How to choose an RV battery wisely?

The battery of the caravan has two parts: the starting battery and the living battery. The starting battery is responsible for the vehicle's ignition, driving lights and driving system equipment power supply and other operational work, simply speaking is the vehicle driving power reserve and output; life battery is responsible for the living area of household appliances, lighting and living equipment support. The two are distinct and related, the assembly, use and maintenance of the car starter battery have clear specifications and experience, but the life battery is much more ambiguous.

The life battery is fundamentally different from the starter battery in terms of usage requirements. The starting battery requires releasing a large amount of current in a short period of time to realize the car ignition function; while the life battery of the caravan requires stable current output for a long time to meet the needs of daily life.

Trends in the application of caravan batteries

The application of caravan life battery is divided into two periods.
 
1. The early application is to use lead-acid battery or colloidal battery as the life battery of the caravan. Like the most used deep-cycle lead-acid battery in the caravan can put the power very low without affecting the life of the battery, but this kind of battery generally has the disadvantages of low power storage and large weight compared with the popular lithium battery now.
 
In recent years, with the development of lithium technology, the safety and reliability of lithium batteries have been greatly improved, and more and more RV manufacturers will directly install or optionally install lithium batteries for users at the factory, while RV users also like to modify the RV with lithium batteries of smaller weight and larger storage capacity compared to lead-acid batteries after purchasing the RV.

Questions about the application of lithium batteries

With the increasing installation of lithium batteries, the discussion on the use of lithium batteries has not stopped. Why do many users choose lithium batteries?

To answer this question, we first need to understand the lithium battery. It has been 27 years since Sony launched the world's first commercial lithium battery in 1991, and then Tesla car is the lithium battery to the limelight, so that people are confident in lithium batteries.
 
Lithium battery according to the different cathode materials are mainly divided into: lithium iron phosphate (LFP), lithium nickel acid (LNO), lithium manganate (LMO), lithium cobalt acid (LCO), and nickel cobalt manganese acid ternary lithium (NCM), nickel cobalt aluminum acid ternary lithium (NCA), negative materials are mainly used graphite carbon materials. The most used battery in the caravan is lithium iron phosphate battery, which is relatively good stability and long service life of other types of lithium batteries, and has certain cost advantages.

Here, ACOUCOU gives you a summary of several advantages and disadvantages of lithium batteries:

Advantages of lithium battery 

1.     Compared with traditional lead-acid batteries, lithium batteries have obvious advantages in terms of charging and discharging electrical efficiency, power storage, volume and weight.
2.     Lithium batteries are much smaller than ordinary batteries, generally the same type of lithium battery is only half the size of a lead battery and one third the weight of a lead battery.
3.     Quality lithium battery life is generally about 5 to 6 years, eliminating the need to replace the battery often; but now the market is mixed, if you don't get down to the cheap to buy poor quality lithium, then the basic can not be used for too long.

To sum up: high battery efficiency, small size, light weight and long life. The point that needs special mention here is an important reason for the high cost of lithium batteries - the high cost of lithium battery protection plates. High research and development costs make a lot of companies are discouraged, and individual RV conversion plants are second best or other uses of the lithium battery protection plate used in the RV. This is also the fundamental reason why many RVers react differently to lithium batteries.

How to choose the right battery for your needs?

Whether it is lead-acid or lithium iron batteries, we can estimate the battery capacity according to our actual needs. It is important to know that most of the battery capacity is going to be piled up by money, and you need to know how much you are going to use.

We should know that energy is conserved, and our total demand of electricity system plus the loss of transmission system cannot be greater than the maximum limit that the power system can provide. Therefore, we inverse what kind of power supply or storage system we need to be able to use based on the demand for electricity. And, it is possible to invert what wire gauge is needed to be safe based on the electricity demand.

Select batteries according to requirements

We use the following example to project the total personal electricity demand by projecting the storage battery capacity.

