Help，need the table of battery voltage and battery capacity percentage

vapcell_Dennis · 2019-04-03T04:27:11.000Z

We need the table of li-ion battery（4.2V） voltage and battery capacity percentage

Perhaps each battery has a different percentage.

Who can share it?

Thank you very much

caramba · 2019-04-03T05:37:15.000Z

I think it will depend on the individual battery, but also temperature.

HKJ is the authority here

He has done some really cool stuff:

https://lygte-info.dk/info/BatteryChargePercent%20UK.html

vapcell_Dennis · 2019-04-03T06:30:58.000Z

caramba:

I think it will depend on the individual battery, but also temperature.

HKJ is the authority here

He has done some really cool stuff:

Battery charge percent

Thank you very much. Last time I saw this form in the forum, I didn’t expect it was the result of HKJ.

Thank you and HKJ again. :+1:

HKJ · 2019-04-03T15:55:13.000Z

I will be able to do this type of tables much easier in the future and expect to have spare equipment to do it also.

Enderman · 2019-04-03T17:13:51.000Z

It depends on the battery model, the temperature of the battery, the discharge rate, and the age.
All of these things will change what voltage corresponds to what percentage.

HKJ · 2019-04-03T17:19:27.000Z

Enderman:

It depends on the battery model, the temperature of the battery, the discharge rate, and the age.
All of these things will change what voltage corresponds to what percentage.

It do not really depends on discharge rate and I also doubt temperature. Do batteries change voltage if you put them the fridge?
The table is measured at zero load and after the battery has had time to recover to nearly stable voltage.

I wonder how much age affect it? If it does.

HKJ · 2019-04-03T19:15:16.000Z

It is something like this I will be able to do soon (I hope):

The above table is generated from a fairly new high quality 21700 cell.

It need to be measured more than 5 minutes after load is removed and I have not decided if I will lose a decimal on the percent.

contactcr · 2019-04-03T20:37:52.000Z

In things like a vape or flashlight with high drain the voltage sag from a high drain device may not even allow you to get it to 3.1V right?

HKJ · 2019-04-03T20:47:54.000Z

contactcr:

In things like a vape or flashlight with high drain the voltage sag from a high drain device may not even allow you to get it to 3.1V right?

You will have to check the discharge curves at specified capacity.
In the above table I have inverted the capacity scale to show how much is remaining, instead of how much is used. Calculating how much capacity is used and check the discharge chart will give your a very good idea about the voltage when loaded with some current.

Do I need to include both capacity remaing and capacity used columns?

contactcr · 2019-04-03T20:50:46.000Z

Not real sure. I guess it depends on what the purpose of such a table is used for. It maybe too many variables to try and include more than you have already

HKJ · 2019-04-03T20:59:19.000Z

contactcr:

Not real sure. I guess it depends on what the purpose of such a table is used for. It maybe too many variables to try and include more than you have already

The purpose of a “Used Ah” would be to use the value in the discharge charts and see what voltage to expect at different loads.

Lightbringer · 2019-04-03T21:57:52.000Z

Bugger… I always thought it was fairly consistent. Kind of a kick in the nads to find out otherwise.

vapcell_Dennis · 2019-04-04T03:15:35.000Z

HKJ:

It is something like this I will be able to do soon (I hope):

The above table is generated from a fairly new high quality 21700 cell.

It need to be measured more than 5 minutes after load is removed and I have not decided if I will lose a decimal on the percent.

so great!!!Thanks you very much,HKJ

if you test 21700 5000mah ,3.0V-2.5V still have about 100-300mah capatity

So each battery is different.

caramba · 2019-04-04T05:37:09.000Z

HKJ:

Enderman:

It depends on the battery model, the temperature of the battery, the discharge rate, and the age.
All of these things will change what voltage corresponds to what percentage.

It do not really depends on discharge rate and I also doubt temperature. Do batteries change voltage if you put them the fridge?
The table is measured at zero load and after the battery has had time to recover to nearly stable voltage.

I wonder how much age affect it? If it does.

I always thought battery voltage varies with temperature, but I was thinking of wet cell batteries. That’s why you need to trickle charge overnight or bring your car battery inside the house when it is bitter cold.

HKJ · 2019-04-04T06:06:17.000Z

caramba:

I always thought battery voltage varies with temperature, but I was thinking of wet cell batteries. That’s why you need to trickle charge overnight or bring your car battery inside the house when it is bitter cold.

Low charge rate is because the chemical processes works slower when it is cold and a wet cell battery with frozen electrolyte is a cracked battery.

I will do a test with temperature change on a LiIon battery.

HKJ · 2019-04-04T06:26:23.000Z

vapcell Dennis:

So each battery is different.

I would expect each chemistry and with fairly similar chemistries I would not expect huge differences.

With the above battery the time from current off to measurement is not that important:

I like the percent better without decimals. All 3 tables are based on the same data file, I have only moved the point where I measure the voltage.

The file used has 27800 samples, that is reduced to 46 sample points. I generate a sample point when the current is turned off, the point is offset with the specified time interval. From them I have interpolated the capacity and energy at the exact voltage point in the table.

vapcell_Dennis · 2019-04-04T09:28:39.000Z

HKJ:

vapcell Dennis:

So each battery is different.

I would expect each chemistry and with fairly similar chemistries I would not expect huge differences.

With the above battery the time from current off to measurement is not that important:

I like the percent better without decimals. All 3 tables are based on the same data file, I have only moved the point where I measure the voltage.

The file used has 27800 samples, that is reduced to 46 sample points. I generate a sample point when the current is turned off, the point is offset with the specified time interval. From them I have interpolated the capacity and energy at the exact voltage point in the table.

You are the man :+1:

Nev · 2019-04-04T13:18:08.000Z

caramba:

HKJ:

Enderman:

It depends on the battery model, the temperature of the battery, the discharge rate, and the age.
All of these things will change what voltage corresponds to what percentage.

It do not really depends on discharge rate and I also doubt temperature. Do batteries change voltage if you put them the fridge?
The table is measured at zero load and after the battery has had time to recover to nearly stable voltage.

I wonder how much age affect it? If it does.

I always thought battery voltage varies with temperature, but I was thinking of wet cell batteries. That’s why you need to trickle charge overnight or bring your car battery inside the house when it is bitter cold.

That’s why I use a cetek battery charger for mY car batterys ,it has temperature compensation ,it will charge at a higher rate when bellow room temperature, also a lead acid battery won’t freeze if it’s charged.

HKJ · 2019-04-04T15:12:02.000Z

Enderman:

It depends on the battery model, the temperature of the battery, the discharge rate, and the age.
All of these things will change what voltage corresponds to what percentage.

When you asked about the temperature I put a partially charged battery in my freezer.

The voltage did change, it increased 0.004V, I suspect it is recovery from an early test I used it for.
The temperature curve drops faster than the battery temperature, my sensor was already in the freezer and the battery started outside at around 25°C. Timescale is in seconds.