Dead Battery, Advance Auto Says Bad Alternator on 2020

[Superspirit]

Thank you for that info. My subscription renews this mo. Guess it won't.

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[Ursulet3#]

I’ve got a 2020 Ranger XLT and the battery(factory) had drained with the cold weather so it wouldn’t start. Hooked a power pack up and it started. Drove to my local Advance Auto store and they wanted to test the battery/alternator before selling me a new battery. He ran the test and said I have a bad alternator because it’s outputting 15.1v. I have had no other issues indicating a bad alternator but have read some about the way this system charges and it seems occasionally seeing 15.1v might not be an issue. They wouldn’t sell me a battery because he said the alternator is bad and it would just burn up the new battery. Having a real hard time believing this. Does anyone have any additional info on the charging voltage in these trucks or any similar experiences to this? Just trying to figure out if I need to go to the dealership or if I just need to pick up a battery at a different store. Thanks!

I had a problem with an interstate battery. Truck would be fine 90% of the time and then would die. At autozone and advance they both said the battery, starter and alternator we good. I took to interstate and thier tested showed that the battery had a problem. They replaced it and a lot of problems went away. My gas mileage jump up also. Just because a battery "tests" good doesn't mean it's good. Hope this helps.

 

[TJC]

15.1v isn't unusual on these trucks when battery is low. I see that even with my new battery I got a couple months ago.

That is the BMS at work. It is near the higher end of the charge range, but I've seen it on my Ranger when the battery was low. And the BMS intentionally keeps the battery at a less than optimal low charge.

 

[Ranger_Rocks]

I had a problem with an interstate battery. Truck would be fine 90% of the time and then would die. At autozone and advance they both said the battery, starter and alternator we good. I took to interstate and thier tested showed that the battery had a problem. They replaced it and a lot of problems went away. My gas mileage jump up also. Just because a battery "tests" good doesn't mean it's good. Hope this helps.

This happened with our 2019 Santa Fe. Dealer always insists the original battery tests good. Yet ASS quit working 2-3 years ago which they blamed on my "light braking" habits. Then one day I flat got locked out. Installed a new battery from Costco and everything works as new again.

 

[Grandaccess]

15.1 is in range, and can take that in bursts of a few Min. at a time, if you keep that up you will boil away your acid, normal with good battery and alt you should see between 13.2v and 13.8v, my last truck witha 1000CCA deep cycle was always at 14.1v
if the Alt was bad and not putting out you would see less not more because its not working LOL
the brain in your truck may have a sense of humor and seen a tester hooked up and said I am going to screw with this guy

 

[got3fords]

You had to jump start it, drove it fine to the parts store, and they say your alternator is bad. If the alternator was bad, you probably wouldn't have made it to the store.

 

[TJC]

You had to jump start it, drove it fine to the parts store, and they say your alternator is bad. If the alternator was bad, you probably wouldn't have made it to the store.

Yep, esp if the battery is already deeply drained. (like you said)

I had an optima yellow top battery in my 2005 Ranger (back when the were high quality, made in the USA) in excellent condition. Alternator failed 120 miles from my destination on Christmas Eve! I called ahead to a parts store that had the alternator and requested that I was limping in and to hold it. I barely made it there. And I MEAN barely. If I pressed the brakes the engine would convulse. All the dash lights lit up like a Christmas tree 10 miles out. 5 Miles out the dash lights and dash went black. I stopped at the parts store and left the truck running rough, knowing that if I turned it off I would not be turning it back on. Drove another mile to my nephew's home where we replaced the alternator, and jumped the truck. Drove it to my parents home where it went on a charger for the night.

The Optima battery never fully recovered, and was replaced 18 months later.

My 2020 Ranger is an electrical energy hog compared to my 2005 Ranger. I doubt I could have gone even half the distance if this had occurred while driving the 5G Ranger.

Alternators do not work when the battery is dead. As battery voltage drops the alternator stator magnetic field strength fades. When the battery is dead, any residual magnetism in the stator coil windings fades away very quickly. No magnetism, No generated electricity.

 

[got3fords]

Yep, esp if the battery is already deeply drained. (like you said)

I had an optima yellow top battery in my 2005 Ranger (back when the were high quality, made in the USA) in excellent condition. Alternator failed 120 miles from my destination on Christmas Eve! I called ahead to a parts store that had the alternator and requested that I was limping in and to hold it. I barely made it there. And I MEAN barely. If I pressed the brakes the engine would convulse. All the dash lights lit up like a Christmas tree 10 miles out. 5 Miles out the dash lights and dash went black. I stopped at the parts store and left the truck running rough, knowing that if I turned it off I would not be turning it back on. Drove another mile to my nephew's home where we replaced the alternator, and jumped the truck. Drove it to my parents home where it went on a charger for the night.

