While double-layer repulsion of charged particles in water is well known, even nonpolar solvents with a dielectric constant as low as two can contain charged ions; and particles immersed in nonpolar liquids can be electrostatically stabilized. Electric current versus time was measured between two flat plate electrodes 2.5cm x 7.5cm separated by 1.2 mm of heptane doped with 0-15% w/w poly(isobutylene succinimide) (PIBS) having a molecular weight of about 1700. The initial current yields the specific conductance of the solution whereas the initial rate of decrease in current yields the Debye length of the solution. Thus we deduced Debye lengths of 30-170 nm which decrease with increasing concentration of PIBS. Values of the Debye lengths were confirmed by performing independent measurements of double-layer repulsion using TIRM. The charge carriers appear to be inverted PIBS micelles, having a diameter of 40 nm, containing a substantial amount of solubilized water. About 25% of these micelles have a single plus or minus charge, independent of concentration of PIBS.