Battery Voltage Drops To Zero When Cranking? The 154 Detailed Answer

Get in your car. Buckle up for safety. Turn the key in the ignition and… nothing. Nothing but a click. The engine will not start and your car will not start. Could be a dead battery. But since the dash lights and radio and headlights seem to be working, maybe something else is the culprit. This could be a sign that your car’s starter relay – or starter solenoid – is faulty.

Relay vs Solenoid

When you turn the key to start your car, you activate the ignition switch. Like most switches in your vehicle, the ignition switch controls only one weak signal, in this case to start the engine. On older vehicles, the signal is an electrical current (like a light switch in your house); On newer vehicles, the signal may be an electronic pulse sent to the vehicle’s computer. In either case, the switch “tells” the starter circuit to engage.

But the starter itself requires a lot of power. Certainly more than the tiny wires leading to the ignition switch can handle. The job of the starter is to get the internal parts of the engine turning and that requires a lot of torque and therefore requires more power. So automakers insert a device that allows a low-power signal to trigger a high-power signal. This allows a large task (like starting an engine) to be activated by a small switch.

Both a relay and a solenoid are devices that receive a low-powered signal as a trigger to close (or sometimes open) a much larger, more powerful circuit. In the case of a starter, the ignition switch signals the relay/solenoid (perhaps via a computer) and the relay/solenoid energizes the starter circuit to engage the starter.

Now the terms relay and solenoid are often used interchangeably and there is a lot of confusion as to what is what. (Hopefully we’re not adding to the confusion). While a relay and a solenoid are technically constructed and function differently, both are remote controlled electromagnetic “switches”. And both can perform the same function: driving a high-power signal with a low-power signal. In this way, the terms are often used in place of each other. Due to its structure and mode of operation, an electromagnet is usually able to switch a higher current than a relay. Still, one person might refer to a starter relay and another to a starter solenoid.

These devices, which further muddy the water, are located in different locations on different vehicles. And some manufacturers use both a relay and a magnet in the ignition system. In this case the relay triggers the magnet. Most often, a true starter relay is a small black cube plugged into an electrical fuse/relay box in the engine compartment, while a starter solenoid is (in most cases) attached directly to the engine’s starter (although sometimes it is located elsewhere). ). in the engine compartment).

Signs of a bad starter solenoid

Since problems are more common with the starter solenoid than with a plug-in relay, for our purposes we will focus on symptoms related to the solenoid. As you turn the key, consider these possible signs of a defective or bad starter solenoid:

Nothing happens. If you turn on the ignition and nothing happens, there are a number of problems that could cause it. One possibility is the solenoid. There is a single “click” sound coming from the engine compartment or under the car. This could mean that the solenoid is trying to engage but the internal components are stuck and not working properly. Repeated “clicking” sounds usually indicate a dead battery. But even a faulty solenoid that isn’t making adequate electrical contact inside can make that telltale noise, causing the battery to have a low voltage that can’t provide enough power to start your engine. Sometimes, instead of preventing the engine from starting, a faulty starter solenoid can cause the engine to start on its own without the key being turned to the “start” position.” This less common problem can be dangerous and should be corrected immediately . If the starter engages but doesn’t disengage when you release the key, the solenoid is probably bad and the starter could be seriously damaged as a result. Sometimes your car starts, sometimes it doesn’t. Intermittent operation can be a sign of a bad starter solenoid.

Other problems that do not constitute a bad solenoid

Problems that can cause your car to behave like it has a bad starter solenoid can include:

Blown Fuse – Sometimes the simplest explanation is the best. A blown fuse in the starter circuit could be the cause of a starting problem.

Broken or Corroded Wiring – Broken or dirty wiring to the battery or starter solenoid (or loose wiring) can prevent enough current from reaching the starter.

Alternator – The purpose of the alternator is to provide power to all of your vehicle’s electrical systems when the vehicle is running. It also charges the battery. If the alternator is defective, the battery may not be able to start the engine.

Starter – Some solenoids are mounted on the starter, but others are located directly in the starter housing. If this is the case then it may be necessary to replace the entire starter if the magneto is faulty. Sometimes the starter itself is the problem.

Electrical problems can be annoying and inconvenient. They can also be dangerous and cause damage. If you’re experiencing symptoms of a bad starter relay or solenoid in your car, truck, or SUV, make sure you have a trusted technician diagnose the specific problem.

