SRT6kXLT Connect Battery

[RoMik2]

We have a SRT6kXLT Smart UPS with an external RBC and a Power Distribution unit.
It has been running for a couple years now, and about a month ago we had the alarm go off prompting us to replace the RBCs batteries. We muted the alarm while information was passed up the corporate ladder to purchase new ones.
Last week it failed completely and turned itself off. We had a spare set of batteries that were supposed to be good but when it is turned on, the display states 'Connect Battery' with the exclamation mark.
Under status of the battery, the internal states 0 and external states 1. All batteries are connected.
Is there a reset control or fuse/breaker that may have disconnected the internal batteries?
This unit will not acknowledge internal batteries at all, old or new.

[Teken]

Did you measure the resting voltage of the so called new battery cartridge before insertion?!?

If so what was the VDC?!? If not what is it now while (NOT) connected to the system and when it (IS) connected?!?

The battery cartridge is a 192 VDC system and must be at a minimum voltage before use.

Let me know . . . 👍

[RoMik2]

Each of the battery packs that were in the unit for the past several years measure approximately 102V resting. (On the bench)

The best of all the new/old stock battery packs that were sitting on the shelf for 2 years measure 52V.

I left the new/old stock batteries in for many hours thinking they may take a charge, but didn't.

So is there an upper limit to the voltage that the system will not function? (i.e. 200V)

[Teken]

The NOS batteries you had on the shelf are dead and garbage now. If these are genuine APC (CSB) batteries you may try to recharge each individual cell on an external 12 VDC charger to see if they recover.

Than reassemble the entire cartridge.

The batteries are rated to endure 260 full depletion cycles before they are toast. Keep in mind it doesn’t matter if the cells are able to take a charge as that is the most basic test.

What matters is (IF) they are able to retain a specific voltage without discharging! ☝️

This is why you take a cartridge out from a working system and leave it on the table for a minimum of 72 hours.

A healthy cartridge will only drop 0.1 ~ 0.3 VDC over that period. If the voltage drops 1-2 volts the batteries / cartridge is EOL / Toast! ☝️

Other important aspects are how the battery / cartridge performs under load. If the cartridge is rated to provide X watts for Y minutes say 1000 watts for 30 minutes but you only see 5 it’s toast.

The most critical part is what the internal resistance is for each battery cell. Depending upon the battery type, maker, and chemistry it will range from 18~20 mOhms.

Regardless, the system needs either a new battery cartridge or cell replacement. As each cartridge is / should be (nominal) 102.4 VDC (12.80) on the low side to 103.2 VDC 100% (12.90) fully charged.

When the system is fully operational and just floating the battery cartridge it will be (approximately) 216 VDC / 13.50 on the high side to 214.40 VDC / 13.40 on the low side.

[RoMik2]

Ok. I follow why the NOS packs are bad, but the last packs in the machine sitting at about 102V and will not even acknowledge there are batteries installed.  The unit still states 'Connect Battery', not that they are bad.

(I'm also guessing when you say "cartridge at 216VDC" you're speaking of a pair of packs.)

The system does acknowledge the external battery bank. Not the internal pair.

I guess there is a test the system does when first turned on to determine if the bank is good? Thus, dropping the 204v (102 per pack) so low it will not pass and not turn on.

Is this correct?

[Teken]

The system will initiate a self test on first power up and based on the user defined schedule. The (Self Test) is a crude method to complete a POST on several areas of the internal system including a battery load test.

The load test and other metrics obtained by the self test helps the system determine if the cartridge is fully operational and fine.

Your system obviously thinks based on the self test the battery cartridge is bad and EOL.

You have a couple of options given you want a break fix until a new cartridge arrives so you may consider doing the following.

You can disconnect the extended battery pack. Install the battery cartridge from the extended battery pack into the main system.

Power down the entire UPS system and disconnect the extended battery pack. Power up the main system and wait for the system to declare a missing / disconnected battery fault and wait another 10-15 seconds.

Than insert the battery cartridges into the system. The system will prompt you to confirm (IF) a new battery cartridge has been installed you will toggle from No to Yes and enter the month / year.

Once that completes manually initiate a Self Test. If it passes validate the current battery SOC and let the system recharge the battery cartridge to 100%.

If that passes you can connect all loads and see how the system responds. Let me know if you have more questions. 👍