Re: Battery (SLA) modeling

On 17/12/2024 4:25 pm, bitrex wrote:

On 12/13/2024 8:57 PM, Bill Sloman wrote:

On 14/12/2024 4:23 am, john larkin wrote:

On Thu, 12 Dec 2024 23:57:54 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:
>

At a fixed time and temperature, is it safe to model a battery as a
fixed voltage source behind a series resistance?  Possibly, additionally,
a parallel RC to cover transients?
>
In particular, does the model need to change based on whether the
battery is being charged or discharged?  (i.e., to estimate that
series resistance)

>
I've wondered about electro-chemical time lags, ions drifting around
in liquids, as in what would the Spice model of some battery be?

>
That's what Warburg impedances are about.
>

And
on a slower time scale, the morphology of a battery changes with time.
Nearly discharged batteries sure go Hi-Z.
>
What we need here is a good physical chemistry guy.

>
I've got a Ph.D. in physical chemistry, but batteries are electrochemistry - I know a guy who has just completed a Ph.D. with a thesis on a particular lithium ion battery chemistry. It's a specialised subject.
>

 I guess not many universities offer a Ph.D. in non-physical chemistry these days. :(

The choices in my day at Melbourne University in Australia  were Organic Chemistry, Inorganic Chemistry and Physical Chemistry. Win Hill started a Ph.D. in Chemical Physics at MIT at much the same time. It's more a theological distinction than anything with any real world significance, but John Larkin never paid much attention to his undergraduate chemistry lectures. I completed a master's degree in Inorganic Chemistry on the way to getting my Ph.D.
The clever thing to have done at the time would have been physical organic chemistry, and the Melbourne professor of Physical Organic Chemistry moved to America while I was getting my Ph.D, and took a couple of his graduate students with him.
--
Bill Sloman, Sydney