Hogan & Sons Tires and Auto | Author: Mike Ales | Copyright ©

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Not to be confused with voltage drop

Voltage drop is the decrease in electrical potential along the path of a current flowing in a circuit. Voltage drops in the internal resistance of the source, across conductors, across contacts and across connectors are undesirable because some of the energy supplied is dissipated. The voltage drop across the electrical load is proportional to the available power that can be converted into another useful form of energy in that load.

For example, an electric space heater may have a resistance of ten ohms and the wires feeding it may have a resistance of 0.2 ohms, about 2% of the total circuit resistance. This means that about 2% of the supplied voltage is lost in the line itself. Excessive voltage drop can result in unsatisfactory performance of a space heater and overheating of cables and connectors.

National and local electrical codes may set guidelines for the maximum allowable voltage drop in electrical wiring to ensure distribution efficiency and proper operation of electrical equipment. The maximum allowable voltage drop varies from country to country.[1] Various techniques are used in electronics design and power transmission to compensate for the effects of voltage drop on long circuits or where voltage levels must be precisely maintained. The easiest way to reduce the voltage drop is to increase the diameter of the conductor between the source and the load, which reduces the total resistance. In power distribution systems, a given power can be transmitted with less voltage drop if a higher voltage is used. More sophisticated techniques use active elements to compensate for excessive voltage drop.

Voltage drop in DC circuits: resistance

Consider a DC circuit with a 9 volt DC power source; three resistors of 67 ohms, 100 ohms and 470 ohms; and a lightbulb – all connected in series. The DC source, the conductors (wires), the resistors, and the lightbulb (the load) all have resistance; all consume and consume, to some extent, input energy. Their physical properties determine how much energy. For example, the DC resistance of a conductor depends on its length, cross-sectional area, material type, and temperature.

If the voltage is measured between the DC source and the first resistor (67 ohms), the voltage potential across the first resistor is slightly less than nine volts. The current flows through the conductor (wire) from the DC source to the first resistor; In this case, part of the energy supplied is “lost” (not available to the load) due to the resistance of the conductor. Voltage drop occurs in both the supply and return lines of a circuit. If the voltage drop across each resistor is measured, the measurement is a significant number. This represents the energy dissipated by the resistor. The larger the resistor, the more energy that resistor dissipates and the greater the voltage drop across that resistor.

Ohm’s law can be used to check the voltage drop. In a DC circuit, the voltage is equal to the current times the resistance. V = I R. Also, Kirchhoff’s circuit laws state that in any DC circuit, the sum of the voltage drops across each component of the circuit is equal to the supply voltage.

Voltage drop in AC circuits: impedance

In AC circuits, resistance to the flow of current arises due to resistors, just as in DC circuits. However, AC circuits also contain a second type of resistance to the flow of current: reactance. The sum of the opposites of resistance and reactance to current flow is called impedance.

Electrical impedance is commonly represented by the variable Z and is measured in ohms at a given frequency. Electrical impedance is calculated as the vector sum of electrical resistance, capacitive reactance, and inductive reactance.

The level of impedance in an AC circuit depends on the frequency of the AC current and the magnetic permeability of electrical conductors and electrically isolated elements (including surrounding elements), which varies with their size and spacing.

Analogous to Ohm’s law for DC circuits, the electrical impedance can be expressed by the formula E = I Z. So the voltage drop in an AC circuit is the product of the current and the impedance of the circuit.

See also[edit]

References[edit]

introduction

Car batteries are essential to vehicle operation, but like everything else, they eventually fail. You can recognize this by the fact that your vehicle will not start or the engine only cranks slightly. If your battery is dead and your vehicle will not start, it is important to determine if it is dead and needs charging, or if it is too weak to hold a charge. Sometimes weak or dead batteries simply need to be charged or recharged. When they lose their ability to hold a charge, they must be replaced.

Proper battery testing makes it easier to figure out what’s wrong with your battery. Learn how to carry out a detailed test of your car battery with a special battery tester. You could use a multimeter, but you won’t get as much information about what’s going on inside the battery.

When your car won’t start, a weak or dead battery is often the cause. Unfortunately, most vehicle owners do not check their battery until it fails. As preventive maintenance, it is advisable to carry out a voltage test of the car battery with a multimeter regularly – at least twice a year.

A multimeter is an electronic meter used to measure volts, amps, and resistance from an electrical source. The most common automotive use for a multimeter is testing the strength of a car battery. When used properly, it provides voltage information with a high degree of accuracy on a digital display. Understanding the data provided is critical to determining if the battery is strong and healthy or should be replaced.

