Sale of Battery Main Switches
We offer a catalog with prices of main switches from the world's best manufacturers of equipment and instruments for marine electrical systems – Blue Sea Systems, Uflex, Quick S.p.A., Ultimatron France and others. All presented in the main section switches are made with special protection for operation in an environment that is aggressive for electrical equipment.
If you find it difficult to choose the type of main switch and the model that specifically suits your yacht’s system, get professional advice from topRik experts right now. Experienced sailors will answer all questions free of charge through the website feedback form or by phone. You can also send a message to [email protected].
Why Are Main Battery Switches Needed
The function of the main battery switch is to de-energize the electrical circuit in the event of a short circuit and prevent a fire from occurring. The switch must be installed with starting batteries, the cold start current of which exceeds 800 A.
The most likely cause of a fire in the starting circuit is a jammed starter. But if the battery is small (less than 800 starting amps), the starter will quickly drain the battery and will not have enough energy to start a fire. Although on a boat with an outboard engine and a starting-only electrical circuit, the standards do not allow a switch to be installed, it is correct to use it everywhere. A switch is also required for a high-capacity traction battery.
The battery disconnect switch is a safety device. But neither single-pole nor selector switches are designed to disconnect batteries under load. Under normal conditions, they isolate the battery only after the current-consuming equipment is turned off. If you regularly use a switch to interrupt the current, its contacts will burn, the resistance will increase, and it itself will cause a fire. Therefore, switches are used to disconnect circuits under load only in emergency situations.
The ability to control your boat battery is central to the safe operation of your boat, and this is the primary purpose of the boat's master switch.
Types of Main Switches
The main circuit breaker on a boat or yacht must be two-pole. Unlike single-pole, it protects the circuit when the polarity is reversed on the shore. For a simple circuit, one machine is enough. In a circuit consisting of several parallel branches, each of them must have its own circuit breaker.
Double pole yacht switches are used where it is necessary to open the positive and negative conductors and completely disconnect the electrical system from the source of voltage.
Single-pole battery switches disconnect the car or boat battery from the load. They are used to open a positive or negative conductor. The tinned copper studs in such devices have low resistance and provide maximum conductivity.
Battery breakers are rated for maximum continuous load (tested at rated current for 1 hour) and short-term load (tested for 5 minutes).
The maximum continuous load capacity of a battery breaker does not have to be equal to the sum of the currents drawn by the devices in the circuit. Powerful devices rarely turn on at the same time, and if they do, they don’t work for long. Therefore, the rating of the switch is chosen equal to (or greater than) the rating of the supply cable. If the cable is protected from overload by a fuse or circuit breaker, then the switch is also protected.
If several powerful devices are turned on at the same time, the fuse will burn out before the switch melts. If the switch rating is less than the supply cable rating, fuses are selected to protect the battery switch.
Another important requirement for battery switches is the magnitude of the short-term load. For the switch on the starting battery, it should not be less than the maximum starting current determined by the engine manufacturer. This condition is not always feasible. Even for small motors, the starting current often exceeds 1000 amperes at 12 volts.
However, this current is present in the circuit for a fraction of a second, and not for five minutes, as during tests. Therefore, Blue Sea Systems has developed a standard that is based on 10 2-second engine start attempts at 2-second intervals for a total test time of 2 minutes. As a result, for switches branded Blue Sea has a new characteristic - “Starting Current”, which is two times higher than the maximum permissible short-term load.
The two batteries on boats and yachts are traditionally controlled using a selector switch. It has four positions. In the first, both batteries are disconnected from the load, in the second and third they are alternately connected to it, and in the “1 + 2” position they are combined with each other.
The disadvantages of the four-position model led to the appearance of a two-pole switch in control systems for two batteries. Compared to the selector, it has the following advantages
- Two positions – ON and OFF. Both batteries are connected to the load simultaneously with one turn of the handle.
- The starting and service battery circuits are isolated from each other. Powerful consumers receiving energy from the service battery do not affect the starting battery.
- Echo sounders and navigation devices connected to the service battery are protected from power surges when starting the engine.
- Electromagnetic interference generated in the service circuit is not transmitted to the electronic engine control circuits.
The battery switch can be with or without battery pooling function. But in both cases, it eliminates the confusion caused by the selector switch and simplifies load management.
When the double pole switch is set to OFF, both batteries are disconnected. In the ON position, current flows from the starting battery to the engine starting circuit, and from the service battery to the on-board equipment. The COMBINE BATTERIES position connects the batteries in parallel. In this position, the service battery can be used to start the engine if the starting one is discharged, or both batteries can be charged from the generator. You can automate the charging process if you install an isolation relay or a DC-DC charger at the same time as the switch.
Modern batteries are clearly divided into two groups – deep discharge and starter. The former are capable of delivering a current of 5-50 A for several hours or even days. They are used as service ones to power on-board equipment. The second type of battery generates a current of 500-1000 A for 10-15 seconds. They start the engine.
A double-pole switch maintains these associations by separating between two types of batteries with different types of connected loads. The connection of the batteries is indicated on it as a forced position in which the batteries should not remain for long, otherwise one of them will be discharged.