<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM ACTIVE
POWER'S BALANCE SHEETS AND STATEMENT OF OPERATIONS AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<S> <C>
<PERIOD-TYPE> 9-MOS
<FISCAL-YEAR-END> DEC-31-2000
<PERIOD-START> JAN-01-2000
<PERIOD-END> SEP-30-2000
<CASH> 134,732,216
<SECURITIES> 17,020,807
<RECEIVABLES> 918,027
<ALLOWANCES> 0
<INVENTORY> 2,015,678
<CURRENT-ASSETS> 150,712,157
<PP&E> 5,821,030
<DEPRECIATION> (1,886,967)
<TOTAL-ASSETS> 159,651,908
<CURRENT-LIABILITIES> 2,470,742
<BONDS> 0
0
0
<COMMON> 38,812
<OTHER-SE> 157,142,355
<TOTAL-LIABILITY-AND-EQUITY> 159,651,908
<SALES> 2,204,363
<TOTAL-REVENUES> 2,204,363
<CGS> 0
<TOTAL-COSTS> 3,782,165
<OTHER-EXPENSES> 15,877,282
<LOSS-PROVISION> 0
<INTEREST-EXPENSE> 1,701
<INCOME-PRETAX> (16,854,188)
<INCOME-TAX> 0
<INCOME-CONTINUING> (16,854,188)
<DISCONTINUED> 0
<EXTRAORDINARY> 0
<CHANGES> 0
<NET-INCOME> (16,854,188)
<EPS-BASIC> (2.18)
<EPS-DILUTED> (2.18)
</TABLE>