Do-it-yourself battery heating

Almost every motorist who is faced with issues of servicing car batteries knows how negatively cold affects the condition of this device.

Therefore, various solutions are being developed to protect batteries from exposure to low temperatures. This is done by insulation or heating.

You can organize battery heating yourself by making the appropriate device. Or buy a ready-made solution that can be easily found in car accessories stores.

What is a thermal case and why is it needed?

Thermal cases for car batteries are special containers or reservoirs that provide heat retention and protect the battery from exposure to cold.

At low temperatures, battery discharge accelerates significantly.

If the battery has not been used for the first season, it is quite worn out, then in severe frosts it may happen that during the night of parking on the street the charge will drop to critical values and it will no longer be possible to start the engine.

Cases can be equipped with heating or go without it. In the second case, special multilayer materials with the effect of heat reflection are used.

In order not to buy a case from the manufacturer, you can make an analogue with your own hands using improvised materials.

When answering the question of why you might need a case for a battery located under the hood of a car equipped with a heating system, it is worth giving several arguments.

This protects the battery from exposure to low temperatures. And this automatically prevents a strong and deep discharge.
The cover or case also protects from exposure to elevated temperatures in the summer. Thermal cases are made from materials that prevent the electrolyte from boiling away in the summer. This extends the life of the device.
The battery is protected from dirt and dust. But the penetration of debris into battery banks can cause destruction of the plates.
Covers prevent the consequences of minor mechanical shocks and vibrations. That is, a barrier is created to preserve the integrity of the body.

Some models of modern car cases are even equipped with an indicator or controller, through which the motorist can promptly learn that the battery charge has dropped to critical levels.

Traditional ways to insulate a battery:

1. The first way is to wrap the battery in a heat-insulating material (say, fur).

Industrial insulation for thermal insulation of a battery

Unfortunately, this method only works if you drive a car often. Unfortunately, the battery itself does not generate heat - only when it is charging or when it is working (giving energy to the load).

If the car is parked for a long time, the battery still freezes completely after just a few hours. You only gain a few hours in battery freezing time.

If you drive a lot—say, several times a day—then this method is very effective, since the battery does not have time to freeze completely. It is always warm and warms itself.

Another negative factor of thermal insulation of the battery is that the heat from a warmed-up engine will not affect the battery - since the thermal insulation will protect from both cold and external heat. 2. Insulation of the entire engine compartment. In this case, we win in several ways.

Firstly, the heat from a hot engine will warm the battery.

Secondly, the engine itself will warm up, including the injector, air filter, and oil. The engine heat will be retained and it will start very easily.

From real experience, this really helps to start the car in the morning as the engine does not freeze deeply. The battery, in turn, is fully charged since it is warm all the time during operation and does not have time to freeze completely in the morning and is accordingly ready to supply the required amount of energy.

How to choose the right one

When choosing a cover or heated case for your battery under the hood of a car, many drivers look towards factory solutions.

When choosing a suitable solution, you should pay attention to the following points:

Device type. This is an ordinary multi-layer cover or a container equipped with a heater. The second type is more effective in severe frosts. But it is demanding on connections, requires a power source, and costs more.
Price. This is an individual parameter that depends on the capabilities of a particular motorist.
Dimensional characteristics. Cases are designed for several types of batteries, depending on their size. These are large, small and medium.
Available space under the hood. To wrap the battery in a case or case, there must be enough space under the hood. Usually it is 10-15 mm. on each side.
Battery case type. Covers and cases can be adapted for batteries used in Europe, Asia or the USA. If this is the USA, the polarity will be reversed.
The dimensions of the plates in the thermal case should not exceed the dimensions of the battery.

All that remains is to study the range of stores that are available to a particular motorist and choose the appropriate option among them.

Options for insulating a car battery?

Comprehensive insulation of the engine compartment

Many people recommend comprehensive insulation of the entire engine compartment. This improves on several fronts. What are the advantages here?

You insulate the engine and radiator, which has a positive effect on their operation in winter;
In addition to the engine, the injector, oil, air and oil filters warm up. All this cools down more slowly and the engine will be easier to start;
The battery is located next to the heated engine and, in turn, is insulated. Therefore, it will not freeze deeply overnight.

Insulation of the engine compartment

To begin with, it is best to insulate the radiator. If there is no suitable material at hand, then this can be done using ordinary cardboard. Here it is important to install it correctly so that it hides the upper and lower pipes from cooling. After this, the motor is insulated. This is done in a complex manner. You can find insulating blankets for different car models on sale. You can also buy thermal insulation material and cut a piece out of it to size. They either cover the engine or attach it to the hood.