Preparing the Battery The first step is to locate the vehicle’s battery (see owner’s manual) and determine if there is dirt or corrosion on the positive and negative terminals. The positive terminal usually has a red cap and a “plus” sign, while the negative terminal has a black cap and a “minus” sign. Since corrosive deposits can prevent the multimeter from making accurate voltage measurements, they should be rubbed off with fine-grit sandpaper. Gloves should be worn to prevent skin exposure to harmful chemicals and battery acid. Once the terminals are clean, they serve as connection points for the multimeter’s probes.

Setting up the multimeter The multimeter may look complicated due to its various measurement settings, but the general operation is fairly simple. To test the electrical output of a vehicle battery, the multimeter scale should be turned to the 20 volt setting. However, before the multimeter can be used, all surface charge must be removed from the battery to provide an accurate reading. To do this, the headlights should be turned on for about two minutes, and then turned off.

Measuring and analyzing To measure battery charge, the multimeter has two probes: red and black. The red probe is for contact with the positive pole and the black probe is for contact with the negative pole. If the probes touch the terminals while the car is off and the battery is resting, the multimeter display should show a reading of 12.2 to 12.6 volts (full charge). This voltage range means the battery is in good condition to start the vehicle. If the reading is less than 12.2 volts, the battery’s open circuit voltage is low, which means it most likely needs to be charged or replaced. Once the resting voltage has been determined, it is time to read the crank cycle. This is the moment when the vehicle is turned on and the battery is most taxed due to the higher amount of energy required to power the starter motor. To get this reading, a second person is needed to start the ignition. As soon as the car is switched on, the voltage display will drop for a short moment, but should not drop below 10 volts. If it drops below 10 volts, the battery does not have sufficient turnover and is prone to failure. In this case, too, charging or replacing the battery may be necessary. Immediately after the crank cycle, the vehicle begins to idle and receives a constant drain on the battery. With the engine running, the multimeter should read between 14 and 14.5 volts. A drop below 14 means either the battery is weak and unreliable for continued vehicle operation, or the alternator is failing. The alternator’s job is to generate energy to power the electrical system and charge the battery while the vehicle is moving.

First some background information:

Good battery

A good battery has about 12.6 to 12.8 volts when fully charged.

When a good battery is stress tested to match its rated CCA (Cold Cranking Ampere), its voltage will drop to around 9.6 to 10.5 volts, depending on the ambient temperature. It will then shoot back to ~12.6 volts once the load is removed.

Bad battery

A battery with one or more dead cells loses about 2.1 volts with each dead cell. A battery with 1 dead cell will therefore have a voltage of about 10.5 volts, 2 dead cells = 9.4 volts etc. But normally the battery will be replaced as soon as one cell dies before others die as well.

A bad battery can show an incorrect voltage if it has surface charge, this occurs for a long time after a battery has been charged. It can read a full 12.6 voltage even though it has a bad cell.

However, if a battery is charged with a defective cell, it immediately drops well below its real voltage of 10.5 volts. Once the load is removed, it only bounces back to its maximum of 10.5 volts.

When are 10 volts enough?

To answer your question, 10 volts under load indicates a good battery, especially if it immediately jumps back up to over 12 volts after removing the load. 10 volts on a battery with no load indicates a dead cell and will usually drop well below 10 volts under load. A battery that reads more than 12 volts but drops below 10 volts under load and only bounces back to 10 volts after the load is removed is also a bad battery and likely has a dead cell.

EDIT: Starting a car is very different from a stress test. The battery is loaded for a significantly shorter time. A battery that drops below 10 volts on start but consistently starts the vehicle is likely either slightly undercharged or aging and has lost some of its cranking performance as all batteries do over time. Connecting the battery to a charger will solve the undercharging problem. If it still drops below 10 volts after a good charge, then the latter problem is the case.

This post is part of a series of motor management blogs that discuss various aspects of integrating large motors into the electrical network and industrial processes.

Voltage drop during load excitation is a major concern in heavy industry. Furnaces, transformers and large motors are examples of loads with high inrush currents that create a voltage drop. At the same time, the torque of motors subjected to a voltage drop is reduced, which leads to deceleration and even stalling. Sensitive electronic equipment can fail if a voltage drop occurs. To overcome these problems, brownout protection is used to disconnect loads at a defined threshold. If voltage drops are not taken into account in the design phase, they can later be responsible for process and production failures.

With large engines, it is best to address the issue as early as possible in the early design phase of a project. However, there are fewer inputs available at this stage, so this can be challenging.

