was responsible for implementing 90% of the electrical structures in Bloemfontein and around 40 years of experience under the belt, with a full solar setup's opinion over yours. zamicro's correct. The only possible issue is with the batteries pulling more current than the charger can supply, which frankly, should be handled by the UPS internally.
And for the record, I have 5 external batteries hooked up to a R400 UPS, so yeah.
 
Enjoy your frankenUPS, but don't call me when you burn out your charger, call your engineer. My UPSs cost a bit more than R400, so I'll take proper care of mine.
 
Drunkard #1 said:
Enjoy your frankenUPS, but don't call me when you burn out your charger, call your engineer. My UPSs cost a bit more than R400, so I'll take proper care of mine.
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Righto. We actually know how to design and build them from scratch. Please explain to me how you overheat something when you implement current limitation. I'd love to hear your reasoning.
 
Drunkard #1 said:
Enjoy your frankenUPS, but don't call me when you burn out your charger, call your engineer. My UPSs cost a bit more than R400, so I'll take proper care of mine.
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Lead-acid batteries are charged by charging them with a source with a limited current and constant voltage once the current drops below that limit... Charging lots of batteries should work, provided that all batteries are working.... (Another problem might be a charger that is not cooled properly and can't operate continuously...) (And supplying 3 amp to 10 batteries will result in a really slow charge...)
 
Messugga said:
Righto. We actually know how to design and build them from scratch. Please explain to me how you overheat something when you implement current limitation. I'd love to hear your reasoning.
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With "daisy chaining", do you mean a series connection or a parallel connection. The obvious would be parallel, but in general the term refers to series connections. If it is a series connection, you push up the voltage, and I'd be surprised if the charger or the inverter works.

Parallel is a different matter: you keep the voltage constant, but you increase the total battery life. In that case it might work. Yes, in certain instances it will work, but in others not. If a lead-acid battery is not charged according to the correct charge profile, it's total life can be decreased. With multiple batteries charging off the same charger designed to charge only one, you forego the advantages of a intelligent charger that takes the battery's characteristics into account. I.e. it will not monitor the batteries' temperature, it will not decrease the charging voltage at the correct time, etc.

Also, I presume that your current limiting is on the inverter side? If not, be careful of overloading the inverter. Cheapie inverters will not necessarily have overload protection, and if you overload it it might just join the South-African workforce in a violent strike action. The components inside (think inductor, caps, transistors) are designed with a few criteria in mind, amongst others are: cost, current rating, switching time. For cheapies, the trade-off between cost and current will be in favour of cost, meaning that they can't handle as much as the batteries provide. Actually, the current limitation applies to ALL inverters, but you're more likely to meet it with cheapies.

I tried to type in laymen's terms - please excuse me if you already knew all this. I'd just prefer not to have someone reading this think that he can driver his house solar/battery system from i.e. a Telkom UPS...
 
Tacet said:
With "daisy chaining", do you mean a series connection or a parallel connection. The obvious would be parallel, but in general the term refers to series connections. If it is a series connection, you push up the voltage, and I'd be surprised if the charger or the inverter works.

Parallel is a different matter: you keep the voltage constant, but you increase the total battery life. In that case it might work. Yes, in certain instances it will work, but in others not. If a lead-acid battery is not charged according to the correct charge profile, it's total life can be decreased. With multiple batteries charging off the same charger designed to charge only one, you forego the advantages of a intelligent charger that takes the battery's characteristics into account. I.e. it will not monitor the batteries' temperature, it will not decrease the charging voltage at the correct time, etc.

Also, I presume that your current limiting is on the inverter side? If not, be careful of overloading the inverter. Cheapie inverters will not necessarily have overload protection, and if you overload it it might just join the South-African workforce in a violent strike action. The components inside (think inductor, caps, transistors) are designed with a few criteria in mind, amongst others are: cost, current rating, switching time. For cheapies, the trade-off between cost and current will be in favour of cost, meaning that they can't handle as much as the batteries provide. Actually, the current limitation applies to ALL inverters, but you're more likely to meet it with cheapies.

I tried to type in laymen's terms - please excuse me if you already knew all this. I'd just prefer not to have someone reading this think that he can driver his house solar/battery system from i.e. a Telkom UPS...
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Thanks for the reply.

