Could you do this?

[TechGeek]

UPS's: They provide backup power for about 20 minutes MAX, depending on what you buy. The batterie(s) are usually 12VDC VRLA type batterie(s) that provide about 50A for a little while until they die and/or the power comes back on. Well, what could you do to e x t e n d the amount of time the UPS runs until it finally gives in, maybe to run a computer setup for 2-3 hours during a power failure?

Replace the tiny batterie(s) built into the UPS with some 12VDC CAR BATTERIE(S!)

Is this possible? It is beneficial to the UPS? Is it even practical, provided you could build a case to enclose the batterie(s)? Thanks.

[Andrew F. Ali]

Re: Could you do this?

I have been doing this for about two years now. I have a car 12V battery outside and run the cables to my UPS and it is working. When power goes I have wifi and can still use my Desktop computer. It works....

[TechGeek]

Re: Could you do this?

how long does it last b/f it gives in?

[stj]

Re: Could you do this?

that would depend on both the battery's and the pc setup.

[Behemot]

Re: Could you do this?

Very stupid idea. It seems OK for short-term and with low loads, but it is wrong because of several reasons. These systems, especially gheto moded for heating water pumps, usually fail after couple years.

Most lower-power rated UPS count with given amount of energy in the accumulators so the heatsinks are designed to accomodate such energy. When increasing the runtime several times you make it overheating like hell, in better case killing it slowly, in worse case blasting the semiconductors. If you use model with a fan, it should be OK but it is better to check.

Non-sealed accumulators always produce corrosive and toxic fumes. If you do not have strong ventilation it will slowly eat everything in the room.

Even standard wet lead-acid accumulators require over 14 volts at least from time to time to revert sulfation and stratification. UPS with 13.6-13.7 V charging voltage does not provide that. But over time it is still enough to slowly electrolyse and vaporize the water so you have to fill it. I am not sure if wasting time and effort gives you some real benefit over initial cost price saving.

Each type of lead-acid accumulator is different and from long-term point of view it is not a good idea to replace one with another. I have been expanding my portfolio for automobile accumulators last two days and the bullshit even distributors tell you (like calling wet Ca/Ca accumulators with clearly visible screws for refilling "maintenance-free") made me do extensive research in this matter. I found there are very few sources of actually important informations. The best one I found and cited from to my website is http://jgdarden.com/batteryfaq/, especially chapter 9 http://jgdarden.com/batteryfaq/carfaq9.htm

If you want long runtime, get a proper UPS for that. Or a laptop. There are such on the market which can work with 100Ah+ SLA's. UPS are not meant for long-term backup, they either bridge the time before diesel aggregate starts up, or just let you turn equipment off. If you can afford on-line UPS, you can get cheapest aggregate from hobby market, the UPS will make clean sine-wave out of that.

[Per Hansson]

Re: Could you do this?

Works fine if the UPS has a fan.
If not it goes boom:

https://www.badcaps.net/forum/showthread.php?t=12904

This thread might have some good info too:
https://www.badcaps.net/forum/showthread.php?t=7872

[kc8adu]

Re: Could you do this?

general rule is if its an apc or best power in a metal case its good to go.
if its anything in a plastic case its hanging on for dear life just on its internal battery.
and i consider those as junk.
i have several units running 24/7/365 for over 15 years on a d31 as the smallest external battery.if they get run way down i put a 12a car battery charger on to not only bring it back to ready in a short time but to take the strain off the internal charger.i added a heatsink anyway.i also charge up to 16v for a few hours every 6 months.since the batteries are stationary this equalises and fixes any stratification.

[ChaosLegionnaire]

Re: Could you do this?

ugh... i think i'll get a petrol/diesel generator instead as my ups. just need to run it outdoors and run a long cable indoors to avoid carbon monoxide silent poisoning (suffocation) from the combustion in the generator. have a 3m multi-gas filter cartridge mask for protection when needed too.

[Andyy]

Re: Could you do this?

Replace the tiny batterie(s) built into the UPS with some 12VDC CAR BATTERIE(S!)

Is this possible? It is beneficial to the UPS? Is it even practical, provided you could build a case to enclose the batterie(s)? Thanks.

The standard components in a UPS (transformer, switching FETs, heatsinking, etc) weren't designed for continuous operation in mind. Even extended operation may stress a borderline cheaply designed Chinese UPS (yes, I'm using that as a generalisation) to the point of failure.

As others have pointed out though, APC UPSes certainly seem to be tolerant of this kind of modification.

[Andyy]

Re: Could you do this?

ugh... i think i'll get a petrol/diesel generator instead as my ups. just need to run it outdoors and run a long cable indoors to avoid carbon monoxide silent poisoning (suffocation) from the combustion in the generator. have a 3m multi-gas filter cartridge mask for protection when needed too.

You'll still need UPS with generator automatic change over switch. Because the generator can't start up instantly after mains failure, the UPS provides power for a few minutes while the generator starts and warms up. As soon as the generator voltage has stabilised, the UPS switches to generator power.

[Behemot]

Re: Could you do this?

As others have pointed out though, APC UPSes certainly seem to be tolerant of this kind of modification.

That is generaly not true. Some units are equipped for external battery pack so they have active cooling and more powerfull charging supply. Especially the Smart-UPS XL models. But that's only a fraction of all the APC units there.

[desert-rat]

Re: Could you do this?

One thing you can do is use an inverter . A 12 v car/rv battery . rv batteries can stand being run flat with out ruining them . I used an inverter in my pu to run a pc to use free wi fi . I now use a lap top .
http://www.harborfreight.com/400-wat...ter-66814.html

[dmill89]

Re: Could you do this?

That is generaly not true. Some units are equipped for external battery pack so they have active cooling and more powerfull charging supply. Especially the Smart-UPS XL models. But that's only a fraction of all the APC units there.

^This, some APC units are good (generally the higher-end "enterprise" ones) and some are real pieces of shit (most of the "consumer" ones you see at BestBuy, Staples, etc.), as bad or worse than the generic cheap Chinese stuff (while costing more). The worst piece of garbage UPS I ever had was an APC Back-UPS XS 900, it had a 40mm sleeve bearing fan that ran 24/7, this failed in a little over 2 years (just after the warranty was up, how convenient) and resulted in the PCB and most of the components on it (FETs, caps, etc.) being cooked. It was replaced with an OPTI-UPS ES 1000C which is now about 6 years old and aside from needing a replacement set of batteries (the cheap Chinese replacements have so far lasted about twice as long as the Yuasas it came with) hasn't had any issues.

[Behemot]

Re: Could you do this?

Some of the super cheap units just don't have any, even the smallest extra circuitry to cut the costs. Just been refurbishing Eaton Nova AVR 1250 which also has fun running 24/7, though some 60-70mm one or so.

On the other hand despite having very simple board, the PCB itself is epoxy-glass, not like that cheap shit from Must Power. And it has huge transformer for its rated power, one that seems like using true copper. Not like that shit from Must Power with smaller core and aluminium winding!!

[TechGeek]

Re: Could you do this?

Must power.... must power and fry everything plugged in!

[desert-rat]

Re: Could you do this?

There are circuits out there . You can build an inverter, what ever spec.s you want . You can use use lead acid or li .

[stj]

Re: Could you do this?

it would be interesting to use a ni-mh or lithium pack from a hybrid car!!

[desert-rat]

Re: Could you do this?

I was looking for into on li chargers . I found a site that showed how to make packs for eletric bikes. As I remember its 4.2 v per cell. You don't exceed 2 amp per cell. Ect. There a bunch of electronic forums some have li battery info.