Voltage Drop

[Holaday1185]

Quick question all:

I've noticed lately that my voltage meter drops from around the usual reading of 13.5 down to 11 - 11.5 volts. This happens around the first 10 minutes of driving, and then usually stops. I've also noticed my headlights dimming when my voltage drops. Would this indicate that I am going to need a new battery in the future, or could other problems exist. I've had the car for 4 years and haven't replaced the battery at all, ha. Just want to confirm my thoughts.

Thanks,

DH

[C man]

How many miles? Seems like your alternator may be starting to fail. Or a combination of both.

[Holaday1185]

1997 PA - 115,000 miles.

Runs beautifully, just the voltage issue, which really isn't an issue post 10-15 minutes.

[HotZ28]

Stop by any major parts store & get the battery load tested & alternator checked for free. Winter is approaching, don't wait too long!

[Holaday1185]

Just did an alternator test --- disconnected the negative battery terminal after the car was already started. I've read that if the alternator is bad, the car dies after running when the negative terminal is disconnected. Everything works smoothly. Thinking that the battery may need to be replaced within the next few months.

[Holaday1185]

I know, hhaha. But I live in Charleston, SC --- we get freezing temps maybe 10 times a year!

[HotZ28]

You should NEVER remove the battery cable when the engine is running. This is no longer a viable way to test alternator output! If you do this, you may destroy the regulator’s computer chip.

[C man]

Yeah taking the negative battery cable off can cause a spike in voltage in the area of 100k for a split second off course you never see it. Also as the weather gets colder the battery power available decreases while the battery power needed increases. So if your battery voltage drops to like 12.2v your car will be hard to start may not start on the first try or take longer. But the battery is probably on its way out. So cooler/colder weather may expose a battery problem more.

[Jrs3800]

Originally Posted by HotZ28

You should NEVER remove the battery cable when the engine is running. This is no longer a viable way to test alternator output! If you do this, you may destroy the regulator’s computer chip.

Agreed... This is the old timer method of checking an alternator, This was from back in the day where cars had nothing for electronics...

Disconnecting the Negative cable while the cat is running can damage not only the alternator but the electronics in the car as well..

NEVER EVER DISCONNECT the NEGATIVE CABLE while the car is running.. This is an absolute No No with any computer controlled car...


Sounds like the Alternator is not producing the voltage/amperage that it should be... May be a good time to have them tested... If the alternator tests bad go a head and replace the battery too if it has more than a few years on it..

[Holaday1185]

Wow. I officially feel like a 6 year old child after being scolded by his/her parent --- sad and defeated. You guys succeeded in making me feel like an idiot. Well, I guess I did deserve it. Fortunately for me nothing major happened to the car as a result of my stupidity. Voltage looked good today to and from work. I also cleaned off the terminals last night which may have helped a bit. I will take everyone's advice and get my battery and alternator checked.

Thanks -

DH

[imidazol97]

Originally Posted by Holaday1185

Wow. I officially feel like a 6 year old child after being scolded by his/her parent --- sad and defeated. You guys succeeded in making me feel like an idiot. Well, I guess I did deserve it. ... I will take everyone's advice and get my battery and alternator checked.

Don't feel bad. Nobody meant to demean you. We just hope to warn you it might cause a problem --AND to warn others not do that to test an alternator.

Have you checked the voltage at the battery terminals with a regular voltmeter if you have one? I'd be interested in seeing if it's the same as your car's meter is reading.

Getting it tested at one of the box stores will let you know what's happening.

good luck.

[C man]

Don't feel bad I did the same thing when my alternator started acting up. But I knew I wasn't suppose to. You could say I was playing russian roulette. I just had to know. It actually took a while before my alternator to start noticable act up. The voltage light would come on for a second and go off after a while and it would do it at diffrent times. Now its on permantly, oh well. Does that happen to you? Seems to just be a battery thing. At first when I would disconnnect it the car wouldn't cut of but eventually it did. Alternator went out around the 130k mark

[Holaday1185]

No, I haven't noticed my voltage light coming on yet. I do have several voltage meters in my classroom so I'll see what I can do. Yeah I have around 116,000 as of current, and I think it's the original alternator. We shall see.