The Optima battery never fully recovered, and was replaced 18 months later.

My 2020 Ranger is an electrical energy hog compared to my 2005 Ranger. I doubt I could have gone even half the distance if this had occurred while driving the 5G Ranger.

Alternators do not work when the battery is dead. As battery voltage drops the alternator stator magnetic field strength fades. When the battery is dead, any residual magnetism in the stator coil windings fades away very quickly. No magnetism, No generated electricity.

I was once drove from central Va. to southern MD to my buddy's shop so he could rebuild my alternator. I hooked up a 2nd battery in parallel and had jumper cables running from the passenger side to the hood.
BTW, the alternator can keep a vehicle running with a dead or bad battery. And the battery can keep it running with a bad alternator, just not for long.

 

[Frenchy]

I was once drove from central Va. to southern MD to my buddy's shop so he could rebuild my alternator. I hooked up a 2nd battery in parallel and had jumper cables running from the passenger side to the hood.
BTW, the alternator can keep a vehicle running with a dead or bad battery. And the battery can keep it running with a bad alternator, just not for long.

Depends on how dead the battery is and how new the vehicle is. I have seen it where batteries are so dead, that after you jump start them and disconnect the jumper the vehicle shuts off. This is more common on modern vehicles

 

[TJC]

Automakers could easily fix this exposure by using a generator / alternator combo in the same housing. Generator has permanent magnets and feeds a small inverter that powers the alternator, eliminating the need of a battery to keep a car running once started.

The designs have existed for decades. So you add a couple of inches to the existing alternator.

I'd give up a lot of the "sizzle electronics" for the option. Keep your integrated cell phone, blue tooth, flat panel, and split AC controls, and give me functional reliability and redundancy.

 

[TJC]

Depends on how dead the battery is and how new the vehicle is. I have seen it where batteries are so dead, that after you jump start them and disconnect the jumper the vehicle shuts off. This is more common on modern vehicles

By definition, a dead battery is DEAD, and you ain't going nowhere with a "dead" battery (except to the store to purchase a replacement... in your buddy's truck ).

If there is voltage or current, it ain't dead. Once the battery is "DEAD", the car stops.

 

[RangerPNW]

So while mine was never dead, i definitely saw a lot of time spent with ~14.8v going into the battery per my Ford Performance tuner. Finally swapped it out for a fresh one, and quickly saw the voltage levels return to normal. My keyless entry door sensors work again! But now my auto up/down switch for the drivers window isn't doing the auto part, so i'll have to whip the laptop out i think.

One thing i will say tho... Ford did NOT make getting the battery in and out a very easy task, and maybe this is exclusive to the Lariats, but man there are a lot of things connected to the terminals... and naturally i didn't want to take them all off for fear of not getting them back in the correct place. Had to go in and out at an angle, which is not the easiest thing to do with how tall trucks are these days (just ignore the fact that it was me who added the taller tires and leveling kit).

 

[RedlandRanger]

Automakers could easily fix this exposure by using a generator / alternator combo in the same housing. Generator has permanent magnets and feeds a small inverter that powers the alternator, eliminating the need of a battery to keep a car running once started.

The designs have existed for decades. So you add a couple of inches to the existing alternator.

I'd give up a lot of the "sizzle electronics" for the option. Keep your integrated cell phone, blue tooth, flat panel, and split AC controls, and give me functional reliability and redundancy.

Yeah, but that would add fifty cents to every alternator - can't have THAT!!!

 

[Dgc333]

FWIW, I have had a voltmeter on the dash in my 21 Ranger for over 3 years. Can't say I have ever seen 15.1 volts but first start in the morning it is not unusual to be at 15.0. it will drop back down to low/mid 14s pretty quickly. After a long drive it is not unusual to see it at 12.9 volts.

 

[TJC]

FWIW, I have had a voltmeter on the dash in my 21 Ranger for over 3 years. Can't say I have ever seen 15.1 volts but first start in the morning it is not unusual to be at 15.0. it will drop back down to low/mid 14s pretty quickly. After a long drive it is not unusual to see it at 12.9 volts.

That is Ford's eco-BMS at work. I only saw the 15+V when BMS was active, and I was coming to a stop or off throttle. On a freshly charged battery at 100% SOC, I have seen 12.4v charge rate, which is undercharging the battery. I only saw the 15+V when battery SOC was at or below the 70%-75% threshold.

While we are talking about BMS, I do not understand the need for a clutch on the alternator. It is quite easy to vary the alternator output by simply modulating the stator input voltages, lowering the stator field voltages lowers the alternator output voltages, and the parasitic drag from the alternator. Remove all voltage and the alternator is effectively an idler pulley. The clutch seems redundant.

Can someone tell me what I am missing?

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