HYBRID 12V Battery Mystery SOLVED

[Red Eyes - Wide Shut]

Good day

I would like to clarify that I cut one of the wires on the Hitch light itself...not my truck!

Butchering my trucks wiring would go against everything I learned as an RCAF Aircraft technician!

And it would suck for the next owner as well, once I move on to our next vehicle. I wouldn't do it.

Cheers,

Andy

I understood what you meant. Never intended to be taken that way. It is just frustrating all the DIY remedies that we are left with.

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[SafetyGuy]

Thanks, this does help. So, if I follow, I want to be clear:

A) If you do connect the light, and you want to keep the backup lines (and the rear parking/backup sensors, if so equipped), you must cut 3/4 of the wires on the light wiring harness so that it functions only as a running light, not a brake light.

B) This light is only suitable to optimize battery charging if you're OK without the backup camera lines (and the rear parking/backup sensors as well). In this case you won't cut the wires because you need the hitch brake light to function to affect battery charging.

C) Which are the wires to cut?

Okay, check completed on what wire I cut to disable the signal lights...it was the green, and only the green wire.

Cutting the green wire on my hitch light (not truck wiring!) disabled the signal light function as well as the brake light function.

My Hitch light, as a result, only functions as another park light in my use case.

All my sensors and back up assistance is working and when I checked, my truck said "No Trailer Attached".

I then plugged in my 7 pin trailer plug tester (Curt brand)into the 7 pin trailer plug on my truck, and it registers as a trailer being connected, disabling back up assistance and I imagine the backup sensors.

I hope this helps, if you have any more questions you can DM me, or post here as it is all good.

Andy

Edit to add a photo or 2..which i forgot.

 

[SafetyGuy]

I understood what you meant. Never intended to be taken that way. It is just frustrating all the DIY remedies that we are left with.

Absolutely no worries here, I just don't want anyone to misunderstand anything I add when trying to help.

Imagine how we all would feel if we were having issues and we did not have MTC here to pass on info and ask for assistance.

And I am glad you responded, as my post helped someone else out...win-win.

I know these are work arounds that are needed to keep our 12 volt batteries fully charged, but the easiest way is to just click on your park lights or headlights whenever we get in our trucks...and turn them off again when we shut it down.

Till/If Ford (and most auto manufacturers) sort themselves out....I will not be holding my breath, but still hoping.

I don't have any other issues with my 2025 Lariat, we love it as it fits our needs.

I have had other vehicles that/still eat batteries if we aren't careful...our current Ram 3500 camper van will eat its starting battery as well...that is why I have 2 smart chargers...as our previous Crosstrek would as well. Gotta keep them all happy.

Sign of the times, so much advancing tech it is hard to get it all perfect.

Andy

 

[El Kabong]

Okay, check completed on what wire I cut to disable the signal lights...it was the green, and only the green wire.

Cutting the green wire on my hitch light (not truck wiring!) disabled the signal light function as well as the brake light function.

My Hitch light, as a result, only functions as another park light in my use case.

All my sensors and back up assistance is working and when I checked, my truck said "No Trailer Attached".

I then plugged in my 7 pin trailer plug tester (Curt brand)into the 7 pin trailer plug on my truck, and it registers as a trailer being connected, disabling back up assistance and I imagine the backup sensors.

I hope this helps, if you have any more questions you can DM me, or post here as it is all good.

Andy

Edit to add a photo or 2..which i forgot.

Errr... that should only have disabled the right turn blinker?

But this is brilliant. Connecting only the brown wire should do the job.

 

[KenE]

Errr... that should only have disabled the right turn blinker?

But this is brilliant. Connecting only the brown wire should do the job.

Indeed, the green/yellow wires are your right/left turn & brake wires. Brown is running lights, white chassis ground. My question is: for this to work to "trick" the 12v charging, wouldn't the parking or headlights still need to be On to provide power to the Brown wire, so it can draw a small current? Or does the mere presence of the plug attached do the trick without lights being on?

