Car battery voltage vs state of charge battery,where to buy battery for car alarm remote,the best car audio battery life - You Shoud Know

27.05.2015
I put together the following chart which indicates the state-of-charge (percent) as it relates to battery voltage or specific gravity.
How I determined the voltage values: I researched as many battery manufacturers that I could find regarding their own published SOC data.
Note: Voltage measurements are only approximate to determine SOC, and measuring battery voltage is NOT the most accurate way to do this (there are variables under varying circumstances). Note: For longer battery life, batteries should remain in the green zone (40% or more SOC).
Note: The 100% voltage is NOT the recommended charging voltage (which will be higher, and multi-stage). If the gravity of each cell stays relatively the same (usually all in the green) does that mean that I don’t need to equalize that battery?
The reason I ask is: I have 90 watts of harbor freight panels, run thru a sunsaver controller that charges 2 wally world deep cycle batteries and the gravity has almost never been below the green level, and I never really have had to add much water. My other set up has about 750 watts of poly panels, run through a xantrex 30 amp charge controller charging a trojan 12 volt golf cart battery. I guess my question is do I need to do this since the wally world batteries always seem to be in good shape as per hydrometer readings?
I built an off-grid system for my home and have expanded and maintained it myself over the years, so that is my knowledge base. Also, NEVER combine different types, or age, or widely differing state of charge of your batteries when charging.
Thanks Carl, and as you insinuated, there are variables, including temperature compensation measurements and others. Saw this as I was looking for a SG to SOC chart and thought I would make a couple of comments.
To obtain maximum service life and capacity, along with acceptable recharge time and economy, constant voltage-current limited charging is recommended. As a result of too high a charge voltage excessive current will flow into the battery, after reaching full charge, causing decomposition of water in the electrolyte and premature aging. If too low a charge voltage is applied, the current flow will essentially stop before the battery is fully charged.
Batteries which are stored in a discharge state, or left on the shelf for too long, may initially appear to be “open circuited” or will accept far less current than normal. Conversely for Gel batteries fitted close to the alternator (under-bonnet with a thick gauge cabling) there is a real risk of damage due to over-charging as the alternator output can be too high for the battery.
Many Portable Generators do not have battery charging circuitry built-in and should be used with care if they provide a DC outlet (although you could plug a battery charger into the 240V socket, it seems a fairly inefficient way to operate).
The later models (from Honda et al) with the built in chargers can provide a reasonably quick and efficient battery top-up on sites where they are allowed (or when off-site), although some users do grow tired of the noise and migrate to solar over time. Part – or most – of the loss in charging and discharging batteries is due to internal resistance. Typical efficiency in a lead-acid battery is 85-95%, in alkaline and NiCad battery it is about 65%. Gelled batteries, or “Gel Cells” contain acid that has been “gelled” by the addition of Silica Gel, turning the acid into a solid mass that looks like gooey Jell-O. Starting (sometimes called SLI, for starting, lighting, ignition) batteries are commonly used to start and run engines. Deep cycle batteries are designed to be discharged down as much as 80% time after time, and have much thicker plates. Unfortunately, it is often impossible to tell what you are really buying in some of the discount stores or places that specialize in automotive batteries. Marine batteries are usually a “hybrid”, and fall between the starting and deep-cycle batteries, though a few (Rolls-Surrette and Concorde, for example) are true deep cycle. There is generally no problem with this, providing that allowance is made for the lower cranking amps compared to a similar size starting battery. Plate thickness (of the Positive plate) matters because of a factor called “positive grid corrosion”.
The 20-hour rate is the most common for standardising batteries in Australia, while the USA uses a 10-hour rating system. The lifespan of a deep cycle battery will vary considerably with how it is used, how it is maintained and charged, temperature, and other factors.
These are some typical (minimum – maximum) typical expectations for batteries if used in deep cycle service.
An inverter has basically two functions – to provide an alternating current (ac) voltage rather than the direct current (dc) available from the battery, and to raise the voltage up to an average of 240V. Tutorials & Quick References This section is for how-to's and quick references for car audio. To do so just go to log in >> once it redirects you click forgot password >> follow the steps provided. If you do not remember the email address associated with your account you can use the contact us tab at the bottom of the page to email us for assistance.
