How far apart do I need powered rail to get up a 1 block ledge and maintain speed

Ok I think I figured it out.

On the Minecraft wiki for Minecarts under Loss of Speed says

One unit of kinetic energy could be defined as the energy gained by a cart going down a one block slope, and lost by a cart when it goes up a one block slope.

Later it says

...an initial height of 60 blocks will result in a final height of 40 blocks, a loss of 20 units of potential energy. But if 20 sections of flat track are inserted between the slopes, the final height will be 35. This implies that one unit of energy is lost for every 4 sections of horizontal track traveled...

So to get the same result you need to bring the powered rail 4 blocks closer i.e. 33 blocks between powered rails with a ledge in between.

This can be extended for any number of ledges by subtracting (ledges x 4) from 37.

Hope this helps anyone else who wonders.