Data captured using software from http://wattsview.com  This graph shows you voltage and current throughout a 20 minute bicycle generator workout period.  The white trend line is shows the battery voltage of the Duracell Powerpack.  When the generator is not being driven, you will see that the Duracell battery is about 12.2 Volts DC.   You can also see that the built in battery charge controller keeps the max voltage on the battery around 14.5 Volts DC range.   This is a healthy voltage / current level to best charge your lead acid AGM battery powerpack.   The red trend line shows you how much current flowed from the bike generator to the duracell powerpack.  Click on the Amp-Hour chart to see the total amount of amp hours.