For this reason, fast simplified calculations can be relevant compared to time-consuming simulations based on multiple assumptions.

A simple calculation method is to focus only on prevailing reactances, neglecting resistances and considering the electrical network as an impedance circuit. This method is valid when cables can be omitted.

Consider the following electrical network with a starter:

Where,

Based on the figure above, the starting voltage and voltage drop can be expressed as follows:

Several parameters can help maintain a high starting voltage and reduce voltage drop during startup.

These parameters are listed in the next table:

Effectively, the voltage drop Vdrop can be limited by:

Increasing the equivalent starting reactance

A load current (1) decreases by disconnecting or derating loads before starting a large motor. This method is limited to certain processes (oil and gas, mining, etc.) and exceptional starts (one start/year) of very large engines (>10 MW). This is a process automation based solution.

A Reduce motor starting current (2) with starting device. This process has the added benefit of reducing mechanical stress. The starting current (2) can also be reduced with a special low inrush current motor, which can be a more economical solution than using a starter.

With:

Reduction of transformer reactance

Higher transformer power (3) and/or lower short circuit voltage (4)

With:

Reducing upstream supply or generator reactance

Check the short-circuit power of the mains (5) with rms inputs. Underestimating the value could have economic consequences due to the pessimistic assessment of the inrush voltage drop.

Increasing the generator power (6) or designing the generator with a lower sub-transient impedance (7).

With:

case study:

Consider the example of 4 x 315kW 0.4kV 550A motors powered by a 1.5MVA 22/0.42kV transformer with 6% short circuit voltage and 750 MVA upstream short circuit power.

For a motor from 6 x In with 3 similar motors fully loaded and running in parallel, the variables can be calculated as follows:

Then the voltage during the start can be calculated as follows:

Next in our blog series: How to estimate voltage drop when starting large motors.

Would you like to learn more about engine management? Let our expertise guide you in this free brochure:

Engine management for LV and MV high performance engine applications

If you’ve heard the term “alternator” before, you probably know that it’s an essential part of your vehicle. But what exactly does an alternator do? Simply put, your alternator keeps your car battery charged so you can turn on your car and use electronic accessories like your headlights and radio.

If you are having alternator problems, you may find that your car will not start or stay on for more than a few minutes. Before that happens, however, you’ll likely encounter one or more of these seven signs of a failed alternator.

7 signs of a bad alternator

1. Dim or excessively bright light

When an alternator fails, it delivers inconsistent voltage to your electronic accessories. Typically, these are under-performing or under-performing devices, such as headlights that are too weak or extremely bright. You may also experience flickering lights or lights that change erratically from light to dark and vice versa.

2. Battery empty

Sometimes a dead battery is just a dead battery – it has reached the end of its life after a few years of use – or maybe you accidentally left your headlights on all night. In other cases, however, a dead battery can be a sign that your alternator is not working properly.

A bad alternator will not adequately charge the battery when the engine is running, causing the charge to drain faster than usual. One way to test if the problem is battery or alternator related is to start the car. If you jump start your car and it keeps running, your battery may need replacing soon. However, if you start the car and it dies shortly after, it may mean your alternator is not delivering enough power to the battery.

3. Slow or faulty accessories

An alternator that isn’t providing enough power to your car’s electronics often results in slow or non-functioning accessories. If you notice that your windows are taking longer than usual to go up or down, or if your heated seats feel “off,” or even if your speedometer and other gauges start acting up, you may have an alternator problem .

Many modern vehicles also have a priority list of devices programmed into the car that tells the onboard computer where to cut power first if the alternator isn’t providing enough power. That way, if you’re driving with a failed alternator, you’ll lose power to your radio (or other unnecessary accessories) before you lose power to your headlights.

4. Problems starting or frequent stalls

As previously mentioned, having trouble starting your engine can mean your alternator is not charging the battery. This means that when you turn the key in the ignition, all you hear is a click instead of the purr of your engine.

However, if your car stalls frequently while driving, it may be a sign that the spark plugs are not getting enough current from the alternator to keep the engine running.

5. Growling or whining noises

Cars make a lot of strange noises – some are harmless while others can indicate serious mechanical problems. If you ever hear a growling or howling noise under the hood, you could have an alternator problem that should be checked by a professional as soon as possible.

This snarling or howling sound occurs when the belt that spins the alternator pulley is misaligned or rubbing against the side of the pulley. You can also hear this noise when the bearings that turn the rotor shaft go bad.

