Post by kelabar on Oct 27, 2020 16:46:25 GMT 10
They are called a lead-acid batteries because they contain both lead and sulphuric acid. They are called 'flooded' because the lead is sitting in a pool of liquid sulphuric acid. If you remove the tops you will see a clear liquid, this is the acid and if the acid level drops too much you will see the grey metallic lead (add distilled water if you can see the lead).
Flooded lead-acid batteries have the advantage of being able to withstand the high temperatures in vehicle engine bays better than other battery types as well as being cheaper and time-proven. There are two main types, 'starter' batteries commonly used to start vehicles and 'deep-cycle' batteries which are used in dual-battery systems and solar systems.
Because the acid is in liquid form be careful around them. Sulphuric acid is strong and can put holes in your clothes or your skin and you definitely do not want to get it in your eyes. Wearing glasses is recommended but a plastic face shield would be better if you are going to mess around with them a lot.
They can also produce hydrogen gas when charging and this is explosive. So imagine a battery exploding and spraying acid everywhere, not good so be bloody careful. You will often see mention of not causing sparks near a battery or when connecting to them. This is because a spark will detonate any hydrogen.
That said, when was the last time you heard of a battery exploding? Not common but it would be very unpleasant. Use care and if you are not sure, don't try something.
They also store a lot of electricity. Enough to weld metal so they can burn you very badly. It is important not to connect the positive and negative terminals directly. This is called 'short-circuiting' or 'shorting' and will happen if you drop a metal tool (or anything metal, including wire) on top of the battery which touches both terminals. Do not do this. You often see red and black plastic covers over battery terminals and this is why. To stop shorting. A lot of heat can be generated very quickly, the battery may boil and acid may go everywhere. It can also start fires from overheated, melted wiring. Best avoided. This is the reason you will hear about fuses and circuit breakers being used a lot in 12V wiring. If the battery does short, the fuse will blow and break the short.
But humans are made of skin which doesn't contain any metal. So we can safely touch both terminals on a 12V battery at the same time with no problems.
The battery is a lot of thin sheets of lead (called plates) dipped into the sulphuric acid. Through the magic of chemistry, when we flick the on/off switch to on, electricity flows out of the battery and runs whatever we have connected to it.
The handy thing is we can then, by putting electricity back into the battery, recharge it and use it again and again. Most excellent and, more importantly IMO, time proven.
But, of course, just to confuse things, they don't actually have exactly 12V. Starter batteries usually sit on around 12.7V when fully charged. Deep cycle batteries on around 12.2V!
How to check this voltage? The easiest way is with a multimeter. You can buy a cheap one for $10-20 (they run on a 9V battery inside). They look like this and are also known as DMMs or digital multimeters. More expensive ones are available but do the same thing.
They come with two leads, a red and a black one; read the instructions to find out which socket each lead goes into.
Then find the DC Voltage setting on the dial. In the picture it is the DCV (DC Voltage) section on the top left with 5 values of 200m, 2000m, 20, 200 and 1000.
Other multimeters may use a 'V' followed by a flat line with three dots under it which means the same thing; again check the instructions if required.
OK, we want to check for a voltage of around 12. So we click the dial to the '20' setting. Why? Because this setting will measure up to 20V. If we use the '2000m' setting (which is 2000 millivolts - the same as 2 Volts) the screen will just show "1" which means the DMM is out of range, 12V is more than the 2V the '2000m' setting can measure. We can, however, use the '200' setting as that setting will measure up to 200V. This gave a measurement of 12.2V for the battery below. So it gave the same reading, just to one less decimal place.
Here is a deep-cycle battery showing 12.18V. It was last charged about two days ago. The pointy multimeter leads have been tightened under the wingnuts to hold them in place for the photo. You can just poke them against the terminals to get a reading too.
Note the spare leads at the front of the picture. These have alligator clips instead of the points on the original leads. They are very handy. You can get replacement leads from electronics stores, cut the points off and add alligator clips instead. Recommended, although more expensive DMMs will sometimes include these as well.
That is it. Now you know how to check a battery voltage.
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Batteries only hold a certain amount of electricity. The bigger the battery, the more power it can hold. But when you use power out of the battery, the voltage drops.
In a fully charged starter battery the voltage will show around 12.7V. As we use power the voltage goes down. Here is an example chart.
As you can see, as the state of charge goes down as we use power from the battery the voltage drops. So if we measure the voltage and it shows 12.2 or less we should recharge the battery. If it was 12.5V then you could recharge it but it isn't a high priority.
As a general rule, keep lead-acid batteries as fully charged as possible. It doesn't harm them to go down to lower voltages but it does reduce their lifespan. The further down they discharge, the less number of times you can recharge them before they wear out. Check them every month or so if you are not using them, they do 'self-discharge' which means they lose power over time even if you don't take any power from them.
In practical usage, if you are using an inverter to get power from the battery the inverter's electronics will usually shut it down at a certain voltage (11V or so) anyway so the battery will never be completely flattened.
There are a couple of other ways to check a battery voltage. Some vehicles have a voltmeter in the dash. But this can sometimes show as only 12V if it is measuring the vehicle's electronic system voltage, not the battery voltage.
