Lead acid battery charging current and voltage transformers,fix hp battery not charging solution,replacement battery for toyota car key zone - Try Out

17.09.2014
Invented by the French physician Gaston Plante in 1859, lead acid batteries were the first rechargeable batteries for commercial use. Lead acid batteries should be charged in three stages, which are [1] constant-current charge, [2] topping charge and [3] float charge. The battery is fully charged when the current drops to a pre-determined level or levels out in stage 2.
During the constant-current charge, the battery charges to 70 percent in 5–8 hours; the remaining 30 percent is filled with the slower topping charge that lasts another 7–10 hours. The switch from Stage 1 to 2 occurs seamlessly and happens when the battery reaches the set voltage limit.
Once fully charged through saturation, the battery should not dwell at the topping voltage for more than 48 hours and must be reduced to the float voltage level. The voltage of a lead acid battery when at rest (not supplying current or being charged) will vary according to how fully charged the battery is.
The graph shown to the right represents a typical 24 volt lead acid battery which has not been charged or had current drawn from it for a couple of hours. With further drawing of current, the rate of voltage drop slows down and will reach around 24.0 volts when the bettery is at half capacity.
As the battery approaches the fully discharged state, the voltage starts to fall more quickly again. It is important for a battery to never be fully discharged, so your inverter will normally disconnect the supply when the voltage is around 22 volts. An interesting point to note here is that when an inverter or other power load is drawing a high current from the battery, the voltage will drop.
The larger the battery, the smaller this voltage drop will be, and the greater the % of the charge will be useable when drawing high currents. If a voltage is applied to the battery which is greater than the battery's voltage, a current will flow through the battery in the reverse direction to when it is supplying current, and the battery will charge.
The rate of charge or current that will flow will depend on the difference between the battery voltage and the voltage that is applied to it (from solar panels etc). While it is beneficial to a battery's performance and life to be fully charged on regular occasions, however once a battery has been charged to it's full capacity, it is important not to continue charging as this will damage the battery. The Lead Acid battery is not 100% efficient at storing electricity - you will never get out as much as you put in when charging. The efficiency will depend on a number of factors including the rate of charging or discharging.
However it has been found that if a battery is only partially charged, efficency may be reduced with each charge. With operational ranges of 20-30 miles, electric bicycles (eBikes) are a fun, inexpensive alternative to fossil-fueled vehicles for many urban and suburban applications. Most of the challenges involved with measuring a battery’s state of charge (SOC) lie in the complex processes that enable a two-way exchange between chemical and electrical energy.
The most obvious downside to using only a lookup-based OCV methodology is that it cannot tell you how much energy is actually available from the battery. Devices such as Maxim’s DS2788 stand-alone fuel gauge use these basic techniques to estimate available capacity for rechargeable lithium-ion (Li+) and Li+ polymer batteries. While some devices can use these relatively simple techniques to deliver battery capacity estimates with accuracies approaching 90 percent, this may not be sufficient for drivers who want to squeeze the last possible mile out of their vehicles’ batteries.


