BU-903: How to Measure State-of-charge

Explore SoC measurements and why they are not accurate.

Voltage Method

Measuring state-of-charge by voltage is simple, but it can be inaccurate because cell materials and temperature affect the voltage. The most blatant error of the voltage-based SoC occurs when disturbing a battery with a charge or discharge. The resulting agitation distorts the voltage and it no longer represents a correct SoC reference. To get accurate readings, the battery needs to rest in the open circuit state for at least four hours; battery manufacturers recommend 24 hours for lead acid. This makes the voltage-based SoC method impractical for a battery in active duty.

Each battery chemistry delivers its own unique discharge signature. While voltage-based SoC works reasonably well for a lead acid battery that has rested, the flat discharge curve of nickel- and lithium-based batteries renders the voltage method impracticable.

The discharge voltage curves of Li-manganese, Li-phosphate and NMC are very flat, and 80 percent of the stored energy remains in the flat voltage profile. While this characteristic is desirable as an energy source, it presents a challenge for voltage-based fuel gauging as it only indicates full charge and low charge; the important middle section cannot be estimated accurately. Figure 1 reveals the flat voltage profile of Li-phosphate (LiFePO) batteries.

Discharge voltage of lithium iron phosphate.
Figure 1: Discharge voltage of lithium iron phosphate.
Li-phosphate has a very flat discharge profile, making voltage estimations for SoC estimation difficult.

Lead acid comes with different plate compositions that must be considered when measuring SoC by voltage. Calcium, an additive that makes the battery maintenance-free, raises the voltage by 5–8 percent. In addition, heat raises the voltage while cold causes a decrease. Surface charge further fools SoC estimations by showing an elevated voltage immediately after charge; a brief discharge before measurement counteracts the error. Finally, AGM batteries produce a slightly higher voltage than the flooded equivalent.

When measuring SoC by open circuit voltage (OCV), the battery voltage must be “floating” with no load attached. This is not the case with modern vehicles. Parasitic loads for housekeeping functions puts the battery into a quasi-closed circuit voltage (CCV) condition.

In spite of inaccuracies, most SoC measurements rely in part or completely on voltage because of simplicity. Voltage-based SoC is popular in wheelchairs, scooters and golf cars. Some innovative BMS (battery management systems) use the rest periods to adjust the SoC readings as part of a “learn” function.  Figure 2 illustrates the voltage band of a 12V lead acid monoblock from fully discharged to full charged.


Voltage Band
Figure 2: Voltage band of a 12V lead acid monoblock from fully discharged to fully charged.

Source: Power-Sonic


The hydrometer offers an alternative to measuring SoC of flooded lead acid batteries. Here is how it works: When the lead acid battery accepts charge, the sulfuric acid gets heavier, causing the specific gravity (SG) to increase. As the SoC decreases through discharge, the sulfuric acid removes itself from the electrolyte and binds to the plate, forming lead sulfate. The density of the electrolyte becomes lighter and more water-like, and the specific gravity gets lower. Table 2 provides the BCI readings of starter batteries.

specific gravity
Open circuit voltage
2V 6V 8V 12V
100% 1.265 2.10 6.32 8.43 12.65
75% 1.225 2.08 6.22 8.30 12.45
50% 1.190 2.04 6.12 8.16 12.24
25% 1.155 2.01 6.03 8.04 12.06
0% 1.120 1.98 5.95 7.72 11.89

Table 2: BCI standard for SoC estimation of a starter battery with antimony.
Readings are taken at 26°C (78°F) after a 24h rest. 

While BCI (Battery Council International) specifies the specific gravity of a fully charged starter battery at 1.265, battery manufacturers may go for 1.280 and higher. Increasing the specific gravity will move the SoC readings upwards on the look-up table. A higher SG will improve battery performance but shorten battery life because of increased corrosion activity.

