Xtreme Power Conversion NXRT-1000 Technical Bulletin

XTREME POWER CONVERSION
Temperature affects on battery charging
Product type:
NXRT UPS internal battery and battery pack modules
Model UPS NXRT-1000
Model EBP NXRT-EBP1
Purpose:
The purpose of this bulletin is to notify NXRT UPS system customers of an issue found in
regard to a small number of NXRT systems exposed to local ambient temperatures >77°F for a periods of
time.
The Problem:
There are battery packs with swollen or failed batteries as a result of overcharging due to high ambient
temperatures (see photos below). As batteries age, the problem worsens under these conditions and
battery replacements are recommended.
Room temperatures may be below 77°F but temperature hot spots may be present close to the UPS and
battery module areas. If temperature hot spots are present at any time, then one or more batteries in
the string may start to fail. The internal battery impedance changes as the battery fails increasing the
charge current through the affected battery and all other batteries in the string. This creates a charging
current imbalance - higher current for some batteries and less for others yielding more failures over
time.
NXRT-EBP chargers are often connected to the UPS systems compounding situations of imbalanced
charging currents as described above by increasing current for a greater imbalance therefore
accelerating the rate failure.
Each NXRT battery pack (EBP) has its own 2A charger built into the NXRT-EBP. These NXRT-EBP chargers
are powered from an external AC source via an IEC/5-15P power cord and should be connected only on
every third NXRT-EBP. Do not connect the IEC/5-15P power cord into a UPS receptacle. Please refer to
the current NXRT user manual
Temperature/Overharged affected battery
www.xpcc.com
XPC USA Denver, CO / Tel (800) 582-4524 / sales@xpcc.com
XPC EMEA Rotterdam, NL / emea@xpcc.com
NXRT-1500
NXRT-EBP2
for more details.
TECHNICAL BULLETIN
NXRT-2000 NXRT-3000
NXRT-EBP3 NXRT-EBP3
Non affected battery