It’s the power for the battery, it's suitable to all battery’s type to avoid the overheat. The battery water (0°, 4° and 28°) guarantee the working and increase the battery’s life’s duration.

Battery water 0°: distilled water recommended for the battery water’s renewel.
Battery water 3 to 4°: slightly acid water it’s basis is of 4° recommended for the battery water’s renewal.
Battery water 28°: slightly acid water it’s basis is of 28° recommended for the new batteries which guarantee a good start.