Sponsored

12V battery charge

chuck27p

Well-known member
First Name
Chuck
Joined
Mar 28, 2023
Threads
4
Messages
53
Reaction score
60
Location
Orange County, CA
Vehicles
F150 Lightning Platinum Black
I've had my truck for a few years and haven't had a problem, but my 12v battery is testing in the 30% range each morning. I've used a trickle charger for two nights, which went from red to green light, and then the tester told me the battery was good and back to 100%. But a day later, in the morning before I have driven it, it's back down to 25-30%. It seems to charge during the day as I drive.

Is my battery shot? Do I need a new one? I don't want to get stranded. Or is it normal for it to be so low after sitting all night and then charge during the day.

I'm wondering if I should preemptively put in a new battery or if mine is still ok? It's a 2023, so it's almost 2 years old.

Thanks.
Sponsored

 

TaxmanHog

Moderator
Moderator
First Name
Noel
Joined
Jan 19, 2022
Threads
207
Messages
15,238
Reaction score
16,922
Location
SE. Mass.
Vehicles
2022 Lightning Lariat-ER & 2024 HD Road Glide CVO-ST
Occupation
Retired
Trickle chargers aren't the best tool to diagnose a LVB capacity issues

If it's suspect have a comprehensive load test done on it at the Ford Service shop, if they find it's below spec, you might get a warranty swap.
 

RLXXI

Well-known member
Joined
Jun 10, 2021
Threads
22
Messages
861
Reaction score
661
Location
S. E. Louisiana
Vehicles
2025 F 150 Flash, 2013 F 150 XLT, 2014 Escape, 2011 Suzuki DR 650SE
Occupation
Auto tech
I've had my truck for a few years and haven't had a problem, but my 12v battery is testing in the 30% range each morning. I've used a trickle charger for two nights, which went from red to green light, and then the tester told me the battery was good and back to 100%. But a day later, in the morning before I have driven it, it's back down to 25-30%. It seems to charge during the day as I drive.

Is my battery shot? Do I need a new one? I don't want to get stranded. Or is it normal for it to be so low after sitting all night and then charge during the day.

I'm wondering if I should preemptively put in a new battery or if mine is still ok? It's a 2023, so it's almost 2 years old.

Thanks.
SLA batteries, including AGM type, are a crap shoot when they go bad. There's no way to know if and/or when it might happen. If you're getting readings like that and you know for a fact your measuring equipment is calibrated properly, I'd replace it to be safe.

I've had them last more than a decade and I've had them give up the ghost at 9 months of age in my own personal vehicles as well as customers.

Considering my career in automotive repair, I keep certain tools available for such things. You can always go to your local auto part store and let them load test it, which is the ONLY true way to determine a batteries health when they don't have built in diagnostics (BMS).

This is what I've used personally and professionally for decades. https://amazon.com/dp/B000AMBOI0?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_9
 
Last edited:

ElectrifyingMe25

Well-known member
First Name
Trav
Joined
Jul 31, 2025
Threads
4
Messages
50
Reaction score
47
Vehicles
F150 Lightning
Occupation
Engineer
I've had my truck for a few years and haven't had a problem, but my 12v battery is testing in the 30% range each morning. I've used a trickle charger for two nights, which went from red to green light, and then the tester told me the battery was good and back to 100%. But a day later, in the morning before I have driven it, it's back down to 25-30%. It seems to charge during the day as I drive.

Is my battery shot? Do I need a new one? I don't want to get stranded. Or is it normal for it to be so low after sitting all night and then charge during the day.

I'm wondering if I should preemptively put in a new battery or if mine is still ok? It's a 2023, so it's almost 2 years old.

Thanks.
Rockauto for a replacement.

Ford F-150 Lightning 12V battery charge Screenshot_20250923_211107_DuckDuckGo
 

Mal106

Well-known member
First Name
Mal
Joined
May 9, 2025
Threads
2
Messages
90
Reaction score
79
Location
SW VA
Vehicles
2025 Lightning Flash
Occupation
Retired Pilot
The acessory mode, the app and the key fob kill those little 12v batteries.

I can't think of a reason for the acessory mode in an electric or plug in hybred vehicle. It eats the small 12v battery quickly and can damage it through regular discharging. Batteries are small due to not needing start amperage and are already stressed with communications with the app and key fob. I ran the Lightning battery down using acessory mode and the app and killed a PHEV 12v the same way.

As I understand it, the little battery is charged when the truck is on or being charged. If plugged in and charging complete, I don't know.

I've stopped using the acessory mode and store the fob well away from the truck when not in use.
 

Sponsored

Maquis

Well-known member
First Name
Dave
Joined
May 20, 2021
Threads
9
Messages
4,054
Reaction score
5,313
Location
Illinois
Vehicles
2021 Mach-E E4-X; 2023 Lightning Lariat ER
The acessory mode, the app and the key fob kill those little 12v batteries.

I can't think of a reason for the acessory mode in an electric or plug in hybred vehicle. It eats the small 12v battery quickly and can damage it through regular discharging. Batteries are small due to not needing start amperage and are already stressed with communications with the app and key fob. I ran the Lightning battery down using acessory mode and the app and killed a PHEV 12v the same way.

As I understand it, the little battery is charged when the truck is on or being charged. If plugged in and charging complete, I don't know.

I've stopped using the acessory mode and store the fob well away from the truck when not in use.
Agree 100% regarding accessory mode.

Key fob / phone is only an issue if you are constantly moving in and out of range.
 
OP
OP
chuck27p

chuck27p

Well-known member
First Name
Chuck
Joined
Mar 28, 2023
Threads
4
Messages
53
Reaction score
60
Location
Orange County, CA
Vehicles
F150 Lightning Platinum Black
The acessory mode, the app and the key fob kill those little 12v batteries.

