As has been said more than once, in its circuit the current reaches hundreds of amperes (up to 400-500 A in the full braking mode!) - the corresponding electrical connections must be extremely reliable.
FIGURE 1. Battery terminal blocks are designed to transmit the maximum starting current. To make the contact area of the terminal with the conical pin of the battery as large as possible, the clip itself is often made of lead. Sometimes - from bronze, brass (here the requirements for manufacturing accuracy are more stringent). The clamp is usually tightened with a bolt and nut. The termination of the wires in such terminals should be very solid - they are usually mechanically crimped or rolled. Here, in the photo, you can see other wires connected to the “plus” of the battery: the main one from this trinity is the thick black (below) connecting the generator to the battery. It is designed for the maximum return current of the generator (up to 70–80 A).
FIGURE 2. A variety of handpieces (not all are shown here!) Are used in those cases when when working on a car - not necessarily related to repair, but any other! - preferably a reliable, but quick-disconnect wire connection: disconnected when necessary, then reconnected. A huge advantage over screw, terminal connection, not to mention soldering or twisting. To install the ferrule, the wire is stripped 5–10 mm and, having inserted into the ferrule’s socket, they are crimped. In factories - in special machines, in service - with a manual device. Some do-it-yourselfers do with pliers, but it is difficult to get a beautiful result with them.
FIGURE 3. The wires supplying a “plus” to consumers, of course, must be protected from short circuit to “mass” (in some schemes, the “minus” contact must be excluded, depending on how the consumer turns on!). Therefore, their tips are almost always insulated with plastic cases. When repairing single connectors, the latter is not necessary. Usually, a piece of vinyl tube (cambric) or an insulating tape winding is enough. If the connection is prepared “forever”, you can use shrink cambric: put on, heated with hot air - and that’s the point. Rubber tubes are dangerous - they tend to “age”, crack, swell, etc., and a bare wire imperceptibly threatens a fire.
FIGURE 4. Often, motorists are faced with miscalculations of factory designers. Looking at the photo, any owner of "Samara" will begin to tell how he was tormented with the mounting block. Guessed how to arrange it as if in a gutter! Electrics - especially in winter, when water, salt, and dirt get here - quickly become worthless. Two foreign wiring, soldered by the owner, confirmation of this. And by the way, soldered joints in these conditions are the most moody! They are acceptable where it is dry and clean, for example, under the dashboard. But there are damp places in the cabin!
FIGURE 5. The traditionally problematic place of the “classic” VAZs is on the floor, near the middle pillar. Here, under the rug, even in the summertime it is dirty and damp - what can we say about winter! Meanwhile, a bundle of wires passes through the “swamp”, here there are branches for powering the interior lights. So they usually become unusable, not only violating the function of the ceiling, but also affecting the alarm. The last one doesn’t care if the wire itself is broken or the contact in the limit switch is broken, so the search for the causes of such a failure must be started with these elements!
FIGURE 6. These are the reliably sealed, trouble-free connectors found on some foreign cars. Neither salt nor dirt penetrates inside. Unfortunately, such a serious approach to business in domestic factories is, rather, an exception. So, in cars with fuel injection, the wiring serving this injection looks more or less decent, but our automakers are not in a hurry to eliminate the childhood illnesses that have come to the headlights, lamps, interior equipment, etc. from the previous carburetor cars. The result - a lot of programmed failures as if programmed - let the owner not be bored.
FIGURE 7, 8, 9 A few more ways to connect wires during repairs. On the left (mainly for circuits with large currents of tens or more amperes) is a clamp made of a bolt, nut and two washers. The latter allow you to compress the wires well without breaking the veins. In the middle - twists. It is important to do everything honestly, otherwise they will fail. A real master will twist the wires with a pigtail - the connection will not be weaker than the whole wire - and even insulate it well. On the right is a fork connector with a plastic case: it is very convenient if you need to tap from some wire, but still do not want to resort to twisting. After inserting the wires into the plastic clip, into the slot we enter a metal double-slotted plug and clamp. By focusing the insulation of the wires, the plug provides a reliable connection. It remains to secure it - click the safety valve.