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Creating on Uninterrupted Power Supply (UPS) ...

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(@grossdan)
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Joined: 3 years ago
Posts: 47
Topic starter  

Hello,

My UPS for my PC apparently broke down -- although the rechargable batteries inside are ok.

 

I am reluctant to touch anything beyond 12 Volt, so i don't want to tinker around a box I don't understand that does have some 220V wires somewhere in there.

But, instead of going out and buying a new UPS + batteries -- which is what is sold here -- i wonder if i can easily build my own?

Can this be done in a safe way?

The (recharable) batteries are, btw, 12Vx7A which can run for 20 hours and there are two of them -- per label on them.


   
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Ron
 Ron
(@zander)
Father of a miniature Wookie
Joined: 4 years ago
Posts: 7195
 
Posted by: @grossdan

Hello,

My UPS for my PC apparently broke down -- although the rechargable batteries inside are ok.

 

I am reluctant to touch anything beyond 12 Volt, so i don't want to tinker around a box I don't understand that does have some 220V wires somewhere in there.

But, instead of going out and buying a new UPS + batteries -- which is what is sold here -- i wonder if i can easily build my own?

Can this be done in a safe way?

The (recharable) batteries are, btw, 12Vx7A which can run for 20 hours and there are two of them -- per label on them.

I assume you meant 12 x 7 AH, batteries are normally listed this way, 7A makes no sense. That means you have 168Wh for 2 batteries (2 x 12 x 7) technically it's VA but forgetting PF we can use Watts. That means to get 20 hours run time means the PC must draw 8.4 W and at 220V that means 0.038 A or 38 milli amps. That is not possible. As to building your own, I just googled 'howto build a ups' and the most interesting hit is https://www.homemade-circuits.com/how-to-make-mini-homemade/

If you are uncomfortable around 220V, the simple answer is don't plug it in unless your hands are safely away. If you need to meter something, get alligator clip leads and other self holding styles to place on the circuit first.

What makes you think the batteries are ok and the circuitry is not? Checking a battery is actually a little tricky, just putting a meter on the bare posts does not tell you much. Unplug the UPS, disconnect the battery, place your meter on the leads you just removed, plug in, what is the reading if any. If it is 13.2, 13.6, 14.2 to .6 then it's ok and the batteries are bad. Let me know what you discover.

First computer 1959. Retired from my own computer company 2004.
Hardware - Expert in 1401, and 360, fairly knowledge in PC plus numerous MPU's and MCU's
Major Languages - Machine language, 360 Macro Assembler, Intel Assembler, PL/I and PL1, Pascal, Basic, C plus numerous job control and scripting languages.
My personal scorecard is now 1 PC hardware fix (circa 1982), 1 open source fix (at age 82), and 2 zero day bugs in a major OS.


   
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(@grossdan)
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Joined: 3 years ago
Posts: 47
Topic starter  

@ronalex4203 thank you for your comments. 

The main reason I felt the unit is defect is that it doesn't turn on when pressing the power switch.

I am now thinking that the batteries could be ok.

In the end I decided to get a new unit, mainly because recently, with the very cold weather and more heating, we had more power outages and we need to have the provided ampere increased by the electric company -- which will take time to do.

 


   
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