Need battery help

Why would you want to run them in series for 24 volts or more ??

 

if you connect them in series you add the volts, so if you have 4 - 12 volt batteries connecting them in series you'll end up with 48 volts. So no you don't want to do that.
If you are draining your batteries you may want to invest in a bigger generator(alternator), or perhaps an a.p.u. system ,that will come on if the batteries are getting low.

 

They should already be in parallel if they where factory installed. If they aren't yes you can.
Till you get an A.P.U. you either have to idle your truck part of the night, or turn your cooler off when you turn your engine off.

 

What you may want to look into is new batteries.

What you should be looking for is a high reserve capacity battery

Reserve capacity is the number of minutes a battery can maintain a useful voltage under a 25 ampere discharge. The higher the minute rating, the greater the battery's ability to run lights, pumps, inverters, and electronics for a longer period before recharging is necessary. The 25 Amp. Reserve Capacity Rating is more realistic than Amp-Hour or CCA as a measurement of capacity for deep cycle service. Batteries promoted on their high Cold Cranking Ratings are easy and inexpensive to build. The market is flooded with them, however their Reserve Capacity, Cycle Life (the number of discharges and charges the battery can deliver) and Service life are poor. Reserve Capacity is difficult and costly to engineer into a battery and requires higher quality cell materials. thicker lead grids (the plate's skeletal structure) to support additional positive plate oxides which are compressed into a denser form in order to add battery reactive material for greater Reserve Capacity and Cycling Performance. In addition, these plates are separated by indestructible separators. These mats hold the active oxides tightly in place during the cubical plate expansion which occurs during deep discharging, instead of allowing the oxides to shed off and precipitate to the bottom of the battery. Construction materials such as those raise the Reserve Capacity of a battery and increase the battery's Cycle Life.

 

Some other items you may want to look into is the battery cables.

Corrosion on the terminal ends usually means that corrosion has also moved up into the cables. Battery connections have a few inherent problems. One is dissimilar metals, lead, steel, copper and aluminum all contribute to galvanic corrosion. Add that most battery terminals are not a gas tight seal, leading to vapor escape and chemical corrosion.
May be a good time to replace them.

The other thing to look into is your alternator. While it may be working, is it putting out the power your systems need to fully recharge the batteries. As brushes wear plus cycle time and heat on the diode bridge you may not be getting a solid output from the alternator. Most newer units have that and the voltage regulator built into the alternator.

If you have low voltage feeding the alternator field, then you will get low output from the unit. It is not uncommon to put a volt meter to the system and see a good voltage reading. The problem is no force behind it, no amperage. That's what you need to get a battery charging.

Automotive batteries are some form of a lead acid type. The most common is the wet cell type. Been around for ever. Newer versions are the AGM, or absorbed glass mat. These are still a close form of wet cell ( the glass matting is a keeps the plates wet like a sponge)
Gel cells are still a lead acid type, but a gelling agent has been added to the liquid electrolyte to thicken or solidify them.

AGM and Gel cell batieries are not user serviceable.

Wet cell batteries are serviceable. Some of the "sealed" batteries can be serviced. Basically servicing a battery is keeping the terminals clean and keeping the fluid level up.
It really is best to use distilled water in a battery, as all contaminates have been removed in the process.
also once a battery has been put into service, only add water, adding electrolyte fluid will damage it. Over filling a battery can lead to problems. When you open the cells cap, look inside and you will see a ring, that's the "full" point.

The death of a battery comes from what is called sulfation.
This is when the battery has been discharged, the sulfur molecules in the electrolyte are dead and start to stick to the plates, this starts to break the plates down. Most commonly identified by grey or black fluid in the battery cells.

Deep discharging a battery will make this happen very fast.

 

If you have good batteries, clean cables, and a properly functioning alternator. You won't have to fire up the truck.

If you have to fire up the truck during a 10, You've got bad batteries, alternator not charging completely, or corroded/loose cables. OR, there's only 1 battery in the truck, or 2, or 3, instead of all 4.

I can run the fridge for 24 hours in the middle of summer before having to fire up the truck. That's when the shutdown shuts down. Shutting down all electrical leaving enough juice to fire engine up.