 Most scan tools will also, as a matter of fact, write up on the screen because voltage has gotten to be so specific. Most scan tools will show you standing voltage of the battery while you're sitting there connected. So while you're sitting there connected, key on, car's not running, manually turn the headlights on if they're not on. Does the voltage go down? Does it go down by a lot? Does it show a drop? All right. You can see general state of charge and what sort of level of charge is in the battery by looking at