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RV Battery 101
About RV BatteriesA battery is a battery, no matter it's construction, a battery is designed to be a tank for electricity. This tank can be designed to output the stored electricity in one 15 second burst, or over time. This page is designed to help you start to understand the differences between deep cycle rv batteries and starting rv batteries. In addition we will cover series battery bank and parallel battery bank installations in your RV. Let's get started…
When choosing RV Batteries, there are roughly 5 things you need to take into account.
1 RV System Voltage
2 AH or Ampere Hour Capacity
3 Cold Cranking Amps, or CCA
4 Life Cycles of the Battery (life span)
Let us take a minute to explain each.
RV System VoltageWhen selecting batteries you need to know the voltage of the system being driven. The size of the batteries currently in your RV or coach is irrelevant to the voltage of the system driving it. The easy way determine the voltage of the coach is to know the voltage of the batteries and then look at the wires. If your system runs on 24 volts, you can can use 4 x 6 volt batteries, or 2 x 12 volt batteries to make the voltage.
To add run time in a series system, you would add strings of batteries (see below).
AH or Ampere Hour CapacityEverything but motor starting typically falls into the deep cycle, or sustained load category of electricity consumption. Therefore, we need a method to rate batteries for loads like stereos, lights, computers, televisions, etc. High AH batteries are affectionately known as deep cycle batteries. These deep cycle batteries are constructed a bit differently that motor starting batteries so they can sustain current over a much longer period of time. Typically thicker lead plates are used in the construction as they don't break down as quickly as thin plates with this type of use. What is AH though? Simply put AH capacity is the ability for the battery to delivery 1 amp, at the specified voltage, expressed in hours. Then with a little math, we can figure out how long the lights will stay on.
Example: So if a 12 volt battery has a 60 amp hour capacity, it can supply 1 amp at 12 volts for 60 hours.
Watts = Volts X Amps
1 ah is an amp for an hour
So for our example the 60 ah battery at 12 volts can supply 720 watt hours of power.
This 720 watt hours will power a 350 watt appliance for 2+ hours
This 720 watt hours will power a 200 watt appliance for 3+ hours
This 720 watt hours will power a 100 watt appliance for 7+ hours
This 720 watt hours will power a 50 watt appliance for 14+ hours
As you can see, if you want your electronic appliances to run longer, you either need to drop consumption, or increase the ampere hours of your battery bank.
Cold Cranking Amps, or CCACold Cranking Amps is a regulated test performed for 15 seconds at 0° F. Typically the battery is short circuited for 15 seconds, and the minimum sustained current is measured in amps and recorded. By short circuiting the battery, you are testing the speed with which the battery can distribute current, not the length of time it can sustain it. This is very similar to the load put on a battery as you try to turn over a cold motor.
The reasoning behind the CCA test is simple, you need a bunch of power for less than 15 seconds to start your engine. This test then gives you an ability to compare the potential power of similar batteries. Be careful not to confuse CA (cranking amps @ 32°), CCA (cold cranking amps @ 0°), marine cranking, race cranking or other various cranking amp tests. Each is performed differently. The only one that is standardized is the CCA test.
Life Cycles of Your Battery - AKA Long Term CostDo you remember that batteries are not ever to be discharged completely? Discharging a battery completely is the most destructive thing you can do to it. It forces the reactions to the chemical limits within the battery box and results in a exorbitant amount of stress on your battery. Most manufacturers recommend a discharge of between 40% and 70% for maximum battery life. Below is a graph of the number of charge and discharge cycles dependant upon the depth of discharge with Lifeline Batteries. Notice that you get 1500 cycles at 40% DOD(depth of discharge), and 1000 cycles at 50% DOD.
What happens when you undersize your battery bank is you get far fewer cycles, for instance 500 cycles at 85% DOD, 350 cycles at 100% DOD or full discharge. The lesson is to always oversize your battery bank to ensure you have the lifespan to keep things economical over time, and the power to run your systems as long as YOU want.
Battery WarrantyJust like anything else, all battery warranties are not created equal. Some battery manufacturers are in the habit of selling sub par quality batteries, and hoping that only half of their customers bring them back for another. They make their money on the half of you that are satisfied with the sub par batteries performance.
Let's just say that isn't how things work for the premier, domestically made brands of batteries that DO WORK AS ADVERTISED, they don't even need a warranty, but it is there to protect you the customer from factory defects.
The Lifeline RV Battery warranty protects against workmanship defects, and material defects, etc. If you abuse your batteries, the warranty doesn't cover it (for instance leaving them uncharged over time). The warranty is for 5 years on Lifeline Batteries, pro rated after the first year, but again, don't abuse your equipment.
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