Battery recharge
Content
- How to determine the overcharge of the battery
- Why is the battery recharging
- What does overcharging a battery do?
- What to do when reloading?
- Frequently Asked Questions
- Will the battery be recharged if a larger generator is installed?
- Does the diameter of the power wires affect the recharge?
- How to correctly connect a second (gel) battery so that there is no overcharging?
- The alternator recharges the battery, is it possible to drive home with the battery removed?
- Do I need to change the electrolyte after a long battery recharge?
- How long can the battery be charged to increase the density of the electrolyte (water evaporation)?
- The arrow of the battery charge sensor is constantly on the plus - is it overcharging?
Recharging a car battery appears when a voltage higher than the maximum allowable - 14,6–14,8 V is applied to its terminals. This problem is most typical for older models (UAZ, VAZ "classic") and cars with high mileage due to design features and unreliability of the elements electrical equipment.
Recharging is possible if the generator fails and if the charger is used incorrectly. This article will help you figure out why the battery is recharging, why it is dangerous, whether a car battery can be recharged on a serviceable car, how to find and eliminate the cause of overcharging, this article will help.
How to determine the overcharge of the battery
You can reliably determine the overcharging of the battery by measuring the voltage at the battery terminals with a multimeter. The check procedure is as follows:
- Start the engine and warm it up to operating temperature, waiting for the rpm to drop to idle.
- Turn on the multimeter in the mode of measuring direct (DC) voltage in the range of 20 V.
- Connect the red probe to the "+" terminal, and the black one to the "-" terminal of the battery.
The average voltage in the on-board network in the absence of consumers turned on (headlights, heating, air conditioning, etc.) is within 13,8–14,8 V. A short-term excess of up to 15 V is permissible in the first minutes after starting with a significant battery discharge! Voltage above 15 V at the terminals indicates overcharging of the car battery.
The following signs also indirectly indicate the recharging of the battery in the car:
Oxidized terminals covered with a green coating are an indirect sign of frequent recharges.
- lamps in the headlights and interior lighting glow brighter;
- fuses often blow out (at low voltage, they can also burn due to an increase in currents);
- the on-board computer signals an excess of voltage in the network;
- the battery is swollen or traces of electrolyte are visible on the case;
- battery terminals are oxidized and covered with a green coating.
With stationary battery charging, overcharging is determined by indications, by sound or visually. The charge voltage should not exceed 15–16 V (depending on the battery type), and the charging current should not exceed 20–30% of the battery capacity in ampere-hours. Gurgling and hissing, active formation of bubbles on the surface of the electrolyte immediately after charging indicates its boiling and non-optimal charging mode.
A recharged battery holds a charge worse, overheats, its case can swell and even burst, and the leaking electrolyte corrodes the paintwork and pipes. Increased voltage in the network leads to failure of electrical equipment. in order to prevent this, the problem must be urgently fixed by finding out why the battery is being recharged. Read below for how to do it.
Why is the battery recharging
Recharging the battery from the charger is the result of an incorrect choice of charging time, voltage and current in manual mode or a breakdown of the charger itself. A short-term recharge from a charger is less dangerous than from a generator, since it usually does not have time to lead to irreversible consequences.
The reasons for overcharging the car battery on board by 90% lie precisely in a faulty generator. Therefore, it is it that needs to be inspected and checked in the first place. Less commonly, the cause of overcharging the battery lies in wiring faults. The specific causes of overvoltage and their consequences are listed in the table.
Table of reasons for overcharging a car battery:
| Causes | What is causing the reload? |
|---|---|
| Generator Relay Problems | The relay does not work correctly, the voltage in the on-board network is too high, or there are voltage surges. |
| Defective generator | The generator, due to a short circuit in the windings, a breakdown in the diode bridge, or for other reasons, cannot maintain the operating voltage. |
| Regulator relay failure | The voltage regulator relay (“tablet”, “chocolate”) does not function, due to which the output voltage significantly exceeds the allowable one. |
| Weak contact of the terminal of the relay-regulator | Due to the lack of contact, an undervoltage is supplied to the relay, as a result of which a compensating effect is not generated. |
| The consequences of tuning the generator | To increase the voltage on older models (for example, VAZ 2108-099), craftsmen put a diode between the terminal and the relay-regulator, which lowers the voltage by 0,5–1 V in order to fool the regulator. If the diode was initially selected incorrectly or the drop increased due to its degradation, the voltage in the network rises beyond the allowable one. |
| Weak wiring connection | When the contacts on the connecting blocks oxidize and leave, the voltage on them drops, the regulator regards this as a drawdown and increases the output voltage. |
On some vehicles, overcharging the battery from the alternator is a common problem caused by design flaws. The table below will help you find out which models are overcharging the battery, and what is the reason for it.
