Carambola wuluh is one of Indonesia’s natural resources that is still less optimized in its utilization. Generally, people use Carambola wuluh only to be processed into sunti acid which is then used as a flavor enhancer in cooking. The content of oxalic acid in sunti acid can be utilized as a raw material for the gel electrolyte which will be used to recharge used batteries. This study aims to determine the potential of sunti acid extract for the recharging process of used batteries. The voltage obtained from the electrolyte gel of the sunti extract is greater when compared to the accuser voltage. The results showed that the best compositions for obtaining the optimum voltage and current strength was 7% (w / v), NaCl 1.25% (w / v) and Glycerol 40% (v / v) for the electrolyte gel and addition of 10% NaOH 1M and 0.01% KMnO4, based on the volume of the electrolyte gel, to increase the voltage and the strength of the resulting current. The results obtained are expected not only to turn on the LED lights and the motor drive (dynamo), but also be an alternative material for recharging used batteries.