	UNITED STATES
	SECURITIES AND EXCHANGE COMMISSION
	Washington, D.C. 20549
	SCHEDULE 13G (Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULES 13d-1 (b), (c) AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO 13d-2 (b)
(Amendment No. 1)*

Active Power, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

00504W100

(CUSIP Number)

December 31, 2001

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

o	Rule 13d-1(b)
o	Rule 13d-1(c)
ý	Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

(Continued on following pages)

Exhibit Index on Page 12

CUSIP No. 00504W100

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only) Austin Ventures IV-A, L.P. Tax ID Number:

	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)		o
		(b)		ý

	3.	SEC Use Only

	4.	Citizenship or Place of Organization Delaware

Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0 shares.

			6.		Shared Voting Power 0 shares.

			7.		Sole Dispositive Power 0 shares.

			8.		Shared Dispositive Power 0 shares.

	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 0

	10.	Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) o

	11.	Percent of Class Represented by Amount in Row (9) 0.0%

	12.	Type of Reporting Person (See Instructions) PN

CUSIP No. 00504W100

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only) Austin Ventures IV-B, L.P. Tax ID Number:

	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)		o
		(b)		ý

	3.	SEC Use Only

	4.	Citizenship or Place of Organization Delaware

Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0 shares.

			6.		Shared Voting Power 0 shares.

			7.		Sole Dispositive Power 0 shares.

			8.		Shared Dispositive Power 0 shares.

	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 0

	10.	Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) o

	11.	Percent of Class Represented by Amount in Row (9) 0.0%

	12.	Type of Reporting Person (See Instructions) PN

CUSIP No. 00504W100

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only) AV Partners IV, L.P. Tax ID Number:

	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)		o
		(b)		ý

	3.	SEC Use Only

	4.	Citizenship or Place of Organization Delaware

Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0 shares.

			6.		Shared Voting Power 0 shares.

			7.		Sole Dispositive Power 0 shares.

			8.		Shared Dispositive Power 0 shares.

	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 0

	10.	Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) o

	11.	Percent of Class Represented by Amount in Row (9) 0.0%

	12.	Type of Reporting Person (See Instructions) PN

CUSIP No. 00504W100

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only) Joseph C. Aragona Tax ID Number:

	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)		o
		(b)		ý

	3.	SEC Use Only

	4.	Citizenship or Place of Organization U.S. Citizen

Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0 shares.

			6.		Shared Voting Power 0 shares.

			7.		Sole Dispositive Power 0 shares.

			8.		Shared Dispositive Power 0 shares.

	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 0

	10.	Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) o

	11.	Percent of Class Represented by Amount in Row (9) 0.0%

	12.	Type of Reporting Person (See Instructions) IN

CUSIP No. 00504W100

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only) Kenneth P. DeAngelis Tax ID Number:

	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)		o
		(b)		ý

	3.	SEC Use Only

	4.	Citizenship or Place of Organization U.S. Citizen

Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0 shares.

			6.		Shared Voting Power 0 shares.

			7.		Sole Dispositive Power 0 shares.

			8.		Shared Dispositive Power 0 shares.

	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 0

	10.	Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) o

	11.	Percent of Class Represented by Amount in Row (9) 0.0%

	12.	Type of Reporting Person (See Instructions) IN

CUSIP No. 00504W100

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only) Jeffery C. Garvey Tax ID Number:

	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)		o
		(b)		ý

	3.	SEC Use Only

	4.	Citizenship or Place of Organization U.S. Citizen

Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 0 shares.

			6.		Shared Voting Power 0 shares.

			7.		Sole Dispositive Power 0 shares.

			8.		Shared Dispositive Power 0 shares.

	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 0

	10.	Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) o

	11.	Percent of Class Represented by Amount in Row (9) 0.0%

	12.	Type of Reporting Person (See Instructions) IN

CUSIP No. 00504W100

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only) William P. Wood (“Wood”) Tax ID Number:

	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)		o
		(b)		ý

	3.	SEC Use Only

	4.	Citizenship or Place of Organization U.S. Citizen

Number of Shares Beneficially Owned by Each Reporting Person With			5.		Sole Voting Power 67,517 shares, all of which are directly owned by Silverton Partners, L.P. (“Silverton”), a Texas limited partnership, and Wood, the sole general partner of Silverton, may be deemed to have sole power to vote these shares.

