The　active　mass　(AM)　utilization　is　a　key　factor　limiting　the　specific　energy　and　performance　of　lead-acid　batteries.　In　this　paper,　the　distributions　of　AM　utilization　on　two　kinds　of　positive　plates　have　been　studied　by　measuring　their　local　discharge　curves.　With　the　discharge　of　the　positive　plate,　the　current　density　decreases　gradually　in　the　lower　and　upper　parts　while　it　increases　in　the　middle.　As　a　result,　the　distributions　of　AM　utilization　are　uneven　on　the　positive　plate.　The　highest　AM　utilization　is　located　in　the　middle,　and　the　lowest　AM　utilization　is　around　the　plate.　Compared　with　a　positive　plate　with　an　orthogonal　grid,　the　positive　electrode　potential　increases　by　10-50　mV　in　most　parts　of　a　positive　plate　with　a　radiation　grid　at　high　discharge　rate　(3C).　The　positive　plate　with　a　radiation　grid　is　more　suitable　for　the　application　at　high　discharge　rates.　©　2005　The　Electrochemical　Society.　All　rights　reserved.