I would not have a problem running them in one of my trucks. The 2.5 and 5 ton alternators are adjustable and I would not expect to have a problem. If you want to charge them out of the truck you can just use the method I told you about in the beginning of this post. Use 2 12v batteries in series with a 2 12v chargers - one on each battery. Then use a pair of jumper cables to hook the 24 volt battery to the 24 volt battery pack.
NiCad batteries may experience what they call the "memory effect" if you use them in a truck. The best way to take care of this is to leave your headlights on until the battery goes all the way dead then recharge it. You should do this once per year.
Sorry, but no.
Nicad's are extremely low resistance cells. Way more so than lead acid. If you charge them with a constant voltage, you have to be accurate to better than 0.05V, and the voltage you need to charge with changes with cell temperature, how much charge the cell has, and how long you have been charging it. If you go too high in voltage, the battery will start to draw high current like it was short circuited. This will smoke your alternator, or blow fuses. If you go too low in voltage, the battery won't take a charge.
Nicad cells are considered dead when they reach 0.9 to 1.0V. During the course of a proper constant current charge, the cell voltage will rise from 1.0V fairly linearly until it reaches about 1.9V, and then it will start to drop again as you overcharge it.
Nicad "memory" is a long standing myth. The only time it ever has happened is in an extremely controlled situation back around 1962. A very early satellite had some newly designed GE Nicad cells in it to run the radios. The cells were charged by solar panels, and because the satellite was in a stable orbit, the cells charged when it was on the daylight side of the Earth, and it discharged when it was in the Earth's shadow. This charge/discharge cycle was very precise.. always exactly the same amount of charge, and always exactly the same amount of discharge. The cells developed a very refined crystalline structure on their plates, and became incapable of being discharged more than the exact amount they had been seeing as they orbited. The satellite would go dead during solar eclipse events. GE took in the information, and redesigned their Nicad cells to prevent the memory problem, and there has been no such problem since.
I know that some of you have seen something like a memory problem in Nicads. There is a problem when you over charge the cells called voltage depression. This does not change the amp-hour capacity of the cell, but it will cause the voltage on a fully charged cell to drop about 0.2V. The solution to voltage depression is to stop overcharging your batteries! That means no more trickle chargers!
Do not fully discharge a large Nicad battery in hopes of curing "memory". This is a very bad thing to do because the weakest cell in the battery will discharge completely long before the other stronger cells do. That will cause the weakest cell to be reverse charged, which will cause it to die a quick death. A 24V Nicad battery has 20 cells. It should never be discharged below 20V.
-Chuck
