FOR LEAD ACID BATTERIES

RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Application No. 62/540,434 filed August 2, 2017, the disclosure of which is incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The invention is generally directed to a consolidated online monitoring and restoration management system connecting to a Lead Acid Battery.

BACKGROUND

[0003] Lead Acid Batteries are widely used as a back-up power supply system in various industries such as telecommunication and energy. However, traditional charging/ discharging and continuous usage of the Lead Acid Battery could easily lead to crystallization of Lead Sulphate within the battery. Moreover, sulphation could also occur in which the electrolyte breaks down while the batteries are left unattended over time. The crystals will grow and coat on the electrodes resulting in deterioration of the battery, loss of efficiency and power capability. In addition, a lead acid battery typically needs to be refilled with distilled water over time because of water loss. Thus, the life span of a Lead Acid Battery is about two to five years leading to significant generation of waste and increase in operational cost for replacement. Although recycling of Lead Acid Batteries are possible nowadays, the batteries are required to be removed and transported to a factory for offline repair and restoration, which leads to a substantial increase in labour, transportation and repair cost and hence lowering the overall economic efficiency. In addition, the removal of the batteries increases the risk of power shortage as no back-up is in place. On the other hand, direct disposal will lead to serious environmental pollution due to the presence of lead and sulphur as well as huge wastage of resources. Traditional charging methods for lead acid batteries utilize DC current to charge the battery. However, this gradually creates sulfur crystals and decomposes water into hydrogen and oxygen, which results in water weight lost.

SUMMARY OF THE INVENTION

[0004] In many embodiments, the invention is directed to a consolidated online monitoring and restoration management system connecting to a Lead Acid Battery.

[0005] Additional embodiments and features are set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by the practice of the invention. A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings, which forms a part of this disclosure.

[0006] In one embodiment, a method of monitoring and restoring a Lead Acid Battery includes charging a lead acid battery using direct current (DC) from a battery monitoring and restoration system during a first DC charging phase, monitoring the crystallization level of the lead acid battery using information captured by a current sensor in the battery monitoring and restoration system, and switching to charging using pulse charging during a pulse charging phase when the crystallization level is detected as reaching a predetermined crystallization threshold.

[0007] A further embodiment also includes switching to DC charging of the lead acid battery in a second DC charging phase.

[0008] Another embodiment also includes inserting pulse charging circuitry in between positive and negative leads of a DC battery charger and positive and negative terminals of a lead acid battery, where the pulse charging circuity is configured to perform the monitoring the crystallization level and the switching to charging using pulse charging.

[0009] A still further embodiment also includes charging the lead acid battery using pulse charging during the pulse charging phase, where pulse charging utilizes using two MOSFETs to adjust the voltage provided to the lead acid battery at a predetermined frequency. [0010] In still another embodiment, pulse charging during the pulse charging phase also includes discharging the lead acid battery for a predetermined period of time during each charge cycle.

[0011] In a yet further embodiment, the discharging the lead acid battery is performed for a percentage of the total pulse cycle time within the range 1 -10%.

[0012] Yet another embodiment also includes switching to pulse charging in a float charging phase at a lower voltage and lower current than the previous charging phase.

[0013] In a further embodiment again, the current provided to the battery passes through an inductor-capacitor (LC) filter.

[0014] In another embodiment again, a system for monitoring and restoring a Lead Acid Battery, includes a direct current (DC) power source, a current sensor, and pulse charging circuitry including a microcontroller (MCU), where the MCU is configured to monitor the crystallization level of a lead acid battery using information captured by the current sensor, and switch to charging using pulse charging during a pulse charging phase when the crystallization level is detected as reaching a predetermined crystallization threshold.

[0015] In a further additional embodiment, the system also includes a lead acid battery.

[0016] In another additional embodiment, the MCU is also configured to discharge the lead acid battery for at least one predetermined time interval during pulse charging.

[0017] In still another additional embodiment, the MCU is also configured to switch to a float charging phase at a lower voltage and lower current than the previous charging phase.

[0018] In a still yet further embodiment, the system also includes switches to adjust the voltage provided to the lead acid battery and where the MCU is also configured to switch the switches at a predetermined frequency during pulse charging.

[0019] In still yet another embodiment, the switches are two MOSFETs.

[0020] In a still further embodiment again, the system also includes an LC filter including an inductor and two capacitors between the DC current source and the switches. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The description and claims will be more fully understood with reference to the following figures and data graphs, which are presented as exemplary embodiments of the invention and should not be construed as a complete recitation of the scope of the invention.

[0022] Fig. 1 is a diagram illustrating a lead acid battery monitoring and restoration system in accordance with several embodiments of the invention.

[0023] Fig. 2 is a diagram illustrating electrical components of a lead acid battery monitoring and restoration system in accordance with several embodiments of the invention.

[0024] Fig. 3 is a diagram illustrating pulse charging circuitry for a monitoring and restoration system in accordance with several embodiments of the invention.

