How to properly monitor Perc RAID controller BBU state

Hi,

I have several Dell servers with PERC controllers and would like to setup nagios monitoring of the BBU state. The issue is that all scripts I've found in the Internet report warning for the BBU that seem to be OK.

For example, here is the output of MegaCli command:

# MegaCli -AdpBbuCmd -GetBbuStatus -aALL

BBU status for Adapter: 0

BatteryType: BBU
Voltage: 4055 mV
Current: 0 mA
Temperature: 19 C

BBU Firmware Status:

  Charging Status              : None
  Voltage                                 : OK
  Temperature                             : OK
  Learn Cycle Requested                   : No
  Learn Cycle Active                      : No
  Learn Cycle Status                      : OK
  Learn Cycle Timeout                     : No
  I2c Errors Detected                     : No
  Battery Pack Missing                    : No
  Battery Replacement required            : No
  Remaining Capacity Low                  : No
  Periodic Learn Required                 : No
  Transparent Learn                       : No
  No space to cache offload               : No
  Pack is about to fail & should be replaced : No
  Cache Offload premium feature required  : No
  Module microcode update required        : No

Battery state:

GasGuageStatus:
  Fully Discharged        : No
  Fully Charged           : No
  Discharging             : Yes
  Initialized             : Yes
  Remaining Time Alarm    : No
  Remaining Capacity Alarm: No
  Discharge Terminated    : No
  Over Temperature        : No
  Charging Terminated     : No
  Over Charged            : No

Relative State of Charge: 96 %
Charger Status: Complete
Remaining Capacity: 832 mAh
Full Charge Capacity: 870 mAh
isSOHGood: Yes

Exit Code: 0x00

# check_megaraid_sas -b
WARNING: 0:BBU Not Charging (96%):0:RAID-6:8 drives:816.75GB:Optimal Drives:8

So, here are my questions:
1. Is there anything I should worry about with this particular controller?

2. Should I take an account that "Fully Charged" is "No" and  "Relative State of Charge" never reaches 100%?

Thanks in advance,
Alex