## Sealed lead acid discharge rate formula,use car battery for laptop,suzuki pink 12v quad atv ride-on battery - Step 1

06.03.2016
During a normal discharge cycle, lead-acid batteries form a layer of amorphous lead sulfate on their plates. When I first started this job, I would often go to the deployment sites to investigate reports of customers receiving dead batteries.
Equation 1 tells us that increasing temperature produces an exponential increase in reaction rate. A battery at a temperature of T+10 °C self-discharges twice as fast as the same battery at a temperature of T. I am not an electrochemist and I will not discuss all the details of Equation 1, but we can learn some things from a qualitative examination of Figure 1.
The chart shows that you do not want to let a battery discharge below 60% of its full capacity. A lead-acid battery can be stored for about a year at room temperature before it needs a recharge. I would not want to explain to my boss that I screwed up by not following the directions included with every battery. Figure 2: Derivation Showing Approximate Equivalence of Rule of Thumb and Arrhenius Equation. Here is an excerpt from a battery reference ("Valve-Regulated Lead-Acid Batteries" by David Anthony and James Rand) that provides a value for the activation energy for the self-discharge reaction in a lead-acid battery.
Excerpt from page 16 of "Valve-Regulated Lead-Acid Batteries" by David Anthony and James Rand that discusses the formation of an insulating layer. I worked in the electronic surveillance industry for about 12 years as an electronics engineer, and I was astonished at the good condition of the 12volt lead-acid jelly batteries in very old (15 to 20 years) bell boxes that had been discarded for other reasons. I concluded that the method of holding the lead-acid bettery at 13.8volt ALL THE TIME as a float charge by a small mains power unit was the reason.
The battery capacity, or the amount of energy a battery can hold, can be measured with a battery analyzer.
When discharging a battery with a battery analyzer capable of applying different C rates, a higher C rate will produce a lower capacity reading and vice versa.
To obtain a reasonably good capacity reading, manufacturers commonly rate alkaline and lead acid batteries at a very low 0.05C, or a 20-hour discharge. While lead- and nickel-based batteries can be discharged at a high rate, the protection circuit prevents the Li-ion Energy Cell from discharging above 1C. Standard charge = ” Standard charge ” means charging the cell with charge current 1075 mA and costant voltage 4.2 V. You mean to say that we have to select the charging current such that it can full charge (100% capacity) the battery in 20 hr. You may again find it will take 30hrs, yet better that going full and charging in 10hrs and slamming the battery with too much. Initial charge of something I just built, personally, I’d have a hard time going over 50% of what I believe it will do. If you just run cyclic voltammetry (potentiostat) you do not need any capacity value, you get it from this experiment.
When you run cyclically (potentiostat), I assume you then get the capacity related to the current over time? Do you know how this compares to a “typical” charging profile where you hold the current (then the voltage) constant? If we use our new device we get a diagram in which the time is the x-axis, one y-axis is capacity and the other one is the voltage.
Right now I can not tell you more, I do not really know what this fig.1 in the link is (but I work not Li-ion batteries). Can any body share the the probability of lead acid automotive battery being exploded dusting cracking of an engine ? Can any body share the probability of lead acid automotive battery being exploded durting cracking of an engine ? I have been busy working over the past few months, if you still check this site i would be happy to try and get a discussion going on. In follow up I have some questions about the voltammetry; I plan on using the technique myself XD but in my initial learning I didnt see how it could be applied to a theoretical capacity. When you send me a mail I will reply with some images, this makes discussion easier (and I can not add pictures here, so mail is the best).
The first paragraph of this article contains the reference to the unit of charge - Coulomb (C) which, in addition to not having any strict relevance for what follows, only creates a possibility for confusion with the charge-rate designation bearing the same symbol. I suggest that this article is edited as to drop the first three paragraphs, as C-rate does not have direct connection with the unit of electric charge, Coulomb, that also bears the same designation, C, as they do not add to understanding of C rate.
The primary reason for the introduction of the C-rate is the need to address the current with which a battery is being charged (or discharged) in terms that bear more relevance to that particular battery than just stating the absolute current value. Since the load (I will use this term for both cases of battery being either charged or discharged as in both cases higher currents present similar challenges) is relative to the capacity of a battery, the C-rate is used to describe the discharge or charge current in terms relative to it’s capacity, that is, to the current that would, under ideal conditions, discharge a fully charged (or completely charge a fully discharged) battery in one hour.
C therefore, in this context, represents a way to describe current, not capacity of a battery, although it is particularly related to its capacity. It is useful to describe a regimen in which the battery is being used regardless of its capacity, so two batteries of different capacities but of the same type can be, current wise, described in mutually comparable terms. Of course, different types of battery chemistry have different requirements, or rather interpretations. Therefore, you will only need to know a universal, C-rate based characteristics of a given battery type (chemistry) and will be able to convert this to actual current values depending on the battery’s capacity. In the late 1700s, Charles-Augustin de Coulomb ruled that a battery receiving a charge current of one ampere (1A) passes one coulomb (1C) of charge per second.
