The Voyager craft don't have batteries. They are powered by a radiothermal generator, which is basically a lump of radioactive material. As it decays, it gives off heat, which is converted into electricity. Over time, the radioactivity decreases and the power produced decreases with it. Eventually, the craft will run out of power. read more
The solar wind has a negligible impact on the craft (no impact at all for Voyager 1, since it has now passed beyond the influence of the solar wind). They keep moving away simply because of momentum. They have escape velocity, so the sun's gravity won't be enough to stop them. read more
Voyager 1 doesn't have any thrust power. So its moving in interstellar with momentum only. Electrical power from thermostate nuclear battery is non chargeable. That battery reduced power after 38 years operation. Marvelous piece of technology. All power will shutdown till 2020 and then it will go further unmonitored blindly in deep space. read more
“It could happen in the next several months, or it could be several more years,” says chief Voyager scientist Ed Stone of Caltech. If Voyager 1 does manage to leave the heliosphere before it runs out of power around 2025, the spacecraft will probe the Local Cloud, a wisp of interstellar flotsam absorbing traces of light from nearby stars. read more