Would Ignition Voltage indicate the condition of the alternator?

[BlackGS]

Just curious. I have had some battery issues lately (losing charge overnight), and I want to make sure the alternator is working to spec. So, I started scanning Ignition Voltage and saw that it reads in the range of 13.7-14.4 while driving. That would seem to me that the alternator is putting out a good charge, right?

[oakleafresin]

Yeah those are good numbers. As the temperature goes up, voltage output goes down. I see right around 14.5 on a cold start

[Google]

keep in mind the alt has volts and amps... volts can show good... but amps can be too low.. this can cause problems.. it's is a good idea to have an amp test to see if it is ok as well..

[passingpower]

My GTP was showing the same numbers a month ago. Wouldn't hold a charge more than two days after a jump start. In the end, it was the cheap battery I installed last year. Replaced it with something good made by Johnson Controls this time. Read this: batteryfaq.org

Go to a reputable parts store and have a load test done. Usually free. You shouldn't need to pay more than $110 or so for ur replacement.

[WaterDog]

Bob,
Mine did the same. Thought it was the 1 year old Alternator or bad ground.
Was reading 13.7+ . Turned out to be the $200 yellow top Optima battery that was 4 years old (Full replacement was 3 yrs!) Been reading about how alot of people have commented on them not lasting like they used to. Bought a Bosch Premium from Pep Boys w/36 mo. replacement for $80, after using $15 Discount Card they have at the register. It's PB's version of the Bosch S5 series battery, CCA 850, CA 1000. More cranking power and $120 less. Never started so well....
Part# 78DT-850B
SKU- 9872822
In stores, not on web site.

[BlackGS]

Thanks for the replies.

The battery is a Die Hard Gold and is one year old. As long as I run the car, the battery seems ok. When it sits overnight in the cold, the battery is either weak or dead in the morning. If I give it a quick charge, it works fine for the day. I'm thinking it is a bad battery at this point, and I will return it to Sears for a replacement.

Charles, I hear you about those Optimas. I went through a yellow top and a red top in my truck, and they were both crap. They were constantly drained after the truck would sit for a few days. I replaced with a Die Hard, and that has been a strong battery for the last 5 or 6 years now.

[TGP-37]

A bad negative cable to the battery can mimic a dying battery. I had a bad negative cable once and these were the symptoms.

Hard/slow cranking start
runs rough for the first few seconds

then all is fine until it is shut down, then it acts like the battery is dead. Turn the key and click, nothing. Wait a few minutes and the power comes back up. Wait another few hours until it started again.

It also made charging difficult and did eventually kill the battery. Apparently the break was slim enough to allow enough to start the car but once the contacts got hot it went down hill which effected the cars ability to recharge what was used to start the engine.

I determined that by attaching a jumper to the negative terminal on the Battery and then the ground of the car. All symptoms went away.