But that is all very theorical; is the battery really charge to full capacity (is your charger calibrate?), C is from what is written on battery or measured?
In conclusion, the battery whose (incomplete) rating you provided would, if it were a 12 V battery, have a C100 capacity of 20 kAh and a C100 charge rate of 200 A. Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts.
Okay, like the title suggests, I need a method of calculating self discharge rates of Lead-Acid batteries.
Standard lead-acid cells have a low self-discharge, about 5% per month, so continuously monitoring makes little sense.

Anyway, self-discharge is exponential, so that the largest change will be right after the cell is charged. Asking people about fine details of cell performance tends to legitimatise and hide the fact that a process of no real certainty is being investigated. Until the underlying issues have been at least lightly investigatred the question is premature and ill advised. In the absence of a good grasp of the chemistry there is no certainty that extrapolated results will be in any way accurate. A "certain" method, for at least the current cycle, is to use a number of cells of each type and discharge them to endpoint after selected periods. For example, a total of 7 batteries would allow all periods of 1 to 12 months to be checked. The new large result per month starts to go wrong as 6+3+2+1 6 months result until after a year.
A key issue is, are the cells going to have increasing capacity over the first few cycles (as eg NimH do) or will they fall progressively with cycles? There is no doubt that you will get some sort of battery in each case, but as the capacity you achieve will be lower at best and probably much lower, then a long self discharge life may not return a better net capacity that a standard lead acid battery for at least 12 months.
Determination of battery state of charge from loaded or open circuit voltage is notionally possible, but depends on many factors - with major ones being temperature & specific gravity of electrolyte.
The above diagram is a rearrangement of the diagram on page 68 from the excellent Lead Acid battery state of charge versus voltage - Home power #36, Aug-Sep 1993. I think you would have to take regular readings of the voltage, using a setup that has less current draw than normal expected self discharge rate, so as not to skew the result.
I guess, the self discharge has a function similar to the discharge of a capacitor+resistor circuit (but of course with much larger time constants). Not the answer you're looking for?Browse other questions tagged batteries or ask your own question. Our products generally ship with an Uninterruptible Power Supply (UPS) that contains a 7.2 A-hr Sealed Lead-Acid (SLA) battery. They are murdered by owners that charge them improperly, cycle them too deeply, let them sit discharged for too long, or store them at too high a temperature. Let's examine how this reaction rate affects a battery that appears to just be sitting there -- it actually is experiencing an internal chemical reaction that is discharging the battery. If it is true, the customer that I mentioned earlier who stored his batteries at 50 °C would see his batteries discharged in his warehouse within about two and half months. Each battery vendor's products have different self-discharge rates because the rates are a function of how the plates are constructed (i.e.
At one deployment site, I saw that the customer had over 900 batteries reported as failures. Replacing a battery is not cheap, and paying for a service call to install the battery is not cheap either. In Figure 1, we see that as the battery temperature raises from 30 °C to 40 °C, the self-discharge time reduces from 8 months to about 5 months, which is less than half. The derivation in Figure 2 shows that the rule of thumb is only true for a limited range of values. I too have had some batteries that have lasted very long in float applications and under the same operating conditions that you list. The owner of this blog makes no representations as to the accuracy or completeness of any information on this site or found by following any link on this site. The owner will not be liable for any losses, injuries, or damages from the display or use of this information.
Some high-performance batteries can be charged and discharged above 1C with moderate stress. Even at this slow discharge rate, lead acid seldom attains a 100 percent capacity as the batteries are overrated. Battery University monitors the comments and understands the importance of expressing perspectives and opinions in a shared forum. While we make all efforts to answer your questions accurately, we cannot guarantee results.
I Mean we do not know how much capacity it can store, in this case how we can choose the C rates.
Once we do this we will find out the full capacity of battery and according to this full capacity we have to select the C-rates. That is why I am getting these silly questions and I am learning slowly and after that only I will start making the battery. Since we do not know the capacity of the test cell, do we first have to measure CV on our old device to know the highest achievable capacity, so that we can calculate e.g. In the first tests with the new one we noticed that the time for one cycle depends on the capacity of the cell (so a short cycle shows less capacity in the capacity-cycle-diagram). 1 C is indeed the standard abbreviation for the SI unit 1 coulomb, but in this article, the notation 1C is used to mean a totally different thing! If you use a battery cycler you need a C-rate (so: yes, using different C values is possible, most people does).
If we run cyclic voltammetry in our old device we just have to add the parameters voltage range, scan number, Esteps and scanrate. And also the same battery being used for DG starting with permanent float cum boost charger connected ? I am somewhat hesitant to put my skype name or email up on a permanent online post, but I think there could be a way to get in contact at least through an email. Wont the measurement only tell you the potentials at which reactions inside the cell are occurring? As I wrote we have two different ones, so it depends a bit if its more of a battery cycler or a potentiostat (at least in this way we name or two ones). Therefore C-rate is a good way to really get a grasp on the load placed upon a battery, regardless of whether it is during the charging or discharging process.