6. Smell of burning rubber or wires

A foul smell from burnt rubber or wiring could indicate that parts of your alternator are wearing out. Because the alternator drive belt is under constant tension and friction—and because it’s close to the hot engine—it can wear out over time and give off an unpleasant burnt rubber smell.

Similarly, if your alternator is overloaded or has frayed or damaged wires, you may smell a burning odor that is comparable to an electrical fire. A reworked alternator tries to force too much current through its wires, causing them to heat up unsafely. Damaged wires also create resistance to the flow of electricity, causing the wires to heat up and give off a foul odor.

7. Battery warning light on dashboard

When the battery warning light comes on on the dashboard, it is often mistaken for a battery-related problem. However, the low battery warning light indicates that there could be a problem with the entire electrical system in your car, including the alternator.

Alternators are designed to operate at a specific voltage, typically between 13 and 14.5 volts. If your alternator fails, its voltage can drop below capacity causing the low battery warning light to appear on your dashboard. Likewise, the battery light will also appear when the alternator exceeds its voltage limit, depending on how heavily it is being loaded.

Depending on the electrical loading from your car’s accessories (headlights, windshield wipers, radio, etc.) you may see the low battery warning light go on and off as the alternator fluctuates in and out of its designed voltage capacity. While this might seem like a minor annoyance, it’s better to take your car for an alternator check than to get stuck on the side of the road.

Alternator service with a smile

If you’re concerned about your car’s electrical system, it might be time to check the alternator. Firestone Complete Auto Care provides quality service aimed at keeping your battery and electrical system performing as it should! Book an appointment online or visit your local Firestone Complete Auto Care today for affordable, quality alternator services.

Car Guides Auto Q&A: Troubleshooting Slow Starting The most likely causes of slow starting and how to check them. Problems with starting do not necessarily indicate a defective battery. Dreamstime/TNS

Q: My van intermittently starts cranking heavily as if the battery is low. So far it hasn’t needed a jump start, but it’s probably just a matter of time. I had the battery tested and it should be fine. Can you suggest what to check next? I want to try some things before I go to a store.

drake

A: Let’s look at the most likely causes of slow cranking and how to check for them.

Battery Health: Most batteries last around 4-7 years depending on the environment and usage. After a long drive (with a good charging system, 14 volt reading on the meter) or an overnight charge, try the following: Turn off the fuel or ignition and crank the engine for 15 seconds with one on the battery terminals, preferably the terminals , attached voltmeter. If the voltage drops below 11 volts while the starter is running, the battery is probably in poor condition. Make sure the cable connections are clean and tight. If in doubt, repeat the test after cleaning/dressing.

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Discharged/Low Battery: Fix this before blaming battery health. This can be caused by insufficient charging (mostly from short trips or poor alternator performance). Try the following: With the voltmeter connected to the battery terminals, turn on the headlights, front and rear defrosters (fans on high), and check the idle voltage. If it is below 13.5 volts, the charging system is suspect. Check belt tension.

Parasitic Discharge: This is a situation where an electrical component consumes energy while parked, draining the battery. A small amount is normal to keep module memories alive. Does your slow starting depend on how long the van has been parked (e.g. is it worse if you’ve parked longer than overnight)? Then we are on the right track. Try this: With the key removed and the doors closed, visually check for illuminated lights – glove box, courtesy, rear area or under the hood – and listen for a whirr or click and feel the alternator for heat (after overnight). The next step is to check for parasitic load with a digital volt/ammeter. Due to the variety of vehicles and space limitations to explain the methods, this is best referred to a professional.

Wire connections and starter condition: if it is possible to safely and conveniently access the starter, one way or another it is proved by checking the voltage supplied to it during cranking. Connect the voltmeter red lead to the large starter input terminal and the black lead to the bare starter metal. With a strong battery, a reading of 11 or more volts at cranking indicates a good voltage supply (battery and cables/connectors). If the starter cranks poorly with this or better applied voltage, this is suspicious. Less than 11 volts at cranking usually indicates a problem with the battery, cables, or cable connections.

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Using an inexpensive digital voltmeter to verify correct vehicle readings is a safe and highly effective means of verifying poor component operation if precautions are followed. Be sure to remove hand/wrist jewelry, stay clear of hot or moving components, wear eye protection, and never work under a vehicle that is not properly supported. The meter’s high input impedance protects both the circuitry and the user in the event of a boo-boo at the terminals when measuring voltage.