Besides charge level and acid density, a low fluid level will also change the SG. When water evaporates, the SG reading rises because of higher concentration. The battery can also be overfilled, which lowers the number. When adding water, allow time for mixing before taking the SG measurement.

Specific gravity varies with battery applications. Deep-cycle batteries use a dense electrolyte with an SG of up to 1.330 to get maximum specific energy; aviation batteries have an SG of about 1.285; traction batteries for forklifts are typically at 1.280; starter batteries come in at 1.265; and stationary batteries have a low specific gravity of 1.225. This reduces corrosion and prolongs life but it decreases the specific energy, or capacity.

Nothing in the battery world is absolute. The specific gravity of fully charged deep-cycle batteries of the same model can range from 1.270 to 1.305; fully discharged, these batteries may vary between 1.097 and 1.201. Temperature is another variable that alters the specific gravity reading. The colder the temperature drops, the higher (more dense) the SG value becomes. Table 3 illustrates the SG gravity of a deep-cycle battery at various temperatures.

Electrolyte temperature Gravity at full charge Table 3: Relationship of specific gravity and temperature of deep-cycle battery.

Colder temperatures provide higher specific gravity readings.
40°C 104°F 1.266
30°C 86°F 1.273
20°C 68°F 1.280
10°C 50°F 1.287
0°C 32°F 1.294

Inaccuracies in SG readings can also occur if the battery has stratified, meaning the concentration is light on top and heavy on the bottom. (See BU-804c: Water Loss, Acid Stratification and Surface Charge.). High acid concentration artificially raises the open circuit voltage, which can fool SoC estimations through false SG and voltage indication. The electrolyte needs to stabilize after charge and discharge before taking the SG reading.

Coulomb Counting

Laptops, medical equipment and other professional portable devices use coulomb counting to estimate SoC by measuring the in-and-out-flowing current. Ampere-second (As) is used for both charge and discharge. The name “coulomb” was given in honor of Charles-Augustin de Coulomb (1736–1806) who is best known for developing Coulomb’s law. (See BU-601: How does a Smart Battery Work?)

While this is an elegant solution to a challenging issue, losses reduce the total energy delivered, and what’s available at the end is always less than what had been put in. In spite of this, coulomb counting works well, especially with Li-ion that offer high coulombinc efficiency and low self-discharge. Improvements have been made by also taking aging and temperature-based self-discharge into consideration but periodic calibration is still recommended to bring the “digital battery” in harmony with the “chemical battery.” (See BU-603: How to Calibrate a “Smart” Battery)

To overcome calibration, modern fuel gauges use a “learn” function that estimates how much energy the battery delivered on the previous discharge. Some systems also observe the charge time because a faded battery charges more quickly than a good one.

Makers of advanced BMS claim high accuracies but real life often shows otherwise. Much of the make-believe is hidden behind a fancy readout. Smartphones may show a 100 percent charge when the battery is only 90 percent charged. Design engineers say that the SoC readings on new EV batteries can be off by 15 percent. There are reported cases where EV drivers ran out of charge with a 25 percent SoC reading still on the fuel gauge.

Impedance Spectroscopy

Battery state-of-charge can also be estimated with impedance spectroscopy using the Spectro™ complex modeling method. This allows taking SoC readings with a steady parasitic load of 30A. Voltage polarization and surface charge do not affect the reading as SoC is measured independently of voltage. This opens applications in automotive manufacturing where some batteries are discharged longer than others during testing and debugging and need charging before transit. Measuring SoC by impedance spectroscopy can also be used for load leveling systems where a battery is continuously under charge and discharge.

Measuring SoC independently of voltage also supports dock arrivals and showrooms. Opening the car door applies a parasitic load of about 20A that agitates the battery and falsifies voltage-based SoC measurement. The Spectro™ method helps to identify a low-charge battery from one with a genuine defect. 

SoC measurement by impedance spectroscopy is restricted to a new battery with a known good capacity; capacity must be nailed down and have a non-varying value. While SoC readings are possible with a steady load, the battery cannot be on charge during the test.

