JPH04196070A - Charging method of lead-acid battery - Google Patents

Abstract

PURPOSE:To charge a sealed lead-acid battery, which is left too much discharged, with a small, simple circuit by applying forward pulse voltage to the lead battery, carrying a backward pulse current to the lead battery for a given time when the lead-acid battery has sudden voltage rise and then carrying a forward current thereto for charging. CONSTITUTION:A relay control section 12 gives few-second output to a relay coil 13 on starting charge to turn on a switch 7 as its contact, operates a forward pulse generating section 5 and applies forward pulse voltage to a lead-acid battery 15. As the lead battery 15, if left too much discharged, has sudden voltage rise, a pulse voltage detecting section 11 detects the voltage and the relay control section 12 gives output to a relay coil 14 after few seconds to turn on a switch 8 as its contact and applies backward pulse voltage to the lead-acid battery 15. After a backward pulse current is carried for a given time, a forward current is carried to provide true charge. It is thus possible to charge the lead battery which is left too much discharged with a small, simple circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a charging method suitable for lead-acid batteries, in particular for sealed lead-acid batteries.

Conventional techniques for charging lead-acid batteries include detecting a predetermined end-of-charge voltage and automatically terminating charging, or switching to charging using a minute current (trickle charging).

A problem with this charging is that lead-acid batteries that are left unused after discharge (over-discharged) have poor charging performance. This problem is particularly serious in so-called cathode absorption type sealed lead-acid batteries in which oxygen generated from the anode is absorbed and consumed at the cathode.

In other words, a sealed lead-acid battery that has been left over-discharged has a high internal resistance, and a high charging voltage is detected immediately after charging starts, determining that it is at the end of charging, and charging is often terminated without being fully charged. Resulting in.

One way to deal with over-discharged lead-acid batteries is to run a current in the opposite direction to the normal direction after charging starts until the battery voltage becomes negative, and then perform normal charging (Japanese Patent Application Laid-Open No. 1983-1993). 176069).

Problems that the invention aims to solve As a means of passing current in the opposite direction, it is necessary to use a negative output power source, or if a single power source is used, it is necessary to change the polarity using a relay etc. It becomes large.

The problem to be solved by the present invention is to enable a sealed lead-acid battery that has been left over-discharged to be charged with a small and simple circuit.

Means for Solving the Problems The charging method according to the present invention provides a charging method for charging a lead-acid battery in which the charging voltage increases by 200 m and when it reaches a predetermined end-of-charge voltage, the charging current is switched to a minute current. When the voltage of the lead-acid battery suddenly rises as a result of applying a pulse voltage, a reverse pulse current is passed through the lead-acid battery for a predetermined period of time, and then a forward current is passed to charge the lead-acid battery. The charging method according to the present invention makes a lead-acid battery that has been left over-discharged in a chargeable state by passing a pulse current, and these operations can be realized using a small and simple circuit.

Embodiment FIG. 1 shows a block diagram of a charging circuit for realizing the charging method according to the present invention. When a predetermined voltage is detected at the end of charging, trickle charging is started using a minute current.

After charging starts, a forward pulse voltage is applied for several seconds, and when the voltage of the connected lead-acid battery rises rapidly and reaches a predetermined value or higher, it is determined that the lead-acid battery has been left over-discharged. After a pulsed current in the reverse direction is passed for a predetermined period of time, the normal current is passed in the forward direction to perform charging.

This will be explained in detail below.

The output of the AC power supply 1 is transmitted through a transformer/rectifier section 2, a current control section 3,
It is connected to the lead-acid battery]5 through a diode 10.

The predetermined end-of-charge voltage is detected by the end-of-charge voltage detection section 9 and output to the control section 4 .

The control section 4 receives as input the output from the end-of-charge voltage detection section 9, the forward direction pulse generation section 5, and the output from the reverse direction pulse generation section 6, and outputs it to the current control section 3. That is, when there is an output from the end-of-charging voltage detection section 9, a 1 to 100% recycle charging current is caused to flow. Forward direction pulse generator 5
Alternatively, if there is an output from the pulse generator 6 in the opposite direction, the current is controlled so as not to flow.

