Battery life

[ianh21]

Hi

I have 14 x APC by Schneider Electric Smart-UPS SMT-SmartConnect - SMT750IC - Uninterruptible Power Supply 750VA (Cloud enabled, 6 Outlets IEC-C13)  in my unit that are new and open box.  the batteries and testing by yourselves was conducted in 2018. 

As they have not been used, will the batteries be fine still?

how long do they last if the units are brand new unused?

[Teken]

The service life of the battery cartridge is rated for 2-5 years based on usage, temperature, and environmental conditions.

If these units were NOS and left to sit on the shelf uncharged for six years. You’ll need to inspect all the battery cartridges for any physical damage such as swelling, bulging, leakage, etc.

If no physical damage is found you may proceed to do some basic voltage tests. Take any cartridge that hasn’t been charged and document what the resting voltage is.

A new cartridge depending upon how long it was allowed to sit on the shelf will span 12.80 ~ 13.XX (Per Cell).

The SMT is a 24 VDC battery system as such the testing voltage should be > 25.60 VDC.

The cells are rated to endure 260 full depletion cycles in normal situations. Afterwards the performance and operational service life begins to drastically decrease.

If you see any cartridge that is below 12 / 24 VDC set them aside as they are suspect. To know the true health of the individual battery cells you must measure the internal resistance of the cell and compare it to the battery manufacturers specification sheet.

This is done with a specialized conductance meter not a standard multimeter set to resistance / Ohms! ☝️

If this is a CSB battery it will be 20 mOhms. If they measure approximately 20 - 25 mOhms recharge the cartridge until the system indicates it’s 100% charged.

Let it sit like this for another 48 hours with the system float charging the cartridge. Afterwords disconnect the cartridge and measure the voltage it will show greater than 25 VDC.

Let the cartridge sit like this disconnected for at least 72 hours. Come back and measure the voltage. It should have lost no more than 0.1 ~ 0.5 VDC.

If the entire cartridge measures below < 24 VDC the battery cells need to be replaced. 

You can validate this simply by completing a battery calibration with at least 30% attached load. Compare the operational runtime to the APC Runtime Calculator for a given load / wattage.

If say the expected operational runtime is 60 minutes but you only see 5-10 minutes the batteries are toast!

If however you see 25~35+ minutes the battery cartridge is marginal. You can continue to use the cartridge knowing it can and will fail at some inopportune moment or order a replacement.

Complete the tests up above and report back your results and findings. 👍

[ianh21]

Thanks for your detailed reply.  These will not be tested by me as i do not have the time nor space.  I will sell them for parts only to clear. 

[MorneMeintjes]

Good Morning

Batteries left in units connected would discharge quicker, of the batteries was disconnected the batteries would self discharge faster.

Either way the batteries would sulfate, internally on the negative  pole, and once it crystalizes it is very difficult to recover the batteries. any recovery would have limited battery life if any. Its always better to leave unused UPS systems plugged in and charging its batteries. but in this case the batteries would be past its normal service life. In addition to the above procedure, you may tru to boost charge the batteries for 12 to 24 hours. See OEM guidance on boost charging. I don't think float charging will reverse the sulfate in the battery. Please let us know if you are able to recover the batteries. best of luck.