Battery drain while on AC

[Anonymous user]

Good Day,

I have a Back-Ups RS500.

It worked fine with the first battery, and - after it was exausted after almost 3 years of work - also the second new battery worked fine. Inserted, powered on the unit, ready to go.

Now the second aging battery is gone (all led blinking, removed the battery and tested it and it was effectively gone, it could not hold no load).

So i bought a new one and replaced it as in the first case.

After restarting the ups the Powerchute sofware (3.0.2) indicated 100% charged battery, charging.

Since that moment, it kept on draining the battery even when connected to the AC power.

I powered down the APC and removed all equipment connected to it when it was around 50% (charging), and left the APC connected to the wall socked but powered off.

After a day in that state the battery was completely drained, and without AC power it wound not start, just make a brief BEEP and stay off.

Also reconnecting it to the AC and tryng to start it wouldn't work. Thought of the battery defective.

So i obtained another brand new battery, connected it and again it indicated 100% load, and again it is draining it as the previous time.

In the same time, external recharging and testing of the first battery showed it was OK.

I then searched and read on this forum that mine is not an isolated event. Other unit showed this behaviour.

So proceeded to check that the load was around 30% with Powerchute, remove the usb cable to avoid shutdown, removed the AC cable and let it discharge until it powered off.

Removed the load, reconnected the Ac and the usb cable and restarted it, and it started to recharge it for a few hours, with the carge counter increasing of 1% around each 3 minutes circa.

Then I left it charging overnight, without any load attached. Thought the problem to be solved... but as soon as I checked again (still without load connected, as before just the usb to rj45 cable to retrieve the data

from the APC unit) it indicated 14% battery left.

So I Powered down the unit again, reconnected the load, and restarted the UPS. Now it idicated 30% charge left, running on AC, and... discharging again the battery.

This unit seems to act werdly, and cannot be used if behaving like this. Can you provide a clear guide on how to fix this issue? It is strange that the UPS started acting weird in this way... especially just for changing a battery.

Regards.

[Anonymous user · Accepted solution]

The first thing I would do is get/borrow a voltmeter and check the DC voltage at the battery terminals - IE access the battery inside the compartment on the bottom --> pull the battery out far enough to expose the terminals. If it doesn't read at least 13 volts or above with the UPS online (and having been online for several hours) your UPS is not charging the battery and could be defective...

[Anonymous user]

Good day Battman,

Thanks for your reply.

I am testing at the moment and the voltmeter reading goes from 12.88 to 12.90. Looks close to 13, but much probably not good enough.

Will check again in the next hours, but It seems you pinpointed the cause of problem!

Regards!

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EDIT>

After a day the new reading of the voltmeter signs 12.09. You were definitely right!

Thanks.