The autonomy of an electric winch is a key factor in its survival in field conditions, especially when the standard generator is no longer enough to maintain the battery charge during long-term operation under load. Many SUV owners mistakenly rely solely on the standard battery, forgetting that starting current When the engine starts, the current consumption of the winch creates a critical energy deficit. As a result, you may encounter a situation where the car is pulled out, but there is no way to start it due to the deep discharge of the battery.
That is why the organization of a separate or additional power circuit is becoming not just a desirable option, but a necessity for serious off-roading. A properly designed system with battery decoupling allows you to use the traction resource without the risk of being left without light and communication. In this article we will look at the technical nuances of creating a reliable power system that will not fail in the mud.
Calculation of power consumption and currents
The first step to creating a reliable system is accurate mathematical calculations. The winch is one of the most voracious consumers of energy in a car, and its appetite grows exponentially as the load on the cable increases. If you plan to use equipment with a towing capacity of 4 tons or more, then the standard wiring and generator may simply not cope with peak loads.
To understand the scale of the problem, consider typical current values for winches of different power. It is important to understand that maximum current occurs when the winch operates at the limit of its capabilities, for example, when pulling a stuck car out of a deep rut.
- ⚡ 3000 lbs (1.36 t) winch - draws about 90-110 amps at full load.
- ⚡ Winch 6000 lbs (2.7 t) - current can reach 200-230 Amps at peak.
- ⚡ Winch 9500 lbs (4.3 t) - requires up to 350-400 Amps, which is critical for the on-board network.
- ⚡ Winch 12000 lbs (5.4 t) - consumption exceeds 450-500 Amps.
Based on these data, it becomes obvious that ordinary wiring with a diameter of 2-3 mm², often used for headlights or a radio, is absolutely not suitable here. You will need power cable with a cross-section of at least 25-35 mm² (according to the American standard AWG this corresponds to 2 or 0 gauge) to minimize voltage drop and heating. Using thin wires will result in a loss of power at the motor output and may cause the insulation to burn.
⚠️ Warning: Never use the vehicle's original fuses to protect the winch circuit. The operating current of standard fuse links usually does not exceed 30-50 Amperes, while the winch in operating mode consumes 5-10 times more. This will lead to an instant blowing of the fuse or, worse, to melting of the wiring before the protection is activated.
Connection diagrams: one or two batteries
The choice of connection diagram directly depends on the frequency of use of the winch and operating conditions. There are two main configurations: connecting to the main battery and using an additional traction battery. The first option is suitable for rare, short-term starts when the engine runs at high speeds.
However, for serious expeditions, a circuit with two batteries is preferable. In this case, the main battery (starter) is responsible for starting the engine, and the second (traction, usually AGM or GEL) powers the winch and additional equipment. The circuits are separated using an isolation relay or an electronic battery isolator.
When using two batteries, it is important to set up the charging system correctly. Isolation relay (VSR) automatically connects the batteries when the engine is running, allowing the generator to charge both sources, and opens the circuit when the engine stops, protecting the starter battery from being discharged by the winch.
☑️ Checking the connection diagram
Selecting the battery type for the winch
Not all batteries are equally useful for winching. Starter batteries (SLI - Starting, Lighting, Ignition) are designed to provide a short-term, but very powerful pulse of current to crank the engine. They are not designed for deep discharges and long-term operation under load, which is exactly what the winch requires.
Deep Cycle batteries such as AGM (Absorbent Glass Mat) or GEL. They have thicker plates, which allows them to withstand many discharge and charge cycles without losing capacity. In addition, such batteries are sealed and safe for installation in a car.
Below is a comparative table of characteristics of various types of batteries used in automobile winches:
| Battery type | Stock Ampere (CCA) | Cyclicality | Charge speed | Price |
|---|---|---|---|---|
| Starter (WET) | High | Low (20-50 cycles) | High | Low |
| AGM | High | Medium (300-500 cycles) | Very high | Average |
| GEL | Medium | High (500+ cycles) | Low | High |
| Lithium (LiFePO4) | Very tall | Very high (2000+) | High | Very high |
The modern trend is the use of lithium iron phosphate batteries (LiFePO4). They are much lighter than their lead counterparts, have a huge current output and are not afraid of deep discharge. However, their cost and the need to use special charge controllers (BMS) so far limit their widespread use in the budget segment.
Can I use an old car battery?
Theoretically, it is possible if it still holds a charge. However, remember that after a deep discharge by a winch, the starter battery may irreversibly lose part of its capacity (plate sulfation). It is better to use a used battery only as a temporary solution or in conjunction with a new battery.
