Change many ESXi Host root Passwords

Change-Passwords.ps1

#Description: Changes ESXi Host root passwords for all specified ESXi Servers
#Author: Jason Coleman
#Website: http://virtuallyjason.blogspot.com/
#Reference: http://virtuallyjason.blogspot.com/2015/10/batch-changing-esxi-root-passwords.html
#Usage: change-passwords.ps1 -oldPass <old root password> -passString <new root password>

param
(
	$passString = "StrongPassword" + '<_<">_>',
	$oldPass = "WeakPassword",
	$hostPrefix = "sac-esx",
	$hostSuffix = ".lab"
)

$hostsChanged = @()

$allHosts = get-vmhost $hostPrefix*$hostSuffix | sort

$allHosts | foreach {
	connect-viserver $_ -user root -password $oldPass
	set-vmhostaccount -useraccount (get-vmhostaccount root) -password $passString
	$hostsChanged += "Host $($_.name) has been assigned the password of $passString"
	cmd /C pause
}

$hostsChanged

Once i do the password reset, do i need to update the password on vcenter?

Sorry, I didn't see this question here earlier. No, you don't have to update the password on vCenter. When you add an ESXi host to vCenter, it creates its own local account on the ESXi host with a randomized password. That's one of the reasons why a given ESXi host cannot be managed by multiple vCenter servers; when you add it to a new vCenter server, that server generates a new password for the management account.