Table with the causes of "congenital defects" on some cars that entail overcharging the battery:
| Car | Cause of overcharging the battery from the generator |
|---|---|
| UAZ | Recharging often occurs due to poor contact of the regulator relay. It often appears on "loaves", but it also happens on the Patriots. At the same time, the native voltmeter is also not an indicator of overcharging, since it can go off scale for no reason. You need to check the recharge only with a known accurate device! |
| VAZ 2103/06/7 (classic) | Poor contact in the contact group of the lock (terminals 30/1 and 15), on the contacts of the relay-regulator, and also due to poor ground contact between the regulator and the car body. Therefore, before replacing the "chocolate" you need to clean all these contacts. |
| Hyundai and Kia | On Hyundai Accent, Elantra and other models, as well as on some KIAs, the voltage regulator unit on the generator (catalog number 37370-22650) often fails. |
| Gazelle, Sable, Volga | Poor contact in the ignition switch and/or fuse block connector. |
| Lada Priora | The voltage drop at the generator contact L or 61. If it is more than 0,5 V lower than on the battery, you need to ring the wiring and look for a drawdown. |
| Ford Focus (1,2,3) | Voltage drop at the alternator regulator connector (red wire). Often the regulator itself fails. |
| Mitsubishi Lancer (9, 10) | Oxidation or breakage in the S contact generator chip (usually orange, sometimes blue), due to which the PP produces an increased voltage. |
| Chevrolet Cruze | The voltage of the on-board network slightly above 15 V is the norm! The ECU analyzes the state of the battery and, using PWM, regulates the voltage supplied to it in the range of 11-16 V. |
| Daewoo Lanos and Nexia | On Daewoo Lanos (with GM engines), Nexia and other GM cars with "related" engines, the cause of overcharging almost always lies in the failure of the regulator. The problem of its replacement is complicated by the difficulty of dismantling the generator for repair. |
What does overcharging a battery do?
When a problem is identified, it is important to urgently eliminate the overcharging of the machine battery, the consequences of which may not be limited to battery failure. Due to the increased voltage, other nodes may also fail. What does overcharging the battery and for what reasons - see the table below:
What threatens to recharge the battery: the main breakdowns
| Consequences of overcharging | Why is this happening | How could this end |
|---|---|---|
| electrolyte boil-off | If the current continues to flow to a 100% charged battery, this causes active boiling of the electrolyte and the formation of oxygen and hydrogen in the banks. | A decrease in the electrolyte level leads to overheating and destruction of the plates. A small explosion and fire are possible, due to the ignition of hydrogen (due to a spark discharge between the exposed plates). |
| Shedding plates | Under the influence of current, the plates that are exposed after the liquid boils away overheat, their coating cracks and crumbles. | The battery cannot be restored, you will have to buy a new battery. |
| Electrolyte leakage | Boiling away, the electrolyte is released through the ventilation holes and enters the battery case. | The acid contained in the electrolyte corrodes the paintwork in the engine compartment, some types of wire insulation, pipes and other parts that are not resistant to aggressive environments. |
| Battery swelling | When the electrolyte boils, the pressure rises and the batteries (especially maintenance-free ones) swell. From deformations, lead plates crumble or close. | With excessive pressure, the battery case can burst, damaging and splashing acid on parts in the engine compartment. |
| Oxidation of terminals | Evaporating from the battery, the acidic electrolyte condenses on neighboring parts, causing the battery terminals and other components to become covered with a layer of oxides. | Deteriorated contact leads to disruption of the electrical network on board, acid can corrode the insulation and pipes. |
| Failure of electronics | Overvoltage causes damage to sensitive electronic components and sensors. | Due to excess voltage, lamps and fuses burn. In modern models, failure of the computer, air conditioning unit and other on-board electronics modules is possible. There is an increased risk of fire due to overheating and destruction of the insulation, especially when using non-standard low-quality accessories and spare parts. |
| Generator burnout | The failure of the relay-regulator and the short circuit of the windings cause the generator to overheat. | If overheating of the generator leads to burnout of its windings, you will have to rewind the stator / rotor (which is long and expensive) or change the generator assembly. |
Regardless of the type of battery, it is important not to overcharge it. For all types of batteries, overcharging the battery is equally dangerous, but the consequences can be different:
Battery explosion - the consequences of overcharging.