In most cases, the voltage is tested while the circuit is active; This can lead to unwanted voltage drops, which are often the problem.

A good circuit delivers 90 percent or more battery voltage (which varies with load) to the component when it is operating. If a component performs poorly when the voltage is good, it is defective. When testing a component that isn’t working at all, one is checking where there is voltage and where there isn’t when trying to operate it.

Here is a short, simple and non-technical explanation of the different types of RV battery voltages ⚡ and their State of Charge or SOC for short.

The reason there is no simple relationship between battery voltage (what a voltmeter reads or how many of those four jerks are flashing on your display) and state of charge (which is the actual storage state of your battery, 100% fully charged) and 0% dead are) is because your RV system is constantly doing different things – power comes and goes all the time.

There’s a simple relationship between the two for a battery that’s disconnected from all charging sources and loads and has been sitting for an hour or so, but you don’t want to do this every time you check the system. However, it’s a good start. This is called the “open cell voltage” or “open circuit voltage” of the battery. Fully charged 12 volt batteries are about 12.8-12.9 volts at rest, and dead batteries are 12.0 volts, so 12.4 volts for a resting battery means it is about 50% charged .

? Overview of RV battery voltage:

In general, charge inputs raise the actual voltage across the battery above its open-circuit voltage, and loads (discharges on the battery) lower it below its open-circuit voltage. Crank up your onan or motor generator or connect to shore power and your voltage will rise to 14.0 – 14.5 volts even if your battery is severely discharged. Turn on a large load like the microwave (if you have a large inverter powering it) and the voltage will drop into the 11.5-11.8 volt range, even with fully charged batteries. Again, in general, the greater the charging current or load, the further above or below your quiescent voltage your system will be. So by looking at the voltage you can’t tell exactly how charged your battery is – you have to adapt to loads and charging sources.

An easy way to determine the State of Charge (SOC) ⚡ of your RV battery?

The foolproof way to accurately determine the state of charge is to use a hydrometer – a simple device that measures the density of your battery electrolyte. Fully charged batteries have a lot of sulfuric acid in the electrolyte, don’t empty them – the acid turns into lead sulphate on the battery plates as the battery discharges. Because sulfuric acid is heavier than water, fully charged batteries have an electrolyte specific gravity in the range 1.255-1.275, 50% discharged batteries have a value of 1.175-1.195, and dead batteries have a value of 1.095-1.115. A hydrometer can be purchased at any auto parts store for less than $10. In addition to specific weight numbers, they have color-coded areas that indicate good battery, fair battery, or dead battery.

To use the hydrometer you now need to pull out your battery case, open one of the caps and suck some electrolyte into the hydrometer so you don’t have to do this often or on the go. If you have AGM batteries like the newer Roadtreks, you won’t, period – you can’t get to the electrolyte at all because there are no caps. For us traditionalists, however, the hydrometer allows you to calibrate your voltage reading under known load conditions and know which voltage reading matches which state of charge.

What are known charging conditions for your RV battery?

What do I mean by “known load conditions”? Well, on my Roadtrek, for example, the TV is always on and we usually have a fan running and an interior light or two on. I charge my batteries, making sure they’re charged by making sure the hydrometer reading is close to 1.26, and checking my voltage gauge when this stuff is running. Three jerk lights and 12.5 volts on the meter. Under this load, it is fully charged. Now I leave the stuff on for a couple of hours, go back with the hydrometer and see that the specific gravity is down to 1.18 – half drained. My volt meter reads 11.7 and I have an idiot light on.

Now I know that under this load of TV plus fan and light, I need to recharge my batteries – don’t let your batteries run below 50% unless you’re in an emergency situation. Now I can put the hydrometer away – I have a voltage number, 11.7, which corresponds to 50% discharge and time to run the generator. Easy.

People have different numbers or different types of batteries and different typical loads, so 11.7 volts in your system may mean more or less than 50% discharged, but the principle is the same – there is a certain voltage, the different states of charge for your system corresponds to batteries under load. For those of you still awake, here’s a discussion on it from Surrette, the fanciest battery maker in the world.

The voltage number their chart has for 50% discharge is 11.58 volts, so it’s probably using a larger load than mine (they talk about turning on all your loads, which is crazy in my RT), but test your own System and use a load that’s easy to determine – for me it’s VERY easy because the TV is on as soon as my wife wakes up and stays on until she falls asleep and I turn it off. With this load on your batteries, there is a foolproof battery voltage that corresponds to a 50% discharge. Stay above that voltage and you and your batteries will live long, healthy lives.

