Measuring specific gravity of battery electrolyte

[guy99]

Measuring specific gravity of battery electrolyte

Recently I purchased a hydrometer to check the cells in my batteries. My main interest was whether any cell or cells deviated substantially from the others.

I checked all 24 cells in my 4 batteries and found them to be very close and concluded that I didn't have any bad cells. BUT, the value of specific gravity I got suggested that the batteries were quite discharged. I charged the batteries again, let them 'settle' for 45 minutes and checked them all again. This time I got a slightly higher reading but still not 'in the green' on the scale. Beginning to suspect that my newly purchased hydrometer might be mis-calibrated I borrowed a friends hydrometer and checked all the cells. On his device all the cells read higher but still not 'in the green'.

I'm wondering if the low readings might be due to the temperature of the batteries (in the 50's)?

I also wonder if there is a way to check the accuracy of an hydrometer, maybe using distilled water?

Both hydrometers I used are like turkey basters with a float inside. I wondered if the other sort that seems to have a curl in it and claims to be temperature compensated are any better.

Last, I poked around looking for an electronic device to measure battery electrolyte specific gravity. I didn't find any. Is such a thing made? If so, how expensive are they?