12v Battery Full Charge Voltage

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Are 124 Volts Ok For A Car Battery

12 volt battery full charge indicator circuit / 6v 9v 12v Adjustable

If the engine is off for some time and if the voltage shows 12.4V, the battery is semi-discharged: the flooded battery is probably around 65-70% SOC, and the AGM battery is around 50% SoC.

The battery most probably can easily crank the engine, but after starting, drive your car for at least 20-30 minutes in order to fully recharge its battery.

How To Tell If A 12v Battery Is Charged

Only 12-volt, lead acid, batteries can be recharged by an electrical battery charging device. There are two basic physical types of the lead acid battery, an SLA , and an open top maintainable battery. The SLA is just as the name applies it allows no access to check the level of battery fluid inside each individual battery cell. The open top or maintainable battery allows the user to check and add fluid to the battery. Both of these types of batteries can be easily tested for a full charge.

Rely On Jiffy Lube To Keep You Rolling

Preventive maintenance, performed by highly-trained technicians, can help save you two of your most valuable resources:

  • Time. Commuting to work, carpooling to school, grocery shopping you need your car! Preventive maintenance can help you avoid a major repair that could keep your vehicle off the road and in the shop for days .
  • Money. Catching a small problem when it’s still a simple fix can save you the cost of an expensive repair.

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What Voltage Should A 12 Volt Battery Read When Fully Charged

Believe it or not, but a 12 volt battery should not be read with 12 volt to see if its fully charged or not. In fact, 12 volt is just a term used to distinguish one battery from another. In reality, the amount is not exactly 12 volt. Thus, the volt should be read in another number to know if its fully charged or not.

When we charge the batteries, we should bring them up to at least 14 volts to have them fully charged.

For example, wet-cell batteries would need at least 14 volts reading to distribute the electrons equally all around the battery. After the electrons distribute themselves though, the volt will balance itself out to 12.6 volts.

Of course, different conditions would apply to gel-cell batteries. As a matter of fact, gel-cell batteries should not be charged no more than 14.1 volts . It should be noted that the reading cannot be applied universally. Different kinds of batteries would have different readings when it comes to fully-charged batteries.

Sounds easy, isnt it? However, there are some things we must do if we want to get accurate reading of the battery when its fully charged.

First, the battery should be in a rest state. Rest state means that the battery should not be attached to any power supply. Manufacturers recommend a 24-hour resting time, but a couple of hours should be sufficient.

11.4 volts means 20% charged

12.3 volts means 50% charged

12.5 volts means 70% charged

12.6 volts means 100% charged

Lead Acid Battery Cycle Charging

What is the Voltage of a Fully Charged 12

Cyclic applications generally require recharging be done in a relatively short time. The initial charge current, however, must not exceed 0.30 x C amps. Just as battery voltage drops during discharge, it slowly rises during charge. Full charge is determined by voltage and inflowing current. When, at a charge voltage of 2.45 ± 0.05 volts/cell, the current accepted by the battery drops to less than 0.01 x C amps , the battery is fully charged and the charger should be disconnected or switched to a float voltage of 2.25 to 2.30 volts/cell. The voltage should not be allowed to rise above 2.45 ± 0.05 volts/cell.

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How To Charge 12v Battery Basics

Before we get into the step-by-step process, its important that you know a little bit about how charging works. Here are some basics:

12 volt batteries do not produce electricity they store it! The alternator in your car is responsible for producing electricity and sending it to the battery. So, when youre attempting to charge a 12-volt battery, what you need to do is use that same alternator but hook it up in reverse! By doing this, youll be tricking the generator into thinking that theres no load on its output which will allow the voltage of the current being produced by the alternator to rise above 13 volts. This causes an effect called electromagnetic induction where electrons are forcefully ripped from one atom and pushed onto another. The end result? Electrons flow through wire connected between two different metals creating power.

A lead-acid storage cell actually contains six separate cells within its casing that are separated by thin sheets of plastic. This design allows the cells to charge and discharge without affecting each other, but more importantly, it provides a way for high voltage power from your cars alternator to be converted into two simple voltages: 12 volts and 24 volts which can be used to both run electrical devices in your RV as well as recharge the batteries inside them!

Undercharging A Lead Acid Battery

If too low a charge voltage is applied, the current flow will essentially stop before the battery is fully charged. This allows some of the lead sulfate to remain on the electrodes, which will eventually reduce battery capacity.

Batteries which are stored in a discharged state, or left on the shelf for too long, may initially appear to be open circuited or will accept far less current than normal. This is caused by a phenomenon called sulfation. When this occurs, leave the charger connected to the battery. Usually, the battery will start to accept increasing amounts of current until a normal current level is reached. 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, and in which case a replacement SLA battery will be needed.

