Is My Battery Going Out?

[Stangfan6818]

I have a 2018 GT which is occasionally driven. If it is not used within a 3 week period, I will put a charger on it for 4 hours to keep it fresh. The other day it was reluctant to start, although it did. The next day when I put the charger on, the charger meter dropped to almost 4. Usually it goes to 2. I left the charger on for just over 6 hours and the meter was almost up to full charge. Today I went for a drive and it started up perfectly, but I noticed that the volt gauge was reading 13 instead of just above 14. As I was driving I saw that the needle was fluctuating between 12 ad 14. I suspect that it is time for a new battery. The 6 hour charge was yesterday. Any thoughts?

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[MiamiGT350]

Put the car in accessory mode (don't start the ignition) and if you have voltage output on your dash, you can see:

 

[MAGS1]

What Miami said. If you turn the car on, the voltage reading will be from the alternator so you won’t get a true reading on the battery itself. Your local auto parts store can do a battery test for you too. Sounds to me like your battery might be going, especially if it’s the original battery on a 6 year old car.

My wife’s SUV battery just died two weeks ago. Luckily the battery was still under warranty so it was free. GM makes it dang near impossible to change yourself too. Sorry a little off topic there.

 

[ice445]

Smart charging algorithm does that, it will run the alternator at different states depending on load and battery charge. From what I've seen it won't really kick on fully until the battery is over 80% so you're probably fine.

 

[#1ford]

Is that the original battery? If so you have done well. Time for a new battery in my opinion

 

[Skye]

Agree with others, it's time for a new battery after six years.

When you do replace it, perform a Battery Management System (BMS) reset, so the car knows it's new.

https://www.mustang6g.com/forums/threads/bms-reset-no-tools-required.151602/

In my DDs, I change the battery every five years, no matter how they seem. YMMV.

If you don't drive the car often, you can also consider a battery tender, wiring it to the car for easy use.

https://www.mustang6g.com/forums/threads/installing-battery-tenders.73725/

https://www.batterytender.com/?gad_...MInrL2ofaDhgMVZzWtBh0n9QZPEAAYAiAAEgKklvD_BwE

https://accessories.ford.com/ford-performance-5-0-smart-battery-charger-maintainer

 

[ORRadtech]

Put the car in accessory mode (don't start the ignition) and if you have voltage output on your dash, you can see:

A somewhat more accurate way to measure battery condition using voltage is to use a DVOM directly on the battery terminals.
After turning the car off turn the headlights on for 15 or 20 seconds to remove the surface charge. Then measure the voltage at the battery terminals. You can use the chart above to get an approximate state of charge.
A hygrometer will also give you a state of charge but if you have a permanently sealed battery that won't help.

Also, you can buy small, hand-held battery testers that are reasonably accurate. I bought mine off Amazon for under $40 and it's been very handy in identifying or eliminating the battery when troubleshooting.

 

[Stangfan6818]

Thanks for the feedback. I will take the battery out for testing, but I believe it is time...

 

[Stangfan6818]

Agree with others, it's time for a new battery after six years.

When you do replace it, perform a Battery Management System (BMS) reset, so the car knows it's new.

https://www.mustang6g.com/forums/threads/bms-reset-no-tools-required.151602/

In my DDs, I change the battery every five years, no matter how they seem. YMMV.

If you don't drive the car often, you can also consider a battery tender, wiring it to the car for easy use.

https://www.mustang6g.com/forums/threads/installing-battery-tenders.73725/

't see the b

https://accessories.ford.com/ford-performance-5-0-smart-battery-charger-maintainer

I followed your BMS reset instructions, but I didn't see the battery indicator flash? Should I repeat?

 

[Skye]

I followed your BMS reset instructions, but I didn't see the battery indicator flash? Should I repeat?

I'd give it another shot.

When I first attempted the reset, like twice, I couldn't get the correct result.

I took a break, re-read the instructions.

That's when I noticed, "Procedure must be carried out in 10 seconds." The first line. In bold. LOL.

I tried again and got a "pass" result.

 

[Stangfan6818]

Thank you!!

 

[Stangfan6818]

I'd give it another shot.

When I first attempted the reset, like twice, I couldn't get the correct result.

I took a break, re-read the instructions.

That's when I noticed, "Procedure must be carried out in 10 seconds." The first line. In bold. LOL.

I tried again and got a "pass" result.

OK, BMS is happy now. Thanks for the clarification.

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