Figure 4 demonstrates the test results of impedance spectroscopy after a parasitic load of 50A is removed from the battery. As expected, the open terminal voltage rises as part of recovery but the Spectro™ readings remains stable. Steady SoC results are also observed after removing charge during when the voltage normalizes as part of polarization.

Figure 4: Relationship of voltage and measurements taken by impedance spectroscopy after removing a load.
Battery is recovering after removing a load. Spectro SoC readings remain stable as the voltage rises.

Last updated 2017-10-25

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Comments (55)

On September 21, 2011 at 12:51pm
Joe Accetta wrote:

There is yet another and quite accurate means of measuring SOC in open port lead acid batterieis through the use of refractometry. The index of refraction of the electrolyte is directlly proportional to the SG. JSA Photonics has developed an in-cell immersion refractometer that yields accurate 24/7 SOC information along with cell temperature for monitoroing and temp correction and in some instances electrolyte level. The sensor replaces the existing battery cap. See www.jsaphotonics.com.

On October 13, 2011 at 4:02am
Josep wrote:

I’m investigating about, and I read that the most common, easy, and accurate way of measuring OSC is Ampere Hour Counting.


On November 29, 2011 at 7:15am
Qaisar Azeemi wrote:

Its really nice information about SOC is given here. But i request to please include measurement steps for all methods mentioned above.
Thank you

On January 20, 2012 at 5:05am
kishore kumar wrote:

Its good to know about soc. There is metal detector to detect metal likewise I need to know how to detect a battery? Can anyone help me.

On January 25, 2012 at 1:34pm
Diego wrote:

the problem of establishing the SOC is not trivial, expecially with LiFePO4 batteries. An interesting article “Fine Tuning TI-impedence Track (TM) battery fuel gauge with LiFePO4 cells in shallow discharge application” can be found at this link


On February 20, 2012 at 2:11am
Kumar wrote:

Please provide me the positive and negative plate behaviour of a lead acid battery during charge & discharge when it is measured with a cadmium rod as reference.

On June 22, 2012 at 1:09pm
TokenGimp wrote:

Assuming I need 2 gel batteries for a power wheelchair and they suggest 12V 75AH. Typically that’s good for 30 miles of rolling on a street..

How much less mileage would I get out of it using 55AH batteries under similar conditions?
I’m trying to decide if I should buy 55AH, 75, 90 or 115AH deep cycle gel if they will fit in the same area.

On June 23, 2012 at 2:17am
Josep wrote:

To TokenGimp,

If they told you 75AH is good for a 30 miles of rolling on a street, you can make rule of three: if 75->30, then 55-> 22miles, 90->36miles, 115->46miles.

That’s is not exact, but I think you can make an idea about how long.  You take the one you think will use.

I hope I was useful.


On August 30, 2012 at 3:29pm
P.F. wrote:


The metal detector use a General Electric MAGNISTOR , Ihave the chematic .

Error :A lead baterie contains sulfate no sulfite
SO4— no SO3 .

On September 6, 2012 at 6:15pm
Mark wrote:

I have a 24V lead acid battery (for a fork truck). I measure 9.0V from the negative terminal to the metal case. Can you suggest what might be causing this? I expected to find 0.0V.

Thank you,

On October 17, 2012 at 3:27am
kingk wrote:

what is the name of the composition of the battery positive and negative plates in a typical lead acid battery when in a charged condition ?

On January 13, 2013 at 11:45am
Sheldon Robidoux wrote:

The 1.98v number here for 0% charge doesn’t seem to line up with the 1.75 figure given for full discharge in another part of this site.  What am I missing?

On June 15, 2013 at 8:59pm
R.ashok kumar wrote:

Given every thing fine automative battery graveti explain detail

On July 10, 2013 at 10:13pm
Chetan Upadhyay wrote:

Nice detailing. Can anyone tell @ Impedance Spectroscopy requirements?

