Repairing a UPS

[IBM_THINKPAD_R51]

Hello Guys, 
I wanted to put this here cause initially when I tried to find info about this problem/fix it took me 2 days to fully figure things out so I wanted to make a basic yt video and write this up to make things easier.

Basically things started with the APC Back-UPS XS 1500 and 1000 (BX1500 & BX1000) however this applies to the RS line too.

I had these two UPS's for a long time since new and ever since about 12-13 years into their lifespan of constant use, a problem started to develop where it would not accept the wall power, it would just run down the battery all the way to 0. I found out at the time that if i lowered its sensitivity to medium, that would fix the issue.

fast forward another couple of years it would happen again and i set it to low sensitivity and it would be good

fast forward another couple of years and I would start to get these two symptoms

eventually What I had to do was get new UPS's 

a long time later I got a third UPS of this gen, a BX1500 and it was working but still in the initial stages of this problem,

after a long time of searching I found out that certain SMD capacitors for the voltage recognition circuit go bad on these and fool the ups into thinking the wall power is bad

a couple bucks from mouser electronics later and a very VERY painful soldering job because of these surface mount components later...and IT WORKS

you might say just get a new ups anyway and heres the pros and one VERY BIG CON of that

BackUPS-Pro 1500
Pro:
pure sine wave output
AVR BOOST
AVR TRIM
Newer
Con:
expensive
no battery expansion slot

BackUPS 1500
Pro:
battery expansion slot
cheap
uses the same 9aH battery as the new ups
AVR Trim
con:
No AVR Boost


the battery expansion slot on the old model is this:


it uses the same connector as the internal battery back and it would essentially double your runtime

so let me know what you guys think about  all of this
here is my yt vid on it

 

[Jarsky]

Ah yes....electrolytic capacitors....almost always the issue

I think those are Panasonic from the looks of them but they'll be aluminum; so over time they can dry out like any normal electrolytic component (e.g battery cells). 

 

Ideally you'd replace them with solid capacitors i.e Aluminum Polymer. 

Not only do they have an extremely high reliability; but they can better handle current ripple, and parasitic inductance in comparison to electrolytes. Perfect for a power regulating circuit.