The situation when the battery is discharged at the most inopportune moment is familiar to every driver. To solve this problem, auxiliary equipment is most often used, which are popularly nicknamed “crocodiles.” However, if you contact a specialized auto parts store or a professional auto mechanic with a request to sell “crocodiles,” you may not be understood or misunderstood, since this is only a slang name. In technical documentation and manufacturers' catalogs, this product appears under completely different names, reflecting its functional purpose.
A correct understanding of terminology is necessary not only for competent communication with sellers, but also for the safe selection of equipment. Jump wires is a complex electrical product that has strict production standards regarding core cross-section, insulation material and terminal design. Incorrect selection of components can result in overheating, short circuiting, or even fire during engine starting. Therefore, it is important to know the exact technical names of the elements of the emergency start system.
In this article we will look in detail at how the components of a lighting kit are correctly named, what types of clips exist, and what to look for when purchasing. We will move away from everyday names and consider the issue from the point of view of automotive electrical engineering. Battery Clamps, as they are often called in import catalogs, have their own design features that directly affect the reliability of contact and the safety of the procedure.
Official terminology and classification
In the professional environment and technical literature, a device for transferring energy from one battery to another is called jumper wires or engine starting cables. The clips themselves, which are popularly dubbed “crocodiles,” are technically called battery clamps or contact clamps. In English-language documentation they are often referred to as Battery Clamps or Booster Clamps. The use of the term "crocodiles" is acceptable in spoken conversation between drivers, but it is not normative.
These products are classified according to several key parameters, knowledge of which will help you choose the right tool. First of all, attention is paid to the maximum starting current that the cable can withstand without overheating. The length of the wires is also important: cables that are too short may not reach the batteries of two cars standing next to each other, and cables that are too long will lead to a voltage drop.
- 🔌 Conductor material: Copper or aluminum are most often used, with copper options being preferred due to better conductivity.
- 🔋 Clamp type: There are spring, screw and combined mechanisms for fixing the terminals.
- ❄️ Temperature: Wire insulation must remain elastic at low temperatures typical for winter operation.
It's important to note that the reliability of the connection directly depends on the contact area of the clamp with the battery terminal, so the shape of the clamp jaws plays a critical role. Some models are equipped with additional teeth to break through the oxide layer on the terminals, which provides more stable contact. When choosing, you should give preference to models with an open spring or a reinforced compression mechanism, which provide maximum clamping force.
Design and types of clamps
The main working element of the starting device is the clamps, which must ensure reliable electrical contact with the battery terminals. Structurally, they are massive copper or brass jaws enclosed in a dielectric housing. Spring mechanism provides the necessary compression force, preventing sparking and heating at the contact point. Poor quality clamps often have a weak spring mechanism, which leads to poor contact and the inability to start the engine.
There are several types of clamp designs. The most common models are those with an open spring, where the compression mechanism is located outside. They are convenient because they are easy to clean from dirt and corrosion, but are more susceptible to mechanical damage. Closed models, where the spring is hidden inside the case, look more aesthetically pleasing and are protected from moisture, but they are more difficult to maintain if the mechanism breaks down.
⚠️ Attention: Never use clamps with damaged handle insulation. If metal parts of two opposite poles (plus and minus) touch, a short circuit will occur, which may cause the battery to explode or burn your hands.
When choosing, pay attention to the size of the “jaw” of the clamp - the distance between the jaws when open. It should be large enough to cover a variety of terminal types, including thick American standards or oxidized domestic vehicle terminals. Serrated surface The jaws allow a better grip on the smooth surface of the terminal, preventing slipping when a high inrush current is applied.
Materials and wire cross-section
The quality of starting wires directly depends on the materials used in their manufacture. The main parameter here is conductor cross-section. To start a gasoline engine of a passenger car, a cross-section of 16 mm² is considered the minimum acceptable, but for diesel engines or cars with a large engine volume, a cross-section of 25 mm² and higher is required. Thin wires will act as a heating element, wasting precious energy.
The material of the core also matters. Copper has the best electrical conductivity, but it is expensive and susceptible to oxidation. Aluminum cheaper and lighter, but requires a larger cross-section to pass the same current. Manufacturers often use a trick by using a copper-coated steel core (CCS - Copper Coated Steel), which is a compromise, but an acceptable solution provided that the cross-section is sufficient. Pay attention to the markings on the insulation: the material and cross-section should be indicated there.
The insulation of the wires must be made of frost-resistant rubber or special PVC, which does not tan in severe frost. Silicone insulation is considered one of the best options as it remains flexible even at extremely low temperatures. The thickness of the insulating layer is also important: it must protect the core from mechanical damage and accidental contact with metal parts of the car.
| Engine type | Minimum cross-section (mm²) | Recommended current (A) | Core material |
|---|---|---|---|
| Gasoline (up to 1.6 l) | 10 - 16 | 200 - 300 | Copper/CCS |
| Gasoline (1.6 - 3.0 l) | 16 - 25 | 300 - 450 | Copper |
| Diesel (up to 2.0 l) | 25 - 35 | 400 - 600 | Copper |
| Diesel (over 2.0 l) | 35 - 50+ | 600 - 1000+ | Copper |
Check the quality of the core before purchasing: lightly press the wire with your fingers. If it flattens easily and does not spring back, most likely there is thin aluminum or steel inside, and not a full-fledged copper wire of the required cross-section.