Then the battery insulation is made from the same material. On the engine side, you can make a removable side to open it for warming up while the engine is running.

DIY battery insulation options

“Fur coat” for batteries made of various materials

Here the question immediately arises: how to insulate the battery? Which material to choose? Below are the main materials that battery owners use to insulate them.

Materials for insulating the battery

Coolant heating

Some people heat the battery with antifreeze, which circulates in the engine cooling system. The car interior heater has a similar circuit. A branch is made from the stove (or from another place in the cooling system). From it comes a tube that encircles the battery. This results in effective insulation. The engine warms up and the hot antifreeze heats up the battery.

But such a scheme is, of course, rare. After all, here you need to make extra pipelines that can leak. Removing the battery for maintenance will be problematic. In addition, it is easy for the battery to overheat. Then the electrolyte will boil, which is not at all good for it. Overheating can be prevented by installing additional heat-insulating material between the tubes and the walls of the battery. But still, the solution, in our opinion, is not very convenient.

Battery heating from the on-board network

This is done by connecting several parallel resistance chains. In each chain, resistors must be assembled in series. The nominal resistance depends on the current and the required heating temperature. As resistance increases, energy consumption will increase and heating will increase.

The significant disadvantage here is that such a garland of resistances will easily drain the battery overnight. Therefore, using such heating makes sense when the engine is running in a cold climate, and not when parked. Or you need to install a controller in the circuit that will open it when the battery voltage is below 12 V. Then in the morning you will have a reserve of battery capacity to start the engine.

There is also an interesting version of this scheme that does not drain the main battery. That is, the energy is taken from an additional battery and power is supplied to the resistance circuit from it. An AGM battery from an uninterruptible power supply is quite suitable for these purposes.

AGM battery from uninterruptible power supply

How to install and use

If you decide to purchase a factory case equipped with heating for your car, or more precisely for the battery, it would be a good idea to learn about the installation features of the case.

It is important to follow several recommendations:

First, the battery must be disconnected from the power supply. That is, the terminals are reset when the ignition is turned off. Depending on the configuration of the case, the battery can be wrapped without removal or after removal from its seat.
The wires are connected to terminal clamps. The case is powered directly from the battery. Therefore, do not forget to strictly observe polarity. Minus to minus, and plus to plus.
If the battery had to be removed, then the reverse installation is carried out with the case already on and connected.
When the engine starts, the heating system will start operating. The heaters operate until the battery warms up to 25 degrees Celsius.
When the engine is turned off, the heating is automatically turned off.

A properly connected battery heater will preserve the battery capacity and extend its service life.

Before you begin installation and operation, be sure to read the instructions from the case manufacturer.

A specific model may have its own characteristics.

Self-insulation of batteries

The desire to save money or the desire to try something new forces motorists to independently make analogues of factory cases for batteries.

Making an effective thermal case for your battery with your own hands is not difficult.

There are 2 main manufacturing options:

make a simple insulation;
create a heated system.

Obviously, a thermal case for a battery, made of special materials that retain heat, is much easier to assemble with your own hands. But its effectiveness will be lower.

Then everyone decides for themselves which path to take.

Homemade case

It’s worth starting with a simple option, which is not equipped with a heating system.

The following materials can be used:

folgisol;
felt;
Styrofoam.

Let's start with Folgisol. This is a plastic and easy-to-work material. It features high heat retention efficiency.

For a foil case to work effectively, it is recommended to use 3 layers.

You can perform insulation with foilzol using the following algorithm:

take measurements of the future case that correspond to the dimensions of the battery;
prepare the required amount of folgisol;
use scissors or a stationery knife to cut out the necessary elements;
you need to make the walls, bottom and top cover;
as a middle layer you can use a layer of foam up to 20 mm thick;
the walls are connected to each other with tape, as is the lid and bottom;
The battery is installed in the received case.

Just make sure the sizes match.

An analogue is a product based on foam plastic.

To make a thermal case from foam plastic, you need:

Choose a material of suitable thickness and size so that it is enough to cover all parts of the battery. The thickness should be no more than 35 mm.
A box is made from polystyrene foam, inside which the battery will be located. You should cut out the walls, bottom, and lid. The connection is made with heat-resistant glue. It is better to coat the joints with sealant.
The battery is installed in the case and covered with a lid.

Don't forget to provide holes through which the terminals and wires will come out. Just don't make them too big, as heat will begin to escape quickly through them.

And another option would be felt. Making a case from felt is quite easy.

The work is carried out by analogy with the use of foilzol. Just remember these nuances:

to increase the efficiency of the insulation, felt is made in several layers;
felt insulation is capable of retaining heat in the battery for 8 hours;
this is the best solution among similar cases for everyday use;
After starting the engine, heat from the internal combustion engine will slowly flow to the battery.

