Firebird - battery issue?-about Pontiac Repair

2000 Firebird V6 base model. Lately whenever I turn on the car and hit either the brakes or gas, the battery gauge drops a few centimeters to around 13 (the middle of the gauge.) When I turn off the car, sometimes all of the gauges max out and then appear to die. I put a new alternator in 2 weeks ago and got a new battery about 1-2 years ago. Any idea what this might be? I just spent a good chunk of change on the car and I'm hoping I don't have do that again. I appreciate any help you can offer.

Well it sounds like an alternator issue even know you sais you just changed it. was it doing this before the laternator was changed or was that the reason for chaging it? Either the alternator is not keeping up with the demands put on the electrical system or the battery is on it's way out. If the laternator went bad all together and you drained the battery way down chances are that it's bad. The only other possibilityI have for you is a loose connection somehwre like at the battery or even a bad ground connection somewhere. stop by one of the auto parts stores they check the charging systems on cars for free and thgey can tell you if you have a battery that's on it way out or an alternator that is not putting out enough voltage/amperage. If it's neither of them they you have to go fishing for a wiring issue. Good luck :}