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APC UPS Replacement Battery Connector

By on February 24, 2015
apcups repairs










This APC Uninterruptible Power Supply (UPS) Model No.: Back-UPS ES 500 was given to me and the complaint was it was not turning on.

 apc ups repair

Then I removed the back cover (battery receptacle) to disarm the unit.

 apc upsrepair

When the battery was out, look what I saw:

 apc ups repairing

The negative terminal was fully corroded, and this situation is synonym of false contact (this situation produces overheating);


therefore it had to be substituted for other terminal in good conditions.


A terminal in good conditions was taken from another out of use UPS. The new terminal was welded into the negative cable which attaches the battery, and isolated later with a piece of shrink tube.

 apc ups repairings

The battery was re-inserted in its receptacle, and when the unit was turned on, look what happened.

 apcups repair

The device worked perfectly. The owner was smiling. Mission accomplished.













This article was prepared for you by Humberto Rodriguez, one of our ‘Master Authors’ from Cuba.

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  1. Robert Calk

    February 24, 2015 at 11:29 pm

    Good job Humberto. You saved another device from the trash. Thanks for the article.

    • Humberto

      February 25, 2015 at 8:32 pm

      Thanks Robert.

  2. yogesh Panchal

    February 25, 2015 at 2:18 pm

    Good work and thanks for sharing.

    • Humberto

      February 25, 2015 at 8:34 pm

      Thanks yogesh.

  3. moniem

    February 25, 2015 at 4:08 pm

    hi Humberto
    good job
    most UPS failure related to battery

  4. Humberto

    February 27, 2015 at 9:23 pm

    Hi moniem, I've found sometimes some other troubles in UPS like open fuse, blown transistors (JFETs), etc.

  5. mel romero

    March 1, 2015 at 9:36 pm

    evening sir,,thanks for the info regaards the UPS,but how about if the terminal is in good condition but and the battery is good but stil did not work,what posible trouble of UPS?thanks and more power.

    • Humberto

      March 3, 2015 at 10:22 pm

      Well, you shoul check on the electronics devices in the PCB: relays, fuses, output transistors (JFETs), etc.

  6. Taring

    March 2, 2015 at 11:56 am

    Very useful information and thank you for sharing

  7. mike retz

    March 3, 2015 at 9:52 am

    you look very satisfied!!!


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