All of them being consistant is a good sign.
Not necessarily. I tested some 6V batts just last week that still had a surface charge. The cells were all even. I then hit it with half it's CCA rating for 15 seconds and waited an additional ten minutes. One cell was off by a large margin and well over the 50 points you want it to be less than. I only did this because the owner was on-board insisting my $$$$$$ analyzer was deficient and his SG readings were perfect. The battery could not support a carbon pile load test and had less than half the cranking capacity it should have had..
You'd often never know of an issue if not clearing the surface charge. 1.30 is a range certainly indicative of a fresh surface charge, warm temps or a thin plate or hybrid, starting/deep cycle, type battery. Most wet deep cycle cells are fully charged at about 1.265 SG but this does vary some by manufacturer. A difference between cells of more than 0.050 is an indication of a bad battery.
Before doing the test you should fill and dispense the hydrometer from the cell and back into the cell three to four times and do this at each cell. If the battery temps are not at about 80F you'll want to add 0.003 - 0.004 per every 10f above or below 80f..
I would conclude from that fact that your batteries are charged as the acid will not get weaker with waiting for things to equalize
Just like an OCV test you should wipe the surface charge or the readings can be erroneous.
Nigel Calder even puts this right in his book...
Nigel Calder said:
Following the discharge or charge, if the battery is left alone the acid and water will diffuse in and out of the plates, the battery will equalize internally, and the electrolyte will reach a homogeneous state. The only time a specific gravity reading will correlate accurately with a batteries state of charge is when the electrolyte is in the homogeneous state.
If the battery has been used vigorously , it can take up to 24 hours for the electrolyte to reach a stable state.
