I UPGRADED FROM THE CASIO ILLUMINATOR TO THIS ATOMIC SOLAR G-SHOCK. ITS GREAT. I RECOMEND AT LEAST TWENTY MINUTES IN THE SUN TO GET A FULL CHARGE ON THE BATTERY CELL.<a data-hook="product-link-linked" class="a-link-normal" href="/Casio-GW500A-1V-G-Shock-Atomic-Solar-Watch/dp/B001AZXN4O/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Casio GW500A-1V G-Shock Atomic Solar Watch</a>