Voltage gauge fluctuate

I have a 2007 Tundra CM SR5 5.7 with 185k on it. A couple days ago the truck wouldn't start. All I hear is a click from the starter solenoid. Tried jump starting without any success. Decided to buy a new 24F battery and the truck fired right up without any issue. After a day of driving, the voltage meter is bouncing all over the place. At a stop light, the needle is a quarter under the half mark and feels like the engine is going to stall. Once I give it gas, the needle moves back up just pass middle mark. While driving, the needle is back to normal. The battery clamps are clean and no corrosion. Could it be the alternator going bad?

 

Wouldn't hurt to get your alternator checked but check all your grounds first starting with the battery ground.

 

How can I check the alternator without removing it? Looks like there's no easy way. I checked and the grounds look good. No corrosion. Here's the voltage that I measured.

Engine off cold-14.14
Engine warmed up-high 13
Truck in park-high 13
Truck in drive-drop down to 12.6
Truck in reverse-drop down to 12.3
Engine off after warm up- high 12

If this is normal readings...anyone's voltage gauge bounce back and fourth when idle vs in drive?

 

Get a new alternator. That should be locked in, voltage can go down with revs but it should never be under like 13.5; my gauge doesn't move regardless.

 

Bad battery.... they do sit for awhile on a counter therefore they can go bad... Mine did that with an Optima yellow top and I got it replaced and it was fine, may have a vid...

 

Taking it in to the shop today.

 

what did it end up being? Having similar issues, but not getting voltage off the alternator...strictly running off the battery voltage

 

A shop, especially one that sells Interstate Batteries, will have a tester that tests the entire charging system.

 

Most autoparts stores will have an alternator tester sitting around, and the good ones will be able to measure ripple to determine how well the regulator is working, as well as the voltage output.

 

He hasn’t been back since the day he posted this.

 

Yeah, I was afraid that might be the case

 

Sorry, it was the alternator. Cost $600 for an after market or $700 for OEM from Toyota. Went with OEM. The cost is with parts and labor.

 

All good, thanks for getting back to me. Bastards quoted me $1300 not including tax...they must want me to spend my stimulus check