equivalent capacitor value of Li-ion battery.......

[firry]

capacitor value

Hi;
I want to use a capacitor instead of the Li-ion battery in the charger simulation.
who can tell me the equivalent capacitor value of the Li-ion battery? I want a actual approximation.
Thanks!!

 

[IanP]

use capacitor as battery

To estimate the equivalent capacitor of Li-ion battery use equation (1) described in the: "An accurate battery model ... "
**broken link removed**

Regrads,
IanP

 

[santaxy]

capacitance mah equivalent

The page is missing.
'Error 404 - Not Found', please redirect it, Thanks.

 

[doraemon]

capacitor instead of battery

Hello!

Even if the page is missing, you can calculate it yourself.
Let's say you want a capacitor instead of a 1 Ah (1000 mAh) Li-ion battery.
(we will suppose it's a one-cell or equivalent, i.e. no serial association,
therefore its average voltage will be 3.7 V.
The battery can therefore store an energy of 3.7 Wh (or in standard units
3.7 x 3600 = 13320 Joules. Let's say 13 kJ.

Now if you want to use a capacitor instead, your capacitor should be able to
store about 13 kJ, but it should do it between usable voltages, so let's set
these voltages to 3.2 and 4.2 V respectively so that it's roughly equivalent
to a Li-ion battery (average is the same).

The energy stored in a capacitor is:
E = CU2/2
where C is the capacitance in Farads, and U the voltage. U2 is U square.
But here, we have to evaluate the energy difference between 4.2 and 3.2 V.
If we call U the lower voltage (3.2V) and V the higher voltage (4.2V), we have:

E = CV2/2 - CU2/2 = C(V2 - U2)/2

Therefore the capacitance you need is:

C >= 2E/(V2-U2)

Now, you can calculate that (V2 - U2) is 7.4.

The result is that the capacitance should be greater than 13320 / 7.4

C >= 1800 Farad.

That's huge!

Note that I have no access to the link above, so I cannot know what they
call "an accurate battery model", but at least it gives you an idea of what
you can do.

Dora.

Hi;
I want to use a capacitor instead of the Li-ion battery in the charger simulation.
who can tell me the equivalent capacitor value of the Li-ion battery? I want a actual approximation.
Thanks!!