By Petra PaulsonYes, sealed lead-acid (SLA) batteries are completely rechargeable.In fact, when used correctly, most 12 Volt and 6 Volt sealed lead-acid batteries can be discharged/recharged over 1,000 times. Manufacturers recommend that users avoid discharging the battery's full capacity, which could limit future performance and battery life. Also, it's suggested that SLA batteries not be left dormant too long in a discharged state without being recharged.
Other benefits of SLA Batteries...
They offer high specific power at a low cost. SLA batteries perform well in both low and high ambient temperatures. However, prolonged exposure to those temperatures can cause a slight reduction in battery life and capacity. They have a low rate of self-discharge when compared to other kinds of rechargeable batteries.
UltraTech UT1240 (12V, 4.5Ah) SLA Battery
Power-Sonic PS-640 (6V, 4.5Ah) SLA Battery