Exhibit 10.28


                          SUBORDINATED PROMISSORY NOTE
                                January 17, 2001


$1,500,000                                                 San Diego, California


         FOR VALUE RECEIVED, the undersigned, Maxwell Technologies, Inc., a
Delaware corporation, ("Maker") hereby promises to pay to the order of Carl
Eibl, an individual, ("Holder") at his office located at 9244 Balboa Avenue, San
Diego, California 92123, or such other place as Holder may designate in writing
from time to time, the principal sum of One Million Five Hundred Thousand
Dollars ($1,500,000), on the terms and conditions of this Subordinated
Promissory Note ("Note").

         This Note reflects a short-term loan from Holder to Maker to assist
Maker in meeting its financial obligations during the remaining term of that
certain Amended and Restated Credit Agreement dated as of October 24, 2000, as
subsequently amended, (the "Credit Agreement") between Maker, as borrower, and
Sanwa Bank California, as lender ("Sanwa Bank") and is intended to be fully
subordinate to the rights of Sanwa Bank under the Credit Agreement and related
loan documents. Holder has obtained the funds representing the principal
hereunder pursuant to borrowings for which the interest rate is based on minimum
thirty (30) day periods for the borrowings to be outstanding, and the first such
30-day period commences on the date of this Note. Accordingly, the entire
principal amount of this Note shall be due and payable at the end of the first
such 30-day period that ends after Sanwa Bank has been paid all amounts owed to
it under the Credit Agreement and related loan documents. No prepayment of
principal is permitted under this Note.

         Interest shall accrue on the unpaid principal of this Note at the rate
of 11% per annum. Accrued interest shall be due and payable on the last day of
each 30-day period described in the preceding paragraph but only if no event of
default has occurred and is continuing under the Credit Agreement. If such an
event of default has occurred and is continuing at the time interest is due to
be paid hereunder, such interest payment shall not be due and payable at that
time and interest shall continue to accrue hereunder until the next interest
payment date on which no such event of default has occurred and is continuing.

         Maker agrees to reimburse Holder for any costs incurred by Holder in
seeking collection of amounts due hereunder, including, but not limited to,
reasonable attorneys' fees, costs and expenses. Maker waives presentment;
demand; notice of protest and non-payment; notice of costs, expenses or losses
and interest; and diligence in taking any action to collect any sums owing under
this Note.

         This Note is made in the State of California, and the law of California
shall apply to the interpretation of the terms and conditions of this Note.

         IN WITNESS WHEREOF, this Note is executed on the date first above
written.

                                            Maxwell Technologies, Inc.


                                            By /s/ Vickie L. Capps
                                               ---------------------------------
                                                   Vickie L. Capps
                                                   Chief Financial Officer