- Antimony (Sb-Sb). Classic serviced batteries, in which the plates are alloyed with antimony, relatively easily survive a short recharge. With timely maintenance, everything will be limited to topping up with distilled water. But it is these batteries that are more sensitive to high voltage, since recharging is already possible at a voltage of more than 14,5 volts.
- Hybrid (Ca-Sb, Ca+). Maintenance-free or low-maintenance batteries, the positive electrodes of which are doped with antimony, and the negative electrodes with calcium. They are less afraid of overcharging, withstand voltages better (up to 15 volts), slowly lose water from the electrolyte when boiling. But, if a strong overcharge is allowed, then such batteries swell, a short circuit is possible, and sometimes the case is torn.
- Calcium (Ca-Ca). Maintenance-free or low-maintenance batteries of the most modern subspecies. They are distinguished by minimal water loss during boiling, are resistant to high voltage (at the last stage they are charged with voltage up to 16–16,5 volts), therefore they are minimally susceptible to overcharging. If you allow it, the battery can also burst, splashing everything with electrolyte. A strong overcharge and a deep discharge are equally destructive, as they cause irreversible degradation of the plates, their shedding.
- Absorbed Electrolyte (AGM). AGM batteries differ from classic ones in that the space between the electrodes in them is filled with a special porous material that absorbs the electrolyte. This design prevents natural degradation, allowing it to withstand many charge-discharge cycles, but it is very afraid of overcharging. The limiting charging voltages are up to 14,7–15,2 V (indicated on the battery), if more is applied, there is a high risk of electrode shedding. And since the battery is maintenance-free and sealed, it can explode.
- Gel (GEL). Batteries in which the liquid acidic electrolyte is thickened with silicon compounds. These batteries are practically not used as starter batteries, but can be installed to power powerful consumers on board (music, etc.). They tolerate the discharge better (withstand hundreds of cycles), but are afraid of overcharging. The voltage limit for GEL batteries is up to 14,5–15 V (sometimes up to 13,8–14,1). Such a battery is hermetically sealed, therefore, when overcharging, it is easily deformed and cracked, but there is no danger of electrolyte leakage in this case.
What to do when reloading?
When overcharging the battery, first of all, you should find the root cause, and then diagnose the battery. What needs to be done when recharging the battery for specific reasons is described below.
Recharging with a stationary charger
Recharging the battery from the charger is possible when using a faulty power supply or incorrectly selected charging parameters in manual mode.
- Maintenance-free Batteries are charged with a constant current of 10% of their capacity. The voltage will be adjusted automatically, and when it reaches 14,4 V, the current must be reduced to 5%. Charging should be interrupted no more than 10–20 minutes after the start of boiling of the electrolyte.
- Serviced. Use the constant voltage recommended for your battery (slightly higher for calcium than hybrid or AGM). When about 100% capacity is reached, the current will stop flowing and charging will stop by itself. The duration of the process can be up to a day.
Recharging a car battery with a charger usually occurs due to the breakdown of certain components. In transformer chargers, the cause of an increase in voltage is often an interturn short circuit of the winding, a broken switch, and a broken diode bridge. In automatic pulse memory, the radio components of the control controller, for example, transistors or an optocoupler regulator, often fail.
Protection of the machine battery from overcharging is guaranteed when using a charger assembled according to the following scheme:
Battery protection from overcharging: do-it-yourself scheme
12 volt battery overcharge protection: charger circuit
Recharging the battery on the car from the generator
If a battery overcharge is detected en route, the battery must be protected from boiling over or exploding by reducing the supply voltage or turning off the supply voltage in one of three ways:
- Alternator belt loosening. The belt will slip, whistle and most likely become unusable and require replacement in the near future, but the generator power will drop.