Thanks
Ken

 

[SafetyGuy]

Good day @El Kabong and @KenE

I would like to reassure you that on my truck and 4 pin Hitch light I only needed to cut the green wire (as indicated in the photo I attached), you only need to cut the green wire.

Just the green wire cuts the circuit and both of the signal lights and brake lights are disabled.

As per my test yesterday (I had to interrupt my wife's knitting and ask for assistance) and with two of us I once again confirmed my results.

Also note that I believe doing this disables the hitch lights ability to help keep the 12 volt battery topped up!

I still turn my park lights/headlights on in the daytime to accomplish the battery top up as discovered by Mavster Mechanic.

But, if you insist on purchasing a hitch tail light like mine and want to cut the wires to test for yourself...wait...don't cut anything yet.

Do the test correctly...Plug the light in and test to see if the hitch light helps maintain the battery...once confirmed, report back here on it, and then start snipping one wire at a time to continue your test and stop when you have achieved what my one wire cut accomplished.....signal lighrs and brake lights disabled....come back here and let us know (on 2nd thought, start your own thread on it, so it keeps it easier to find).

You might want to order 2 of these lights, as you may need the 2nd if you don't want to splice the wires back together afterwards, so that it helps keep your 12 volt battery charged.... ;-)

This is the process I followed when I got my light, to test what I wanted to do.

Have a great day,

Andy

 

[MakinDoForNow]

Good day @El Kabong and @KenE

I would like to reassure you that on my truck and 4 pin Hitch light I only needed to cut the green wire (as indicated in the photo I attached), you only need to cut the green wire.

Just the green wire cuts the circuit and both of the signal lights and brake lights are disabled.

As per my test yesterday (I had to interrupt my wife's knitting and ask for assistance) and with two of us I once again confirmed my results.

Also note that I believe doing this disables the hitch lights ability to help keep the 12 volt battery topped up!

I still turn my park lights/headlights on in the daytime to accomplish the battery top up as discovered by Mavster Mechanic.

But, if you insist on purchasing a hitch tail light like mine and want to cut the wires to test for yourself...wait...don't cut anything yet.

Do the test correctly...Plug the light in and test to see if the hitch light helps maintain the battery...once confirmed, report back here on it, and then start snipping one wire at a time to continue your test and stop when you have achieved what my one wire cut accomplished.....signal lighrs and brake lights disabled....come back here and let us know (on 2nd thought, start your own thread on it, so it keeps it easier to find).

You might want to order 2 of these lights, as you may need the 2nd if you don't want to splice the wires back together afterwards, so that it helps keep your 12 volt battery charged.... ;-)

This is the process I followed when I got my light, to test what I wanted to do.

Have a great day,

Andy

It was posted in 22-23 that cutting green brake wire on trailer/device side of circuit caused the computer to think a trailer was not attached resulting in brown wire supplying current for bed lights, etc and trailer attached sensors were not ignored.

 

[Tall Hobbit]

There is a circuit straight to the battery that is not on rest of the 12V circuit.

So the lamps aren't getting 36 A during initial min of being on.

Longer trips may not get it there if starting low enough for SOC%. But start out with a charged battery before a trip - and trip is more likely to keep it there doing the tricks as needed. Well, unless just degraded enough.

This extra charging is no skin off the DCDC convertors teeth. (whatever that means!)
No extra load here.
Your engine is running already for the higher highway speeds - there is some charging of the HVB anyway. And 1-2 A on a 12V system from the 220V system - You bringing a big gulp on the trip is probably adding more strain!

Thanks; I'm having a bit of trouble grasping the upshot, so to restate, would you speculate that The Tricks are of any benefit to me until my SOC reaches a level where the USB adapter readout shows a direct response to the tricks? I'm not worried about saving electricity, extra engine strain etc. of course, but the parking lights aren't good for unlimited hours, plus if it's no help why do it?

