Do you travel with the refrigerator on?

[Brian B-P]

Originally Posted by TTMartin

This is a photo of a 9 degree angle which would be 10% of 90 degrees I guess.

That's not what "10%" means when describing slope. A 10% gradient means that the rise is 10% of the run, so for instance over ten feet of floor length one end is one foot higher than the other. That's a pretty steep slope, of 5.74 degrees. The example shown, of 9 degrees, is a 15.8% gradient... steeper than almost any highway grade.

If you remember some basic trigonometry, the tangent of the angle from horizontal is equal to the ratio of the opposite over adjacent sides of the triangle, which is the ratio of the rise over the run, which is the grade in percent multiplied by 100. So...
tan(5.74°) = 0.10 = 10%
tan(9°) = 0.158 = 15.8%

[Brian B-P]

Originally Posted by Raider47

Would a higher amperage alternator on the tow vehicle effect the rate of battery charge, or is the wiring the limiting factor?

As long as the tow vehicle's alternator maintains the target voltage at the alternator output, it is large enough... and it is almost certainly more than large enough. Voltage loss in wiring is the main issue, but also modern vehicles don't even try to maintain the voltage required to charge the trailer battery in many conditions, as that is not required for the tow vehicle; in some case, the "tow/haul" mode selection may switch the tow vehicle's charging system to maintain a higher voltage (again, at the alternator output) at all times to address this issue.