Normal battery gauge readings?

I've noticed my 89 4.0 XJ's "Battery" gauge dips off center the more I turn on accessory's like lights, wipers and blower. It's still well away form the lower hash-mark but below center. Should it show electrical draw or is my battery or alt. (Or both.) starting to crap out? Having a gauge with just an outline of a battery has me wondering just exactly it's telling me. :dunno:

Take your volts/ohms multi-meter and measure for yourself at the alternator and at the battery. The alternator should putting out between 13.5 to 14.4 volts at 1500 rpms. 15 minutes after the engine was shutoff, you should read 12.2 or more volts at the battery. If you don't have a multi-meter, spend $10-20 and buy one. It is used for all kinds of diagnostic and troubleshooting tests. If you Google you can find out how to measure the amperage draw of the Jeep when you switch on stuff, and the amperage output capacity of your alternator.

Guy here at work taught me a great trick I haven't tried yet.

Universal cigarette lighter plug with wire leads. Now you can. Use your volt meter while driving down the road.

-Hank-

Hey good one! Yes at idle I've got 14.35 volts showing off the battery with my meter. I'll try adding loads by turning stuff on and see what readings I get off the battery. I'm gonna make a lighter adapter, that's a good idea!