Heat soak starter coil, or weak battery?

[zirconxi_imp]

Hi all, its been hot here where I live, recently my bike will not start after riding in the heat for some times (about 20 minutes ride). The symptom are akin to weak battery where crank are weak and meter reset after crank. 2 to 3 tries later the battery will be too weak to crank anymore. But leaving the bike to cool down like 30 minutes later the bike can crank easily just like normal, without the need to charge the battery. Before I replace the battery, I read there's this "heat soak starter" problem in car and wonder if there could be same problem for bikes.