JDToumanian said:
It's my understanding that 6TL/U6TL batteries are very durable - The plates are thick and well supported so the batteries can take a beating and survive. Normal el-cheapo batteries will not stand up to the vibration and jarring of off-road usage, and you can get shorted cells... Not something you want to happen on a battlefield, and one reason why Optima batteries are so popular with off roaders, and the military these days... Optimas a're very durable, too.
What he said!
I've done this rant before, but I'll try to keep it short this time. It is 20F outside and snowing and blowing like crazy, but I went out and checked the specs on my U6TLs. They are rated 875 amps at 32F, 750 amps at 0F.
There are many different types of batteries - starting batteries, deep cycle batteries, etc. Our concern here is of course starting batteries, which are designed to deliver a relatively large amount of current for a relatively short period of time. Now you can get 875CCA from a huge battery like the 6TL, MAYBE 800CCA from a much smaller car battery as bottleworks states. Group 31 civvy batteries are probably as close as you can get to a real military battery. H*ll, you could probably get by with a pair of big lawn tractor batteries. All deliver 12 volts, so why are they so different? The difference is in the internal construction of the batteries themselves, the service they are expected to provide, and the operating life they are expected to provide.
The 6TL battery has much thicker plates and support grids than the smaller civvy battery (or lawn tractor battery, for that matter) . All have the same NUMBER of plates, but the 6TL plates are much stronger, thicker and spaced further apart. When you use the battery to crank your engine, a chemical reaction occurs inside the battery to produce the current you are drawing.
This chemical reaction causes heat in the plates, a lot of heat. This heat is enough to slightly warp the plates. The more times you crank the engine and especially the longer you crank it more heat is produced and the plates warp more and more. Over enough time the plates can warp to the point they will short out and the battery is toast.
The second cause of battery failure is sulphation. If you have ever pulled the caps off an old, dead battery, you can see the plates are covered with a grey powdery substance. During the normal discharge/recharge cycle, most of this sulphate flakes off and falls to the bottom of the battery case and stays there. Some of the sulphate however remains attached to the battery plate, increasing the plate's electrical resistance and causing a gradual decrease in battery voltage.
Over time this sulphate collects on the bottom of the battery until enough builds up to short the plates and again the battery is toast. The 6TLs have a larger sump in the bottom of the case to handle more sulphate buildup.
BTW, I have read of a product called EDTA which can be added to the battery electrolyte to dissolve and reverse the effect of the sulphate. If anyone cares, I'll try to find the link to the article. The authors claimed they did an excellent job of rejuvenating a near dead HD deep cycle battery. It can also be added to fresh batteries to retard the sulphation process.
OK, now to the point. Car batteries will work, especially in warmer climates where you do not need to to a lot of cranking to start your engine. Most civvy cars are traded in before the batteries fail, so life expectancy is not a big issue there. But civvy batteries are physically weaker than the 6TLs and will fail sooner. Up here in the cold north, I need all the cranking life I can get. The 6TLs are designed for a very long service life and to provide extreme amounts of cranking power over their service life.
So the choice is yours - buy a cheap set of car batteries and use them, or get a get of 6TLs and use them. My bet is that if you keep your truck long enough, the 6TLs will be cheaper in the long run.