Electrical circuit protection and fuses
Safety is not just a word, but a mandatory condition for the operation of powerful electrical equipment. A fast-acting fuse or circuit breaker must be present in the winch power circuit. It is installed as close to the positive terminal of the battery as possible to protect the entire cable section all the way to the winch.
The fuse rating is selected with a margin of 20-30% of the maximum operating current of the winch, but it must be less than the maximum permissible current for the selected cable cross-section. For example, if the winch consumes a maximum of 250A, and the cable can withstand 350A, then the fuse is set to 300-320A. Using a fuse that is too powerful (“so that it doesn’t blow”) turns it into a useless piece of metal that will not save the wiring from a fire.
It is also worth mentioning the thermal relays built into some winch models. They open the circuit when the electric motor overheats, allowing it to cool. However, you cannot rely on them alone, since they protect the winch itself, and not the vehicle wiring.
⚠️ Attention: When installing power cables, avoid sharp edges of the body. Vibration during movement can wear down the insulation of even a very high-quality cable, which will lead to a short circuit to ground. All passages through metal must be lined with rubber bushings.
Installation and laying of power lines
The quality of installation determines the reliability of the entire system. When laying cables from the battery to the winch, try to minimize the length of the route. The longer the wire, the greater the voltage drop, especially at currents of hundreds of amps. If the standard length of the wires that come with the winch is not enough, it is better to extend them rather than pull them across the entire car.
For connections, use only tinned copper ferrules and a reliable crimping tool. Twisting and soldering in highly loaded AC circuits (and pulsations from the generator and motor operation create difficult conditions) are not recommended due to the risk of oxidation and increased contact resistance. It is advisable to treat the joints with dielectric grease.
Use heat shrink tubing with adhesive to insulate the connections. Conventional electrical tape dries out and slips over time, especially under conditions of vibration and temperature changes under the hood.
Fasten the cables to the body with plastic clamps or metal brackets with a rubber lining. Sagging of the cable is unacceptable, as it may get caught in moving parts or be heated by the exhaust system.
Control organization and consoles
The winch is controlled via a remote control, which is also part of the electrical circuit. Standard remote controls have a short cord, which is inconvenient when working from the outside of the car. The solution to the problem is to use wireless remote controls or extend the wired one.
Wireless remote controls operate on radio frequencies and allow you to control the winch at a distance of up to 30 meters. This increases operator safety by keeping the operator out of the rope tension zone. However, they require power from batteries, which can run out at the most inopportune moment, so having a wired backup remote control is a good idea.
When extending the remote control cable, it is important to use a shielded cable to avoid interference from power lines. The cross-section of the control wires can be small (0.5-0.75 mm²), since the currents there are minimal, but the quality of the insulation must be high.
The optimal length of the control panel wire is 3-4 meters. This allows you to safely control the winding process from the side of the cable without moving too far from the control lever.
Frequent errors when assembling the system
When assembling a power system for a winch, enthusiasts often step on rakes that they could bypass if they had the information. One of the most common mistakes is saving on cable cross-section. An attempt to save a few hundred rubles leads to the fact that the winch works at half capacity, and the wires get so hot that you can get burned on them.
Another mistake is poor ground contact. Many people forget that the current must not only reach the consumer, but also return back. Stripping the ground contact down to the body metal and using washers and bolts of sufficient size are critical. An oxidized ground contact can “eat” up to 30% of the power.
Moisture protection is also often ignored. Connectors and terminals under the hood or in the trunk are constantly exposed to water, dirt and reagents. Regularly treating contacts with a moisture-displacing spray will extend the life of your electrical equipment.
Is it possible to connect the winch directly to the generator?
Technically it's possible, but it's a bad idea. The generator produces current only when the engine is running. If the engine stalls in water or mud, you will lose the ability to control the winch. In addition, power surges from the generator can damage the winch electronics. Always use the battery as a buffer.
Which battery is better: AGM or GEL?
AGM is better for a winch. They are better at delivering high currents (high starting current) and are charged faster from the generator. GEL batteries are more suitable for autonomous lighting systems and refrigerators, where deep discharge and voltage stability are important, but they are less able to withstand winch peak loads.
Do I need to remove the terminal when idle?
If the car is stored for more than two weeks, it is recommended to disconnect the negative terminal from the additional battery. This will prevent self-discharge of the battery and discharge through possible current leaks in the on-board network.
Why does the wire to the winch get hot?
Heating of the wire indicates that the resistance in the circuit section is too high. Reasons: insufficient cable cross-section, poor contact in the terminals (oxidation or loose tightening), or damaged insulation. Stop work immediately and check the entire circuit, otherwise a fire may occur.