ffbatterymon: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/ffbatterymon - from package: fawkes-guis

You may install the required package with command yum install {package}

Error in other languages:
ffbatterymon: bevel nie gevind nie
ffbatterymon: comandă negăsită
ffbatterymon: comando não encontrado
ffbatterymon: commande introuvable
ffbatterymon: command not found
ffbatterymon: käsku ei ole
ffbatterymon: không tìm thấy lệnh
ffbatterymon: komanda nerasta
ffbatterymon: Kommando nicht gefunden.
ffbatterymon: kommandot finns inte
ffbatterymon: komut yok
ffbatterymon: nie znaleziono polecenia
ffbatterymon: níor aimsíodh an t-ordú
ffbatterymon: no se encontró la orden
ffbatterymon: no s'ha trobat l'ordre
ffbatterymon: opdracht niet gevonden
ffbatterymon: parancs nem található
ffbatterymon: perintah tidak ditemukan
ffbatterymon: príkaz nenájdený
ffbatterymon: příkaz nenalezen
ffbatterymon: команда не найдена
ffbatterymon: командата не е открита
ffbatterymon: 命令找不到
ffbatterymon: コマンドが見つかりません