Voltages and Specific Gravity are listed for a 6-volt or 12-volt battery, and battery banks of 24 and 48 volts. Some were slightly different from each-other with regards to their SOC values, however I averaged all of them together to come up with a chart which represents what I believe to be a good general indication.
A more accurate method is to measure the specific gravity of each cell within the battery, however for many batteries this is difficult or impossible (AGM batteries, for example). Occasional dips into the yellow may not be harmful, but continual discharges to those levels will shorten battery life considerably. Just thought it might be helpful to add that one tool I’ve found useful is the little floating balls thing for checking individual cell status in lead acid batteries. I mainly use this system for 12 volt water pumps,a few LED’s and cfl lights and occasionally power tools. My immediate thought about the differences in your two battery banks is that the wally world batteries are newer, or less heavily used than the Trojan. I do off grid solar for a living, 25 years now and I sent a customer the link to this chart to give him an extra tool to keep tabs of his system.
As the battery reaches full charge, the positive plate begins generating dioxide causing a sudden rise in voltage due to decreasing internal resistance.
This allows some of the lead sulfate to remain on the electrodes, which will eventually reduce capacity.
They are not battery chargers however, and will never fully charge a Deep Cycle battery, so it’s best to use a battery charger when main power is available to top up the battery charge and avoid reduced battery life from sulphation.
It is for this reason that we highly recommend NOT using GEL batteries with car alternators.
A battery rated at 180 amp-hours over 6 hours might be rated at 220 AH at the 20-hour rate, and 250 AH at the 48-hour rate. If a battery is discharged to 50% every day, it will last about twice as long as if it is cycled to 80% DOD.


The advantage of these batteries is that it is impossible to spill acid even if they are broken.
If overcharged, voids can develop in the gel which will never heal, causing a loss in battery capacity.
The major difference between a true deep cycle battery and others is that the plates are SOLID Lead plates – not sponge. In the hybrid, the plates may be composed of Lead sponge, but it is coarser and heavier than that used in starting batteries. As a general rule, if you are going to use a true deep cycle battery also as a starting battery, it should be oversized about 20% compared to the existing or recommended starting battery group size to get the same cranking amps.
In extreme cases, it can vary to extremes – AGM’s can be killed in less than a year by severe overcharging. There are so many variables, such as depth of discharge, maintenance, temperature, how often and how deep cycled, etc. These are usually special purpose “float service”, but often appear on the surplus market as “deep cycle”. If a battery has been discharged for some time, or the load was left on indefinitely, it may not readily take a charge. Caution should be exercised to ensure that the charger is disconnected after cycle charging, or that the float voltage is set correctly. Differences in capacity can cause some batteries to overcharge while others remain undercharged, thus causing premature aging of batteries. To determine the approximate recharge time of a fully discharged battery, divide the battery’s capacity (amp.
The difference in characteristics will cause damage to the batteries and possibly to the attached equipment.
Due to the high volume of emails going out and some service providers blocking them as spam, users have either been getting them late, or not at all. Batteries that are being charged will be higher - the voltages while under charge will not tell you the state of charge, you have to let the battery sit for a atleast 3hours.To get the correct state of charge voltage. Measuring and knowing the SOC of a battery or battery bank is useful when applying towards alternative energy, or any other situation where you need to know its condition.
Many (most) alt-energy systems incorporate a DC-shunt which keeps track of SOC by monitoring the current flow in and out of the battery or battery bank, which is a very accurate way to track state-of-charge. To be somewhat accurate, the battery should be in that condition for an hour or two before taking a measurement, while for a more accurate measurement you should wait 6 hours up to 24 hours. Generally speaking, the less you discharge the battery before recharge, the longer the battery will last. The Trojan sounds like it is getting old, and needs more frequent watering and equalizing to keep it functioning. The one thing I would disagree with somewhat from your well written article is concerning the accuracy of state of charge meters. The selection of suitable charging circuits and methods is as important as choosing the right battery for the application. A constant voltage charge, therefore, allows detection of this voltage increase and thus control of the current charge amount. Much of this loss of efficiency is due to higher internal resistance at higher amperage rates – internal resistance is not a constant – kind of like “the more you push, the more it pushes back”.