The relay control section 12 receives the output from the pulse voltage detection section 11 and outputs it to the relay coil 13 or 14. First, the relay control unit 12 outputs an output to the relay coil 13 for several seconds at the start of charging, and turns on the switch 7, which is the contact point, to operate the forward direction pulse generator 5 and apply the forward direction pulse voltage to the lead-acid battery 15. to be applied. When the lead-acid battery] 5 has been left over-discharged, the voltage rises suddenly, so this voltage is detected by the pulse voltage detector], 1
After a few seconds, the relay control unit 12 outputs an output to the relay coil 14 and turns on the switch 8, which is a contact point thereof, to apply a pulse voltage in the opposite direction to the lead acid battery 15. After passing a pulsed current in the reverse direction for a certain period of time, a current is passed in the forward direction to begin normal charging.

When the pulse generating circuit 5 or 6 is in operation, it outputs to the control section 4 so that the original charging current does not flow.

With this operation, while the relay control section 12 is outputting the pulse current to the relay coil 14, it is possible to flow a pulse current in the opposite direction.

FIG. 2 shows the characteristics when charging a sealed lead-acid battery (4V, 4Ah, internal resistance: ○○Ω) that has been left to over-discharge. When a forward pulse voltage is applied for several seconds after charging starts, the voltage suddenly rises, and when that voltage is detected, a reverse voltage is applied for one hour. After that, normal charging is performed. The peak voltage of the pulse current in the reverse direction is about 50V, and the voltage application interval is about 10 seconds.

It was possible to recover a lead-acid battery that had been left over-discharged by applying a pulse voltage in the opposite direction for one hour and then starting normal charging, and the IC discharge capacity was 40 minutes. This shows the rise in voltage when a forward pulse voltage is applied to a sealed lead-acid battery that has been left over-discharged and a regular product that is not. In lead-acid batteries that have been left over-discharged, there is a sudden rise in voltage. I understand that.

The above sealed lead-acid battery has 4. V-4-A h,
The internal resistance after overdischarge is 100Ω.

The ambient temperature during charging was 25±2°C.

Effects of the Invention As described above, in the charging method according to the present invention, it is determined whether the lead-acid battery has been left over-discharged by applying a pulse voltage in the forward direction, and if it has been left over-discharged, it is determined by applying a pulse voltage in the reverse direction. Since the battery can be restored to a state where it can be charged, it can be handled with a simple and small charging circuit.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a charging circuit applied to the charging method according to the present invention, Fig. 2 is a charging characteristic curve diagram when an over-discharged lead-acid battery is charged by the method according to the present invention, and Fig. 3 is a diagram showing an over-discharged lead-acid battery. FIG. 3 is a curve diagram comparing voltage rise states at the initial stage of charging when a lead-acid battery that has been charged and a lead-acid battery that has not been charged are charged by the method according to the present invention. 1 is an AC power supply, 2 is a transformer/rectifier, 3 is a voltage control unit, 4 is a control unit, 5 is a forward pulse generator, 6 is a reverse pulse generator, 7.8 is a relay coil contact, 9 is a charging end voltage detection unit, 10 is a diode, 11 is a pulse voltage detection unit, 12 is a relay control unit, 13.14 is a relay coil, 15 is a lead acid battery 12 is a sealed lead acid battery

Claims (1)

[Claims] (1) When the charging voltage increases and reaches a predetermined end-of-charge voltage, the charging current is switched to a minute current.When charging a lead-acid battery, as a result of applying a forward pulse voltage to the lead-acid battery, the voltage of the lead-acid battery suddenly increases. A method for charging a lead-acid battery, characterized in that when the battery starts up, a reverse pulse current is passed through the lead-acid battery for a predetermined period of time, and then a forward current is supplied to charge the lead-acid battery.