Not sure. It is apparently a three cell pack (6 volt nominal) as one Amazon poster measured it as 6.6 volts fully charged and lead acid technology normally gives about 2.2 volts per cell fully charged. Looking at the lantern base with the D size battery holder removed the two contact springs are readily accessible so any reasonable current source from 4.5V to 6.6V should be easy to hook up and work fine it looks like.