On October 1, 2013 at 3:11am
Jero wrote:

I have a question, is there not a relationship between the pH of the acid and the state of charge? I can’t seem to find anything on the net about this, but it is intuitive for me for them to have a relation, as the chemical reactions occur which also change the SG.

On November 2, 2013 at 12:03pm

i have 4 electric bike vrla based batteries showing 13.0v ocv, on 3 times load test shows 10.8v, but when put on road, does not give mileage.  even after discharge the ocv reduces momentarily but again the ocv goes upto 13.0v.  so while connecting a charger the battery gets charged much faster.  can anyone help and explain what is wrong inside the battery.
the batteries are hardly one year old.

On July 26, 2014 at 5:31am
peter carvalho wrote:

very good info.. thanks

On August 13, 2014 at 11:30pm
sarvani wrote:

Is there any relationship between the pH of the acid and the specific gravity?

On August 29, 2014 at 6:13am
satheesh wrote:

hi i want know the program for how to measure the battery level and indicator can any know??

On March 28, 2015 at 2:54pm
Lucy wrote:

What is the correlation of the acid level (in mm) of each cell of a SLI battery to its determination of defectiveness?

On July 4, 2015 at 6:55am
Tom wrote:

Coulomb counting is like balancing the check book. I put this much in and therefore I should be able to take the same amount out??
Pulsed usage case loading to verify and validate cell voltage during pulse is used in life safety (smoke alarms) which check the battery capacity once a minute when the LED flashes.  This method actually measures the power “wattage” delivering capacity of the battery instantly. This method will report capacity changes due to temperature. This is the reason that smoke alarms always chirp low battery in very late evening hours due to temperature being colder causing cell impedance to increase, yielding lower terminal voltage and cell capacity. Pulsed loading method verifies the health of power path physical layer as coulomb counting doesn’t. Pulsed loading verifies actual power delivery in real time, where coulomb counting assumes that power delivery is present. Pulsed loading method doesn’t require a sense resistor in the load path to burn cell capacity 24/7 as CC method requires.

On July 16, 2015 at 4:43am
Mike Biswell wrote:

I live on a finca in Spain we have 12 2v deep cell lead acid and a 2kva studer inverter, 5 solar panels from the end of june until august the temperature is in excess of 100 f and the batteries do not seem to take the full charge, in times of moderate temperature the regulator shows a charge of 14v in summer 13v is this a normal temperature situation?

On September 12, 2015 at 9:07pm
Rey wrote:

My location is Phils. Island. I have a .6Amp/14.4V smart charger. I started to used it on my 24 months 60AH 12V Maintenance Free Battery. After charging for 36 Hours the stable Voltage after 12 hours rest was only 12.52. Prior to charging it has 12.42V. It seemsthe battery is responding. Will i reached 12.6V state of charge if i charged longer ? Thanks.

On November 19, 2015 at 8:25pm
Bob King wrote:

Hi, I use two package of Lead Acid battery(Panasonic LC-R127R2) as the power source to supplement a medical device, now I am on the software development of the power management board to realize a functionality that monitor the SOC(state of charge) and send the value of SOC to a computer via UART periodically. the software has already the capability to measure the (1)battery voltage(2)Charging current during charging(3)load current during discharging. Does anyone has a good solution to realize it?
P.S. The source code I am using comes from a previous project which is also used for a power management board, it’s already has a formula in software to estimate the SOC, here it is, during charging, SOC= 100%(1-(Vmax_- Vbatt + Ichrg*Ro)/2.5V)  (Vmax_ = 25.5v, Vbatt is the value of battery voltage measured by SW, Icharg is the value of charging current measured by SW), during discharging, SOC = 100%(1-(Vmax -  Vbatt-Iload* Ri)/2.5V)  (Vmax = 25.5v,Iload is the current of load measured by SW). However, I don’t know the principle behind the formula and if it’s good enough to use for estimation of SOC…..

