APC SRT3000XLI charging issue

[gaber2611]

hello everybody 

the APC have bad batteries, and they are bigger size, so I doubt there is bad charging voltage 

when I tried to measure the charging voltage , it go up at start and then down suddenly, then up again , for a certain time then down, and so on, when down it's not big value , it can be for example, 12.7 , then 12.8, then 12.9, then 13.0, then 12.6 down , like this and again to 13.1, 13.2 v and so on

is this normal charging voltage?, this how the APC charging circuit work?, or it's a problem in the charging circuit?

by the way, I've checked all components of charging circuit and it look good and measure ok

is this normal?

[Teken]

The unit you reference is a 96 VDC system. Where are you measuring 12 ~ 13.XX VDC?!? At the individual battery cells???

If the battery cartridge is known to be bad why haven’t you replaced it??? As to what you’re seeing relating to fluctuating input voltage it indicates the charging circuit is struggling / trying to elevate the SOC to the predefined level but can’t.

Allowing the system to remain in this state (best case) will damage the units internal charging circuit. 

Worst case the batteries will continue to heat up, deform, and soon vent. At which point if there is a spark there will be a nice hot fire inside the unit that will cause anything else that’s attached to lose power and shut down. 🤦‍♂️