 

[Doggtyred]

Watch this video.

12.x volts and discharging to 14.x volts and charging. All I did was manually turn on my headlamps.

What device/hardware/equipment are you using to monitor?

 

[MakinDoForNow]

Thanks; I'm having a bit of trouble grasping the upshot, so to restate, would you speculate that The Tricks are of any benefit to me until my SOC reaches a level where the USB adapter readout shows a direct response to the tricks? I'm not worried about saving electricity, extra engine strain etc. of course, but the parking lights aren't good for unlimited hours, plus if it's no help why do it?

The USB adapter/cig voltage readout is only measuring the buss voltage not what the battery is accepting in its current soc. Plug a smart charger into a voltage/current monitor to observe what it's drawing. Then while watching that monitor take voltage and amp readings across the charger clamps. This will show actual float charging from the charger as what it determines the battery can accept without overheating/etc. When my noco g5 is flashing green in optimization stage it's 120v current flow will pulse from 0-0.9 amps with varying intervals depending on ambient temps and amount of current 12v is accepting of floating voltage offered. The noco will periodically check to replace any loss of soc while it's resting in standby mode.

 

[HeyBales]

Thanks; I'm having a bit of trouble grasping the upshot, so to restate, would you speculate that The Tricks are of any benefit to me until my SOC reaches a level where the USB adapter readout shows a direct response to the tricks? I'm not worried about saving electricity, extra engine strain etc. of course, but the parking lights aren't good for unlimited hours, plus if it's no help why do it?

It's a bummer that Ford's special SOC% isn't directly tied to a resting Voltage - but it seems close enough.

But several have shown that if the battery isn't high enough (is that mid-upper 80's%), The Tricks don't work.

Just guessing that if the system is willing to discharge from 92% to (was it 88%?) before it applied a charge again - it's that lower limit your battery already needs to be at to be taken higher.
And The Trick's didn't seem to do anything special until you hit the 92%, BMS was going to charge up to that anyway. Don't recall postings that were higher than normal float charge until 92% was reached, and The Trick's deployed.

So with only a Volt reading available to try to discern, it seems the following is about all you can decipher.

Morning resting Voltage - hopefully 12.5 or better.
(push button start with no brake which actually connects the HVB, then quickly off again to Accessory only mode - decent enough estimate)

While driving - normal upper 14.x - 15.x V - still charging, may be float level < 1A.
(I've seen the 15.x when colder, 14.x when warmer)
This could take awhile.

While driving - changes to 12.8 V - 92% SOC reached, discharge has started
Geordi engage The Tricks!
Should go back to upper 14.x V.

After doing that for awhile - shows mid 13.x - reached 100% and charging Amps at little to none now.

If corrected I'll correct the above - that's what I recall from the 2-4 testers.

My testing has confirmed when at 50% SOC - none of The Tricks matter.

(ETA: corrected 100% SOC voltage seen. spent some time trying to find the post of the lower limit. Wow - 45 pages now, no wonder I didn't find it!)

 

[Mavster Mechanic]

It's a bummer that Ford's special SOC% isn't directly tied to a resting Voltage - but it seems close enough.

But several have shown that if the battery isn't high enough (is that mid-upper 80's%), The Tricks don't work.

Just guessing that if the system is willing to discharge from 92% to (was it 88%?) before it applied a charge again - it's that lower limit your battery already needs to be at to be taken higher.
And The Trick's didn't seem to do anything special until you hit the 92%, BMS was going to charge up to that anyway. Don't recall postings that were higher than normal float charge until 92% was reached, and The Trick's deployed.

So with only a Volt reading available to try to discern, it seems the following is about all you can decipher.

Morning resting Voltage - hopefully 12.5 or better.
(push button start with no brake which actually connects the HVB, then quickly off again to Accessory only mode - decent enough estimate)

While driving - normal upper 14.x - 15.x V - still charging, may be float level < 1A.
(I've seen the 15.x when colder, 14.x when warmer)
This could take awhile.

