I am not sure the angle BFL is saying to use, but I would not use 90 degrees, perhaps 45.
In my experience those plastic hydrometers like the EZ red are not accurate nor precise. If there are any bubbles that stick to the float, the reading is invalid, and the lower the SG, it seems more bubbles will stick to the float.
Do a couple bulb squeezes before trying to take a reading. i like to pull from one side of the cell and push to the other side of the cell a few times if the battery has been sitting.
Maintainers have a loyal following, but some seem to think they can fully charge a battery if left on Long enough. They should only be put on after the battery has been fully charged by a more powerful charging source which can hold the battery in the mid 14v range for 2 to 4 hours.
Interstate has never manufactured a battery. They are a battery marketer. Maximum profit is the name of the game. They best battery does not yield the best profit.
Beware of marketing and loyal subjects of marketing.
Marketing = dishonesty, for maximum profit.
