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                                                                    EXHIBIT 4.28


September 12, 2002


Jackson Walker L.L.P.
2435 N. Central Expressway, Suite 600
Richardson, Texas 75080

         Attn: Richard F. Dahlson, Partner

Dear Rick:

         Mobility Electronics, Inc., a Delaware corporation (the "Company"), and
Jackson Walker L.L.P. ("JW") are parties to a letter agreement, dated as of
August 7, 2002 (the "Prior Agreement"). This letter agreement supercedes the
Prior Agreement, and the Prior Agreement shall be deemed to be of no further
force or effect. The Company currently owes JW the sum of $868,988.69 for legal
services and fees with respect to JW's invoice numbers 694093 (dated April 26,
2002), 699105 (dated May 23, 2002), 703685 (dated June 21, 2002), 705742 (dated
July 19, 2002), 711952 (dated August 16, 2002) and 716799 (to be dated September
17, 2002) (collectively, the "Owed Fees"). The Company acknowledges and agrees
that it owes the Owed Fees to JW and has no dispute or claim against JW with
respect to the Owed Fees. The Company desires for JW to convert $600,000 of the
Owed Fees (the "Convertible Fees") into 571,428 shares (the "Shares") of common
stock, par value $0.01 per share, of Mobility (the "Common Stock"), and JW is
agreeable to such request on the terms and conditions set forth below.

         For good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged and agreed, the Company and JW hereby agree as
follows:

         1. If on or prior to December 5, 2002 (the "Deadline"), the Company has
filed a registration statement (the "Registration Statement") with the
Securities and Exchange Commission (the "SEC") which registers the resale of the
Shares by JW, and the Registration Statement has been declared effective by the
SEC (the "Effective Date"), then the Convertible Fees shall automatically be
deemed to be converted into the Shares as of the Effective Date, and within five
(5) business days after the Effective Date, the Company will cause its transfer
agent to deliver to JW a certificate representing the Shares (or, at JW's
discretion, the transfer agent will cause the Shares to be DTC transferred into
JW's brokerage account).

         2. If the Registration Statement has not been declared effective by the
SEC on or prior to December 5, 2002, then on December 6, 2002 the Company shall
wire transfer to JW the sum of $600,000 as payment for the $600,000 of the
Convertible Fees not so converted pursuant to Section 1 above.

         3. If the average closing price of the Common Stock for the period
between the Effective Date and December 31, 2002 (the "Average Closing Price"),
does not exceed $1.16 per share, then on or prior to January 10, 2003, the
Company shall pay to JW by wire transfer an amount equal to the difference
between $1.16 and the Average Closing Price, less an amount equal to the amounts
received by JW (net of commissions) from the sale of Shares from the



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Richard F. Dahlson
September 12, 2002
Page 2


Effective Date to December 31, 2002, in excess of the product of $1.16 per Share
multiplied by the number of Shares sold during such period.

         4. On October 1, 2002, the Company shall wire transfer to JW the
$268,988.69 of the Owed Fees which are not included in the Convertible Fees.

         5. This letter may be executed in two or more counterparts, each of
which shall be deemed to be an original but all of which shall constitute one
and the same instrument. If the terms set forth in this letter agreement are
acceptable to you, please sign and date the enclosed copy of this letter and
return it to the Company.

                                                MOBILITY ELECTRONICS, INC.



                                                By: /s/Joan W. Brubacher
                                                    ----------------------------
                                                    Joan W. Brubacher,
                                                    Chief Financial Officer

AGREED TO AND ACCEPTED
as of the date first above written:

JACKSON WALKER L.L.P.


By: /s/Richard F. Dahlson
    --------------------------------
    Richard F. Dahlson, Partner