# Modified UPS- How to- with PICS



## 10101 (Oct 31, 2008)

Just wanted to share my upgrade of a UPS (uninterruptible power supply)

I will give credit where its due, this project was inspired by this

UPS

I liked this guys idea, however he was using the wrong batteries that will kill you if they are charged indoors (car batteries) not to mention they are starting batteries and not for deep cycle use.

So heres what i got.

I purchase four items:

1. APC BK500 = $2.50
2. APC BK200= $2.50
3. UNIVERSAL D5722 SEALED LEAD ACID BATTERIES (12V; 35 AH; UB12350) = $50.32
4. UNIVERSAL D5722 SEALED LEAD ACID BATTERIES (12V; 35 AH; UB12350)= $50.32
5. Shipping for batteries= $33.00

Grand total: $138.64 (this is the price of one brand new unit folks) + beer money

I bought the UPS from a computer salvage store in my local area, the guy told me 5 bucks for both, he advised they were old, untested and probably had dead batteries. I bought them anyway.

Sure enough the small 12v 7amp hour batteries were fried, so i went online to find replacements. Well turns out these suckers can get pricey. So instead of buying the 12v 7amp hour battery i bought much bigger ones.

I bought two 12v 35amp batteries from electOtronics.com

These batteries are generally used for wheel chairs and emergency lighting. They are SLA deep cycle batteries. so they dont give off fumes while charging, which makes them perfect for this application

Once the batteries arrived, I lengthened the wires from the UPS to the batteries and connected them. I have found that these batteries fit nicely inside a 50 cal ammo box.

This setup is not apart of my alt.energy setup and is soley for my computer and monitor.

The 7amp hour battery's were good for about 10mins of backup, So far I have tested these at 45 mins. I will do some longer testing after my kill-a-watt meter arrives (I am not sure on the watts my compuer and large monitor require)

I plan on installing a couple of small computer fans in the UPS case to allow for proper cooling as these units were not designed to run for longer that 10 minutes.

By all means this is not a comprehensive guide but i feel it is a good FYI.

I have since found these batteries on overstock.com for $60ish and the shipping is like 3 bucks.


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## 10101 (Oct 31, 2008)

I don't have build pics,, so i will give you what i got.

finished Setup:










Battery in 50 cal box:









Original UPS 7amp hr battery:










Battery shipping box:










Thats all the photos I have, the "build" was super easy, just get some extra wire and some connectors and crimp em down. Keep in mind I built two units, two batteries and two ups required, one for pc and one for monitor. If you have a larger UPS you can run both pc and monitor on one UPS.

So far the run time is 45 minutes with plenty of time to spare (i am shooting for 1 hr before the battery gets to 50% draw), however because these are old UPS they are considered "dumb" which means they only relay basic info via serial cable to the APC powerchute software, which is the following, online, on battery, low battery, low battery shut down.

The software is configurable and will shut down your PC at a predetermined low battery setting.

Like i said earlier due to the much larger battery the run time is much more than the UPS are rated for which means they will get hot. In addition I am not sure if the built in charger will bring the battery back up to 100%. I may have to invest in a cheap smart charger to bring battery to 100%.

This project is very simple. The MFR even provides instructions on battery replacement, just keep in mind the larger battery does not fit and thus requires the wire extensions.

So whatcha think?


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## endurance (Nov 26, 2008)

Nice! I've been thinking of getting the old UPS that I have around the house with a dead battery and wiring it up as an inverter. Sure, I couldn't fit the batteries inside, but I have the perfect place just outside to store the battery and just run the leads to UPS in my utility closet.

Nice project. Thanks for sharing. How many AC amps or watts is your unit rated for?


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## 10101 (Oct 31, 2008)

endurance said:


> Nice! I've been thinking of getting the old UPS that I have around the house with a dead battery and wiring it up as an inverter. Sure, I couldn't fit the batteries inside, but I have the perfect place just outside to store the battery and just run the leads to UPS in my utility closet.
> 
> Nice project. Thanks for sharing. How many AC amps or watts is your unit rated for?


one UPS is rated at 200w and the other at 350watt, I have the monitor plugged into the smaller one and the pc into the larger. So far I have tested the runtime at 45mins, however I think I should be able to get about two hours tops.

Both UPS units will shut down when the battery voltage reaches about 10 volts, this protects the batteries from being 100% discharged.


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## endurance (Nov 26, 2008)

Considering a 500 watt pure sinewave inverter without any battery capacity would cost several hundred bucks, this is a great way to go to keep critical items operating. My most important item remains my bread machine, boiler circulator pump and my freezer. The freezer is already 12vdc and only needs a 75w solar panel and deep cycle battery to keep it running, but the bread machine has a high peak demand of 1200w, so I doubt I'll find a cheap UPS for it, but the boiler should be pretty easy. I think it's a 75w ac motor.


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