However, there are often ratings for other depth of discharge cycles, the most common ones are 10%, 20%, and 50%. The problem is that “golf car” refers to a size of battery (commonly called GC-2, or T-105), not the type or construction – so the quality and construction of a golf car battery can vary considerably – ranging from the cheap off brand with thin plates up the true deep cycle brands, such as Crown, Powersonic, Trojan, etc. It is often hard to tell what you are getting in a “marine” battery, but most are a hybrid. With modern engines with fuel injection and electronic ignition, it generally takes much less battery power to crank and start them, so raw cranking amps is less important than it used to be.
The positive (+) plate is what gets eaten away gradually over time, so eventually there is nothing left – it all falls to the bottom as sediment.
While plate thickness is not the only factor in how many deep cycles a battery can take before it dies, it is the most important one.
Gelled cells batteries can be destroyed in one day when overcharged with a large automotive charger. The most expensive provide a pure sine wave which is preferred for any sensitive equipment, especially laptops. A 150W unit will handle most camp requirements, but may have trouble starting a laptop (even though the average drain by the computer is much less than this.) A 300W unit is probably a sensible minimum. To overcome this, leave the charger connected and the battery should eventually begin to accept charge. Given the right set of circumstances, such as extreme overcharging or shorting of the battery, these gases might vent into the enclosure and create the potential for an explosion when ignited by a spark. It is, therefore, not advisable to mix batteries of different capacities, make, or age in a series string. If you have not received your password reset email please use the password reset function ?forgot password?. Most alternative-energy systems are designed to keep the battery bank at least 50% or higher. When batteries are in series they do not necessarily charge at the same rate and can become imbalanced.
Usually, the battery will start to accept increasing amounts of current until a normal current level is reached. You have to be careful when looking at ratings that list how many cycles a battery is rated for unless it also states how far down it is being discharged. Obviously, there are some practical limitations on this – you don’t usually want to have a 5 ton pile of batteries sitting there just to reduce the DOD. These are also called “starved electrolyte”, as the mat is about 95% saturated rather than fully soaked.
The plates are composed of a Lead “sponge”, similar in appearance to a very fine foam sponge. Although these can be cycled down to 20% charge, the best lifespan vs cost method is to keep the average cycle at about 50% discharge. Starting batteries are usually rated at “CCA”, or cold cranking amps, or “MCA”, Marine cranking amps – the same as “CA”. On the other hand, many cars, boats, and RV’s are more heavily loaded with power sucking “appliances”, such as megawatt stereo systems etc. Thicker plates are directly related to longer life, so other things being equal, the battery with the thickest plates will last the longest.
Golf cart batteries can be destroyed without ever being used in less than a year because they were left sitting in a hot garage without being charged. The cheapest simply provide a square wave ac, which is satisfactory with most motors and some small chargers for cameras, phones etc, but not for most laptop computers.


Bear in mind that Watts = Volts x Amps, so, if we draw the full 300 watts, we will require 25 amps from the 12volt battery, plus 20% to account for inefficiency. It is set to equalize every 30 days, however sometimes I have to do it more than that, to bring them all back to green.
The plates may have become heavily sulfated enough that the equalize mode can’t get it all off into solution. The equalizing charge ups the charging voltages in order to get enough voltage to the lesser charged batteries in the series chain. Batteries that are being charged will be higher – the voltages while under charge will not tell you anything, you have to let the battery sit for a while. If there is no response, even to charge voltages above recommended levels, the battery may have been in a discharged state for too long to recover. The generally accepted AH rating time period for batteries for nearly all deep cycle batteries is the “20 hour rate”. For example, one of the widely advertised telephone type (float service) batteries have been advertised as having a 20-year life. They cannot be fast charged on a conventional automotive charger or they may be permanently damaged. The newer AGM (absorbed glass mat) batteries have all the advantages (and then some) of gelled, with none of the disadvantages. This gives a very large surface area, but if deep cycled, this sponge will quickly be consumed and fall to the bottom of the cells. Any battery with the capacity shown in CA or MCA may or may not be a true deep-cycle battery.
