I found an old Related Question here: [Can electric and magnetic forces act on their sources?](https://physics.stackexchange.com/questions/390029/can-electric-and-magnetic-forces-act-on-their-sources)

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From the paragraph from Griffith's E&M

> 
> Suppose we have some charge and current configuration which, at time t, produces fields $\mathbf E$ and $\mathbf B$. In the next instant, $dt$, the charges move around a bit. According to the Lorentz force law, the **work done** on a charge $q$ is:
> \begin{split}
> dW=\mathbf F \cdot dl &=q(\mathbf E + \mathbf v \times \mathbf B) \cdot \mathbf dl\\
> \end{split}
> Poynting’s Theorem writes:
> $$dW = - d\left[ {\int {\frac{1}{2}\left( {{\varepsilon \_0}{E^2} + \frac{1}{{{\mu \_0}}}{B^2}} \right)} d\tau } \right] - \left[ {\oint\limits\_S {\frac{{\left( {E \times B} \right)}}{{{\mu \_0}}}} da} \right]dt$$
> 
> 
> 

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I am thinking of an ideal chemical battery which keeps producing EM field to charges stored inside of the battery so the charges in the cofiguration (battery) will move by $dl$.

But in this case, since the field inside of the battery is constant, the first term (inward term) in poynting's theorem equals to zero
$$
- d\left[ {\int {\frac{1}{2}\left( {{\varepsilon \_0}{E^2} + \frac{1}{{{\mu \_0}}}{B^2}} \right)} d\tau } \right]=0
$$

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So what does it mean by saying the $\mathbf E$ and $\mathbf B$ field produced by charge/current configuration does work to the charges inside configuration itself?

What are some real examples of this **work done** on the charges in the configuration?