-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 c+LVngJEhclhmdgqKP6jwA==

<SEC-DOCUMENT>0001179110-08-015110.txt : 20080812
<SEC-HEADER>0001179110-08-015110.hdr.sgml : 20080812
<ACCEPTANCE-DATETIME>20080812151849
ACCESSION NUMBER:		0001179110-08-015110
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080808
FILED AS OF DATE:		20080812
DATE AS OF CHANGE:		20080812

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			EnerSys
		CENTRAL INDEX KEY:			0001289308
		STANDARD INDUSTRIAL CLASSIFICATION:	WHOLESALE-ELECTRICAL APPARATUS & EQUIPMENT, WIRING SUPPLIES [5063]
		IRS NUMBER:				233058564
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		2366 BERNVILLE ROAD
		CITY:			READING
		STATE:			PA
		ZIP:			19605
		BUSINESS PHONE:		(610) 208-1600

	MAIL ADDRESS:	
		STREET 1:		2366 BERNVILLE ROAD
		CITY:			READING
		STATE:			PA
		ZIP:			19605

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Metalmark Capital LLC
		CENTRAL INDEX KEY:			0001298477

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-32253
		FILM NUMBER:		081009549

	BUSINESS ADDRESS:	
		STREET 1:		1177 AVENUE OF THE AMERICAS , FLOOR 40
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10036
		BUSINESS PHONE:		1-212-823-1900

	MAIL ADDRESS:	
		STREET 1:		1177 AVENUE OF THE AMERICAS , FLOOR 40
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10036
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-08-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001289308</issuerCik>
        <issuerName>EnerSys</issuerName>
        <issuerTradingSymbol>ENS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001298477</rptOwnerCik>
            <rptOwnerName>Metalmark Capital LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1177 AVENUE OF THE AMERICAS,</rptOwnerStreet1>
            <rptOwnerStreet2>40TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10036</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2008-08-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4602</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5666136</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Reporting Person may be deemed to have beneficial ownership of the securities in Table I(5)held by Morgan Stanley Dean Witter Capital Partners IV, L.P. and MSDW IV 892 Investors,L.P.</footnote>
        <footnote id="F2">Reporting Person has no direct pecuniary interest in securities in Table I(5).  Reporting Person may be deemed to beneficially own an indirect pecuniary interest in securities in Table I(5).  Reporting Person disclaims beneficial ownership therein except to the extent ultimately realized.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Kenneth F. Clifford, Managing Director, on behalf of Metalmark</signatureName>
        <signatureDate>2008-08-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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