[0025] Fig. 4 provides a flow chart of a method of monitoring and restoration of a Lead Acid Battery according to several embodiments of the invention.

DETAILED DESCRIPTION

[0026] Turning now to the drawings, a consolidated online monitoring and restoration management system connecting to a Lead Acid Battery in accordance with embodiments of the invention is provided. In many embodiments, the online connected system can immediately restore the battery by de-crystallization, minimizing the loss of electrodes and electrolyte. In various embodiments, electrical and electronic mechanisms are provided such that an online system can continuously monitor the battery conditions to maintain the overall competency of the battery. For example, an external internal resistance meter measuring internal resistance of the battery can detect a level of crystallization. Alternatively, a current sensor may be used to detect the presence of rapid drop in charge current and/or rise in voltage, indicative of crystallization. Other types of sensor may be used in different embodiments as appropriate to a particular application. In some such embodiments, once the crystallization level reaches a pre-set limit, ordinary direct current charging is automatically replaced by high frequency pulse charging, together with the system's associated safety features for over-charging checks. In some embodiments, the system is an automatic circulation restoration system that can be remotely monitored and controlled. In various such embodiments, a high-frequency isolation filter system may be provided to remove possible disturbances to the original power system, while battery restoration is taking place. In several embodiments, small amounts of discharge time are inserted into the charging process during the pulse charging phase. Using such systems and methods according to embodiments can extend the life span of the Lead Acid Battery by up to 20 years or above at over 90% capacity by preventing formation of sulphur crystals and/or reducing hydrogen and oxygen gas generation.

[0027] Charging systems in accordance with embodiments of the invention can also be produced by modifying a DC charger to insert pulse charging circuitry. For example, telecommunications transmission towers typically include a UPS (uninterruptible power supply) system that utilizes a lead acid battery for online backup power. Inserting a monitoring and restoration system in accordance with embodiments of the invention into the link between the main DC power bus and the battery can maintain the lead acid battery to over 10 years life, in contrast to traditionally replacing batteries every 2 to 5 years. This can greatly improve the uptime of telecommunications equipment, which is particularly useful for towers in remote areas that have little road access. Monitoring and restoration systems in accordance with embodiments of the invention can be very light weight and hand carried to a tower equipment room.

[0028] A monitoring and restoration system in accordance with several embodiments of the invention is illustrated in Fig. 1. The system 101 includes a direct current (DC) battery charger 102, a pulse charger 104, and a battery 106. The positive and negative terminals of the DC battery charger 102 and connected to the pulse charger 104. The positive and negative leads of the pulse charger 104 are connected to positive and negative terminals of the battery 106. The DC charger 102 can provide a substantially constant voltage to the pulse charger 104. The pulse charger can be configured to switch between providing DC charging (e.g., during one or more DC charging phases) and providing pulse charging (e.g., during one or more pulse charging phases). In several embodiments, an estimation of crystallization level in the battery is made, which determines the switching to and/or from pulse charging of the battery.

[0029] A monitoring and restoration system in accordance with several embodiments of the invention is illustrated in Fig. 2. The system 301 includes positive and negatives leads 302 and 304 as connections to a DC charger 306. The positive lead connection has a current sensor 308 and the leads are connected to an LC (inductor-capacitor) filter circuit (which can also be referred to as an incoming filter). LC filters can be used to reduce high frequency noise, such as electromagnetic interference (EMI). The LC filter includes a first inductor 310 from the positive lead, a first capacitor 312 connecting the positive lead before the first inductor to the negative lead, and a second capacitor 314 connecting after the first inductor to the negative lead. The first inductor leads to a first MOSFET transistor 316 and first diode 318 in parallel. The first MOSFET-diode parallel circuit leads to a second inductor 320 (which can also be referred to as an outgoing filter) and the second inductor 320 leads to a connection 322 to the positive terminal of the battery 323. The first MOSFET-diode parallel circuit also leads to a second MOSFET-diode parallel circuit having a second MOSFET 324 and a second diode 326. The other end of the second MOSFET-diode parallel circuit is connected to the negative lead 304 of the DC charger and provides a connection 328 to the negative terminal of the battery 323. The first and second MOSFETs are controlled by a microcontroller (MCU) 330.

[0030] The MCU 330 controls the first and second MOSFETs 318 and 324, which in turn allow or prevent current from flowing across the MOSFET. Over a threshold voltage Vit the first MOSFET 318 is switched on (i.e., closed) allowing current to flow and over a threshold voltage V2t the second MOSFET 324 is switched on (i.e., closed) allowing current to flow.

