Well DavidHK
looks like you have two excellent testers lined up.
For a 24 or 36v circuit, I think the simplest is the best. This circuit looks to only need a few milliamps to run 99% of the time. I would use a 3W resistor of around 1k in the positive power input line to the main board, and use a 12v 1watt zener (actually i would use 18v as I have a thousand of them....)to pull the higher voltage to a lower voltage that will not bother the rest of the circuit. The 7809 will take care of the rest after that.
The only time it will use a few more milliamps is when the relays are pulled in.... and I would use a different/separate 5w 500R resistor to drive the relay primary... or just use 24v coils in the relays... but a resistor does this fine..... ie run the relays on a separate line to the regulated 339 system
It is brutally simple, and has 20 years use in our battery charger boards we used to build ( in the good ole days)
Those boards were running 24/7, even when they switched off the load... in this trackers case, the relays are used for very short times, so the rest of the time only the 339 is running... and it is a mostly turned off high impedance.
Whilst silly simple, it also protects from spikes that will terminate voltage regulators and buck chips. Suggest you try this first.
Here it is in a similar setup, you can see two big resistors, the 270R drives the black relay from 24v, the 470R comes down from the 24v to 12v (see tiny zener) and then goes through a 1205 regulator to a voltage divider and trimmer for a comparator.... very similar to your needs.... ie a stable voltage , and a "wild" input of a higher value than you need. and this circuit is also used up to 50v with different resistors of course.... but has stood the test of time.
Ruddycrazy as you can see on this board, I have no problems with right angles on low voltage DC boards... frequency and voltage changes this to avoid corners, but for this and the tracker will make zero difference.
Also losses in the resistor system will be small if you get the R correct for the A that the board uses, so the zener is only barely used.
Volvo "
I need something that will run on 24V nominal and not blow up when I equalize batteries at 32V though."
This is exactly what I'm talking about with using this system. One of these boards is used in my EV to control my mill. It is resistored for a 36v system, but regularly sees 48v from the mill, and has done so for years now. (if it sees > than 45v for more than 5 mins, it shuts the mill down)....
observations from the side
...................oztules