Wondering if it's a good idea to install a deep cycle battery to replace the standard car battery that's in my truck. I want more available power without having to keep the truck on

 

NO, not a good idea...

you want a "Starting" battery... like from the factory..

different animal.. different use..
they are not designed for high amp "Starting" work

 

They do have a "marine" battery that is a compromise. But as was said, a starting battery will give the best starting. A deep cycle will stand up best to radical draining and re-charging without damage.

It would be best to buy a deep cycle and mount it somewhere on the truck, so the truck can charge it when it's running, and then the deep cycle can be used with the truck off, saving the truck's starting battery from use. They have battery isolators for this purpose.

 

Deep cycles are normally used for RV or Marine use.

 

The problem usually, a deep cycle battery that meets the CCA requirement for your application is fricking yuuuuge, and wouldn't physically fit no way no how. It isn't really the optimal use for this type of battery, though it's OK compared to the other way around - an automotive start battery pressed into deep cycle service will be ruined in short order.

AGM are often also sold as deep cycle batteries and are sort of a hybrid. You could look at those. Most people only look at CCAs and assume the higher the CCA the better the battery. This is only partially true. If you live in Saskatoon you need all of those 1000 CCAs, but if you don't you don't.

Usually a battery that is heavier all things being equal, is a better value and will last longer, and be able to operate accessories for a longer time period. Just so long as it meets or exceeds the OEM specs.

Lots and lots of CCAs, above and beyond what the engine needs, comes at a price, both in terms of $$ and, being prone to physical damage in rough service - like off-roading. This is because in order to supply the higher instantaneous starting amperes manufacturers install more plates to increase the total surface area, consequently though they are also very thin and prone to breakage. If you don't truly need 900 or 1000 CCA battery don't buy one!

 

My concern was electrical drain from using all different types of custom accessories even with the engine on

 

A dual battery setup is an option.
A true deep cycle lead acid battery wouldn't start your truck. Not enough instantaneous amperage.
Even in the world of AGMs, there's different construction between deep cycle and normal. Automotive use (optima red vs yellow). I don't know much about them. I stick with FLA batteries.

All battery construction is a compromise between durability, cost, instantaneous amperage, long life, deep discharge and price.

 

ah I didn't think about dual battery! Would that up voltage to 24v or be 12v still?

 

A dual battery in automotive parlance is in parallel (12 volts). That would be one way to go. Remember batteries take a long time to charge back up - esp. that last 10%. Forever. Two batteries in parallel - is now electrically one large battery. Individual cells make up a battery. 6 cells in a 12 volt battery. When the cells get mismatched, whether in a flashlight or whatever it causes problems.

When you jump start a truck, that's parallel too. 12 volts still, twice the amperage, hopefully enough to turn the dead vehicle over and get it started.

Normally the alternator supplies all the juice needed for ignition, lights and accessories. The battery really has only one purpose, and that's to start the truck. So depending on what you're running with the engine off, and for how long, this can overtax the charging system. Normally the engine starts instantly, and very, very little is discharged from the battery. Alternators don't do well at all trying to charge up a discharged battery. Dual setups are worse because they get mismatched and are "fighting" each other.

 

I'm no expert but I thought most trucks with dual batteries has some kind of isolation between them so that they didn't "as they as one big battery"?
Like one was the main starting battery and the other mainly ran auxiliary systems?

 

You can, but mostly the whole point of doing that is to increase the current for starting. Electrically it's one battery. Diesels in particular, have glow plugs that need lots of juice so this is common. When I was in the .mil the trucks used four (4) big-*** batteries in a parallel series arrangement. 2 batteries connected in series to make 24 volts. Then two more series connected batteries paralleled with the other two.

Recreational vehicles are big on extra batteries w/ isolation.

 

As I said in post #3, I would run dual batteries, with a isolator. Keep your regular battery and add a deep cycle type for running accessories while the engine is off. The regular battery will always be fresh and ready to start the truck, no matter how dead the deep cycle gets.

 

Oops. Wrong post.

 

Optima make a yellow top and a red top battery that are AGM and deep cycle. I've used the yellow in several application. Currently gone to the red top for my mustang which has a lot of parasitic draw. Like alarm, remote start, emmissions and who knows what else. go to thier web site and look for your application.