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Can I Use Any Battery To Start My Car

No, “any” battery can’t be used to start the car. However, another battery can be connected to the car in order to jump-start the engine.

In the process of connecting, a good battery will transfer part of its charge to the discharged battery – recharge the “good” battery as soon as possible and let the car charger recharge the discharged battery.

How Do You Know When A Car Battery Needs Replacing

12v Battery Full Charging Voltage Limit For UPS ? ð?

If your battery frequently dies or it takes you multiple attempts to start your engine every morning, there’s a good chance it needs replacing. You may also notice that the “Check Engine” light turns on. You can also pop the hood and take a look at the battery itself. If you notice a buildup of corrosion on the terminals, that’s another sign that your battery is past its prime.

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How I Made The Battery State Of Charge Chart

How I determined the voltage values:

I researched as many battery manufacturers that I could find regarding their own published SOC data. 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.

At What Voltage Is A 12v Battery Dead

It depends on the battery chemistry and temperature, but if the voltage is below 10.5 volts, the battery should be recharged as soon as possible, preferably with an advanced battery charger that analyzes the battery first and then charge it according to the battery’s condition.

Anything below 11.7-11.8 volts means that the battery is almost fully discharged.

Note: It is possible to recover car batteries discharged down to 0-1V using “force” charging, but that should be avoided since the buildup of lead sulfate crystals may easily physically damage the battery.

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Two Step Constant Voltage Charging

This method uses two constant voltage devices. In the initial charge phase the high voltage setting is used. When charging is nearly complete and the charge voltage has risen to a specified value , the charger switches the voltage to the lower setting. This method allows rapid charging in cycle or float service without the possibility of overcharging, even after extended charging periods.

How To Measure A 12 Volt Battery Voltage At Rest

12v Agm Battery Full Charge Voltage

To measure the voltage on your car battery you will need to use a tool called a multimeter. These are relatively inexpensive and can measure voltages, resistance and current on electrical items.

First, youll need to find your car battery, these are often in the engine compartment of your vehicle, but on some models, they can be found in the boot.

To connect the multimeter to your car battery youll need to first disconnect the terminals from the battery and connect the wires from the multimeter. To do this, remove the positive terminal cover first and connect the positive lead from your multimeter to the battery. Once this is done, you can remove the negative terminal cover and connect the negative lead from your multimeter to the battery.

After you have your multimeter connected youll need to turn it on and check the reading.

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Use A Solar Charge Controller

Pros: Convenient

Cons: Inaccurate

You may be thinking:

My solar charge controller already measures battery voltage. I can just use it to check battery capacity.


This voltage reading is inaccurate. It suffers from all of the problems mentioned above, plus its done while the battery is connected to loads and chargers.

For example, recall that when I checked my batterys voltage with a multimeter at the battery terminals, I got a voltage reading of 13.23 volts. That correlates to a roughly 80% state of charge.

But when I connected my battery to an MPPT charge controller, the controller measured 13.0 volts. That correlates to a roughly 30% state of charge a difference of 50%! Granted, some charge controllers have much more accurate battery voltage readings than others.

After all, voltage drops under load. And a charge controller is a load. If I were to connect a solar panel and start solar charging the battery, its voltage would instantly jump.

Checking battery capacity this way is convenient. But beware that it can be quite inaccurate. I generally use this voltage reading just to make sure my battery isnt close to being fully discharged.

If you use this method and want to make sure its as accurate as possible, you can buy a battery voltage sensor, such as the Renogy Battery Voltage Sensor or Victron Smart Battery Sense. A voltage sensor gives the controller a more accurate voltage reading, especially in solar power systems with long wire runs.

Sooooo How Exactly Do You Charge A 12

Connect your 12-volt battery to the battery charger by attaching the BLACK negative cable from your charger to the negative terminal of the 12-volt battery. Make sure to use the clips or clamps to connect to the terminal securely. Generally, the negative terminal is labeled . You also need to connect the positive cable from your charger to the RED positive cable of the battery. Youll find the + mark on the positive terminal.

Leave your charger on for as long as you want. This wont damage your battery. Check the battery charger display to see when your battery is fully charged. Disconnect the cables, and now your battery is ready to use.

If you are looking for a top quality charger, this Schumacher SC1281 100 Amp 30 Amp 6V/12V Fully Automatic Smart Battery Charger is simply one of the best out there that will last a lifetime.

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How Long Does It Take To Charge A Battery

The more discharge your battery is, the longer it takes to charge it fully. Yes, batteries take time to recharge. It could take hours. A 12-volt battery could take up to 12-24 hours to charge fully. When recharging your battery, remember that if it gets too hot while youre charging it, you need to stop charging. It should not get too hot above 125 Fahrenheit.

