2025 PowerBoost Drawing Power from Trailer Battery

[P.S.N.]

I got currious about how the battery isolator functions on my 2025 F150 PowerBoost Lariat, with tow/hall package. So I hitched up my travel trailer that has a 12V 200Ah Lithium (LiFePO4) battery to see how the seven-pin trailer cord's power wire would function. After trying multiple configurations (engine off, engine on but no EcoBoost, EcoBoost at ideal, EcoBoost at 2,100 RPMs, etc.), when the engine is on, regardless if the EcoBoost is running or not, my PowerBoost was drawing a steady 29W from my trailer's battery. When first put into accessory or start mode, there is an initial surge of 85W of draw from my trailer before it settles down to a consistent 29W draw. I don't like this one bit for I need every amp my trailer battery has for camping.

Since the 2024/2025 PowerBoost does not have a starter/generator (the hybrid system does that job now), is there an equivalent "alternator like system" that provides the traditional 13.7V-14.7V for charging 12V batteries when the engine is running? It does not look like it to me, but if there is maybe mine is not working properly. What do you all think is happening?

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[tsigwing]

My 25 PB certainly provides a charge to my trailer, but I have a LA battery.

 

[P.S.N.]

My 25 PB certainly provides a charge to my trailer, but I have a LA battery.

That is good to know, thank you.

Since lithium batteries are at 13.6V-14.6V, well above a LA or AGM battery, I am think this is why the power is flowing in the wrong direction. Connected batteries like to balance one another.

I was hoping that my PowerBoost's battery isolator was intelligent enough to recognize this and stop the flow. It would be great if the 2025 PowerBoost was intelligent enough to recognize what is happening with a connected trailer and provide the correct voltage to push power to the trailer, but wishing is not fixing.

I think I need to invest in a DC-to-DC charger or disconnect the charge wire within the seven-pin wiring block at the trailer to fix this.

What do you all think I should do to fix the flow of power between my 2025 PowerBoost and my travel trailer?

 

[Davexxxx]

That is odd. Not at all how mine works. I was worried the other way (camper LFPs sucking too much and hurting the truck's charging system) but found it to be a non issue.

I'd have to dig into that and find out if it is functioning as designed, because if it is, thats a boneheaded move on Ford's part.

 

[turbopilot]

What do you all think I should do to fix the flow of power between my 2025 PowerBoost and my travel trailer? Sponsored

Forget the 7 pin, 12 volt feed. The voltage regulation is not going to do much charging your LFP trailer batteries.

You have PPoB 7.2. Just feed the trailer with that feed via an umbilical. I have been doing this since 2021 with my PB.

See this post.

https://www.airforums.com/threads/electric-globetrotter.1420558/post-16019985

 

[tsigwing]

I've got 300w of solar on my roof, because I run my fridge on DC while traveling, and it can use 15A while the truck can only deliver about 10A. When it is rolling down the road with solar, the voltage is 14-15V, trailer battery is what it is, but not more than 13.2V at full charge. Truck voltage is never about 13.2V. I just checked Victron app for its output, and I have a bluetooth battery meter on my truck.

All of that to say, I think you have an issue if your camper is providing power to your truck.

 

[P.S.N.]

I've got 300w of solar on my roof, because I run my fridge on DC while traveling, and it can use 15A while the truck can only deliver about 10A. When it is rolling down the road with solar, the voltage is 14-15V, trailer battery is what it is, but not more than 13.2V at full charge. Truck voltage is never about 13.2V. I just checked Victron app for its output, and I have a bluetooth battery meter on my truck.

All of that to say, I think you have an issue if your camper is providing power to your truck.

Thank you for sharing your thoughts on what may be happening with my rig (truck and trailer).

I too have 382W of solar, but I tend to camp under trees and in cloudy conditions, so solar is not as much help as I would like.

The numbers you provided do not make sense. Do you have a LiFePO4/LFP battery on your trailer and how is your trailer wired with the charge pin?