Texas Instruments has developed its own enhanced battery modeling technique called Impedance Track, which supplements coulomb counting with measurement techniques that determine the actual physical condition of the battery.
The Impedance Track methodology is used by most of Texas Instruments’ recently-released battery fuel gauges, including its bq20Z70 battery gas gauges (Figure 4). Estimating how much battery energy is left is a key factor in determining the range of an e-Bike.
In spite of the fact that it is one of the oldest types of batteries, lead acid batteries continue to be in wide use today, for various reasons. The engineers argued that the term “sealed lead acid” is a misnomer because no lead acid battery can be totally sealed. The charge time of a sealed lead acid battery is 12–16 hours, up to 36–48 hours for large stationary batteries. The constant-current charge applies the bulk of the charge and takes up roughly half of the required charge time; the topping charge continues at a lower charge current and provides saturation, and the float charge compensates for the loss caused by self-discharge. The topping charge is essential for the well-being of the battery and can be compared to a little rest after a good meal. The current begins to drop as the battery starts to saturate, and full charge is reached when the current decreases to the three percent level of the rated current. As current is drawn off and the level of charge is reduced, the voltage will fall quite quickly at first (again it would be necessary to stop drawing current for a couple of hours to be able to measure the true voltage of the battery).
This may mean that the battery needs to be somewhere over 50% charged to avoid the inverter cutting out due to low voltage. Solar panels intended for a 24 volt system are likely to be capable of producing over 30 volts. With the battery at half charge or less, the charge efficiency may be over 90%, dropping to nearer 60% when the battery is above 80% charged.
If this situation persists (the batteries never reaching full charge), the life of the battery may be reduced. However, since the load, battery condition, and terrain all dramatically affect an eBike’s range, it can be difficult to estimate whether you will make it home without having to pedal your grocery-laden vehicle up that last hill.
Among the phenomena common to all these processes is that a battery cell’s open-circuit voltage (OCV) drops as it discharges, a behavior that can be used to infer its state of charge.
The simplest solution for these applications is interpreting the voltage readings against a hardware or software lookup table that contains a set of chemistry-specific battery profiles which correlate a cell’s DoD with output voltage.
This is because a battery’s charge capacity decreases as a function of age and the number of discharge cycles it experiences. The cell-specific characteristics and application parameters are stored in the DS2788’s on-chip EEPROM and used to calculate conservative estimate of the amount of useable charge, given the present temperature, discharge rate, stored charge, and application parameters. In addition, it can be highly desirable to have a battery fuel gauge that can give accurate predictions of run time at a particular discharge rate, which then can be used to produce reliable estimates of how far the vehicle’s remaining charge will carry it. The self-learning mechanism produces a more accurate model of the battery by monitoring the increases in impedance a lithium battery experiences as it ages. It monitors capacity change, battery impedance, open-circuit voltage, and other critical parameters of the battery pack, and reports the information to the system host controller over a serial-communication bus. Lead acid batteries are very dependable and much cheaper with respect to the cost-per-watt. This is true and battery designers added a valve to control venting of gases during stressful charge and rapid discharge.


With higher charge currents and multi-stage charge methods, the charge time can be reduced to 10 hours or less; however, the topping charge may not be complete. If deprived, the battery will eventually lose the ability to accept a full charge and the performance will decrease due to sulfation.
A battery with high leakage may never attain this low saturation current, and a plateau timer takes over to initialize the charge termination. Charging beyond what the battery can take turns the redundant energy into heat and the battery begins to gas. Some battery chemistries, such as the lead-acid (PbA) gel cells used in most early eBikes, have a relatively linear voltage profile and a large voltage difference between their charged and discharged states (Figure 1). The relatively flat discharge curves of most modern battery chemistries require accurate, high-resolution (12 bits or more) voltage measurements to provide useful SOC data within their 20 percent and 80 percent charge region. Without some sort of compensation, there will be a big difference between the distance delivered by a new battery and a year-old unit when they both show a 75 percent charge reading. The gauge’s capacity estimates can be displayed on a 5-segment LED, or made available to a host processor via a series of registers that report the remaining charge in terms of mAh remaining and percentage maximum capacity (Figure 3). Unlike traditional fuel gauges, the ModelGauge algorithm eliminates the need for battery relearn cycles and an external current-sense resistor. Impedance Track does this by taking a series of voltage and current readings, when the battery is at rest and under load, and using them to calculate changes in the battery’s impedance and its total chemical capacity (Qmax). Very few types of batteries can deliver bulk power as cheaply as lead acid batteries, and this makes the battery cost-effective for auto-mobiles, uninterrupted power supplies (UPS), golf cars, and forklifts. Rather than submerging the plates in a liquid, the electrolyte is impregnated into a moistened separator, a design that resembles nickel- and lithium-bases system. In this case, a simple mechanical voltmeter can give the rider a useable, if imprecise, sense of the percentage of charge remaining.
Since the OCV curves tend to shift as a function of temperature, even a simple lookup-based fuel gauge also needs to also factor the battery’s thermal status into its capacity calculations. Temperature compensation is possible in the application with minimal interaction between a µC and the device. It also accounts for the fact that battery impedance also varies significantly between cells and at different usage conditions, such as temperature and state-of-charge. This enables to operate the battery in any physical orientation without leakage. Driven by these advantages, several types of sealed lead acid have emerged and the most common aregel, also known as valve-regulated lead acid (VRLA), and absorbent glass mat (AGM).
When processed to account for charging losses, discharge losses (due to the battery’s internal impedance), temperature, and other effects, this current data can be used in conjunction with the SOC lookup table to provide a reasonable estimate of the actual charge remaining in the battery. The universal battery charger using Lm317Here comes very simple idea is the universal battery charger circuit. The SCR1 (Silicon controlled rectifier) turn off, then not has a bias current path to ground. Automatic Charger and Full charged indicator using LM317K-TL431This is circuit Automatic Charger and Full charged indicator. There is a tube LED show the work with use integrated number circuit LT431 perform check the level , voltage battery and systematically protect short circuit with IC LM317.



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