To check Power Supply status on ESX 4.1 from CLI its easy you just need to run few commands and please note below commands will work if the Server is a HP Server and HP SIM Utility is installed in it.
First Command which you need to run is as follows
hpasmcli -s “show powersupply”
This above command will show up the Power Supply status on ESX 4.1
And to check the HP Logs on Power Supply status on ESX 4.1 is below command
hplog -v | tail
Will list out the recent logs as below
You can also check the Power Supply status on ESX 4.1 from Virtual center
You need to Select the ESX Server and double click on it and then you need to navigate to the Hardware Status which gets refreshed after some interval.
Into that you need to go to Power Section and you will see the Power Supply Status on ESX 4.1 as below