12V battery charge

[B177y]

I'm using this tester and I've been testing it at various times throughout the day. I charge about 1x per week, and I don't think I've tested after charging it. I'm charging tonight, so I can check it in the morning. Thanks.

When you use your trickle charger are you attaching it to the jump posts under the passenger side frunk trim or directly to the battery posts at the center-rear of the frunk?

If you attach the charger directly to the battery, you could bypass the BMS and you'll get all sorts of weird 12 volt issues.

You should be using the jumper posts to charge. If you are already doing that, then I agree with the other suggestions that you need to get a load test and possibly new 12 volt battery.

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[RickLightning]

You need to test it 30 minutes, or more, after opening the frunk, and approach without fob or PaaK.

 

[chuck27p]

When you use your trickle charger are you attaching it to the jump posts under the passenger side frunk trim or directly to the battery posts at the center-rear of the frunk?

If you attach the charger directly to the battery, you could bypass the BMS and you'll get all sorts of weird 12 volt issues.

You should be using the jumper posts to charge. If you are already doing that, then I agree with the other suggestions that you need to get a load test and possibly new 12 volt battery.

I am attaching the trickle charger to the battery directly (inside the frunk, center, behind sliding panel). I didn't know there are jump posts. Just looked it up and found it in this video.

I have trickle charged twice to the battery directly. The last one was about a week ago. Should I try again to trickle charge with the jump posts instead? Sounds like it. Thank you for the help.

 

[chuck27p]

You need to test it 30 minutes, or more, after opening the frunk, and approach without fob or PaaK.

I charged last night, it concluded at 3:30 am and when I came out to leave at 8 am I tested the battery while the charging cord was still in. I did not have the fob, but I did have my phone in my pocket. It gave me a 61% reading.

Sounds like I need to do this again and without my phone with me.

 

[RickLightning]

I charged last night, it concluded at 3:30 am and when I came out to leave at 8 am I tested the battery while the charging cord was still in. I did not have the fob, but I did have my phone in my pocket. It gave me a 61% reading.

Sounds like I need to do this again and without my phone with me.

Right.

You need to open the truck, then leave it for 30 minutes or longer and then come back without PaaK or fob, so it doesn't wake up, then hookup your meter.

 

[B177y]

I am attaching the trickle charger to the battery directly (inside the frunk, center, behind sliding panel). I didn't know there are jump posts. Just looked it up and found it in this video.

I have trickle charged twice to the battery directly. The last one was about a week ago. Should I try again to trickle charge with the jump posts instead? Sounds like it. Thank you for the help.

I would:

- Completely disconnect the 12 volt, charge to full as indicated with your charger on the battery posts (preferably with a "real" charger instead of a trickle charger, but use what you got)

- Reinstall 12 volt when full

- Reset BMS from @Tom M post above here

Only charge or jump from the jump posts from now on. If you still have issues after this, get your battery tested.

 

[WXman]

Since CCA's aren't needed, would a deep-cycle marine battery cause any issues with the Lightning?

I was going to ask the same thing. Or even a larger capacity battery. Is there any reason NOT to upgrade the 12V battery to something larger/better?

 

[bmwhitetx]

For charging, it's okay to use spots in the battery compartment as long as the negative is downstream of the BMS. I have a post here on the process. But here's a pic (blue circle OK, red X not OK)

The problem for me with the jump spots under the frunk side cover is there are about 10 clips to undo and they sometimes break.

 

[chuck27p]

For charging, it's okay to use spots in the battery compartment as long as the negative is downstream of the BMS. I have a post here on the process. But here's a pic (blue circle OK, red X not OK)

The problem for me with the jump spots under the frunk side cover is there are about 10 clips to undo and they sometimes break.

That would be more simple for me too. I can try that.

So I need to reset the BMS and then charge the battery using the blue spots in the pic. I'll try that.

 

[RickLightning]

I was going to ask the same thing. Or even a larger capacity battery. Is there any reason NOT to upgrade the 12V battery to something larger/better?

Yes - because the BMS is set for the battery the vehicle comes with.

 

[bmwhitetx]

So I need to reset the BMS and then charge the battery using the blue spots in the pic. I'll try that.

My research indicated you don't need to reset the BMS. The BMS tracks the age of the battery among other things. When you reset it, it tells the truck you have a new battery (see point 3 in the process link I posted above). Whether the truck uses the age for anything, I can't answer.

Ford's Service Manual for the Lightning doesn't even have the tech reset the BMS after battery replacement.

 

[ElectrifyingMe25]

When you use your trickle charger are you attaching it to the jump posts under the passenger side frunk trim or directly to the battery posts at the center-rear of the frunk?

If you attach the charger directly to the battery, you could bypass the BMS and you'll get all sorts of weird 12 volt issues.

You should be using the jumper posts to charge. If you are already doing that, then I agree with the other suggestions that you need to get a load test and possibly new 12 volt battery.

Here is a bit more information concerning your 12V Lightning battery. This info may help you and others:

Question asked:

Does the 12V AGM accessory battery on a F150 Lightning haveva complex or simple Battery monitor in it. Does it have a BMS?

ANSWER:
Searched for "Does Ford F-150 Lightning have BMS on 12V battery"

The 12V AGM accessory battery in the Ford F-150 Lightning uses a complex Battery Management System (BMS), not a simple one. This BMS is a dedicated monitoring sensor (often referred to as the Battery Monitor Sensor) mounted on the battery's negative terminal. It continuously tracks key parameters like state of charge (SOC), voltage, current, temperature, and overall health, while communicating real-time data to the vehicle's Body Control Module (BCM) and DC-DC converter to optimize charging from the high-voltage battery pack.Key Aspects of the BMS:

• Monitoring Capabilities: It performs advanced diagnostics, including learned value tracking (e.g., it "learns" the battery's capacity over time and can detect degradation). If the SOC drops below thresholds (e.g., ~30-50%), it triggers alerts, load-shedding to prevent deep discharge, or blocks over-the-air (OTA) software updates until recharged.
• Charging Integration: The system controls the DC-DC converter's output to maintain the AGM battery at optimal levels (e.g., ~14.6V float charge), preventing sulfation from prolonged low SOC—a common issue in EVs where the 12V battery isn't always actively recharged like in ICE vehicles.
• Reset Procedure: After battery replacement or disconnection, a manual reset is required (e.g., enter accessory mode, flash high beams 5 times, press brake pedal 3 times, confirm via instrument cluster icon). This recalibrates the BMS to avoid false low-SOC readings.
• Known Issues: Ford issued Customer Satisfaction Program 23B70 for 2021-2024 Lightnings, replacing faulty BMS sensors that underreport SOC, leading to erroneous low-battery warnings or failed OTAs despite a healthy battery.

This setup is more sophisticated than a basic voltage sensor (e.g., in older non-AGM vehicles), as it adapts to battery chemistry, supports multiple battery configurations (up to 3 monitors), and integrates with the EV's power management for efficiency and longevity. Aftermarket lithium replacements often include their own internal BMS for compatibility, but swapping to a larger/higher-capacity AGM can confuse the system's algorithms.Yes, it explicitly has a BMS as described above. If you're experiencing issues (e.g., frequent low-SOC alerts), check for the CSP 23B70 eligibility via FordPass or a dealer, and always charge via frunk jump points (downstream of the sensor) to avoid skewing readings.

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