Battery Charging Issue

[dablackgoku1234]

Lately, I've been noticing my volt meter on the car is barely reading 14v with the car at idle. When cruising on the highway, it would read slightly over 14v. However, in stop and go traffic, the needle is just under 14v.

Also, noticed when I roll the windows up, the voltage drops to 13v and the engine idle drops slightly from 750-800 down to 600 causing it to vibrate.

When the car off, the battery voltage is slightly over 12v and the car starts everytime. Is this an alternator issue or a ground issue?

 

[ftuhy]

Voltage dropping when RPM dropping to 600 rpm is reasonable. Is your AC also on at the time this happens? If so, its more likely the engine managment is not keeping the RPM up under load. I'd clean the intake air passages and idle speed air adjuster (not near my manual and forgot the exact name it uses).

Quick battery test to tell if its getting fully charged: after the car has sat a few hours, engine off, in a dark spot so you can see the headlights shining on a wall. Turn on the headlights, then crank the engine. If the headlights only dim slightly during cranking, your battery is healthy and battery cables connections are good. In general that would also mean the alternator is charging to the proper voltage, but there's a small possibility the alternator might not be able to deliver the full amperage.

 

[dablackgoku1234]

It's almost like because I am rolling up my windows, the voltage drops and causes the engine RPMs to drop. When I release rolling up the windows, the RPMs go back to normal. This happens with and without the AC being on.

I will do a quick battery test to confirm it's not the battery.

 

[JD Cross]

The first question is what month and year did you install the battery?
The second question is have you ever run the battery dead?
Third with the engine off and using a multimeter what voltage does the battery show?
Fourth, with the engine running and using the same multimeter, what voltage does the battery show?
The answers will help determine if you need a new battery,new alternator, or nothing?

 

[ftuhy]

The first question requires knowledge of a lot of operating condition information. The previous OEM battery lasted 10 years / 35,000 miles in my NSX. But I don't drive in heavy traffic where battery temps can go very high. And that battery was run too low once at about 2 years of age when I forgot to connect the float charger during the winter.

I wanted to start with a very simple test before digging out the voltmeter.
But, +1 on using a multimeter. The meter in the car is not very accurate.
Also measure the voltage during cranking the engine. That tells a lot about the battery health.

The first question is what month and year did you install the battery?
The second question is have you ever run the battery dead?
Third with the engine off and using a multimeter what voltage does the battery show?
Fourth, with the engine running and using the same multimeter, what voltage does the battery show?
The answers will help determine if you need a new battery,new alternator, or nothing?

 

[JD Cross]

Dablackgoku1234
Any news on your electrics?