I can't think of a reason for the acessory mode in an electric or plug in hybred vehicle. It eats the small 12v battery quickly and can damage it through regular discharging. Batteries are small due to not needing start amperage and are already stressed with communications with the app and key fob. I ran the Lightning battery down using acessory mode and the app and killed a PHEV 12v the same way.

As I understand it, the little battery is charged when the truck is on or being charged. If plugged in and charging complete, I don't know.

I've stopped using the acessory mode and store the fob well away from the truck when not in use.
I don't use accessory mode much at all. I have in the past, maybe sitting waiting in the truck, camping, or charging, but on a regular basis I do not. Just park it, then drive it.

Maybe earlier usage diminished the battery?

What I'm getting from these responses is I should go replace the battery before I get stuck, and there's no way to know if/when that's going to happen.

Does the dealer have to do it? Is there some reprogramming after, or can I swap it out?
 

astrand1

Well-known member
First Name
Alex
Joined
Dec 16, 2021
Threads
8
Messages
576
Reaction score
559
Location
Michigan
Vehicles
2023 Ford F150 Lightning lariat ER
Occupation
Studio truck driver
I don't use accessory mode much at all. I have in the past, maybe sitting waiting in the truck, camping, or charging, but on a regular basis I do not. Just park it, then drive it.

Maybe earlier usage diminished the battery?

What I'm getting from these responses is I should go replace the battery before I get stuck, and there's no way to know if/when that's going to happen.

Does the dealer have to do it? Is there some reprogramming after, or can I swap it out?
Nope. You can easily do it yourself. It’s just like changing a battery in a normal car. Once done you do need to reset the BMS.
 

Mal106

Well-known member
First Name
Mal
Joined
May 9, 2025
Threads
2
Messages
90
Reaction score
79
Location
SW VA
Vehicles
2025 Lightning Flash
Occupation
Retired Pilot
Make sure you carry one of those little jump boxes. A very small (cheap) one will do as it takes very little current to start the truck with a weak battery.
 

Sponsored

ElectrifyingMe25

Well-known member
First Name
Trav
Joined
Jul 31, 2025
Threads
4
Messages
50
Reaction score
47
Vehicles
F150 Lightning
Occupation
Engineer
Make sure you carry one of those little jump boxes. A very small (cheap) one will do as it takes very little current to start the truck with a weak battery.
You are 100% correct. A little jump box goes a long way. I got stranded on the road one night because of an accident. I was driving an Explorer (ICE). I rand the radio, so I turned on the accessories mode. God only knows what else was running. I guess my battery must have been a little weak. I only ran it for 10 minutes or so. Luckily I tried to start the vehicle before traffic started moving. I got the dreaded "click, click, click" sound.

I didn't have one of those Li-Ion jump boxes. I was dead on the road in a construction zone with one-lane traffic. I was soon to be the cause of backed up and stopped traffic on the interstate. It was now a race to get me jumped vs. the accident clearing ahead of me.

No one around me had jumper cables. Luckily I had a friend who lived 5 miles away who brought an old battery and some jumper cables. He dropped off both next to me in the other lane that was also under construction and one-lane. I got started thanks to his generosity and decent luck. ... the accident was cleared 10 minutes later.

I felt so blessed to get going before traffic started moving.

The next day, I ordered the lithium-ion jump boxes for all my vehicles. And my neighbor friend. The are so worth the cost. I ordered Vtoman from Amazon like the one in the picture. Is a good quality jump starter.

I've used them a couple of times so far in the cold cold winter to get me going. I've never used it on my Lightning Truck. But if I need it I have it there.

Trust me, you don't want to get into the predicament I got into on the interstate that night. The small investment is great insurance.

Ford F-150 Lightning 12V battery charge Screenshot_20251005_174052_Amazon Shopping
 

RLXXI

Well-known member
Joined
Jun 10, 2021
Threads
22
Messages
861
Reaction score
661
Location
S. E. Louisiana
Vehicles
2025 F 150 Flash, 2013 F 150 XLT, 2014 Escape, 2011 Suzuki DR 650SE
Occupation
Auto tech
You are 100% correct. A little jump box goes a long way. I got stranded on the road one night because of an accident. I was driving an Explorer (ICE). I rand the radio, so I turned on the accessories mode. God only knows what else was running. I guess my battery must have been a little weak. I only ran it for 10 minutes or so. Luckily I tried to start the vehicle before traffic started moving. I got the dreaded "click, click, click" sound.

I didn't have one of those Li-Ion jump boxes. I was dead on the road in a construction zone with one-lane traffic. I was soon to be the cause of backed up and stopped traffic on the interstate. It was now a race to get me jumped vs. the accident clearing ahead of me.

No one around me had jumper cables. Luckily I had a friend who lived 5 miles away who brought an old battery and some jumper cables. He dropped off both next to me in the other lane that was also under construction and one-lane. I got started thanks to his generosity and decent luck. ... the accident was cleared 10 minutes later.

I felt so blessed to get going before traffic started moving.

The next day, I ordered the lithium-ion jump boxes for all my vehicles. And my neighbor friend. The are so worth the cost. I ordered Vtoman from Amazon like the one in the picture. Is a good quality jump starter.

I've used them a couple of times so far in the cold cold winter to get me going. I've never used it on my Lightning Truck. But if I need it I have it there.

Trust me, you don't want to get into the predicament I got into on the interstate that night. The small investment is great insurance.

Screenshot_20251005_174052_Amazon Shopping.webp
I keep one like it in my console just in case. Originally bought it when my z turn battery started going bad. It would run the entire time but shut it off and let it sit a day, click. Built in usb charging ports and a light.
Sponsored

 
 







Top