See if this is any use:

http://www.dstan.mod.uk/data/61/005/06000500.pdf

A.

hi,
I worked for CATERPILLAR dealer where 24 volts are used and 27 volts is the normal charging voltage.

hope this help

most modern alternators now provide approx. 14.4v for charging a 12v system. 24v systems run at approx. 28.8v
if you make your circuits to stand 30 volts you should be ok.

Usually vehicle elctronics here in Europe are rated at 32Vmax and 24V nominal.  Bear in mind that the actual voltage can go down as well as up so design for a range of about 17-32 if the electronics are critical.  (ie, need to be active when starting etc)

Gentlemen,
I have some equipment that uses cat 3512b engines that are 24 volt systems. The mechanic that works on these units wants to hookup 6 12 volt 55 watt work lights and pull the 12 volt off the center post on the 24 volt batteries(2 12 volt in series) I need some reference materials on unbalanced charging.

There is no definite fixed voltage because temperature comes into it.

What you want is a voltage high enough to charge the battery fairly quickly, but not high enough to cause gassing. The lower the ambient temperature the higher the gassing voltage. In cold climates a higher charging voltage would be appropriate.

Gassing occurs when the voltage is sufficient to break down the water into hydrogen and oxygen through electrolysis. It is not harmful in itself, but it does require the battery to be continually topped up with water.

For twelve volt automotive systems typically 14v to 14.5v is specified. (Double that for a 24v system). A twelve volt system can be trickle charged at much lower voltages say 13.5v, but it would take forever to recharge the battery.

The best way to do it will be to just set the charging voltage to perhaps 28.5 volts and see what happens. If the battery requires frequent topping up with water, lower the charging voltage. If no water at all is required over say a month, try a bit more voltage.

It very much depends if you are located in Greenland or North Africa.

The nominal voltage for a running 24V system is 28V.

tirby,
Since your mechanic wants to install an even number of lights, why not have him just hook them up in groups of two, wired in series?

Tirby,
A simple way to use the 12v lights with a 24v system and not worry about the battery charge balancing is use a 24v to 12v inverter.  Inverters are sold with different output wattage ratings.  

I hope it is appropriate to ask a related question.  I am pricing a new battery charger...one that will last me the rest of my life  (the roll around kind, say 200, 100, 60 10, 2 amps as an example).  I see there are two similar models but one will charge 24 and 12 and 6 volts and one will charge 12 and 6 only.  

In my lifetime (let's assume a good number, like 40 more years) will I NEED the 24 volt charger.  My habit is to buy and drive older rather than newer cars...but I am always eager to upgrade the old cars if the idea makes good sense.  Any thoughts?

Thanks

The most common place you will find 24v road systems these days is in the larger trucks.

I believe you will find that most commercially available  lead acid batteries for road vehicles are either 6v or 12v, and the higher voltage systems use these common batteries connected in series.

I have never seen a 24v lead acid battery, although they may exist somewhere.

If you are suddenly confronted with a huge Kenworth truck fitted with four giant six volt batteries, strictly speaking, you don't really need a 24v charger to get the job done.

You remove the batteries from the truck, and either charge them individually, or connect them all up together and simultaneously charge them at either 6v or 12v.