APC Back-UPS RS 800 overload problem with no load: Solved

That is a quick and easy fix of a very common problem of APC Back-UPS series.

The problem is that the UPS overload red light is constantly turned on even with no load at all. A google search did not reveal any solution other than the board is faulty and there is nothing you can do about it.

I was handed this UPS and naturally I employed all my google foo in order to save a seemingly fine UPS. This time however the solution didn’t come from google but from youtube. If you are like me then you are totally against the wave of video tutorials that are flooding our everyday life. I prefer a text with properly defined steps than a 15′ video documenting a series of three clicks in order to access the desired submenu.

However in electronics repair hackery it actually makes some sense to present your work in a youtube video. I doubt if it is faster this way but lots of people are actually posting very useful stuff there especially for obscure repairs such as this one.

I am writing the post because the solution is not in a youtube video but in a comment. If it was in the video or in the title then the solution will be findable by google. Instead the solution was in the comment section (yes I read youtube comments – can you imagine that?) in Spanish by Lujan Luis Giaccardi with the picture that shows the faulty capacitors red circled. Totally not findable. So I am posting it here for future reference.apc_rs_800

The comment translated in google translate says:

If you turn on the red light of “overload” you have to change the two electrolytes marked in the photo this:

The youtube video where you can find the original comment is https://www.youtube.com/watch?v=66oKHjCo5AA

Since I am not much of an expert in soldering and removing surface mount (SM) electrolytic capacitors I found (easily this time) another youtube video to figure how to get rid of them. Here it is:


I changed the faulty capacitors with normal capacitors and lo and behold! It worked!

Hope that helps.


Author: vasvir

Interested in a wide range of topics from deep learning and big-data to embedded, from web GUI (GWT) to API and code consolidation. Maintainance is also fun for me unlike many other normal people...

18 thoughts on “APC Back-UPS RS 800 overload problem with no load: Solved”

  1. Incredible, I arrived here as you do, following that unreadable youtube video and checking the comments. I’m going to replace those capacitors, but I have one question, what do you mean with: “I changed the faulty capacitors with normal capacitors”. You have changed those capacitors with a different kind or just with brand new? Thanks a lot

    Liked by 1 person

    1. Hi Vasvir,
      Thank you to share the information about the ups overload issues. I can not view the youtube video.Can you send me the pictures to indicate which capacitors on the board?



      1. Now, I can find the pictures. Sorry. Can you show me the thero of overload control? My thinking is that the ups must detect a huge current then the signal will be sent to singlechip to dealwith. How the detected circuit worked ? Thank you!


  2. Sorry but I don’t know the answer in your question.

    I just replaced the bad capacitors (red circles) in the photo and it worked.

    The UPS is still in service!


  3. Ok, Thank you. I just want to find the circuit and know about the control theory. If I find the circuit, I will share it with you.


  4. I can confirm this also works for the APC Smart-UPS 1000 (and probably for the 1500 as well since the circuit board is almost identical). However with the Smart-UPS 1000 and 1500 the capacitors are blue and regular capacitors not the SMD-type.
    Please make sure you don’t mix up the positive and negative side when you replace them!

    Also APC programmed the Smart-UPS-es with a to high float charge causing the batteries to wear out way to fast and even swell and/or leak. The following video shows how you can fix this: https://www.youtube.com/watch?v=jeVqtc2dbbc


  5. I replaced 3 capacitors, not just 2. I wanted to tell you and thank you for the article. They are the C56, C60 and C71, all from 22 uF, I put them from 50 volts to be sure. How can I send you a picture? If you wanted to publish it. Thank you!


  6. Sir can u provide me link to buy similar capacitor mentioned in this post for APC RS 800. I have same problem of overload.


  7. What are the specification of this capacitor bro pls help i cant find its specification. Please comment the specification required to replace the old capacitor. I have no idea about electric things so your advise will be very helpful.


    1. Rohan,

      I am sorry but I don’t remember the capacitors specification by heart. Here is what you can do. Take a photo with your cell phone the faulty capacitors. Make sure the letters are readable and show them to an employee in the electronic shop. They should be able to help you.

      However if you know nothing about electric things as you say then you need some help from a more knowledgeable guy with at least some soldering skills.

      Hope that helps.


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