The last point can be considered a conditional disadvantage.

We insulate the car battery for winter

Experienced car enthusiasts know that cold causes the battery in the car to drain faster. Therefore, often in the morning you can see people unsuccessfully trying to start an engine that has been standing in the cold all night.

Experts know that when the outside air temperature is below 15 °C, a decrease of 1 degree contributes to a 1% drop in battery charge. So it’s quite possible to be left with a completely discharged battery in the morning. In addition to an “empty” battery, cold winters lead to a strong increase in the viscosity of oil and fuel, especially diesel fuel. As a result, attempts to turn on the engine turn into a very difficult test for the car.

There are many ways to solve this problem, including such simple ones as "lighting up" for luckier drivers and keeping the battery warm. But they are completely unreliable, since there may not be a working car nearby, and removing the battery is difficult. In this situation, it is worth resorting to insulating the battery. You can do it yourself or purchase ready-made devices: thermal cases, heaters or bags for batteries.

Why do we need thermal cases for batteries?

If the winter frosts are severe and the car is left in the cold for more than 8 hours, this can greatly reduce the battery capacity. To protect and insulate it, special devices are used - thermal bags and covers. They are inexpensive - you can find them from 500 rubles.

They protect against the negative effects of low temperatures and do not allow the battery to quickly discharge. As a result, it remains operational. Even after a very frosty night, the car owner starts the engine without any hassle.

By avoiding frequent discharge of the battery, this extends its service life. Battery heaters can simplify the winter operation of a car in harsh winters. Their use in mild climates is not necessary.

How they work and what they are

All car enthusiasts are well aware of such a device as a car blanket. It is made of materials that can retain heat and reflect it inside the engine compartment, keeping the engine and battery from freezing at low temperatures. Battery protection is made from similar materials using the same principle.

All heaters come in two types : those that do not use battery power and those that are powered by a battery to retain heat. They differ in the material used for insulation:

Foam based.
Made from foil polystyrene foam.
Covered with fabric.
Finished with polyethylene sheathing.
Equipped with additional heating elements powered from the machine’s on-board power supply.

The main function of a battery case, no matter what type it is, is to protect the device from sudden temperature changes. It is not able to warm the battery or prevent it from completely cooling over a long winter night, but it actively prevents a strong loss of capacity. And this is necessary for normal engine startup.

Many different modifications of thermal boxes are produced, which are selected according to the dimensions of batteries made in European, American and Asian production. The average cost does not exceed the equivalent of 10 dollars. One of the common models is EX BOX battery 50-65Ah, suitable for most popular batteries.

Is it possible to do it yourself?

Since the battery case is a fairly simple product and is made from available inexpensive materials, it is quite possible to make it yourself. There are a number of requirements for it:

The use of flammable materials is prohibited.
Do not leave seams or gaps through which cold air can freely penetrate (with the exception of technological openings for the exit of wires and fasteners).
To fasten parts, you can use glue and tape (for attaching foil materials).

The most accessible materials for manufacturing at home are the following materials:

Styrofoam. This is the cheapest material for insulation, and it is also easy to work with. Measurements are taken from the battery, and foam sheets are cut according to them. The entire structure is carefully glued together, making sure that there are no gaps left. The battery is placed in the resulting foam box, tightly closing it with a specially fitted lid made of the same material.
Folgoizol on polystyrene foam. Folgoizol is a modern insulating material that protects against increased heat loss. To enhance the efficiency of its operation, it is used in conjunction with polystyrene foam, with which it forms a “sandwich” of three layers: foil insulation + foam plastic + foil insulation. This achieves the maximum level of battery protection. The polystyrene foam is glued together, and the layers of foil insulation can be securely fastened with tape.
Felt. This is another accessible material. A pattern is made from it according to the shape and size of the battery. To improve the protective properties, take several layers of felt and cover them with dense material. Velcro fasteners can be added to make working with the battery easier.

All thermal insulation devices have one drawback - they block the flow of heat from a running engine to the battery. Those. To prevent the battery from freezing, it must first be heated. If it is not insulated, then this is done due to the heat of the engine. With insulation it becomes more difficult to heat up. Here it would be appropriate to buy a heated thermal case - this is the best solution.

Video - DIY battery case

This protection method is more suitable for motorists who often drive a car with stops for no more than 3-4 hours. After 7-8 hours of leaving the car in the cold, the battery will freeze, with or without insulation. We advise those car enthusiasts who have the battery not in the engine compartment to do insulation - then it helps a lot.