You might also want to read through these recent posts:

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When the car stops running

If the car stops running completely after you start it and drive it for a while, it’s probably a sign that the battery is dead and no longer holding the charge it’s getting from the alternator. Even if the vehicle is operated with the electricity provided by the alternator after starting, this electricity first flows through the battery. This acts as a sort of capacitor to regulate the amount of current going to lights, cigarette lighters, interior lights, wipers and electronics.

We can help

Too much amperage will burn out these electrical components and stop the car from operating if it cannot put the necessary amperage into the vehicle. If the charge can’t allow it, that’s usually a sign that the battery is dead or very close to it.

For a professional and friendly service, visit us – or call us on 03 477 1972

Sulfation is the formation or accumulation of lead sulphate crystals on the surface and in the pores of the active material of battery lead plates. If the battery is left unattended once sulfation has started, it will form larger crystals on the plates and the battery capacity will gradually decrease as sulfation progresses, until it reaches a stage where the battery may not function at all.

With normal use of the battery, lead sulphate crystals form only temporarily, they dissolve during charging. The problem with sulfation occurs when the larger lead sulfate crystals become permanent.

TYPES OF BATTERY SULFATION

There are two types of sulfation in lead-acid batteries, reversible (also known as soft) and permanent (also known as hard). Luckily, their names are self-explanatory and imply the effects of sulfation on the battery. If sulphation is caught early enough, you can sometimes undo sulphation of the battery. This should only be done by an experienced professional as it can overcharge the battery and increase battery temperature. Some research has been done on inverse charging for recovery of sulphated lead-acid batteries, if interested you can find it here.

An indication of whether or not sulphation of a lead-acid battery can be reversed can be seen on the voltage-discharge curve. If a fully charged battery can maintain a stable voltage profile while discharging, there is a possibility of reversal. However, if the voltage drops rapidly under load, it is highly unlikely that it can be reversed.

Permanent sulphation occurs when a battery is left in a low state of charge for weeks or months. At this stage, battery recovery or sulfation reversal is highly unlikely and as a result the battery will suffer the effects of permanent sulfation.

WHAT DOES A SULFIDATED BATTERY CAUSE?

All lead-acid batteries suffer from sulfation during their lifetime as it is part of a battery’s chemical reaction. However, sulfation builds up faster if the battery is discharged, undercharged, stored at high temperatures, left unused for a long time (charged and discharged), or stored without first being fully charged.

Battery sulphation is the most common cause of premature battery failure in lead-acid batteries.

Applications that can suffer from battery sulphation more often than others include starter batteries for cars and powersports vehicles. This can be due to short or infrequent trips that don’t give the battery enough time to charge. Off-grid renewable applications such as wind and solar can also suffer from sulfation as they do not guarantee a full battery charge due to their intermittent nature.

HOW TO FIND OUT IF A BATTERY IS SULFATED

When your battery suffers from sulphation, you will begin to notice a decrease in the battery’s efficiency. The most common sign that a battery might be sulphated is that it doesn’t hold a charge very well or at all, other signs include the battery dying long before expected performance or electronic devices not getting the power they need they require (ie weak headlights, weak air conditioning, slow start). From the outside, you might not see a difference in the battery’s appearance. The best way to find out if you have sulphation is to test the battery withstand voltage with a multimeter if the voltage is less than 12.6 volts for an AGM battery or 12.4 volts for one starter battery, this is a clear indication that the battery is undercharged, which could be due to sulphation.

THE EFFECTS OF A SULFIDATED BATTERY

Permanent battery sulfation can cause a variety of problems, including:

Loss of starting/starting power

Significantly longer loading times

Increased heat development

Shorter run times between charges

significantly shorter battery life

complete battery failure

HOW TO PREVENT BATTERY SULFATION

The best way to prevent permanent battery sulphation is to maintain your lead-acid battery, follow recommended storage guidelines, and follow lead-acid battery charging best practices.

To prevent sulfation during storage, a battery must be maintained at a minimum charge of 12.4 volts and stored in an environment where temperatures do not exceed 24°C (75°F). For every 10°F increase above this temperature, the battery’s self-discharge rate doubles.

Even if you are storing a new, fully charged lead-acid battery, you still need to make sure the voltage does not drop below 12.4 volts. Regular charging (also known as trickle charging) helps prevent sulphation build-up.

Sulfation is the main reason why you should not store your lead-acid battery without a charge. Once sulphation of the lead plates has taken place the effects are highly unlikely to reverse, so it is important to take care of your batteries from the start.

