Exhibit 99.4

                                 PROMISSORY NOTE


Amount: Aggregate amount set forth in Schedule A of             August 13, 2001
Purchase Agreement (as defined below)

     FOR VALUE  RECEIVED,  pursuant to the terms of that certain  Series A Stock
Purchase Agreement ("Purchase  Agreement," all of the terms and defined terms of
which  are  incorporated  herein)  among  Tanisys  Technology,  Inc.,  a Wyoming
corporation ("Borrower"), and the Persons and Entities Listed on the Schedule of
Purchasers  Thereto  ("Purchasers or Lenders"),  Borrower promises to pay to the
order of the Lenders the principal  sum equal to the aggregate  amount set forth
in Section 1.5 of the Purchase  Agreement  (the "Debt").  All sums hereunder are
payable to Lenders at their  addresses,  as listed in the Schedule of Purchasers
attached to the Purchase  Agreement,  or at such other  locations as Lenders may
designate in writing from time to time, in lawful  currency of the United States
of America and in immediately available funds. All payments and prepayments made
hereunder shall be made without setoff, counterclaim or deduction of any kind.

     1.  Terms  and  Repayment.  This  Note  shall  be paid by the  Borrower  in
quarterly  installments to the Lenders  commencing  March 31, 2002. The payments
shall be calculated by  multiplying  the excess of the quarterly  EBITDA for the
Borrower less quarterly capital expenditures over $300,000, by .5 (or 50%). Such
payments shall be paid until the Debt has been repaid in full.  The  affirmative
consent of New Century  shall be required and  sufficient to approve any capital
expenditures that would exceed the budget contained in Exhibit B to the Purchase
Agreement.  At the sole option of New Century,  the payments required herein may
be converted into Series A Preferred  shares,  in lieu of cash, at a price equal
to the Series A  Preferred  Purchase  Price (or as such Price may be adjusted as
provided  in Section 1.3 of the  Purchase  Agreement).  If New Century  does not
elect to convert such required  payments  into Series A Preferred,  the required
payments shall be paid in cash in accordance with the foregoing  provisions.  If
the Debt is not repaid in full to the Lenders on or before July 15, 2003, at New
Century's  sole  option,  the  Borrower  shall issue to the  Lenders,  pro rata,
additional Series A Preferred equal in number to fifty percent (50%) of the then
outstanding Common Stock and Preferred Stock (including the outstanding Series A
Preferred),  and any Common Stock equivalents,  including but not limited to any
options, warrants or other rights to subscribe for any Common Stock, on an as-if
converted and fully diluted  basis;  provided,  if such option is not exercised,
the Debt shall then mature and be payable in full on July 13, 2003. The Debt may
not be prepaid.  Prior to  maturity,  the Debt shall not  include  any  interest
payable thereupon; upon maturity, and until such time that New Century exercises
the option described immediately hereinabove,  the Debt shall accrue interest at
18% per annum.

     2. Waiver. Borrower, and each surety,  endorser,  guarantor and other party
now or  hereafter  liable for the  payment of any sums of money  payable on this
Note,  hereby  severally (a) waive demand,  presentment  for payment,  notice of
nonpayment,  protest, notice of protest, notice of intent to accelerate,  notice
of  acceleration  and all  other  notices,  filing  of  suit  and  diligence  in
collecting  this Note or enforcing any other  security with respect to same, (b)
agree  to any



substitution,  subordination,  exchange  or release of any such  security or the
release of any parties  primarily or secondarily  liable hereon,  (c) agree that
Lenders  shall not be required  first to institute  suit or exhaust its remedies
hereon  against  Borrower,  or others  liable or to become  liable  hereon or to
enforce  its rights  against  them or any  security  with  respect to same,  (d)
consent to any and all renewals, extensions,  indulgences,  releases or changes,
regardless of the number of such renewals, extensions,  indulgences, releases or
changes, without notice thereof, and (e) agree to the application of any deposit
balance with Lenders as payment or part payment hereon or as an offset hereto.

     3. No Waiver. The failure to exercise the option to accelerate the maturity
of this Note upon the  happening  of any one or more event of default  shall not
constitute  a waiver of the right of Lenders to  exercise  the same or any other
remedy at that time or at any  subsequent  time with  respect  to such  event of
default or any other event of default.  The remedies of Lenders,  as provided in
this Note,  shall be cumulative and  concurrent  and may be pursued  separately,
successively or together, as often as occasion therefor shall arise, at the sole
discretion of Lenders.  The acceptance by Lenders of any payment under this Note
which is less than payment in full of all amounts due and payable at the time of
such  payment  shall not  constitute a waiver of or impair,  reduce,  release or
extinguish  any of the rights or remedies of Lenders to exercise  the  foregoing
remedy or any other remedy  granted to Lenders in this Note,  at that time or at
any subsequent time, or nullify any prior exercise of any such remedy.

     4. Event of Default. Failure to pay this Note or any installment hereof, or
the  occurrence  of any event of default,  as defined in the Security  Agreement
attached as an exhibit to the  Purchase  Agreement  ("Security  Agreement")  and
signed by the  Borrower,  after  written  notice by Lenders to Borrower  with no
required cure pursuant to the terms of the Security Agreement, shall mature this
Note and the principal then remaining unpaid, which shall at once become due and
payable and Lenders may enforce all their rights and remedies as provided in the
Purchase  Agreement,  the Security  Agreement  and all other  documents  related
thereto.

     5. Purpose. Borrower warrants and represents that the proceeds of this Note
are to be used for the business purposes and no portion thereof will be used for
personal, family or household use.

     6.  Attorney's  Fees and Cost of  Collection.  If this  Note is not paid at
maturity (whether by acceleration or otherwise) and is placed in the hands of an
attorney for collection, or if it is collected through a bankruptcy or any other
court,  then Lenders shall be entitled to reasonable  attorneys'  fees and other
costs of collection.

     7. Limitation on Interest.  Borrower acknowledges and agrees that it is the
intention of the Lenders and  Borrower to conform  strictly to the usury laws in
force  that  apply to this  transaction.  Accordingly,  all  agreements  between
Lenders and Borrower  (including,  without limitation,  this Note),  whether now
existing or hereafter arising and whether written or oral, are hereby limited so
that in no contingency, whether by reason of acceleration of the maturity of the
Note or otherwise,  shall any interest (and all other sums that are deemed to be
interest)  contracted

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for,  charged  or  received  by  Lenders  exceed the  interest  permitted  under
applicable law of the State of Texas, or any other applicable law.

     8. Exchange. At New Century's sole option, this instrument may be exchanged
for one or more  instruments,  issuable  by  Borrower to each holder of Series A
Preferred, pro rata, in the aggregate amount of the Debt.

     9.  Subordination.  This  instrument  and the Debt shall be  subordinate to
Borrower's obligations to Silicon Valley Bank.

     10.  GOVERNING  LAW/VENUE.  THIS  NOTE  SHALL  BE  DEEMED  A  CONTRACT  AND
INSTRUMENT  MADE UNDER THE LAWS OF THE STATE OF TEXAS AND SHALL BE CONSTRUED AND
ENFORCED IN  ACCORDANCE  WITH AND GOVERNED BY THE LAWS OF THE STATE OF TEXAS AND
THE LAWS OF THE UNITED STATES OF AMERICA.


                                                     BORROWER:

                                                     Tanisys Technology, Inc.,
                                                     a Wyoming corporation


                                                     /s/ Charles T. Comiso
                                                     ---------------------------
                                                     Charles T. Comiso
                                                     President


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