But if the charging was carried out with constant current, you should not control the current, it will be as it was originally set, - look at the voltage. If the charger has a built-in ammeter instead of indicator lights, how many amperes the charger (which charges with constant voltage) will show may be a question, but you will also see an arrow at zero (0,1 A) when fully charged. Therefore, how many amperes a charged battery should show is not a correct question. On the terminals check the voltage, which should be at least 12.7V half an hour after charging and about 13.4V if checked immediately after disconnection. To check if the battery is charged, do not check how many amperes the multimeter shows, because a charged battery will not take any more amperes. How long should I charge the battery to start the car?.In the “Charging current” cell, you need to indicate with what kind of current you plan to charge the battery from the charger.īy pressing the “Calculate” button you will get the necessary time to fully charge a car battery.In the “Discharge level” field, you can enter both the percentage ratio calculated from the table and the voltage measured by a voltmeter.In the “Nominal Capacity” field enter the capacity of the rechargeable car battery.To find out how long you need to charge your battery there is no need to go into the details of all the processes and calculation formulas to use this calculator.įor online calculation, you must fill in all three fields: The magnitude of the final voltage depends on: the magnitude of the charging current, temperature, internal resistance of the battery, the presence of impurities in the electrolyte and the composition of the alloy railings. When within an hour at the battery terminals, when charging, the voltage stops increasing - the battery is charged at 100%. The use of the calculation formula must be accompanied by monitoring the progress of the charging process, especially when it is completed, so as not to miss the beginning of rapid boiling. The formula for calculating how much time to recharge the car battery looks like that:
After substituting your values, you will see that a lot of time is obtained, but since, often, it does not require full charging, but only restoring the lost capacity, then this figure will be two or one and a half times less.įor an approximate estimate of the time required to charge a car battery with direct current, you must first determine the degree of discharge of the battery (in percent), then determine the lost capacity (in Ah), and then select the amount of charging current to calculate the full charge time. Proceeding from such a recommendation, the calculation of the time that is needed for a fully loaded battery has the following form: T = Q / I. The formula for calculating the charging current is: I = Q * k, where Q is the battery capacity, and k is a certain ratio of the nominal (its ideal value is within 0.04… 0.06, and the optimal value is 0.1). Stages of discharged car battery Battery charging time at constant current The purpose of this method is to ensure full recovery of the active masses in all battery plates. So for a battery with a capacity of 55 Am / h, this value is 2.75 A, and for 60 Ah it is already 3 amperes. The optimal charging current of the battery is considered to be current equal to 0.05 of its capacity ( equalizing charge). Also, an additional battery requires that battery, the density in the banks of which differs by more than 0.02 g/cm³. The lead-acid battery, which in summer is discharged by more than 50%, and in winter, even more than 25% must be removed and recharged. The degree of charging should be determined by the bank having the lowest density. The decrease in density by 0.01 g / cm3 compared to the nominal means that the battery is discharged by about 6-8%. The lower the density, the more discharged it is. Everything will depend on what density of electrolyte has been initially installed in the new battery of your region of residence, it can be as 12.7V so as 12.9V. The density of a fully charged battery should be 1.26-1.28 g / cm ³, voltage not less than 12.5 V. Generally, the state of battery charging is judged by the density of its electrolyte. When, how and what current is needed to charge A heavily discharged battery may take 14–16 hours or more.
How long a used battery will be charged depends on its degree of discharging, time of operation and condition. The first charging of a new (uncharged) battery can last for a relatively long time: 25–50 hours (depending on the state of the battery).