Fill the jar with electricity - an expression from the dictionary of V. I. Dahl: so he explained the meaning of the word «charge». It fits perfectly with modern car batteries of six cans. True, the banks in fact turn out to be different - both in design and condition. How to fill them with electricity?
All battery conditionally can be divided into low-maintenance, unattended and completely unattended. The oldest of them are low-maintenance, with gratings made of lead-antimony alloy, the coolest ones are completely maintenance-free, with gratings made of the purest lead. It should be noted that under «unattended» means extended intervals for topping up water or the complete absence of this procedure during the entire service life. But any maintenance-free battery requires periodic inspection on a par with other vehicle components. Contrary to popular belief, there is not much difference in the charging of these three types of batteries.
Should I charge or not?
There is a simple, objective way to assess the condition of a battery. It is necessary to measure the voltage at the battery terminals with a voltmeter, while it is not necessary to disconnect it from the car's electrical system. Open circuit voltage (NRC) should be 12.6-12.7 V. It is important that several hours pass between stopping the engine and measuring the voltage (ideally at least ten), otherwise the readings may be too high.
In low-maintenance and maintenance-free batteries with plugs or a block of plugs in the lid, you can also check the density of the electrolyte - you need a hydrometer (he is a densimeter). This will give you an idea of the battery charge «by jar». The density of the electrolyte in a fully charged battery should be 1.27 g/cm3. This value is ideal in terms of the efficiency of the active materials and the internal resistance of the battery. Density less than 1.25 g/cm3 is used in hot countries where short discharge characteristics are not so important. By the way, at such a density, the corrosion rate decreases, which prolongs the service life. Densities above 1.29-1.30 g/cm3 are used in the Far North, where an undercharged battery is in danger of freezing.
Is it possible to charge in the cold?
The lower the ambient temperature, the worse the battery accepts a charge. The normal temperature range for charging is 0...+ 25°C. Therefore, in winter, the probability that the batteries will have time to recover during the trip depends on the rate of heating of the electrolyte. And it is strongly influenced by the location of the battery on the car - under the hood, in the trunk or even outside. From this point of view, delivery trucks with an external battery location are in the worst position.
How to charge for infrequent trips?
Many cars are more often laid up than driven. Their owners often use so-called recharging - chargers that constantly feed batteries with low currents to maintain 100% charge. This mode is not useful: it increases the corrosion rate of the plate grids and reduces battery life. Therefore, if the car is not moving for more than three weeks, it is better to recharge the battery in the usual way - from a charger or from a generator after starting the engine. And before the next performance «for storage» the battery must be fully charged, otherwise there is a high probability of experiencing a deep discharge, the car refusing to start normally and the need to buy a new battery.
Charger or generator - which charges better?
Under normal operating conditions, no charger is needed. The battery must be charged by the generator. And charging at a constant voltage of a serviceable car is the most correct and useful for the battery. The task of a stationary charger is to restore the battery, albeit not completely, but enough so that the generator has already recharged by 100%. When charging with constant current, in order to avoid overcharging and «boil-off», that is, the consumption of water from the electrolyte, the stationary charger interrupts operation at the level of 14.4 V, switching to the minimum current recharge mode during storage. This usually prevents the battery from being fully charged. And the generator charges it in constant voltage mode.
Depending on the settings of the car's power supply system, the voltage regulation range is 13.8-14.5 V. The charge current is determined by the internal resistance of the battery, which characterizes its state at the moment, and decreases as the voltage value at the battery terminals approaches the generator voltage. That is, a stationary charger gives out a specific current in accordance with its algorithm, and the battery takes the current it needs from the generator. This is why a charger cannot charge in the same way as a generator.
What should be the charge mode?
With an open circuit voltage of less than 12.3 V, the battery has the right to be capricious when starting the engine, especially in winter. And if it has been in this state for a long time, then the charge can be completely restored at a constant voltage, but with a low current - about 1 A. After the battery can take on large values, the current will increase. In any case, such «resuscitation» preferably carried out in a specialized service. Do not start the situation and control the battery charge, especially before long-term storage - for example, if you are flying on vacation.
When the NRC drops below 10.5 V, it is already an ultra-deep discharge. If the battery was planted in a short time, it can be quickly charged with a large current of 10-20 A (10% of rated capacity) from a stationary device within a few hours. If the battery experienced chronic undercharging and died slowly, the charge must be started with a minimum current at a constant voltage. To do this, you will have to contact a specialized service.
Should the battery be removed from the car to charge?
No, it's reinsurance. Although theoretically gassing can really cause a battery to explode. The rules of conduct are very simple: do not smoke near the battery while charging and do not short the terminals.
Can «light up» from another car?
Opinions on this subject often differ, but the disputes are only about the safety of the electrical equipment of the car and the compliance with its operating instructions. One thing is certain: the battery will definitely not suffer!
In our opinion, «smoking» it is safe if a simple scheme is followed: we connect the positive terminals of the donor and acceptor to each other, and put the negative terminal of the donor on the body «lighted» car.