Alternator or battery?

[matthewr87]

Today I noticed the car having trouble cranking over. The voltage readout in the center screen while driving was between 12.1 to 12.9V with occasional spikes to 14.5V. If the car is on and the alternator is working, shouldn't the voltage be in the 14.5V range constantly if the battery is low?

Battery is a 6 year old Motorcraft with 470 CCA that the dealership installed when I bought the car new in April 2019.

I keep it on a tender when the car sits for more than a week or so.

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[_zOmbIE_]

Normally I'd say that's the alternator, but in this case I'd say it's more likely the battery just due to age.

Take it in to an autozone or something and they should be able to test the battery for you.

 

[dirtwarrior]

Crank it over. While running remove negative battery cable. If alternator is good it will stay running

 

[The Chairman]

I kept my 2016 GT350 on a tender and it lasted 6.5 years before a no start.
Dropped in a new 696 CCA from Batteries Plus and all is well.
My GT500 battery is now 5.5 years old and on a tender. Wonder how long it will last…

 

[honeybadger]

Def sounds like a battery issue to me. The car will throw codes once the alternator starts going out.

 

[Racer5973]

Today I noticed the car having trouble cranking over. The voltage readout in the center screen while driving was between 12.1 to 12.9V with occasional spikes to 14.5V. If the car is on and the alternator is working, shouldn't the voltage be in the 14.5V range constantly if the battery is low?

Battery is a 6 year old Motorcraft with 470 CCA that the dealership installed when I bought the car new in April 2019.

I keep it on a tender when the car sits for more than a week or so.

Sounds like the battery has a bad cell.

 

[MidnightStars]

I agree with the others. With age, the battery will lose capacity after cycling. The readout pretty much confirms the battery is as charged up as it can go.

 

[Scuba]

Occasional 14.5v spikes - did you check the terminal connections?

 

[Shelby2017]

Also have a GT350 (2017) of about the same age and just replaced first battery as well, so most likely it's the age of the battery.

 

[lunatect]

Get a new battery. I am blown away that your battery lasted that long!

 

[FUN2RIDEFAST]

Today I noticed the car having trouble cranking over. The voltage readout in the center screen while driving was between 12.1 to 12.9V with occasional spikes to 14.5V. If the car is on and the alternator is working, shouldn't the voltage be in the 14.5V range constantly if the battery is low?

Battery is a 6 year old Motorcraft with 470 CCA that the dealership installed when I bought the car new in April 2019.

I keep it on a tender when the car sits for more than a week or so.

I

Today I noticed the car having trouble cranking over. The voltage readout in the center screen while driving was between 12.1 to 12.9V with occasional spikes to 14.5V. If the car is on and the alternator is working, shouldn't the voltage be in the 14.5V range constantly if the battery is low?

Battery is a 6 year old Motorcraft with 470 CCA that the dealership installed when I bought the car new in April 2019.

I keep it on a tender when the car sits for more than a week or so.

If the battery is six years old that's most likely the issue. If you have a volt meter just start the car and measure the voltage coming out of the alternator by attaching the meter to the battery terminals. It should be putting out 14 volts. You can put the a/c and it should still be 14. I'd just about bet it's the battery. In six years I'm usually looking at a third battery for that time span. Three years is about it in my experience.

 

[Garfy]

Crank it over. While running remove negative battery cable. If alternator is good it will stay running

Definitely NOT a good idea. The instant you disconnect the cable, the system voltage will spike to who knows what level before the regulator can drop the voltage. That spike can kill modules unless they have some kind of overvoltage protection (which most do not). Back in the non-electronic age (like my old '71 Mustang) it wouldn't harm anything. I wouldn't do it on any modern car. That's what DVOMs are for.

 

[NightmareMoon]

I its normal for voltage to fluctuate while running. It wont hold 14.x and thats normal.

If its too low while cranking, I’d suspect the battery first and at that age, its worth replacing even if its good so it doesnt leave you high and dry later.

 

[matthewr87]

Thanks guys. Just picked up a new battery. This is the first time I've ever had to change the battery on a car. I've never owned any other car long enough to necessitate a swap

Should I charge the new battery before install?

Also, is there a trick to remove the cables from the battery terminal? I've loosened the nut but still can't remove the cable. There is no obvious corrosion. Videos make it look very easy online.

Never mind. Looks like the dealership tech who installed the battery when I took delivery didn't loosen the nut enough and just hammered the clamp down on the negative battery terminal. It had dug into the metal of the terminal, which made it difficult to remove......

Positive came off easy afterwards.

 

[TonyT930]

Today I noticed the car having trouble cranking over. The voltage readout in the center screen while driving was between 12.1 to 12.9V with occasional spikes to 14.5V. If the car is on and the alternator is working, shouldn't the voltage be in the 14.5V range constantly if the battery is low?

Battery is a 6 year old Motorcraft with 470 CCA that the dealership installed when I bought the car new in April 2019.

I keep it on a tender when the car sits for more than a week or so.

Check to see if your battery terminals, cables, and grounds are tight and clean first.

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