<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2024-04-01</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002018289</rptOwnerCik>
            <rptOwnerName>Matthews Mark E.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ENERSYS</rptOwnerStreet1>
            <rptOwnerStreet2>2366 BERNVILLE ROAD</rptOwnerStreet2>
            <rptOwnerCity>READING</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19605</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>President, Specialty Global</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13960.7652</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>75.39</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2024-08-17</value>
            </exerciseDate>
            <expirationDate>
                <value>2030-08-17</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Stock Options</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2940.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>91.81</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2031-08-16</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Stock Options</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3916.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>70.88</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2032-08-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Stock Options</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5223.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>94.71</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F8"/>
            </exerciseDate>
            <expirationDate>
                <value>2033-08-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Stock Options</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3752.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">This amount includes 960.3235 unvested Restricted Stock Units (RSUs), in connection with the grant of RSUs on August 17, 2020, and adjusted for previously declared and paid cash dividends.  One quarter of the RSUs granted vested on each of August 17, 2021, August 17, 2022, and August 17, 2023, and one quarter will vest on August 17, 2024.</footnote>
        <footnote id="F2">This amount includes 1,588.7407 unvested RSUs, in connection with the grant of RSUs on August 16, 2021, and adjusted for previously declared and paid cash dividends.  One quarter of the RSUs granted vested on August 16, 2022 and August 16, 2023, and one quarter will vest on each of August 16, 2024 and August 16, 2025.</footnote>
        <footnote id="F3">This amount includes 3,422.7382 unvested RSUs, in connection with the grant of RSUs on August 12, 2022, and adjusted for previously declared and paid cash dividends.  One quarter of the RSUs granted vested on August 12, 2023, and one quarter will vest on each of August 12, 2024 and August 12, 2025.</footnote>
        <footnote id="F4">This amount includes 3,535.9629 unvested RSUs, in connection with the grant of RSUs on August 11, 2023, and adjusted for previously declared and paid cash dividends.  One quarter of the RSUs will vest on each of August 11, 2024, August 11, 2025, August 11, 2026, and August 11, 2027.</footnote>
        <footnote id="F5">This amount includes 4,453 shares of EnerSys common stock.</footnote>
        <footnote id="F6">1,305 of these options will vest on August 16, 2024.</footnote>
        <footnote id="F7">1,741 of these options will vest on August 12, 2024, and 1,741 will vest on August 12, 2025.</footnote>
        <footnote id="F8">1,251 of these options will vest on August 11, 2024, 1,250 will vest on August 11, 2025, and 1,251 will vest on August 11, 2026.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Karen J. Yodis, by Power of Attorney</signatureName>
        <signatureDate>2024-04-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
