® Trick Tools #7: Battery Hydrometer
Mike Nixon

Many will argue the fact, but a graduated float type hydrometer is the only accurate type. It so happens that only one company makes one small enough for use in flooded-cell powersports batteries, and that is the premier battery supplier, Yuasa. Available by part number from both Honda and Harley-Davidson dealers.

Update 2013: It appears this tool is no more, from either Harley or Honda. (Part numbers M989X-268-94228 from Honda, and 96910-35 and 96802-63 from Harley). All that can be found today is the ball type. In case you're curious, the problem with ball type hydrsometers is the first time you use one it's fine, but eventually the plastic balls absorb the acid and then become unpredictable. The problem with standard automotive hydrometers is volume. They require too much liquid to raise their floats, usually well over 10cc, whereas hydrometers made for powersports are designed to work on just 5cc of fluid. The many digital hydrometers show promise but so far all that I have seen require too muc fluid, just as the standard float type unit does. Varta, at one time BMW's battery supplier, seems to have a smaller unit (#EELEBATTAT), but I have not been able to confirm this. Meantime, I have found a supplier of good float type hydrometers and have had some supplied to me for investigation. Stay tuned.

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