Ideally, slow charging your batteries is the best option. Of course, the rate varies depending on the kind of battery that youre charging and its capacity. A 12-volt automotive battery, for instance, takes a while to charge. In fact, fast charging for this kind of battery is not recommended. 10 amps are the recommended current. This is a slow charge. 20 amps are already fast charging. Repeated fast charging could overcharge your battery. This could reduce the batterys service life in the long run.

In order to determine how long itll take for you to charge your battery, you need to know your batterys reserve capacity and your charger’s output charge current. A 100aH battery that is being charged by a 10A charger will be fully charged in 10 hours.

When To Charge The Battery

Simple 12 volt battery full charge indicator circuit

We know the battery should be charged. When it has a low capacity of about 35%.

But how do we know that we have reached that point? Of course, usually, the manufacturer will always tell you. Look at the battery.

This battery is filled with acid. If we measure the stabilized open circuit or its voltage is below 12.4V. This needs charging.

If you leave it, do not charge the battery. It will cause that battery to continue to deteriorate.

Make Gel cell battery charger circuit

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Idle Or Rested Battery Cells:

When a battery is charged up and not in any use , we call this a resting stage of cells. This is the best time to check battery reading. But before this, if it was charged up, you have to keep it in the resting stage for more than 4 hours to get an actual reading.

Four hours of rest can allow the battery to cool down to a certain neutral point allowing all surface charges to be dismissed within the electrolytes.

How To Charge 12v Battery Step

You can choose between three different ways to charge your 12v batteries. These are trickle charging, equalization charging and using an Automatic Charger with Engine Running.

Trickle charger is the most common way of recharging deep-cycle batteries which are used in cars, trucks, SUVs as well as boats and RVs. The best part about this method is that it doesnt require any supervision at all! You simply plug in the device, connect it to your battery and forget about it.

Equalizing is a process that should be carried out every once in a while if you want to keep your 12v batteries last longer. It shouldnt take more than an hour or two per month depending on the frequency of use when using RV air conditioning system, for example, this would require much more frequent equalization charges!

Automatic chargers are great because they allow charging without any supervision at all which makes them ideal for deep-cycle marine batteries both aboard boats as well as RVs. This type of chargers can detect when your battery needs recharging and will turn itself off before overcharging starts happening again. They also prevent sparks when connected to the battery because they can sense when your 12 volt batteries are full. Another great thing is that they will never overcharge your RV or boat batteries which in turn prolongs their lives.

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Voltmeter To Determine State Of Charge Of 12

The best way to determine the real state of charge of sealed batteries is the thorough voltage as the basis because the hydrometer cannot read the specific gravity of a battery which can cause a rough estimate of voltage when we are using voltage as the base to take an accurate reading of the state of charge.

Be sure that it is necessary to keep your battery resting for more than 4 to 6 hours. Voltage testing of a battery immediately after charging can cause fluctuation of accurate reading. Thus the state of charge reading may show high.

Level 3 Ev Charger Installation

New Car Motorcycle 12V Battery Smart Charger 2A Full Automatic LCD ...

More than 8% of the cars sold in Canada today are electric vehicles . Thats a pretty amazing fact when you consider that just a decade ago there were only a couple of thousand EVs in all of Canada. As electric vehicles become more and more popular the need for more and more charging stations increases in lockstep.

There are 3 types of charging stations in use today: Level 1 charging, Level 2 charging and Level 3 charging stations. Level 1 is charging at its most basic. You simply plug your EV into a standard 110 or 120 Volt AC outlet in the garage. Level 2 charging uses a 240 Volt system that cuts charging times by 60 or 70%. And Level 3 charging or DC Fast Charging as its known bypasses the AC charging system and plugs directly into the battery. It is Level 3 charging that we will look at in this article.

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Battery Capacity Is Lost When A Lead Battery Is Discharged Faster

In the case of a lead-acid battery, the capacity is always indicated in, for example, C1, C5 or C20 . The C stands for capacity and the number stands for the number of hours in which the capacity can be delivered . For example, if a battery says C20=100Ah, this battery can deliver a total of 100Ah if it is discharged in 20 hours. So a device that draws 5 Amps can run for 20 hours on this battery. However, if the battery is discharged faster, the total capacity drops radically. The same battery can have a C-rate of C5=70Ah. If you disconnect the battery in 5 hours it will only deliver 70Ah in total. This is because the internal resistance of a battery increases when it is discharged faster and capacity is lost by heat. By default, lead batteries are often measured over 20 hours discharged .

The faster a lead-acid battery is discharged, the less capacity it has. While with lithium batteries this is not the case. For a Rebelcell 12V50, for example, C1=C5=C20=50Ah applies. The effective battery capacity therefore depends on how deep you can discharge a battery, and how much energy is lost due to the speed of discharge of your battery.

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