I thought I'd try an inexpensive refractometer. Most reviewers claimed it to be accurate, but I'm suspecting that they don't know how to check the accuracy, or I'm doing something wrong. Perhaps some one here has enough experience to set me right. If it turns out that the refractometer itself is junk, I won't be all that upset. I knew I was getting a budget tool and wanted to try it out.
I set the zero using some bottled water. I know that it is supposed to be distilled water, but I don't have access to distilled water at the moment. I could make a little to test this, but I don't think it would make much difference anyway. When I put a drop of tap water on the refractometer, the zero was very close to the zero line (32°F). It was within the thickness of the scale line anyway. I got the same result with the bottled water. No zero adjustment was necessary, although I did adjust it slightly to center the mark on the zero line.
I then got a commercial 50% mixture and put a few drops of this mixture on the refractometer. It measured as a 56% mixture, quite far off. I made my own 50% mixture using syringes and keeping everything at 70°F and got the same result, 56%.
My possible thoughts are:
1) the refractometer prism is incorrect for the scale that is printerd. (faulty refractometer)
2) The additives in addition to the ethylene glycol have the effect of increasing the actual % from 50 to 56.
3) The water used is not pure enough.
I do plan to use distilled water next, but I'm not convinced that it would cause such a discrepancy. Remember, even the commercial 50% mixture was reading the same as the mixture I made.
This difference is not so concerning when it comes to coolant. However, if the battery acid is off by the same "distance" on its scale, that makes a difference of 1.27 (full charge) to 1.24 (80%) charge.
Those of you who have refractometers, do the commercial mixture read 50%?
I set the zero using some bottled water. I know that it is supposed to be distilled water, but I don't have access to distilled water at the moment. I could make a little to test this, but I don't think it would make much difference anyway. When I put a drop of tap water on the refractometer, the zero was very close to the zero line (32°F). It was within the thickness of the scale line anyway. I got the same result with the bottled water. No zero adjustment was necessary, although I did adjust it slightly to center the mark on the zero line.
I then got a commercial 50% mixture and put a few drops of this mixture on the refractometer. It measured as a 56% mixture, quite far off. I made my own 50% mixture using syringes and keeping everything at 70°F and got the same result, 56%.
My possible thoughts are:
1) the refractometer prism is incorrect for the scale that is printerd. (faulty refractometer)
2) The additives in addition to the ethylene glycol have the effect of increasing the actual % from 50 to 56.
3) The water used is not pure enough.
I do plan to use distilled water next, but I'm not convinced that it would cause such a discrepancy. Remember, even the commercial 50% mixture was reading the same as the mixture I made.
This difference is not so concerning when it comes to coolant. However, if the battery acid is off by the same "distance" on its scale, that makes a difference of 1.27 (full charge) to 1.24 (80%) charge.
Those of you who have refractometers, do the commercial mixture read 50%?