			6.		Shared Voting Power 0 shares.

			7.		Sole Dispositive Power 67,517 shares, all of which are directly owned by Silverton, and Wood, the sole general partner of Silverton, may be deemed to have sole power to dispose of these shares.

			8.		Shared Dispositive Power 0 shares.

	9.	Aggregate Amount Beneficially Owned by Each Reporting Person 67,517

	10.	Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) o

	11.	Percent of Class Represented by Amount in Row (9) 0.2%

	12.	Type of Reporting Person (See Instructions) IN

This statement amends the Statement on 13(G) filed by Austin Ventures IV-A, L.P., Austin Ventures IV-B, L.P., AV Partners IV, L.P., Joseph C. Aragona, Kenneth P. DeAngelis, Jeffery C. Garvey and William P. Wood, the general partners of AVP IV. The foregoing entities and individuals are collectively referred to as the “Reporting Persons.”

Item 4.	Ownership.
The following information with respect to the ownership of the Common Stock of the issuer by the persons filing this Statement is provided as of December 31, 2001:
	(a)	Amount beneficially owned:
		See Row 9 of cover page for each Reporting Person.
	(b)	Percent of class:
		See Row 11 of cover page for each Reporting Person.
	(c)	Number of shares as to which the person has:

		(i)	Sole power to vote or to direct the vote:
			See Row 5 of cover page for each Reporting Person.
		(ii)	Shared power to vote or to direct the vote:
			See Row 6 of cover page for each Reporting Person.
		(iii)	Sole power to dispose or to direct the disposition of:
			See Row 7 of cover page for each Reporting Person.
		(iv)	Shared power to dispose or to direct the disposition of:
			See Row 8 of cover page for each Reporting Person.

Item 5.	Ownership of Five Percent or Less of a Class
If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following: ý Yes

Signatures

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: February 11, 2002

AUSTIN VENTURES IV-A, L.P.	/s/ John Nicholson
By AV Partners IV, L.P.,	Signature
Its General Partner
	John Nicholson
	Chief Financial Officer/Attorney-In-Fact

AUSTIN VENTURES IV-B, L.P.	/s/ John Nicholson
By AV Partners IV, L.P.,	Signature
Its General Partner
	John Nicholson
	Chief Financial Officer/Attorney-In-Fact

AV PARTNERS IV, L.P.	/s/ John Nicholson
	Signature

	John Nicholson
	Chief Financial Officer/Attorney-In-Fact

JOSEPH C. ARAGONA	/s/ John Nicholson
	Signature

	John Nicholson
	Chief Financial Officer/Attorney-In-Fact

KENNETH P. DeANGELIS	/s/ John Nicholson
	Signature

	John Nicholson
	Chief Financial Officer/Attorney-In-Fact

JEFFERY C. GARVEY	/s/ John Nicholson
	Signature

	John Nicholson
	Chief Financial Officer/Attorney-In-Fact

WILLIAM P. WOOD	/s/ John Nicholson
	Signature

	John Nicholson
	Chief Financial Officer/Attorney-In-Fact

EXHIBIT INDEX

Exhibit

Exhibit A: Agreement of Joint Filing

Exhibit B: Reference to John Nicholson as Attorney-In-Fact

EXHIBIT A

Agreement of Joint Filing

The Reporting Persons hereby agree that a single Schedule 13G (or any amendment thereto) relating to the Common Stock of Active Power, Inc. shall be filed on behalf of each of the Reporting Persons. Note that copies of the applicable Agreement of Joint Filing are already on file with the appropriate agencies.

EXHIBIT B

REFERENCE TO JOHN NICHOLSON AS ATTORNEY-IN-FACT

John Nicholson has signed the enclosed documents as Attorney-In-Fact. Note that copies of the applicable Power of Attorneys are already on file with the appropriate agencies.

AUSTIN VENTURES IV A LP SC 13G/A