[Moved] Battery power and capacity calculation per hour

[Sayer_1]

[Moved]Battery power and capacity calculation per hour

I want to calculate the energy level of a lead acid battery on each hour. The following equation is mentioned here.
E(t+1)= E(t)+ P(t)
E(t)= Energy level and P(t)= Charging/ discharging power
The following constraints are and information is given
0=> Emax<= 300kwh
-10kwh >= P(t) <=10kwh
if P(t)<0 discharging and if P(t)>0 charging
charging and dischrging rate is = 10kwh
I am confuse how to calculate battery energy level on each according to this given data.

Kindly guide me in this case

 

[KlausST]

Re: [Moved]Battery power and capacity calculation per hour

Hi,

-10kwh >= P(t) <=10kwh

should be:
-10kW >= P(t) <=10kW

****

I am confuse how to calculate battery energy level on each according to this given data.

This is the formula.
E(t+1)= E(t)+ P(t)

It means you need to measure power in defined steps of time (t)
* Maybe you choose 1s (but you could choose any other value. like 10us or 1 hour)
* Then you need to calculate the average power for a period of 1s
* then add up (integrate, kumulate) the power value of each second and get the energy level.

Klaus

 

[Sayer_1]

Re: [Moved]Battery power and capacity calculation per hour

Thats the issue how to calculate energy level at each houror each second even i have only these information. and 10kwh are the discharging and charging rate of a battery. how it utilize to find out the energy level.

 

[KlausST]

Re: [Moved]Battery power and capacity calculation per hour

Hi,

please learn basics: P is power. The unit of power is W or kW, not kWh. Power is the same as energy per time.

If you integrate power over time then you get energy.

***
An example.
You have a light bulb with 10W of power.
If the bulb is ON for 1s then the consumed energy is 10W x 1s = 10Ws
If the bulb is ON or 12345s, then the consumed energy is: 10W x 12345s = 123450Ws.
If the bulb is on for 3h then the energy is 10W x 3h = 30Wh
..
--> simple multiplication of values and simple multiplication of units.

***

When you use a fixed period for energy calculation of 1 s then:
* Initially energy E = 0
(Because you calclulate the average power over one second, the value for the energy is the same as for the power, only the unit changes. 10W (averaged over 1s) = 10W x 1s = 10Ws)
* after second 1: E = E + 10Ws; E = 0Ws + 10Ws = 10Ws
* after second 2: E = E + 10Ws; E = 10Ws + 10Ws = 20Ws
* after second 3: E = E + 10Ws; E = 20Ws + 10Ws = 30Ws
* after second 4: E = E + 10Ws; E = 30Ws + 10Ws = 40Ws
and so on...

Klaus

 

[Sayer_1]

Re: [Moved]Battery power and capacity calculation per hour

Here I am attaching the reference paper from where i get the battery models and its parameter. Kindly guide me according to this. I want to use this model as backup source and want to calculate the battery charging and discharging energy at each hour out of 24 hour.

 

[Sayer_1]

Battery Charging and Discharging Rate

What is the meaning of charging and discharging rate of a battery.
In a research paper i have been study the charging and discharging rate of a battery is 0.6MW then what its actual means in terms of battery specifications.
and in another research paper I have been study the charging and discharging rate= 10kwh. How we can elaborate this term and can use in battery calculations.


Thankyou

 

[barry]

Re: Battery Charging and Discharging Rate

0.6 MW is not a discharge rate. Perhaps you mean 0.6MW/hour? It doesn't mean anything as far as battery specifications go, it's a DISCHARGING specification. 10kwh is not a discharge rate, either; it's a measure of energy. Kw/h, maybe?

But assuming you get your units straightened out, when you have a discharge rate of, say, 10 kw/h that means you will draw 10 kw of power out of your battery in an hour. Batteries are usually rated in ampere-hours. So, say you had a 10V, 1000 Ampere-hour battery. That would be 10kw-h. So with a 10 kw/h discharge rate that battery would be completely drained in an hour.

 

[RobertFalbo]

Re: Battery Charging and Discharging Rate

the charging rate can be expressed in, power with units of watts, or current in units of amps.

Watts just being the voltage applied,multiplied by the charging current.

Typically the cells can only take a limited current based on plate size and chemistry. A certain inefficiency leads to heat. This is a major factor in charging rates.

 

[Sayer_1]

Re: Battery Charging and Discharging Rate

can you guide me with this charging and discharging rate I'll be able to find out the per hour energy level in a battery using following equation
E(t+1) = E(t) + delta T ( Pcharging- Pdischarging)

 

[KlausST]

Re: [Moved]Battery power and capacity calculation per hour

Hi,

0.6 MW is not a discharge rate. Perhaps you mean 0.6MW/hour? It doesn't mean anything as far as battery specifications go, it's a DISCHARGING specification. 10kwh is not a discharge rate, either; it's a measure of energy. Kw/h, maybe?

I see it completely different.
I'd say 0.6MW is a discharge rate.
MW/h, kW/h ... is power per time. It means the power changes with time. I don't know a useful application for such an unit.

Back to MW, kW, W....
Imagine you have an SMPS. Battery 12V, 15Ah.
And you have a load connected. The load - it may be a pump, a PC, lights, - will discharge the battery.
And the load is rated with power.
The more power the load draws, the faster the battery gets discharged.
The battery 12V x 15Ah gives 180Wh of energy.
Now connect a 10W load..
After one hour the battery energy is 180Wh - 10W x 1h = 170Wh, after another hour 160Wh, ...150Wh..and so on.
So I'd say 10W is a constant discharge rate.
It is energy / time. 10Wh per hour. Which is 10Wh/h ... "h" can be canceled and remaining is 10W

Klaus