Trailer battery charging
Thread Starter
|
Fleet Mechanic
Joined: May 2011
Posts: 1,866
Likes: 84
From: Rainier OR
2018 F450 Platinum
Lead Driver
Joined: Jun 2005
Posts: 8,475
Likes: 728
From: Calgary Canada
There's all sorts of "smarts" in these trucks that mean the trailer doesn't charge all the time. I don't know all the scenarios, but I ***THINK*** that if you put the parking brake on the truck, and let it idle in drive, it ***SHOULD*** send current to charge that battery. That replacates the "going down the road" condition where the batteries would normally be charging. Maybe you have to have the drivers door closed too, I'm not sure.
Cargo Master
Joined: Sep 2013
Posts: 3,264
Likes: 1,330
From: Pryor, OK
There's all sorts of "smarts" in these trucks that mean the trailer doesn't charge all the time. I don't know all the scenarios, but I ***THINK*** that if you put the parking brake on the truck, and let it idle in drive, it ***SHOULD*** send current to charge that battery. That replacates the "going down the road" condition where the batteries would normally be charging. Maybe you have to have the drivers door closed too, I'm not sure.
Lead Driver
Joined: Jun 2005
Posts: 8,475
Likes: 728
From: Calgary Canada
On my travel trailer, I consider the truck-to-trailer connection enough to maintain a full battery, but I always plan to have the travel trailer hooked up to 120V shore power overnight before and after each trip, and if I can't, I use my generator to charge it up ever 2-3 days.
Thread Starter
|
Fleet Mechanic
Joined: May 2011
Posts: 1,866
Likes: 84
From: Rainier OR
There's all sorts of "smarts" in these trucks that mean the trailer doesn't charge all the time. I don't know all the scenarios, but I ***THINK*** that if you put the parking brake on the truck, and let it idle in drive, it ***SHOULD*** send current to charge that battery. That replacates the "going down the road" condition where the batteries would normally be charging. Maybe you have to have the drivers door closed too, I'm not sure.
The last tests where all done while stopped and it did charge while sitting, in park, engine running, and like posted, only if the door was closed and the keyless start key fob was in the truck, and the trailer batter voltage dropped below 12 volts to get the charge circuit started.
what SEEMS to be what gets my system working is voltage at the trailer battery low enough to get the system running fully. I am not sure where that voltage is yet.
So far for me seeing what keeps the system from working make a big difference on how to trouble shoot.
.
Thread Starter
|
Fleet Mechanic
Joined: May 2011
Posts: 1,866
Likes: 84
From: Rainier OR
Wanted to update this.
I got a chance to hook up to my camper recently and moved the Bluetooth volt meter to it. The trucks charge system seems to work much better with the camper batteries, they would start charging as soon as the truck was started and my foot was on the brakes. Thr voltage got up to over 14.8 volts. After that the voltage stayed around 12.8 volts. I ACTED like there are two stages, a charge state that went to around 15 volts and a float stage that stayed under 13 volts. If this is the case it would explain the odd behavior of the charging of my dump trailer. I think it has a bad battery, I have not load tested it but the voltage dropped way down when it was running the pump, but showed unloaded voltage off a fully charged battery. My thought is that if the battery is showing good unloaded voltage the truck charge circuit will go to "float" charge and keep the voltage below 13 volts. It the battery is showing discharged voltage the trucks charging system goes into charge mode and go up to 15 volts to charge the battery. It is still too early to tell for sure if this is the case but right now it looks like what is happening.
I got a chance to hook up to my camper recently and moved the Bluetooth volt meter to it. The trucks charge system seems to work much better with the camper batteries, they would start charging as soon as the truck was started and my foot was on the brakes. Thr voltage got up to over 14.8 volts. After that the voltage stayed around 12.8 volts. I ACTED like there are two stages, a charge state that went to around 15 volts and a float stage that stayed under 13 volts. If this is the case it would explain the odd behavior of the charging of my dump trailer. I think it has a bad battery, I have not load tested it but the voltage dropped way down when it was running the pump, but showed unloaded voltage off a fully charged battery. My thought is that if the battery is showing good unloaded voltage the truck charge circuit will go to "float" charge and keep the voltage below 13 volts. It the battery is showing discharged voltage the trucks charging system goes into charge mode and go up to 15 volts to charge the battery. It is still too early to tell for sure if this is the case but right now it looks like what is happening.
Tuned
Joined: Aug 2020
Posts: 314
Likes: 90
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
New User
Joined: Jan 2021
Posts: 10
Likes: 2
If you hooked up a DC to DC charger in the trailer, did you also run heavier gauge wires from the Engine Battery B+ back to the bumper of the truck?
I have a trailer that has 340W solar and 4 AGM's, but I'm upgrading to LiFePo and was thinking this upgrade.
I'm towing with an F350 6.7L Diesel with a 397 AMP (total) dual alternator system.
(First : Separate the 7 pin charging circuit from the main trailer battery charging for the reasons you mentioned.)
NEW Circuit:
1) Run a fused B+ and Ground from engine bay to back bumper connected to Anderson Connector. (Appropriate gauge for the 50AMP load)
2) On trailer, run higher gauge wires + and GND with Anderson mating Connector back through to the Trailer Batteries area.
3) Near those batteries install a Redarc DC/DC 50 Amp Charger which is connected to the new B+ from truck.
My assumption is this will properly isolate the LiFePo's in a way that they don't pull huge amperage from the Dual Alternators in the F350.
What I don't know is if I need to put a battery isolation solenoid or relay in that circuit up in the engine bay, or if I should just directly connect a fused link to the B+ / GND of the Engine Batteries.
I have a trailer that has 340W solar and 4 AGM's, but I'm upgrading to LiFePo and was thinking this upgrade.
I'm towing with an F350 6.7L Diesel with a 397 AMP (total) dual alternator system.
(First : Separate the 7 pin charging circuit from the main trailer battery charging for the reasons you mentioned.)
NEW Circuit:
1) Run a fused B+ and Ground from engine bay to back bumper connected to Anderson Connector. (Appropriate gauge for the 50AMP load)
2) On trailer, run higher gauge wires + and GND with Anderson mating Connector back through to the Trailer Batteries area.
3) Near those batteries install a Redarc DC/DC 50 Amp Charger which is connected to the new B+ from truck.
My assumption is this will properly isolate the LiFePo's in a way that they don't pull huge amperage from the Dual Alternators in the F350.
What I don't know is if I need to put a battery isolation solenoid or relay in that circuit up in the engine bay, or if I should just directly connect a fused link to the B+ / GND of the Engine Batteries.
Thread
Thread Starter
Forum
Replies
Last Post