On January 22, 2016 at 3:39am
rhea wrote:

hello. I am rhea from the Philippines, we are having trouble on what electronic componenet should be used in switching two 48 volts lead acid batteries, meaning there are four 12 volts lead acid batteries in series and another four 12 volts batteries in series, we ae trying to have a switching process,  like 00 01 10 11 logic, if A bat is empty, then it will switch to the other battery which is B. or vice versa, I just want to ask if you do have circuits for this and how to program this using microcontroller to know the power rate, voltage and current in charging and discharging. Your reply would be a great help. Thank you!

On February 26, 2016 at 11:01am
George Moore wrote:

I am interested in reducing the SG slightly in a string of 12 V starter batteries to increase their calendar lifetime by reducing the corrosion potential.  The text says reducing the SG reduces the energy capacity but can anyone speak to the reduction in power capacity of slight reductions of the SG in starter batteries, i.e. how much increase in the voltage sag will result.  An example of specific interest is reducing the SG from 1.265 to 1.24 for a SLI battery with 850 A CCA when operated at 500 A at 68 F for 10 seconds.  What would be an expected voltage at 1.265 SG vs. the voltage at 1.24 SG.

On March 7, 2016 at 11:15pm
Mohammed Saleh wrote:

what is the best way to keep the used battery in stock

On March 20, 2016 at 8:26am
Jeff McRaney wrote:

I’ve read many of your articles - lots of wisdom here - I know this is a lightweight question: at what fully charged State of Charge should a car battery be considered for replacement?  In other words, if the battery is charged until the charging current reaches zero, or will not decrease more, and then the surface charge is removed, and the SOC is determined by either hydrometer or volt meter method?  Should you replace it for a SOC of less than 70% or 50%, or what is that number?  I understand the weaknesses of using voltage and SG to estimate SOC.

On April 13, 2016 at 5:01am
John Ryan wrote:

under “Coulomb Counting”
The statement “discharging one ampere (1A) per second passes one coulomb” is back to front. One coulomb per second is one ampere.

On April 26, 2016 at 3:19pm
David Kelly wrote:

Thanks for the info, I’m not in a panic yet, I will wait 24 hours to check SG.  I have 8 brand new 6Volts L16HC lead acid batteries. I have gotten the U.S. Battery spec sheets and have the controller set accordingly. Every time I check the Specific Gravity, it’s in the red, 1.175 or lower.  Took the new batteries back to store, all 900 lbs.  They said they were good and the SG was over 1.275 when I picked them up.  Brought them back home and put back into system and immediately the charge controller said “Charged”.  I have solar panels, charge controller and an inverter.  The first night got about 5kw and voltage stayed above 49.  But keeps getting lower and lower and SG getting lower as well.  This is driving me crazier, don’t know if I’m over charging, under or just lost.  Oh, I’m getting 6.6 volts on each battery when fully charged, which seems high to me and the SG at 1.175.  Can anyone spare a clue?

On May 30, 2016 at 9:33pm
Pyroslav wrote:

That was like a L-o-n-g infotainment comercial for Spectro™ or whatever thing, without explaining how the damn thing really works, or what it is, like, “it is microcontroler in a box with lcd screen with our properitary code that measures curent, voltage and temperature in sucha way,  and u connect it to such battery type in this or that way”

On July 20, 2016 at 2:27pm
Rean Bootsma wrote:

” Opening the car door applies a parasitic load of about 20A”.  Is this really the case?

I can think of the “cold current” of a filament door lamp, but 20A still seems quite high. 

If this is not a typo, I’d like to understand it a bit better.

Can anyone show an oscilloscope trace of this current spike, please?

On July 22, 2016 at 2:48am
chohan wrote:

how to count a battery beck up timing

On November 10, 2016 at 9:47am
Rodolfo Martinez wrote:

We must remember that the SOC is a measure referenced to the capacity of the battery and the capacity of the battery changes with charge-discharge cycles and the passage of time.  It will be always an approximate measurement.

