Battery gauge drops when I'm at a light??

[bgtaylor]

Well I've started noticing my 85 z28's battery gauge drop to about 10.5 when I'm sitting at a light while it is in drive. I put it in drive and it goes right back up to the intermediate line (13 I believe). My car tends to stall from another issue and this building on top of it doesn't help. If my car stalls and doesn't have enough juice to start back up in traffic, then I'm going to have a real problem. Has anyone encountered this issue with either their third gen or any camaro?

I'm assuming its because the drop in RPM when I'm sitting at a light, but I didn't seem to notice it a few months ago. Time for a new alternator??

Thanks for the help and advice guys.

[Fbomb]

could pull it and go get it checked for free. Really easy to remove it because it's on top and only like 3 bolts/nuts

[Boost Addict]

You shouldn't even have to pull it. Most parts stores have a handheld tester.

[meissen]

Yup, and try multiple places testing it since they can do it in-car. I had O'Reilly telling me my alternator was fine, then I went to Advance Auto and they were saying they couldn't even get the tester to work on it because it was so bad.

[farmington]

check and clean all of your grounds.

[WMCCjames]

If you need an alternator, I have a lightly used one from my 85 I'll sell ya. It's a high output one with a lifetime warranty.

[TylerT/AZ28]

do you by chance have underdrive pulleys? i know my friends truck 305 92 tbi truck had underdrive pulleys, and at idle his battery guage would drop severely, then when he started moving it would skyrocket back upwards

[2002Z4CSS]

I agree with the underdrive pulleys. Make sure the belt is tight and the pulley does not slip. If not get the alternator checked. Could be a poor connection in a battery cable or a bad regulator in the alternator.

[85z28kid]

How is you're alternator wired? Does the the #2 wire (red wire) go right to the little post that battery cable connects to or does it run to the actual battery?

It affects how much power your alternator sends out to the charging system.

[1BADAIR]

turn the idle up

[Gaspo]

like previously stated, take it to a few different places and get it checked in car. i took the battery out of my camaro to advance, they said it was bad. i put it in my saturn, drove it back to advance and they said it was good. lol

[bgtaylor]

do you by chance have underdrive pulleys? i know my friends truck 305 92 tbi truck had underdrive pulleys, and at idle his battery guage would drop severely, then when he started moving it would skyrocket back upwards

Nope, just a stock 305 TPI

[bgtaylor]

Well I haven't had the time to get the alternator checked out nor have I checked the grounds. I'm sure it could probably use a new alternator, but that will have to wait. I still have to get a throttle body, cat-back exhaust, Y-pipe, TPS, and now probably an alternator. Priority needs to be the alternator and Throttle Body and new TPS. Exhaust will still hold up for a while. It's just loud and it has been since we've gotten the car. Will do some more investigating soon. No motivation with no garage and poor weather. Thanks for the help so far.

One question where would a faulty ground be possibly located in the engine bay? Still a newbie... lol

[TylerT/AZ28]

do you have a chiltons or any manual for the car should give you a diagram. i have one ill look at for you if i can remember to tonight

[bgtaylor]

turn the idle up

When we first got the car the idle was way too high. We since turned it down. I'll try turning the idle up this weekend to see if it helps at all. What idle should the car be at when in park vs when in drive? It's moody when it comes to staying at a regular idle sometimes while in park. In drive it can be between 750rpm-550rpm usually.