sentence

Hi N2G

It's OK grammatically, but I'm not sure that the meaning is accurate. It sounds a bit as though 5 seconds of sunlight is all the battery needs in order to recharge itself.
However, I would probably assume that the battery is to be left in the sunlight until recharging is complete.

Maybe someone else will comment on that.

Thanks, Yankee,

I have two questions.

1. Are the commas neccessary?

2. How would you rephrase it to mean the battery only starts recharging after being exposed to sunlight for 5 seconds?

Here's my take.

This special battery, when placed in the sun, will start recharging itself after 5 seconds.

Hi N2G

Yes, I'd use the commas.
I like your second version of the sentence much better.

Thanks, Yankee!

New2grammar
1. Are the commas neccessary?

This special battery, when placed in the sun, will start recharging itself after 5 seconds.

necessary (typo?)

If you had such a battery, you should become a millionaire soon.

Thanks for pointing out my mistakes. I wish I had