An effective way to reduce the sensitivity of an application to SOC accuracy is to oversize the battery bank.  This approach has the unintended benefit of prolonging battery bank life.

On November 12, 2016 at 9:02pm
Amos wrote:

Has anyone had a battery de-saulfator on deep cycle batteries? I bought one on e-bay and it seemed to work on an old battery. The battery was about 4 years old and would not hold a full charge. After using it by the instructions, I got it to hold a full charge and used it for 2 more years.

On November 16, 2016 at 4:03pm
Conny wrote:

There is a company in Sweden called Insplorion AB that has been able to measure SOC chemically with the help of nanosensors (NPS - Nano Plasmonic Sensing) - It is now being commersialized - https://www.insplorion.com/en/news/strategic-collaboration-with-multinational-component-company-and-agm-batteries/

On November 18, 2016 at 12:12am
Rodolfo Martinez wrote:

nanosensors (NPS - Nano Plasmonic Sensing) would be particularly useful in Lithium ion batteries. I would like to see a study that shows three models: 1) a model describing the capacity loss as a function of charge/discharge cycle in Lithium ion batteries,  2) a model that describes to total amount of energy the battery can store a discharge as a function of depth of discharge, and 3) a model that describes the total amount of energy the battery can store as a function of charge/discharge power.  In all cases, the end of life of the battery would be indicated by the failure of the battery to retain and discharge at least one half the nominal capacity.

As an analogy to understand the problem I am referring to:  What would be the meaning of having a car gas indicator indicate a half a tank of gas if every time we refuel the car its gas tank got a little bit smaller?

On November 18, 2016 at 11:25am
Conny wrote:

Very good thoughts Rodolfo, and thank you for ending with a good analogy. Just to pint out, I’m not a scientist, I’m just a very curios individual.

These sensors should be able to also detect the state of health (they also talk about state of ageing). In the PDF the method is explained. Maybe that is something that can be of help in sorting out the the models you where looking for.


Would love to hear more opinions.

On November 19, 2016 at 1:45pm
Conny wrote:

Here is another link that explains the project a little further:


On December 2, 2016 at 1:19am
Alain Poitras wrote:

I like to know with battery ...

On December 26, 2016 at 9:32am
Glenn wrote:

Help please….I have two 12v AGM on my scooter that are about 1-1/2 years old, being a disabled senior sometimes I am not able to ride everyday and have gone for a few weeks and they have died on me. I removed the screw on caps and noticed all cells were dry and sulfated. One batt has 10.5v the other .5-1v.  My questions are, how do you check SG on a AGM battery? Can AGM batts be de-sulfated? Any way to revive them enough to be used? Being on fixed income I can’t afford new batts, any and all suggestions and or recommendations are very greatly appreaciated.

On February 18, 2017 at 4:59pm
Joel wrote:

If the test reading is red before and after charging the battery. Can we replace the battery acid with a new one and charge again or garbage the battery

On April 7, 2017 at 1:47am
Sharad Patankar wrote:

Please explain the influence of temperature on specific gravity and voltage of lead acid battery in tropical conditions?

On May 14, 2017 at 11:37am
Anita wrote:

To Glenn
I hope you received some answer before today
how do you check SG on a AGM battery? CANNOT
Can AGM batts be de-sulfated? USUALLY NOT
Any way to revive them enough to be used?
it depends on the age and condition of the battery. if the battery is at the end of its life, nothing can be done
if the battery was neglected, often charging with a current limited high voltage can restore some life
high voltage means 36 to 78V on a 12V battery (not recommended for higher voltage batteries)
current limited, means instantaneous limiting, with a resistor (not internal charger’s internal components)
limit the current to 0.1% or less
leave on charge foe a while (sometimes much more than a week)
if the battery is sulphated, the voltage will be high
if after a week the voltage did not drop significantly, there is not much hope

On June 21, 2017 at 11:35pm
Niraj Agarwal wrote:

Can anyone help me with a code for Arduino, for finding the SOC using Coulomb Counting method?  I am using the ACS712 for reading Voltage and current and LM35 for temperature.