Is C rate defined by the specific mah capacity of each cell in a pack, or is it defined by the aH rating of the pack as a whole? Here's the catch: I varied the electrolyte which the batteries were using, replacing sulphuric acid with hydrochloric acid, another one with nitric, and another one with phosphorous acid.
To measure this I would take a reading with a DMM every few days, and you may need to take readings over a period of more than a month to get a decent graph.
Materials and construction of lead accus have been optimized long ago now, and have proven their worth. Take measurements at a few hours interval, and decide if one measurement every few days is still sufficient.

It has adopted colloid electrolyte technology, avoiding density stratification problem of acid solution and eliminating plate corrosion and passivation caused by density stratification. Applied with German Gel formula, grid alloy and plate formula, the battery is performed very well in cycling and recovery from deep discharge, especially in rainy days.
More suitable for using in harsh condition than AGM battery as the rich electrolyte inside of the GEL battery makes it working stable in high temperature or over charge.
Good performance in cold environment and the battery capacity decreases little when using in low temperature. Little self discharge because of the super-pure material and the low density of the electrolyte, it can be stored over 6 months. Unfortunately, when a discharged battery is stored for a long period of time (usually weeks or months), the amorphous lead sulfate changes into a crystalline form that cannot be converted back to lead through normal charging. Since our UPS units have built-in controllers and the units are rarely deeply discharged, the primary battery killer is heat.
Chemical reactions exist within a battery that cause them to discharge while just sitting in storage.
Every failed battery had been stored improperly and then installed in a private residence when fiber service was installed at that home.
There were many tens thousands of dollars worth of avoidable problems at this one customer site alone. Excerpts and links may be used, provided that full and clear credit is given to Mark Biegert and Math Encounters with appropriate and specific direction to the original content. The sum should be the same since the identical amount of energy is dispensed over a shorter time. Manufacturers provide capacity offsets to adjust for the discrepancies if discharged at a higher C rate than specified. However, all communication must be done with the use of appropriate language and the avoidance of spam and discrimination. Neither can we take responsibility for any damages or injuries that may result as a consequence of the information provided. Initially I thought that we need to select the C-rates according to the theoretical capacity of anode and cathode (combined capacity) do we select C-rates according to theory?. Does this mean that the new device notices when all active material has reacted and automatically starts the charging process, or what else can be the reason?
What is the acceptable charge range for it (Im expecting to end up with a disharge rate of around 14 hours in my application, should that matter)? This is, of course, implying that during such discharge, the rated voltage will remain just that - (practically) the same.
Unless you have worked though the chemistry it is not certain that there will be a satisfactory outcome.
Note the shape of the curve is not a concave exponential one, as might be expected, but a convex curve - ie voltage change per % of capacity change increases with increasing discharge (and doesn't decrease as in a normal exponential decay). Since we charge the batteries just before shipment, I know the batteries left our facility functional and with a full charge. The UPS did a battery load test every ten days, so the battery would be reported as failed 10 days after it was installed, which means a technician had to physically go out to a person's home and replace the failed battery (often with another failed battery).
Losses at fast discharges reduce the discharge time and these losses also affect charge times.
If a 1Ah battery provides 1A for one hour, an analyzer displaying the results in percentage of the nominal rating will show 100 percent. In reality, internal losses turn some of the energy into heat and lower the resulting capacity to about 95 percent or less. Please accept our advice as a free public support rather than an engineering or professional service. I would expect an influx of 0.8 V from solar energy that contributes to slow down the discharge rate to show a higher SoC. Than you just have to calculate the area under the redox-peaks and with this (and the active mass) calculate the specific capacity. You would probably have to lightly load the battery during measurement as Voc will probably be less representative of the real state of charge. In every single case, the customer had not properly handled the batteries -- the batteries had become fully discharged because they had been stored for too long between charging cycles. Both of these reactions are accelerated by temperature according to the Arrhenius equation, which I state in Equation 1. If the discharge lasts 30 minutes before reaching the end-of-discharge cut-off voltage, then the battery has a capacity of 50 percent. Discharging the same battery at 0.5C, or 500mA over 2 hours, will likely increase the capacity to above 100 percent.
I think that you would need some sort of time scale to know the amount of charge you are putting into the batter?
I read that resistance increases with higher C-rate but can i have detail explanation on the chemistry part and in electrical part too? A discharged lead-acid battery will eventually become sulfated -- a state where the battery plates are coated with a crystalline layer of lead sulfate and lead oxide.
A new battery is sometimes overrated and can produce more than 100 percent capacity; others are underrated and never reach 100 percent, even after priming.
Some people refer to this layer as a "varnish" because sulfated plates look like they are coated with wood varnish. The UPS units and their batteries were stored in the loft of the barn at a temperature of about 50°C (122 °F).
I told my customer that the batteries were not being stored according to the vendor's battery storage requirements. He said that no one ever told him what the battery handling requirements were and I needed to pay to replace every one of his failing batteries (including service call).
I then reached into a UPS box and pulled out the battery handling specification that ships with every UPS. He seemed pretty sheepish after seeing that he had received thousands of battery handling instruction sheets.