- Turn off the generator. By removing the wires from the generator and insulating the hanging terminals, you can get home on the battery, using electrical appliances on board to a minimum. A charged battery is enough for about 1-2 hours of driving without headlights on, with headlights - half as much.
- Remove belt from alternator. The advice is suitable for models in which the generator is driven by a separate belt. The effect is identical to the previous option, but the method can be easier if you unscrew the two tension screws to remove the belt. This is more convenient than removing the terminals and isolating the wires.
If the generator voltage does not exceed 15 volts, and you do not have to go far, you do not need to turn off the generator. Just move at low speed to the place of repair, turning on as many consumers as possible: dipped beam, heater fan, glass heating, etc. If additional consumers allow you to reduce the voltage, leave them on.
Recharging the battery from the generator occurs when the control elements (diode bridge, regulator relay) do not work correctly. The general check procedure is as follows:
- The voltage at the battery terminals at idle should be 13,5–14,3 V (depending on the model of the car), and when they increase to 2000 or more, it rises to 14,5–15 V. If it rises noticeably more, there is a recharge.
- The difference between the voltage at the battery terminals and at the output of the relay-regulator should not exceed 0,5 V in favor of the battery. A large difference is a sign of poor contact.
- We check the relay-regulator using a 12-volt lamp. You need a regulated voltage source with a range of 12-15 V (for example, a charger for a battery). Its “+” and “-” must be connected to the PP input and ground, and the lamp to the brushes or PP output. When the voltage increases more than 15 V, the lamp that lights up when power is applied should go out. If the lamp continues to glow, the regulator is faulty and must be replaced.
Scheme for checking the relay-regulator
Checking the regulator relay: video
in order to prevent overcharging of the battery, monitor the condition of the wiring and periodically monitor the voltage at the terminals. Don't twist the wires, solder the connections, and use heat shrink tubing instead of duct tape to protect the connections from moisture!
In some cars, in which charging goes from the B + output of the generator directly to the battery, it is possible to protect the battery from overcharging through a voltage control relay like 362.3787-04 with a control range of 10–16 V. Such protection against overcharging a 12 volt battery will cut off the power supply on it when the voltage rises above the allowable for this type of battery.
The installation of additional protection is justified only on older models that are particularly prone to overcharging the battery due to design flaws. In other cases, the regulator independently copes with the management of charging.
A relay is connected to the break in the wire P (marked with red stripes).
Generator connection diagram:
- Accumulator battery.
- Generator.
- Mounting block.
- Battery charge indicator lamp.
- The ignition switch.
Frequently Asked Questions
Will the battery be recharged if a larger generator is installed?
No, because regardless of the power of the generator, the voltage at its output is limited by the relay-regulator to the maximum allowable for the battery.
Does the diameter of the power wires affect the recharge?
The increased diameter of the power wires in itself cannot be the reason for overcharging the battery. However, replacing damaged or poorly connected wiring can increase the charge voltage if the alternator is faulty.
How to correctly connect a second (gel) battery so that there is no overcharging?
in order to prevent overcharging of the gel battery, it must be connected through a decoupling device. To prevent overvoltage, it is advisable to use a limiter terminal or another voltage controller (for example, voltage monitoring relay 362.3787-04).
The alternator recharges the battery, is it possible to drive home with the battery removed?
If the relay-regulator is broken, you can’t turn off the battery at all. Reducing the load will raise the already high voltage from the generator, which can damage the lamps and on-board electronics. Therefore, when recharging on a car, turn off the generator instead of the battery.
Do I need to change the electrolyte after a long battery recharge?
The electrolyte in the battery is changed only after the battery has been refurbished. By itself, replacing the electrolyte that has become cloudy due to crumbling plates does not solve the problem. If the electrolyte is clean, but its level is low, you need to add distilled water.
How long can the battery be charged to increase the density of the electrolyte (water evaporation)?
Time limits are individual and depend on the initial density. The main thing is not to exceed the charge current of 1–2 A and wait until the electrolyte density reaches 1,25–1,28 g/cm³.
The arrow of the battery charge sensor is constantly on the plus - is it overcharging?
The charging indicator arrow on the dashboard in the plus is not yet a sign of overcharging. You need to check the actual voltage at the battery terminals. If it is normal, the indicator itself may be faulty.