On August 17, 2017 at 7:22am
zamin wali wrote:

Please show me any method or device which can be used to find the amount of charge in coulumb in a DC battery.

On November 21, 2017 at 1:53am
Marekk wrote:

The Car door 20A might refer to Tesla Model X opening the wings might require some power though…

On January 19, 2018 at 9:13pm
Francisco Javier Briseno wrote:

Battery capacity is directly proportional to surface area of plates. Porous plates have a higher surface area, which is great at first, but the deep crevices get sulfate buildup faster and thus reducing the surface area for the exchange of electrons. Each chemical molecule provides two electron exchanges and the the exchange rate geometrically decreases, or decays by Euler’s number (e), which is not so bad, unless you allow the plates to remain sulfated longer, which makes the sulfation harder to remove and thus decreasing the capacity “AVAILABLE”. The battery capacity is the same as when new as when it goes to battery heaven, or better yet recycled. The capacity that geometrically decays is the “AVAILABLE” capacity, and not the overall capacity. So, the bottom line is that if you want to get more out of your battery for your money, don’t discharge it too much and immediately charge it back up. Don’t expose it to thermal shock; even one degree Fahrenheit causes thermal shock at the atomic level. You get what you pay for and you reap what you sow, so take good care of your batteries and they will take good care of you longer. Read, read, read similar blogs and data like this webpage and you will get more in return than your investment, which is only time with the reward of knowledge. Measure voltages, temperatures, chemistries such as specific gravities and write them down then analyze your data to your specific needs and uses. I love all the questions, answers, opinions on this site from people of all walks of life and varied usages of batteries. In essence, we are like ranchers trying to keep our herd of electrons together, but there will always be those strays (parasitic losses) due to our ignorance, ego, or just plain laziness, which I would be the first to raise my hand and plea guilty. There is a saying that says cleanliness is godliness; well, is a deep subject or such a shallow mind, so take your voltmeter and set it to the range above your battery voltage then put one probe on either post and the other probe, probe around on the battery case and see your voltage drop (parasitic) due to dirt, grime, conductive goo and there you will find your main culprit for early battery death. Clean it with a mild soapy solution and rinse it with hot water then clean outwards from each individual cell, or else one weaker cell will discharge a stronger cell giving you a false sense of security. I close by a thankyou to batteryuniversity and this venue.

On February 27, 2018 at 1:58am
Raj wrote:

I would like to understand, if there are automation sensors available to check specific gravity of acid during Charging / discharging process? we want to take input of these parameters in a dashboard.

Please suggest

On April 15, 2018 at 2:58am
Gary Welham wrote:

Can tubular plate deep cycle traction batteries be charged safely above 2.45v per cell?

On April 29, 2018 at 7:36pm
Jaeyoung choi wrote:

Hi, guys. I really wonder how AH-counting process works? Would you tell me the process or the web-site that I can learn?

On April 30, 2018 at 9:43am
chase magnuson wrote:

what should each of a fully charged lead-acid automotive battery measure?

On July 1, 2018 at 10:33pm
Ananda Krishnan wrote:

What is the manufacturing difference between C20 deep cycle battery and C10 solar battery??
What is the recommended charging volts for C10 tubular per cell at 27℃??
Can I use C10 flodded tubular battery for backup power during night I.e will it cause any damage to the battery when stored in partial SoC during overnight???

On September 15, 2018 at 2:09pm
Stephen Monteith Albers wrote:

The published lead acid charge curve from 0”-100%  is 12.0-12.9 volts.  So, how come my car starts with a battery voltage of 11.5 volts?

On February 19, 2019 at 11:38pm
abhilash wrote:

Can i have a mathematical relationship between soc and open circuit voltage of a lead acid battery?