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  Are Uninterruptible Power Supplies (UPS) a Scam? 
 
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john albrich May 13, 2012, 08:16pm EDT Reply - Quote - Report Abuse
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Edited: May 13, 2012, 08:28pm EDT

 
>> Re: Are Uninterruptible Power Supplies (UPS) a Scam?
BoT said:
there is a nice little video over at revision3 made by systm
http://revision3.com/systm/hackedups
that might explain a few things on how to go about hooking up a car battery to a ups

I didn't go through the entire video or all the comments, but one thing to keep in mind re: increasing battery capacity is something I've discussed before here on HWA.

While not true for every model, limiting battery capacity as a primary protection feature is common enough that you do not want to connect a larger capacity battery to a UPS unless you understand the technical and practical impact of doing so.

Quite a few UPS units, especially economy models, are designed with low-capacity batteries INTENTIONALLY to limit the run-time for technical reasons. For example, limiting the run-time lets them use smaller heatsinks and/or eliminates the need for a cooling fan (and any associated fan control circuitry)...either of which equals lower manufacturing cost.

This is because the heatsink/cooling system may not be designed to cool the unit at full-rated continuous output for more than X minutes (perhaps 10 minutes or so on cheaper models). Depending on the unit, running longer could damage the UPS and/or provide unstable AC output (possibly damaging the computer) as the UPS overheats due to running continuously for longer than it was designed. It depends on all the protections designed into the UPS, and in some models using a "small" battery to limit the run-time IS considered a primary protection.

It should be noted that with insufficient protections a catastrophic UPS failure could have major consequences (fire, battery explosion, etc).

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john albrich Apr 26, 2013, 10:26pm EDT Reply - Quote - Report Abuse
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Edited: Apr 26, 2013, 10:29pm EDT

 
>> Re: Are Uninterruptible Power Supplies (UPS) a Scam?
NOTICE. Any and all equipment and/or software modifications by the user are at the user's own risk.


BoT said:
there is a nice little video over at revision3 made by systm
http://revision3.com/systm/hackedups
that might explain a few things on how to go about hooking up a car battery to a ups


I've said this in other posts, but it bears repeating here. This safety and functionality issue is NOT covered in the referenced video at this time.

Some UPS battery amp-hour choices are based on the maximum self-cooling ability of the UPS. If you run some UPS units too long by using a battery that provides much more than the specified amp-hours of the original battery, there is a risk of destroying the UPS due to overheating. For example, a given UPS might run fine at room temperature for 15 minutes, but if you use a larger battery and try to run it for say...30 minutes...it will overheat. Some UPS units use a lot of heatsink and some also add a fan, while others (usually much cheaper units) use tiny slivers of heatsink and no fan.

In other words, the lower amp-hours battery is a means of self-regulating the maximum run-time and thus the maximum possible heat build-up in the UPS (at specified maximum output power) without adding circuitry to provide over-temperature regulation within the UPS. Manufacturers looking to cut costs to the bone might use such a design.

Such a failure could have unpredictable and costly results.

In some cases simply adding a fan and providing ventilation to the UPC case could vastly extend the run-time and allow use of a somewhat higher amp-hours battery.

G. G. Apr 26, 2013, 10:37pm EDT Reply - Quote - Report Abuse
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>> Re: Are Uninterruptible Power Supplies (UPS) a Scam?
In a power outage..... a UPS is only meant to keep the the devices long enough to give time to have an orderly shutdown, i.e. giving you time to close out your database, save that edited resume, finish up the video editing and so forth and then shutdown.

If the UPS system is not design to run continuosly, doing so by means of modification will only cause detramental risks.

My APC when it swithes from source power to battery power due to a power outage, it has a fan built in that automatically turns on.... and I tellya, that exiting air gets really warm the longer you try to keep things up.

I can say with certain, my APC UPS has done its job well in all the multiple power failures and flutuations that have run across it for many years now. I have had it now for 5 years... I have only had to replace the battery at the end of the third year. Tip: battery from APC is real costly..... but, i got mine from another source that was much more reasonable for the same exact battery.


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Larry Groom May 12, 2014, 11:35am EDT Reply - Quote - Report Abuse
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>> Re: Are Uninterruptible Power Supplies (UPS) a Scam?
Living in Panama, it is a must for us to use inline protectors for EVERYTHING and not the cheapy kind either. Best to purchase a protector that has over/under voltage protection as well as when the power goes completely. I had a UPS that was damaged for lack of the protector but it wasn't a power surge. The power went out and came back immediately about 4 times within a 5 second period. With the protectors, that hasn't happened again with the other UPS.

Larry Groom May 12, 2014, 11:44am EDT Reply - Quote - Report Abuse
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>> Re: Are Uninterruptible Power Supplies (UPS) a Scam?
Presently in the process of hooking up another system for my home computers and TV. One UPS for the Computers (hers is a laptop, mine a desktop with wireless router) and another UPS for the TV an Cable box. That in turn would be connected to AC Power but in the event of an AC power outage, the UPS units would be powered by an inverter run off of two 180 amp deep discharge car batteries which are kept charged by three solar panels for that purpose. Since we have plenty of sun at my location, with frequent power outages of short durations, this system seems to work okay without damaging the UPS units from over usage or heat buildup. The UPS units keep everything running until the inverter kicks in so there is no need for a fancy transfer relay. Just a relay with contacts that can withstand the amperage going through the contacts, one set for the City AC Power and the other for the Inverter Power, using regular contacts that break before make and non arcing.

john albrich May 15, 2014, 09:30am EDT Reply - Quote - Report Abuse
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>> Re: Are Uninterruptible Power Supplies (UPS) a Scam?
Larry Groom said:
...there is no need for a fancy transfer relay. Just a relay with contacts that can withstand the amperage going through the contacts, one set for the City AC Power and the other for the Inverter Power, using regular contacts that break before make and non arcing.


Looks like an interesting and effective setup to address your particular situation.

If you haven't done so already, you may want to consider some redundancy in the relay power transfer subsystem. If I'm reading it correctly, it appears that all it would take is the failure to operate per spec of one relay in your system and you could have a serious power cross-over problem. Without details, one can't be certain, and it looks like you're paying attention to and doing things right vis-a-vis the relay designs, but just thought I'd make the observation. Redundancy for safety usually isn't a bad thing, and if absolutely necessary a failed redundancy component can be designed to be bypassed in an emergency.


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