Hi
I tested the LVM regulator (which we couldn't get to work with the Kiss turbine) on the bench with a variable power supply, small 12V battery and a 20W light bulb in place of the dump load. The light bulb started to glow at 13.9V battery voltage and was fully on at 14.2V. Very predictable and no difficulty reading it.
So, I expected that using a light bulb in parallel with the dump load on the C40 would give an equally predictable indication. So if the battery bank was full and the engine was running, I could turn the set voltage down until the bulb starts to glow and then turn it ever so slightly up again.
Oh, and the manual warns against using light bulbs as dump loads because they are unreliable, not against using a small light bulb in parallel with the dump load as an indicator.
If I were to use lightbulbs as dump loads, I would use an array of at least 10 or 20 bulbs so one bulb blowing would not make much difference.
Owen