Secure Connection Rules
Knowing the correct terminology is only the first step. It is much more important to be able to use it correctly jumper wires. The “lighting up” process requires a strict sequence of actions, violation of which can lead to failure of the car’s electronics or damage to the battery. The main danger lies in the possibility of reverse polarity or creating a short circuit.
Before starting the procedure, make sure that the battery voltage is the same (usually 12 Volts). You should not attempt to start a 12-volt vehicle from a 24-volt truck battery without special equipment. Also make sure both engines are turned off and the keys are removed from the ignition. This will prevent voltage surges in the on-board network at the time of connection.
☑️ Connection algorithm
First connect the positive lead (red) to the positive terminal of the dead battery, and then to the positive terminal of the donor. The negative wire (black) is connected to the donor's negative wire, and the other end is connected to an unpainted metal part of the engine or body of the receiving car ("ground"). Direct connection to the negative of a discharged battery It is not recommended, since sparking may ignite electrolyte vapors, especially if the battery is serviceable.
⚠️ Attention: It is strictly forbidden to allow clamps of opposite polarity to come into contact at any time. A spark near the battery can cause it to explode due to the ignition of oxyhydrogen gas.
Typical mistakes when choosing and using
One of the most common mistakes is buying wires “by eye” without taking into account the characteristics of the car. Drivers often choose the cheapest options in beautiful packaging, without paying attention to the actual wire cross-section. Visual thickness insulation can be deceiving: there may be a tiny wire inside, surrounded by a thick layer of cheap plastic. Such wires will not be able to transmit the necessary starting current.
Another mistake is improper storage. Jumper wires should not be kept rolled up in a tight ball or under heavy objects in the trunk. This may damage the insulation or deform the clamps. Regular check the integrity of the insulation and the cleanliness of the contacts of the clamps should become a good habit for every motorist.
Many people also neglect to clean the terminals before making connections. Dirt, oil and oxides on the terminals create additional resistance, which negates all efforts. Use a wire brush or sandpaper to clean the contacts before installing the crocodile clips. This will ensure maximum energy transfer efficiency.
Why do the wires get hot when starting?
If the wires get hot, this means that their cross-section is not enough to carry the current, or the contact in the terminals is poor. Resistance increases, energy goes into heat, not into the starter. Abort the procedure immediately to avoid melting the insulation.
Alternatives to classic wires
The modern car accessories market offers not only classic cables with clamps, but also more advanced solutions. Starting devices (boosters) - These are portable lithium-polymer batteries that allow you to start the engine without the participation of another car. They are compact, safe and often equipped with intelligent reverse polarity protection, making them ideal for inexperienced users.
There are also capacitor starters. They work on the principle of storing energy from the weak residual charge of a discharged battery or from a 12V network (if possible) and giving it a powerful impulse to start the engine. Such devices are especially effective at low temperatures, when chemical reactions in the battery are slowed down.
Despite the emergence of new technologies, classic jumper wires remain the most affordable and widespread means of roadside assistance. Their main advantage is their simplicity of design and the absence of the need for recharging or maintenance. The main thing is to choose a quality product that matches the parameters of your car and know how to use it correctly.
High-quality starting wires with large-section copper conductors and reliable clamps are a mandatory element of a motorist’s winter kit, which can save them in a critical situation.
Is it possible to use smaller gauge wires if the engine is small?
It is highly undesirable to use wires with a cross-section smaller than the recommended one. Even for a small engine, at the moment of starting, the starter consumes a huge current (200-300 Amperes). A thin wire will create high resistance, the voltage at the starter will drop, and the engine may not start, and the wires themselves will melt.
How to distinguish copper wire from aluminum?
This cannot be done visually by the color of the insulation. You can look at the cut: copper has a reddish tint, aluminum is silver-gray. Copper is also heavier and softer. The most reliable way is a magnet: copper is not magnetic, but steel (which is often used to replace copper in cheap wires) will be. Aluminum is also non-magnetic, but it is much lighter than copper.
Why do “crocodiles” do not stick well to the terminals?
This may be due to worn spring mechanism, dirty clamp teeth, or incompatible clamp size with terminal type. Sometimes the problem is solved by cleaning the terminals and clamping jaws from oxides. If the spring is weakened, it is better to replace the clamp, as poor contact will lead to heating and sparking.
Is it possible to light a car with an automatic transmission?
Yes, you can. The process of starting the engine from an external source is identical for cars with manual and automatic transmission. The main requirement is to observe the connection polarity and the sequence of actions described in the instructions. The gearbox is not involved in this process.