There are also plug-in voltmeters (image below) that go into a cigarette lighter socket. I like these, very convenient. But again in a vehicle it may only show the vehicle's electronics voltage, not the battery voltage depending on how the cig lighter has been connected.
A lot of larger inverters also have a voltage display feature, very easy to check.
Flooded lead-acid batteries have the advantage of being able to withstand the high temperatures in vehicle engine bays better than other battery types as well as being cheaper and time-proven. There are two main types, 'starter' batteries commonly used to start vehicles and 'deep-cycle' batteries which are used in dual-battery systems and solar systems.
Because the acid is in liquid form be careful around them. Sulphuric acid is strong and can put holes in your clothes or your skin and you definitely do not want to get it in your eyes. Wearing glasses is recommended but a plastic face shield would be better if you are going to mess around with them a lot.
They can also produce hydrogen gas when charging and this is explosive. So imagine a battery exploding and spraying acid everywhere, not good so be bloody careful. You will often see mention of not causing sparks near a battery or when connecting to them. This is because a spark will detonate any hydrogen.
That said, when was the last time you heard of a battery exploding? Not common but it would be very unpleasant. Use care and if you are not sure, don't try something.
They also store a lot of electricity. Enough to weld metal so they can burn you very badly. It is important not to connect the positive and negative terminals directly. This is called 'short-circuiting' or 'shorting' and will happen if you drop a metal tool (or anything metal, including wire) on top of the battery which touches both terminals. Do not do this. You often see red and black plastic covers over battery terminals and this is why. To stop shorting. A lot of heat can be generated very quickly, the battery may boil and acid may go everywhere. It can also start fires from overheated, melted wiring. Best avoided. This is the reason you will hear about fuses and circuit breakers being used a lot in 12V wiring. If the battery does short, the fuse will blow and break the short.
But humans are made of skin which doesn't contain any metal. So we can safely touch both terminals on a 12V battery at the same time with no problems.
The battery is a lot of thin sheets of lead (called plates) dipped into the sulphuric acid. Through the magic of chemistry, when we flick the on/off switch to on, electricity flows out of the battery and runs whatever we have connected to it.
The handy thing is we can then, by putting electricity back into the battery, recharge it and use it again and again. Most excellent and, more importantly IMO, time proven.
But, of course, just to confuse things, they don't actually have exactly 12V. Starter batteries usually sit on around 12.7V when fully charged. Deep cycle batteries on around 12.2V!
How to check this voltage? The easiest way is with a multimeter. You can buy a cheap one for $10-20 (they run on a 9V battery inside). They look like this and are also known as DMMs or digital multimeters. More expensive ones are available but do the same thing.
They come with two leads, a red and a black one; read the instructions to find out which socket each lead goes into.
Then find the DC Voltage setting on the dial. In the picture it is the DCV (DC Voltage) section on the top left with 5 values of 200m, 2000m, 20, 200 and 1000.
Other multimeters may use a 'V' followed by a flat line with three dots under it which means the same thing; again check the instructions if required.
OK, we want to check for a voltage of around 12. So we click the dial to the '20' setting. Why? Because this setting will measure up to 20V. If we use the '2000m' setting (which is 2000 millivolts - the same as 2 Volts) the screen will just show "1" which means the DMM is out of range, 12V is more than the 2V the '2000m' setting can measure. We can, however, use the '200' setting as that setting will measure up to 200V. This gave a measurement of 12.2V for the battery below. So it gave the same reading, just to one less decimal place.
Here is a deep-cycle battery showing 12.18V. It was last charged about two days ago. The pointy multimeter leads have been tightened under the wingnuts to hold them in place for the photo. You can just poke them against the terminals to get a reading too.
Note the spare leads at the front of the picture. These have alligator clips instead of the points on the original leads. They are very handy. You can get replacement leads from electronics stores, cut the points off and add alligator clips instead. Recommended, although more expensive DMMs will sometimes include these as well.
That is it. Now you know how to check a battery voltage.
--------------------------
Batteries only hold a certain amount of electricity. The bigger the battery, the more power it can hold. But when you use power out of the battery, the voltage drops.
In a fully charged starter battery the voltage will show around 12.7V. As we use power the voltage goes down. Here is an example chart.
As you can see, as the state of charge goes down as we use power from the battery the voltage drops. So if we measure the voltage and it shows 12.2 or less we should recharge the battery. If it was 12.5V then you could recharge it but it isn't a high priority.
As a general rule, keep lead-acid batteries as fully charged as possible. It doesn't harm them to go down to lower voltages but it does reduce their lifespan. The further down they discharge, the less number of times you can recharge them before they wear out. Check them every month or so if you are not using them, they do 'self-discharge' which means they lose power over time even if you don't take any power from them.
In practical usage, if you are using an inverter to get power from the battery the inverter's electronics will usually shut it down at a certain voltage (11V or so) anyway so the battery will never be completely flattened.
There are a couple of other ways to check a battery voltage. Some vehicles have a voltmeter in the dash. But this can sometimes show as only 12V if it is measuring the vehicle's electronic system voltage, not the battery voltage.
There are also plug-in voltmeters (image below) that go into a cigarette lighter socket. I like these, very convenient. But again in a vehicle it may only show the vehicle's electronics voltage, not the battery voltage depending on how the cig lighter has been connected.
A lot of larger inverters also have a voltage display feature, very easy to check.