While driving - changes to 12.8 V - 92% SOC reached, discharge has started
Geordi engage The Tricks!
Should go back to upper 14.x V.

After doing that for awhile - shows lower 14.x - reached 100% and charging Amps at little to none now.

If corrected I'll correct the above - that's what I recall from the 2-4 testers.

My testing has confirmed when at 50% SOC - none of The Tricks matter.

On a multiple hour drive; once 100% is reached, after some number of minutes voltage went to 13.5v and held there and held 100% SOC till end of drive. Never dropping from 100%. Never dropping into the 12's.
With parking lamps on.

For those contemplating cutting wires
On a hitch light: DON'T do it.
The whole point is for the truck to know the hitch light is there.
If you clip a wire or wires to hide it from
The computer, it defeats the battery charging hack.

 

[Mavster Mechanic]

I am going in for my free recalled trailer module reprogramming July 3rd.

I'll let you know if anything changes.

 

[Tall Hobbit]

The USB adapter/cig voltage readout is only measuring the buss voltage not what the battery is accepting in its current soc. Plug a smart charger into a voltage/current monitor to observe what it's drawing. Then while watching that monitor take voltage and amp readings across the charger clamps. This will show actual float charging from the charger as what it determines the battery can accept without overheating/etc. When my noco g5 is flashing green in optimization stage it's 120v current flow will pulse from 0-0.9 amps with varying intervals depending on ambient temps and amount of current 12v is accepting of floating voltage offered. The noco will periodically check to replace any loss of soc while it's resting in standby mode.

Thanks for the tip. I'll probably get a smart charger, around the same time as the national debt is brought to zero. Really, my time is super divided and my calendar is not my own. But who knows? It's nice to have something to refer back to in a future mythical quiet moment, so thanks again.

 

[Tall Hobbit]

It's a bummer that Ford's special SOC% isn't directly tied to a resting Voltage - but it seems close enough.

But several have shown that if the battery isn't high enough (is that mid-upper 80's%), The Tricks don't work.

Just guessing that if the system is willing to discharge from 92% to (was it 88%?) before it applied a charge again - it's that lower limit your battery already needs to be at to be taken higher.
And The Trick's didn't seem to do anything special until you hit the 92%, BMS was going to charge up to that anyway. Don't recall postings that were higher than normal float charge until 92% was reached, and The Trick's deployed.

So with only a Volt reading available to try to discern, it seems the following is about all you can decipher.

Morning resting Voltage - hopefully 12.5 or better.
(push button start with no brake which actually connects the HVB, then quickly off again to Accessory only mode - decent enough estimate)

While driving - normal upper 14.x - 15.x V - still charging, may be float level < 1A.
(I've seen the 15.x when colder, 14.x when warmer)
This could take awhile.

While driving - changes to 12.8 V - 92% SOC reached, discharge has started
Geordi engage The Tricks!
Should go back to upper 14.x V.

After doing that for awhile - shows mid 13.x - reached 100% and charging Amps at little to none now.

If corrected I'll correct the above - that's what I recall from the 2-4 testers.

My testing has confirmed when at 50% SOC - none of The Tricks matter.

(ETA: corrected 100% SOC voltage seen. spent some time trying to find the post of the lower limit. Wow - 45 pages now, no wonder I didn't find it!)

Thanks; I grasp this better and says about what I guessed. Mornings are 11.9-12.1 now @ cold crank. XL doesn't have push-button start. So it seems the main thing I can to for 12v battery life is combine frequently whipping the horses on long journeys in this economy truck, simultaneously using The Tricks. I'm not likely to do the former often enough to satisfy anyone, which makes the latter pointless. Hopefully Ford will be buying me 12v replacements until they eventually reprogram the DC/DC recharging.

This is becoming just another version of the 'you're not driving it enough' excuse that gets customers to go away.

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