Car Guides Auto Q&A: Troubleshooting Slow Starting The most likely causes of slow starting and how to check them. Problems with starting do not necessarily indicate a defective battery. Dreamstime/TNS

Q: My van intermittently starts cranking heavily as if the battery is low. So far it hasn’t needed a jump start, but it’s probably just a matter of time. I had the battery tested and it should be fine. Can you suggest what to check next? I want to try some things before I go to a store.

drake

A: Let’s look at the most likely causes of slow cranking and how to check for them.

Battery Health: Most batteries last around 4-7 years depending on the environment and usage. After a long drive (with a good charging system, 14 volt reading on the meter) or an overnight charge, try the following: Turn off the fuel or ignition and crank the engine for 15 seconds with one on the battery terminals, preferably the terminals , attached voltmeter. If the voltage drops below 11 volts while the starter is running, the battery is probably in poor condition. Make sure the cable connections are clean and tight. If in doubt, repeat the test after cleaning/dressing.

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Discharged/Low Battery: Fix this before blaming battery health. This can be caused by insufficient charging (mostly from short trips or poor alternator performance). Try the following: With the voltmeter connected to the battery terminals, turn on the headlights, front and rear defrosters (fans on high), and check the idle voltage. If it is below 13.5 volts, the charging system is suspect. Check belt tension.

Parasitic Discharge: This is a situation where an electrical component consumes energy while parked, draining the battery. A small amount is normal to keep module memories alive. Does your slow starting depend on how long the van has been parked (e.g. is it worse if you’ve parked longer than overnight)? Then we are on the right track. Try this: With the key removed and the doors closed, visually check for illuminated lights – glove box, courtesy, rear area or under the hood – and listen for a whirr or click and feel the alternator for heat (after overnight). The next step is to check for parasitic load with a digital volt/ammeter. Due to the variety of vehicles and space limitations to explain the methods, this is best referred to a professional.

Wire connections and starter condition: if it is possible to safely and conveniently access the starter, one way or another it is proved by checking the voltage supplied to it during cranking. Connect the voltmeter red lead to the large starter input terminal and the black lead to the bare starter metal. With a strong battery, a reading of 11 or more volts at cranking indicates a good voltage supply (battery and cables/connectors). If the starter cranks poorly with this or better applied voltage, this is suspicious. Less than 11 volts at cranking usually indicates a problem with the battery, cables, or cable connections.

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Using an inexpensive digital voltmeter to verify correct vehicle readings is a safe and highly effective means of verifying poor component operation if precautions are followed. Be sure to remove hand/wrist jewelry, stay clear of hot or moving components, wear eye protection, and never work under a vehicle that is not properly supported. The meter’s high input impedance protects both the circuitry and the user in the event of a boo-boo at the terminals when measuring voltage.

In most cases, the voltage is tested while the circuit is active; This can lead to unwanted voltage drops, which are often the problem.

A good circuit delivers 90 percent or more battery voltage (which varies with load) to the component when it is operating. If a component performs poorly when the voltage is good, it is defective. When testing a component that isn’t working at all, one is checking where there is voltage and where there isn’t when trying to operate it.

introduction

Car batteries are essential to vehicle operation, but like everything else, they eventually fail. You can recognize this by the fact that your vehicle will not start or the engine only cranks slightly. If your battery is dead and your vehicle will not start, it is important to determine if it is dead and needs charging, or if it is too weak to hold a charge. Sometimes weak or dead batteries simply need to be charged or recharged. When they lose their ability to hold a charge, they must be replaced.

Proper battery testing makes it easier to figure out what’s wrong with your battery. Learn how to carry out a detailed test of your car battery with a special battery tester. You could use a multimeter, but you won’t get as much information about what’s going on inside the battery.

battery voltage

Voltage refers to the amount of electrical potential your battery will hold. The standard car battery in today’s vehicles is a 12 volt battery. Each battery pack has six cells, each rated at 2.1 volts when fully charged. A car battery is considered fully charged from 12.6 volts.

If the battery’s voltage drops even slightly, it makes a big difference in its performance. The table on the left shows how much energy remains in a battery as the battery voltage gauge changes.

Even if not fully charged, a car battery is considered charged at 12.4 volts or higher. It is considered discharged at 12.39 volts or less.

Note: Assumes an 80°F corrected specific gravity of 1.265 when fully charged.

Turn on the headlights and try to start the engine, there should be no noise