Common RV electrical power valuation: air conditioning heating is generally about 2500W (electric auxiliary heating); air conditioning cooling is generally about 800W; induction cooker is generally about 2500W; electric kettle is generally about 1500W. Note: RV is not recommended to choose high-power appliances. The power of individual appliances should preferably be below 3000W, and high-power appliances should not be used at the same time, which is determined by the maximum power that can be provided by the generator or inverter we can carry.

The above calculation is the theoretical value, other electrical appliances can be analogous, the total energy consumption of all electrical appliances is added up to the total power consumption demand. The power consumption demand should be estimated according to the larger value to ensure that the backpropelled power supply is sufficient.

12V and 48V, the greater the voltage the better for sure?

The higher the voltage, the higher the efficiency

Electric power = voltage * current, in the case of a certain electric power, voltage and current are inversely proportional to each other, the higher the voltage, means the lower the current. According to Joule's law, the current through the conductor, will heat and lose part of the electrical power, and heat loss of power, and current square and resistance product is proportional to the relationship, which means that the higher the current, the more heat loss when energized, we will use the lower the efficiency of electrical energy.

This is also the fundamental reason why the power supply system should use high-voltage power supply, the higher the voltage, the lower the current will be, and the less power will be lost because of the heat.

Through this, it is easy to understand that the 48-volt power supply system, the efficiency is higher than the 24-volt, and the 24-volt will be more efficient than the 12-volt, just from the efficiency, the choice of 48-volt power supply system is far stronger than the 12-volt power supply system. Now many hybrid models, have used the 48-volt power supply standard, because the new technology, easy to break the original standard system, and the traditional 12-volt battery system, there has been a huge inertia system is difficult to break through, or 12 volts.

Voltage is not the higher the better 

The human body's safety current is 10 mA, but the amount of current in actual use is not good to determine, after all, the human use of power, basically a voltage source, so according to the average resistance of the human body, resulting in a safe voltage of 36 volts said, in fact, if in a humid environment, may be 24 volts will give you the danger of electricity, of course, 12 volts is still very safe, probably this is also the early car voltage use 12 volts is an important reason for it.

The voltage is high, which means that the insulation material should be chosen higher, otherwise it will be easy to be penetrated, especially for the car such as outdoor use of equipment, it is easy to be exposed to the wind and rain and the sun's high temperature radiation, the overall is also not a small expense.
 
Caravan is also an ordinary car engine, its power supply system voltage is basically 12 volts, if your electricity backup battery, also count on the car generator through the rectifier regulator to output supply, of course, 12-volt backup battery is relatively easy to use, so directly without much modification can be used. If the original car is already 24 volts, of course, is also used 24-volt backup battery is more reasonable. But if the battery is 48V, you must add an energy converter to step down to 12V in order to work properly, this process also requires power consumption. In addition, the 48V battery has the following disadvantages.

Inconvenient maintenance: Compared with 12V battery, 48V battery wiring harness is more complicated, which undoubtedly increases the difficulty of maintenance.

High failure rate: During the energy conversion process, the converter may have problems, and the conversion process is accompanied by heat dissipation, which also accelerates the aging of the wiring harness, and the high temperature may also lead to spontaneous combustion.

Fast power loss: whether boost or buck will generate power loss.

Low transmission efficiency: increase the converter with 48V electricity, charging with an extra link, undoubtedly reduces the efficiency of electrical energy transmission.

Low economy and practicality: adding 12V/48V converter requires extra cost.

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Develop good electricity habits

1, must be fully charged before shelving the battery, and in the premise of full charge is generally recommended in 2 to 3 months must be supplemented to the battery, if possible, the best 1 to 2 months to replenish the electricity. Most of the caravans use lead-acid batteries, due to the self-discharge of lead-acid batteries themselves will cause sulfation, if not replenished for a long time will cause capacity recovery difficulties to affect the life.
 
2、When the caravan is not in use, it should be stored in a ventilated and cool place, and the load line should be disconnected after the battery pack is fully charged to avoid discharging the battery due to no-load current.
 
3, most of the battery temperature should be controlled at minus 10 degrees to 40 degrees, the temperature exceeds 40 degrees, the battery activity of each active material increases, affecting the battery life. The battery can not fully play a role, the temperature is below -10 degrees, it can not be fully charged.