 

[tsigwing]

I have a LA battery in my trailer. Solar is wired directly to the 7 pin trailer connector charging wire.

 

[Davexxxx]

Solar is wired directly to the 7 pin trailer connector charging wire.

Why?

 

[Buyer2021]

I think I need to invest in a DC-to-DC charger or disconnect the charge wire within the seven-pin wiring block at the trailer to fix this.

This is what I did with my trailer having a 400Ah LiFePO4 battery + 800W nominal solar but no DC/DC charger.

If you install a DC/DC charger, which will prevent trailer>tow vehicle current-flow, be sure to do that in way that does not prevent current-flow from the battery to your breakaway-brakes when the trailer is not connected to the truck. Depending on how your trailer is wired and where you install the DC/DC charger, that may require a new jumper from the battery (or battery-side of the DC/DC charger) to the breakaway-brakes switch stud in your trailer junction box.

I too have 382W of solar, but I tend to camp under trees and in cloudy conditions, so solar is not as much help as I would like.

Understood, but this is about charging when driving, not when parked / camping under trees. If you disconnect the charge wire within the seven-pin wiring block at the trailer, your solar will likely fully-replace the charge you would otherwise get from the truck when towing.

 

[Snakebitten]

Since the 2024/2025 PowerBoost does not have a starter/generator (the hybrid system does that job now), is there an equivalent "alternator like system" that provides the traditional 13.7V-14.7V for charging 12V batteries when the engine is running?

By the way, that starter/generator on the 2021-2023 Powerboost isn't what you might think. It was neither a generator nor an alternator, in the way Ford deployed it on the Powerboost. It was simply a belt drive starter.

Your Powerboost has the exact same low voltage battery charging mechanism as the 2021-2023 Powerboost has.

 

[turbopilot]

Your Powerboost has the exact same low voltage battery charging mechanism as the 2021-2023 Powerboost has.

And the voltage output of the DC/DC converter going to the 7 pin is not generally not enough to charge an LFP battery found in a towable RV. External DC/DC converters expect to see charging from the 7 pin associated with a normal alternator and voltage regulator, so they get confused and will often just shut down.

Bottom line the output from the DC lead on the 7 pin connector found on the PowerBoost is not going to be very helpful charging an LFP battery in a camper.

 

[Buyer2021]

External DC/DC converters expect to see charging from the 7 pin associated with a normal alternator and voltage regulator, so they get confused and will often just shut down.

Just FYI for those interested in going the DC/DC charger route, the Victron Orion XS 12|12 (the "XS" model specifically) should work just fine with the PB.

Among its many features is the ability to configure very precisely the maximum current it will draw from the tow vehicle, helpful to ensure that the trailer battery demand does not overload the tow vehicle charging system or wiring ampacity. Limiting the XS' maximum input current does, of course, limit its maximum output potential.

It does offer proper output charging profiles for all types of trailer batteries including FLA, AGM, and LiFePO4.

 

[Davexxxx]

Just FYI for those interested in going the DC/DC charger route, the Victron Orion XS 12|12 (the "XS" model specifically) should work just fine with the PB.

Among its many features is the ability to configure very precisely the maximum current it will draw from the tow vehicle, helpful to ensure that the trailer battery demand does not overload the tow vehicle charging system or wiring ampacity.

If I didn't have a PB and all else was equal, I'd certainly use a DC to DC charger.

But with 600ahs and 1200W on the roof, coupled with the ease of PPOB, should I need it, don't see the need.

 

[Snakebitten]

It's amazing how many options we have today that didn't exist just a few years ago. I've been RVing for a while and so much has changed regarding keeping the lights on.

The Powerboost is like the safety net for almost any battery based strategy. No matter what strategy I take with batteries, solar, chargers........if I get in a 12V jam, I can just crank up PPOB and fill in the energy gap!

The sheer lack of boondocking anxiety is liberating.

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