I had something typed up in response, but realized that I'm just agreeing with you on all fronts. Interestingly enough, I've found some cheap UPS units to actually be smarter than one would think, and learning the characteristics of the battery setup, to an extent. That being said, I'm sure that it's not ideal with regards to battery life, but when you're talking about a few hundred Rand worth of batteries, it's not such a big deal as R4000 each units.

Also, I'd like to emphasize your point that people shouldn't attempt to drive anything outside of the UPS's parameters. It's a good way to kill your UPS. Adding one or two extra batteries to a cheaper UPS is an excellent way to increase capacity though, and worth the effort of looking into, in my opinion. People who are interested can probably find quite a bit on it by doing a bit of Googling.
 
Messugga said:
Thanks for the reply.

I had something typed up in response, but realized that I'm just agreeing with you on all fronts. Interestingly enough, I've found some cheap UPS units to actually be smarter than one would think, and learning the characteristics of the battery setup, to an extent. That being said, I'm sure that it's not ideal with regards to battery life, but when you're talking about a few hundred Rand worth of batteries, it's not such a big deal as R4000 each units.

Also, I'd like to emphasize your point that people shouldn't attempt to drive anything outside of the UPS's parameters. It's a good way to kill your UPS. Adding one or two extra batteries to a cheaper UPS is an excellent way to increase capacity though, and worth the effort of looking into, in my opinion. People who are interested can probably find quite a bit on it by doing a bit of Googling.
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Even the cheap ones should - lead acid batteries are fairly similar, and in a parallel setup you might even have the same batteries, which will discharge at roughly the same rate, with very similar characteristics. It is a good way of increasing capacity, though it will void your warranty. :-p I've actually read a few articles on this before, so yeah, it is on google, and if you're willing to take the risks, go for it!
 
Messugga said:
Also, I'd like to emphasize your point that people shouldn't attempt to drive anything outside of the UPS's parameters. It's a good way to kill your UPS. Adding one or two extra batteries to a cheaper UPS is an excellent way to increase capacity though, and worth the effort of looking into, in my opinion. People who are interested can probably find quite a bit on it by doing a bit of Googling.
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(Except for the VA ratings and possible assumptions about max-on-time for the inverter which may result in overheating... (Which is mostly what I understand under "...people shouldn't attempt to drive anything outside of the UPS's parameters...."))

One issue: An cheap UPS should not be used to drive certain loads for extended times.. They typically have "simulated sine wave" / "modified block wave" / "stepped sine wave" output which is usually not the best thing to feed to some loads... (it is mostly a block wave with the same peak as the sine wave of the same voltage, but with an off time...) (http://www.tomshardware.com/news/ocz-ups-battery-backup,7489.html have an image... I'm sure some UPSes have better approximations and that some filtering and the transformers also improves the final waveform under load...)

These waves have higher frequency harmonics which may / may not mess around with some loads... (with audio devices the most obvious issue...)
 
MoHaG said:
(Except for the VA ratings and possible assumptions about max-on-time for the inverter which may result in overheating... (Which is mostly what I understand under "...people shouldn't attempt to drive anything outside of the UPS's parameters...."))

One issue: An cheap UPS should not be used to drive certain loads for extended times.. They typically have "simulated sine wave" / "modified block wave" / "stepped sine wave" output which is usually not the best thing to feed to some loads... (it is mostly a block wave with the same peak as the sine wave of the same voltage, but with an off time...) (http://www.tomshardware.com/news/ocz-ups-battery-backup,7489.html have an image... I'm sure some UPSes have better approximations and that some filtering and the transformers also improves the final waveform under load...)

These waves have higher frequency harmonics which may / may not mess around with some loads... (with audio devices the most obvious issue...)
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That refers to the amount of juice being pulled from the UPS when there isn't mains power - doesn't have anything to do with the battery capacity.
 
Messugga said:
Righto. We actually know how to design and build them from scratch. Please explain to me how you overheat something when you implement current limitation. I'd love to hear your reasoning.
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A condescending engineer that's completely missed the point:rolleyes:, never seen one of those before. <-- can you feel the sarcasm?
 
In South Africa it makes absolute sense to use notebooks as workstations at your company....and notebooks are easier to move around. :)
 
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