Thank you for asking…luvrbus.
Battery gets less sulfating if you charge at high end of adjustable setting.
The lower the setting the thicker the sulfate coating in time.
Charging the lead-acid batteryhttp://www.batteryuniversity.com/partone-13.htm
MCI call for 28 volts @ 80°F is for 24hrs day uses. Very little cranking cycle per “passenger” miles.
However, for us motorhome uses…higher setting is better at 29.4v @ 70°F (alternator & regulator temperature). You may use little more water in battery but it keeps it more alive and last as long or longer however, if you can desulfate the batteries….you will get even more life still.
All electronic devices, blower motor, headlight and miniature bulb are factory design to be a least 15v for 12v and 30v for 24v system.
This one of the common reason for the 8D batteries that came with from charter companies for bus conversion is very weak to say the least. Voltage setting is too low for bus nuts purposes.
Do can do what you want to set it at whatever. It your money and time for the long run.
Car & light & medium truck of today are set at the middle range.
Ace…Now that I was thinking why you said that?…you are right about bus being use passenger and motorhome, have difference voltage setting. Only because it not running nearly 24hrs every day and never stay warmed …you need to set higher then their spec our uses. Set it at least 28.5 for warm climate to 29.4 volts @ 80°F for cold climate with a load on such as bright headlights and front heater motor on.
Sorry for confusion but after seeing many bus nuts post about the hard starting with old 8Ds in mild cold day that it starter barely cranks the DD fast enough to raise the combustion temperature high enough (at least 700°F) to ignites. So I am learning that buses manufacturing is spec for low voltage setting, we need to increase it to be in our style of uses.
BTW…High end charger is set 15.5v for 12v and 31v for 24v battery.
Gerald, if you double the 12v for 24v that would be 29.4 volts are you sure about that formula my Prevost manuals states 27.5 for both the seated and conversion shell . good luck