The negative plate in batteries expands somewhat during discharge, which is why nearly all batteries have separators, such as glass mat (AGM) that can be compressed. Even the so-called “dry charged” (where you add acid when you need them) have a shelf life of 18 months at most. There are also intermediate types, “modified sine wave”, which combine a number of square waves to approximate a sine wave shape. I combine the batteries whenever we lose power for more than a few hours so we can run TVs, fans DVD player and lights etc. The standard meter for years has been the Tri-Metric meter but I finally gave up on using them because they arent very accurate unless fine-tuned beyond the level most homeowners are capable of understanding.
Yes it will over charge the higher charged batteries, which is why the equalizing charge is only applied for a short time, however if the system uses a single battery equalization is not required and can be detrimental.
A 10Hr rating is widely used in the USA, therefore many batteries can have 10hr, 20hr or both specifications stated. If you look at the fine print, it has that rating only at 5% DOD – it is much less when used in an application where they are cycled deeper on a regular basis. This is not usually a problem with solar electric systems, but if an auxiliary generator or inverter bulk charger is used, current must be limited to the manufacturers specifications. Automotive batteries will generally fail after 30-150 deep cycles if deep cycled, while they may last for thousands of cycles in normal starting use (2-5% discharge). They are not totally dry – they are actually filled with acid, the plates formed and charged, then the acid is dumped out.
These are usually satisfactory for laptops, but, like the square wave types, often create a lot of radio interference. This will draw from the battery in 1 hour about the same as all other loads discussed above take in a day. You should probably start saving your shekels for a new battery because that one is not going to live much longer. It doesnt help that the manual makes little sense to the layman or that the meter cant read battery voltage and often keeps compounding small errors into bigger ones. It would be wise to buy a desulfator unit for your batteries in order to reverse sulfation of the plates after long periods of less than 100% charge.
Occasional dips into the yellow are not harmful, but continual discharges to those levels will shorten battery life considerably. The 20hr rating means that it is discharged down to 10.5 volts over a 20 hour period while the total actual amp-hours it supplies is measured. It’s just that when designing a system when you have some idea of the loads, you should figure on an average DOD of around 50% for the best storage vs cost factor. Better inverters commonly used in solar electric systems can be set to limit charging current to the batteries.
The meters that you can get that take their info from the inverter or in the case of Midnite Solar from the charge controller are more accurate because they temperature compensate but they need fine-tuning as well. Sometimes ratings at the 6 hour rate and 100 hour rate are also given for comparison and for different applications.
For example, most golf cart batteries are rated for about 550 cycles to 50% discharge – which equates to about 2 years. Also, there is an upper limit – a battery that is continually cycled 5% or less will usually not last as long as one cycled down 10%.
Unfortunately, the only positive way to tell with some batteries is to buy one and cut it open – not much of an option.
A 2000W one will provide enough power to run power tools or even an electric jug, but at full output they will draw from the battery about 150-200 amps.
Just yesterday a customer called because his inverter shut down at 23 volts, a definite low battery but the SOC meter claimed he was at 81% full. The best determination is to measure the specific gravity, but in many batteries this is difficult or impossible.
The 6-hour rate is often used for industrial batteries, as that is a typical daily duty cycle. This happens because at very shallow cycles, the Lead Dioxide tends to build up in clumps on the positive plates rather than an even film. That’s as much current as they winch when fully loaded, and way outside the comfort zone of any deep cycle battery for long periods of time.
I sent him a link to your chart and told him to call Magnum tech support to learn to tweak the meter.
Sometimes the 100 hour rate is given just to make the battery look better than it really is, but it is also useful for figuring battery capacity for long-term applications like backup, solar, and camping amp-hour requirements. Most 1500w-2000w applications such as microwaves and electric kettles will only run for a few minutes, this will be fine to use with a 100AH+ battery.



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Comments Car battery voltage vs state of charge battery

  1. sevgi
    From another company for a similar increase the car battery voltage vs state of charge battery capacity know if this type of charging will cause.
  2. ADMIRAL
    100-200 cycles before a gradual decline all the imput efficiency even.