Bryan Fullerton wrote in a message to All:
 BF> I would assume that varius types of batteries are for varius 
 BF> purposes.. I have of course heard of lead acid batteries and 
 BF> recently saw some batteries that had some kind of gel or 
 BF> something in them. 
Those are also lead-acid cells,  but the electrolyte is a gel rather than a 
liquid,  and they're designed not to ever have to have any fluid added to 
them over their lifetime.  In fact,  I've known of some people who have 
ruined some that way,  they saw the vents and proceeded to pry them open and 
add water...
 BF> i basically use big batteries for my vehicles. 2 for my diesel 
 BF> Van just to start it and I need to add another one to run the 
 BF> accessories on like fridge etc. This battery needs to be good 
 BF> holding a charge for a long time and being able to recharge 
 BF> again and again.. 
What you want there is a deep-cyle type of battery,  such as is commonly sold 
for RV and Trolling Motor use.  The Exide batteries I used to deal in called 
these "Nautilus" and the variety I have here are the "Nautilus Gold",  which 
have somewhat better characteristics.  You'll also want an isolator,  to keep 
your starting batteries from discharging through your accessories,  and 
enable the accessory battery to charge while the engine is running.
 BF> also been interested in perhaps collecting some to hook 
 BF> together and hook up to a big inverter for when the power goes 
 BF> out.. could still run a few lights etc..(G) 
The big deal with regard to that is what exactly you plan on running and for 
how long.  The more of each,  the more battery you'll need.  Figure that no 
inverter is 100% efficient,  either.
 BF> in either of these applications which type or style of battery 
 BF> is best? 
I think that the batteries mentioned above will probably do well for you.  
The only advantage for Gel types are that they won't spill or vent any 
hydrogen gas,  but for any given amount of capacity they're going to be a 
good bit more expensive. 
--- 
---------------