Midnite, MNHYDROMETER, Hydro-Volt Temperature Compensated Hydrometer Go to amazon.com Related posts Top 8 best hydrometers battery: Which is the best one in 2022? DescriptionBattery Hydrometer for use on flooded batteries to check specific gravity. * Warranty - 5 yrs. Description: Easy to use battery hydrometer for checking the specific gravity on all "Flooded" style batteries.