Using Battery for something else while driving?

I'm curious about using a seat massager while driving. I've avoided using it without really knowing how it might harm my battery consumption, or rather, increase it to an unacceptable level?

I know full well that this seat massager is a bic electrical hog.

So any ideas regarding this....before I plug that adapter into my car? If Ever?

As long as the battery light does not illuminate the charging system is providing more than the car needs.

The light will come on if the you are using power from the battery and not the charging system.

Later,

If you're always using the car for only short distances, then yes in the long run, you might drain the battery, because the alternator isn't capable of charging the battery to full with short distances.

thanks for the input.

Yah, I guess that counts out my use of that item considering how much I drive. Might just use it briefly after every long driving stint for the backs of my shoulders when they're aching awfully bad.

Thanks again!

You might be able to install a second battery, even a gel battery, usually in the trunk, to run it. Then recharge that battery overnight at home.

How much current does it use in amps.?