[0031] In several embodiments, the MCU 330 controls switching based on a level of crystallization in the battery 323. The level of crystallization can be measured or deduced, for example in some embodiments using the current sensor 308. During charging (e.g., a DC charging phase), a quick drop in charge current and/or faster than normal rise in voltage can be indicative of more crystallization present in the battery. [0032] In many embodiments, the MOSFETs are controlled to provide pulse charging at a selected frequency or variable over a range of frequencies during a pulse charging phase. The MOSFETs can be closed so that the first MOSFET 318 is closed and the second MOSFET 324 is open during high portion of a pulse, and so that the first MOSFET 318 is open and the second MOSFET 324 is closed during the low portion of a pulse. In some embodiments, the frequency of pulses (pulse repetition) can be from variable from 50 Hz to 10 kHz. In further embodiments the frequency varies within the same pulse charging phase. In several embodiments, the low portions of the pulses are in the range of 1 to 10% of the total cycle time (corresponding to high portion having approximately 99% to 90% of cycle time).

[0033] In several embodiments, the pulse charging phase includes at least one discharge cycle. In some embodiments, in any number of low periods or all low periods of pulse cycles during pulse charging the pulse charging circuitry can discharge the battery, e.g., using a MOSFET or other switch. One skilled in the art will recognize that other types of transistors or switches and other configurations may be used to regulate the charging mode, e.g., between DC charging and pulse charging and that other types of filters may be used at the incoming and/or outgoing filters as appropriate to a particular application. For example, high and low portions of pulses may correspond to an opposite order or closing and opening switches than the scheme described above. A pulse charging control circuit that can be utilized in a monitoring and restoration system in accordance with embodiments of the invention is discussed below with respect to Fig. 3.

[0034] A pulse charging control circuit in accordance with several embodiments of the invention is illustrated in Fig. 3. The pulse charging control circuit 351 includes a microcontroller (MCU) 350 that can provide a positive pulse to first MOSFET 352 and a negative pulse to second MOSFET 354. In certain embodiments, the positive pulse can be modified by level shift 360, for example to adjust the voltage to be within the operating range and/or reach the threshold voltage Vit of first MOSFET 352. Similarly, the negative pulse can be modified by level shift 362, for example to adjust the voltage to be within the operating range and/or reach the threshold voltage Vati of second MOSFET 354. The MCU 350 receives input from DC battery charger 356 and a current sensor 358 on the connection to the battery charger 356. As shown in Fig. 2, opening the first MOSFET can cut the charge current and allow some time for negative charge to function. The second MOSFET 354 when closed can allow the battery to discharge energy, which is stored at the outgoing filter then recycled to the filter capacitors.

[0035] Although monitoring and restoration systems and pulse charging control circuits that can be used to charge batteries are discussed above, one skilled in the art will recognize that different components, circuitry, and/or electrical characteristics may be utilized as appropriate to a particular application in accordance with embodiments of the invention. Processes for charging a battery while reducing crystallization in accordance with embodiments of the invention are discussed below.

Processes

[0036] A process for monitoring and restoring a lead acid battery while charging in accordance with several embodiments of the invention is illustrated in Fig. 4. The process 400 can include inserting (402) a pulse charging system between a DC charger and a lead acid battery. In some embodiments, an existing charging system can include a DC charger connected to a battery, and the system can be modified to accommodate pulse charging by inserting a pulse charging system to accomplish a configuration such as that illustrated in Fig. 1.

[0037] The process 400 includes monitoring (404) the condition of the lead acid battery. In some embodiments, the monitoring can be performed during a first DC charging phase. When a threshold crystallization level is detected, the process switches (406) from DC charging to pulse charging. Pulse charging can be performed using systems and processes such as those described above with respect to Figs. 1 -3. In some embodiments, pulse charging is performed at a voltage the same or similar to the voltage used in DC charging.

[0038] In several embodiments, pulse charging includes at least one discharge cycle. After a pulse charging phase is completed, pulse charging is halted. In some embodiments, pulse charging is halted after a threshold lower level of crystallization is detected. In several embodiments, the process switches (408) to a second DC charging phase once pulse charging is halted. In some embodiments, the process switches to a trickle charge phase, which may utilize similar voltage to other charging phases. The capabilities of monitoring and restoration management systems and pulse charging circuitry, such as those discussed with respect to Figs. 1 -3 may be utilized in such processes.

[0039] Although a specific process is described above with respect to Fig. 4, one skilled in the art will recognize that any of a variety of processes may be utilized for monitoring and restoring a lead acid battery using pulse charging in accordance with embodiments of the invention.

[0040] Test results of particular monitoring and restoration systems in experimental procedures are discussed below.

Test Results

[0041] Testing was performed on a 5 year old retired UPS lead acid maintenance free battery composed of 2V 500AH battery in series of 24 set. Over a test period of one year, weight and internal resistance was recorded over around 150 charge and discharge cycles. There was no decrease in weight which means that there is no loss of water due to generation of hydrogen and oxygen gas. There is a slight reduction of internal resistance, which means that after 150 charge cycle, the sulphur crystal had not increased but it had reduced.

[0042] While the above description contains many specific embodiments of the invention, these should not be construed as limitations on the scope of the invention, but rather as an example of one embodiment thereof. Various other embodiments are possible within its scope. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their equivalents.